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1
Powell, Charles A., i Youjian Lin. "Separation of Citrus Tristeza Virus Isolates in Mixed Infections through Transfer by Single Brown Citrus Aphids". HortScience 40, nr 3 (czerwiec 2005): 694–96. http://dx.doi.org/10.21273/hortsci.40.3.694.
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One hundred single brown citrus aphid (BCA) (Toxoptera citricida Kirkaldy) transmission attempts were made from each of 16 different citrus trees [8 grapefruit (Citrus paradisi Macf.) and 8 sweet orange (C. sinensis (L.) Osbeck)] previously inoculated with decline-inducing (T36-CTV), non-decline-inducing (T30-CTV), a mixture of the two Citrus tristeza virus isolate types, or no CTV. Successful CTV transmission occurred in 1.5% of attempts from grapefruit trees that had been bark-chip-inoculated with T36-CTV, 3% of attempts from orange trees inoculated with T36-CTV, 3% of attempts from grapefruit trees inoculated with both T36- and T30-CTV, 4% of attempts from orange trees inoculated with both T36- and T30-CTV, 1.5% of attempts from grapefruit trees inoculated with T30-CTV, and 3.5% of attempts from orange trees inoculated with T30-CTV. Single BCA were able to recover T30-like-CTV from trees believed to be inoculated only with T36-CTV, and T36-like-CTV from trees believed to be inoculated only with T30-CTV, suggesting that these inoculum sources were also mixtures of T36-CTV and T30-CTV. The T36-CTV was not immunologically detectable in some of the trees from which it was transmitted indicating that single BrCA can recover T36-CTV from a T36-CTV/T30-CTV mixture in which the T36-CTV is an undetectable, minority component.
2
Long, Amy, Francis LeBlanc, Jean-René Arseneau, Nellie Gagne, Katja Einer-Jensen, Jan Lovy, Mark Polinski, Simon Jones i Kyle A. Garver. "Distribution and Pathogenicity of Two Cutthroat Trout Virus (CTV) Genotypes in Canada". Viruses 13, nr 9 (31.08.2021): 1730. http://dx.doi.org/10.3390/v13091730.
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The sole member of the Piscihepevirus genus (family Hepeviridae) is cutthroat trout virus (CTV) but recent metatranscriptomic studies have identified numerous fish hepevirus sequences including CTV-2. In the current study, viruses with sequences resembling both CTV and CTV-2 were isolated from salmonids in eastern and western Canada. Phylogenetic analysis of eight full genomes delineated the Canadian CTV isolates into two genotypes (CTV-1 and CTV-2) within the Piscihepevirus genus. Hepevirus genomes typically have three open reading frames but an ORF3 counterpart was not predicted in the Canadian CTV isolates. In vitro replication of a CTV-2 isolate produced cytopathic effects in the CHSE-214 cell line with similar amplification efficiency as CTV. Likewise, the morphology of the CTV-2 isolate resembled CTV, yet viral replication caused dilation of the endoplasmic reticulum lumen which was not previously observed. Controlled laboratory studies exposing sockeye (Oncorhynchus nerka), pink (O. gorbuscha), and chinook salmon (O. tshawytscha) to CTV-2 resulted in persistent infections without disease and mortality. Infected Atlantic salmon (Salmo salar) and chinook salmon served as hosts and potential reservoirs of CTV-2. The data presented herein provides the first in vitro and in vivo characterization of CTV-2 and reveals greater diversity of piscihepeviruses extending the known host range and geographic distribution of CTV viruses.
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Wu, Fengnian, Mochi Huang, Eduardo G. P. Fox, Jiaquan Huang, Yijing Cen, Xiaoling Deng i Meirong Xu. "Preliminary Report on the Acquisition, Persistence, and Potential Transmission of Citrus tristeza virus by Diaphorina citri". Insects 12, nr 8 (17.08.2021): 735. http://dx.doi.org/10.3390/insects12080735.
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Citrus tristeza virus (CTV) is one of the most important citrus tree viruses: a graft-transmissible virus that can be vectored by several aphid species. Diaphorina citri is the insect vector of “Candidatus Liberibacter spp.”, a bacterium associated with citrus Huanglongbing (HLB). However, no detailed description of the relationship between CTV and D. citri has been reported. In this study, D. citri adults collected from CTV-infected “Shatangju” mandarin, “Newhall” sweet orange, and “fingered citron” trees in different orchards yielded CTV-positive rates of 40%, 65%, and 95%, respectively, upon detection by conventional PCR. Illumina HiSeq sequencing followed by de novo assembly recovered the primary full CTV genome from the RNA of 30 D. citri adults sampled from CTV-positive citrus plants. Molting and adult emergence did not affect the presence or titers of CTV within the D. citri; however, the persistence of CTV in psyllids varied among different host plant species. Groups of 10 D. citri (from a population 85% CTV-positive) were shown to potentially transmit CTV to two citrus species, “Shatangju” mandarin and “Eureka” lemon, yielding 58.33% and 83.33% CTV-positive plants, respectively. No transmission of CTV to orange jasmine plants occurred. Thus, this study reports on the ability of D. citri to acquire and transmit CTV, making D. citri as a vector of two important citrus pathogens, warranting further attention and investigation.
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Biswas, Kajal, Supratik Palchoudhury, Prosenjit Chakraborty, Utpal Bhattacharyya, Dilip Ghosh, Palash Debnath, Chandrika Ramadugu, Manjunath Keremane, Ravi Khetarpal i Richard Lee. "Codon Usage Bias Analysis of Citrus tristeza Virus: Higher Codon Adaptation to Citrus reticulata Host". Viruses 11, nr 4 (8.04.2019): 331. http://dx.doi.org/10.3390/v11040331.
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Citrus tristeza virus (CTV), a member of the aphid-transmitted closterovirus group, is the causal agent of the notorious tristeza disease in several citrus species worldwide. The codon usage patterns of viruses reflect the evolutionary changes for optimization of their survival and adaptation in their fitness to the external environment and the hosts. The codon usage adaptation of CTV to specific citrus hosts remains to be studied; thus, its role in CTV evolution is not clearly comprehended. Therefore, to better explain the host–virus interaction and evolutionary history of CTV, the codon usage patterns of the coat protein (CP) genes of 122 CTV isolates originating from three economically important citrus hosts (55 isolate from Citrus sinensis, 38 from C. reticulata, and 29 from C. aurantifolia) were studied using several codon usage indices and multivariate statistical methods. The present study shows that CTV displays low codon usage bias (CUB) and higher genomic stability. Neutrality plot and relative synonymous codon usage analyses revealed that the overall influence of natural selection was more profound than that of mutation pressure in shaping the CUB of CTV. The contribution of high-frequency codon analysis and codon adaptation index value show that CTV has host-specific codon usage patterns, resulting in higheradaptability of CTV isolates originating from C. reticulata (Cr-CTV), and low adaptability in the isolates originating from C. aurantifolia (Ca-CTV) and C. sinensis (Cs-CTV). The combination of codon analysis of CTV with citrus genealogy suggests that CTV evolved in C. reticulata or other Citrus progenitors. The outcome of the study enhances the understanding of the factors involved in viral adaptation, evolution, and fitness toward their hosts. This information will definitely help devise better management strategies of CTV.
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Okano, Takumi, Naoki Kobayashi, Kazuki Izawa, Tomoya Yoshinari i Yoshiko Sugita-Konishi. "Whole Genome Analysis Revealed the Genes Responsible for Citreoviridin Biosynthesis in Penicillium citreonigrum". Toxins 12, nr 2 (15.02.2020): 125. http://dx.doi.org/10.3390/toxins12020125.
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Citreoviridin (CTV) is a mycotoxin that is produced by Aspergillus terreus, Eupenicillium ochrosalmoneum and Penicillium citreonigrum, and CTV has been detected in a wide range of cereal grains throughout the world. Furthermore, it is especially a serious problem in regions where rice is consumed as a staple food. Moreover, CTV is a well-known yellow rice toxin, and outbreaks of beriberi have occurred due to consumption of rice that is contaminated by CTV even in the recent years. Although CTV biosynthetic genes of A. terreus have been described, those of P. citreonigrum remain unclear, which is concerning since P. citreonigrum is the main cause of CTV contamination in rice. In the present study, we determined the draft genome of the P. citreonigrum strain IMI92228 and revealed the presence of all four genes that form a gene cluster and that are homologous to the CTV biosynthesis genes of A. terreus. The expression of these four homologous genes were highly correlated with CTV production, suggesting that they may play an important role in CTV biosynthesis in P. citreonigrum. We concluded that the gene cluster is a CTV biosynthesis cluster of P. citreonigrum. The findings will contribute to the understanding of the biosynthetic pathway of CTV and will ultimately lead to improvements in the CTV management of agricultural products.
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Roy, Avijit, G. Ananthakrishnan, John S. Hartung i R. H. Brlansky. "Development and Application of a Multiplex Reverse-Transcription Polymerase Chain Reaction Assay for Screening a Global Collection of Citrus tristeza virus Isolates". Phytopathology® 100, nr 10 (październik 2010): 1077–88. http://dx.doi.org/10.1094/phyto-04-10-0102.
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The emerging diversity of Citrus tristeza virus (CTV) genotypes has complicated detection and diagnostic measures and prompted the search for new differentiation methods. To simplify the identification and differentiation of CTV genotypes, a multiplex reverse-transcription polymerase chain reaction (RT-PCR) technique for the screening of CTV isolates was developed. Variable regions within the open reading frame (ORF)-1a of diverse CTV genotypes were identified to develop first a simplex (S) and then a hexaplex (H) RT-PCR. CTV isolates have been grouped previously into five genotypes (namely, T3, T30, T36, VT, and B165) based on the nucleotide sequence comparisons and phylogenetic analyses. Nucleotide sequences from GenBank were used to design species and genotype-specific primers (GSPs). The GSPs were initially used for reliable detection of all CTV genotypes using S-RT-PCR. Furthermore, detection of all five recognized CTV genotypes was established using the H-RT-PCR. Six amplicons, one generic to all CTV isolates and one for each of the five recognized genotypes, were identified on the basis of their size and were confirmed by sequence analysis. In all, 175 CTV isolates from 29 citrus-growing countries were successfully analyzed by S- and H-RT-PCR. Of these, 97 isolates contained T36 genotypes, 95 contained T3 genotypes, 76 contained T30 genotypes, 71 contained VT genotypes, and 24 contained B165 genotype isolates. In total, 126 isolates contained mixed infections of 2 to 5 of the known CTV genotypes. Two of the CTV isolates could not be assigned to a known genotype. H-RT-PCR provides a sensitive, specific, reliable, and rapid way to screen for CTV genotypes compared with other methods for CTV genotype detection. Efficient identification of CTV genotypes will facilitate a better understanding of CTV isolates, including the possible interaction of different genotypes in causing or preventing diseases. The methods described can also be used in virus-free citrus propagation programs and in the development of CTV-resistant cultivars.
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Wallis, Christopher M., Zachary Gorman, Rachel Rattner, Subhas Hajeri i Raymond Yokomi. "Amino acid, sugar, phenolic, and terpenoid profiles are capable of distinguishing Citrus tristeza virus infection status in citrus cultivars: Grapefruit, lemon, mandarin, and sweet orange". PLOS ONE 17, nr 5 (10.05.2022): e0268255. http://dx.doi.org/10.1371/journal.pone.0268255.
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Citrus tristeza virus (CTV) is the most severe viral disease for citrus production. Many strains of CTV have been characterized and their symptomology widely varies, ranging from asymptomatic or mild infections to severe symptomology that results in substantial yield loss or host death. The capacity of the different CTV strains to affect the biochemistry of different citrus species has remained largely unstudied, despite that associated metabolomic shifts would be relevant toward symptom development. Thus, amino acid, sugar, phenolic, and terpenoid levels were assessed in leaves of healthy and CTV-infected grapefruit, lemon, mandarin, and two different sweet orange cultivars. Both mild [VT-negative (VT-)] and severe [VT-positive (VT+)] CTV genotype strains were utilized. When looking at overall totals of these metabolite classes, only amino acid levels were significantly increased by infection of citrus with severe CTV strains, relative to mild CTV strains or healthy plants. No significant trends of CTV infection on summed amounts of all sugar, phenolic, or terpenoid compounds were observed. However, individual compound levels were affected by CTV infections. Subsequent canonical discriminant analysis (CDA) that utilized profiles of individual amino acids, terpenoids, or phenolics successfully distinguished leaf samples to specific citrus varieties and identified infection status with good accuracy. Collectively, this study reveals biochemical patterns associated with severity of CTV infections that can potentially be utilized to help identify in-field CTV infections of economic relevance.
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Fang, D. Q., C. T. Federici i M. L. Roose. "A High-Resolution Linkage Map of the Citrus Tristeza Virus Resistance Gene Region in Poncirus trifoliata (L.) Raf." Genetics 150, nr 2 (1.10.1998): 883–90. http://dx.doi.org/10.1093/genetics/150.2.883.
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Abstract Resistance to citrus tristeza virus (CTV) was evaluated in 554 progeny of 10 populations derived from Poncirus trifoliata. A dominant gene (Ctv) controlled CTV resistance in P. trifoliata. Twenty-one dominant PCR-based DNA markers were identified as linked to Ctv by bulked segregant analysis. Of the 11 closest markers to Ctv, only 2 segregated in all populations. Ten of these markers were cloned and sequenced, and codominant RFLP markers were developed. Seven RFLP markers were then evaluated in 10 populations. Marker orders were consistent in all linkage maps based on data of single populations or on combined data of populations with similar segregation patterns. In a consensus map, the six closest marker loci spanned 5.3 cM of the Ctv region. Z16 cosegregated with Ctv. C19 and AD08 flanked Ctv at distances of 0.5 and 0.8 cM, respectively. These 3 markers were present as single copies in the Poncirus genome, and could be used directly for bacterial artificial chromosome library screening to initiate a walk toward Ctv. BLAST searches of the GenBank database revealed high sequence similarities between 2 markers and known plant disease resistance genes, indicating that a resistance gene cluster exists in the Ctv region in P. trifoliata.
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Maragos, Chris M., Yosuke Uchiyama, Naoki Kobayashi, Fumichika Kominato i Yoshiko Sugita-Konishi. "Development and Characterization of Monoclonal Antibodies for the Mycotoxin Citreoviridin". Toxins 11, nr 11 (30.10.2019): 630. http://dx.doi.org/10.3390/toxins11110630.
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Citreoviridin (CTV) in an inhibitor of mitochondrial ATPase that has been isolated from molded yellow rice and linked to the human disease Shoshin-kakke (acute cardiac beriberi). The disease results from a deficiency of thiamine, however, purified CTV can reproduce the symptoms in experimental animals. The link between CTV and Shoshin-kakke has been difficult to resolve, in part because cases of the disease are rare. In addition to rice, CTV has been found in maize, pecan nuts, and wheat products. A method to screen for CTV and its geometric isomer, iso-CTV, in commodities was developed, based upon the isolation of two novel monoclonal antibodies (mAb). In an antigen-immobilized competitive enzyme-linked immunosorbent assay format (CI-ELISA), the observed IC50s for CTV were 11 ng/mL and 18 ng/mL (mAbs 2-2 and 2-4, respectively). The assays were relatively tolerant to methanol and acetonitrile, which allowed their application to the detection of CTV in spiked polished white rice. For quantification, a standard mixture of CTV and iso-CTV was used, along with matrix matched calibration. The dynamic range of the ELISA using mAb 2-4 was equivalent to 0.23 to 2.22 mg/kg in rice. Recoveries over the range of 0.36 to 7.23 mg/kg averaged 97 ± 10%. The results suggest that the mAb 2-4-based immunoassay can be applied to the screening of white rice for CTV. Both mAbs were also observed to significantly enhance the fluorescence of the toxin.
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Hughes, G., i T. R. Gottwald. "Survey Methods for Assessment of Citrus Tristeza Virus Incidence When Toxoptera citricida Is the Predominant Vector". Phytopathology® 89, nr 6 (czerwiec 1999): 487–94. http://dx.doi.org/10.1094/phyto.1999.89.6.487.
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Citrus tristeza virus (CTV) incidence may be assessed by sampling groups of citrus trees, recording the groups as CTV positive (one or more infected trees) or CTV negative (no infected trees), and then calculating disease incidence at the scale of the individual tree by means of a formula involving incidence at the group scale and the number of trees per group. This procedure works well when the CTV status of a tree can be regarded as independent of the CTV status of other trees in the same group. This is the case when the main vector species is Aphis gossypii and the groups comprise four adjacent trees, because the spatial pattern of CTV incidence at the within-group scale can be regarded as random. However, when the main vector species is Toxoptera citricida, this simple procedure is not appropriate, because the spatial pattern of CTV incidence at the within-group scale cannot be regarded as random. Using field data and computer simulation, an alternative procedure for assessment of CTV incidence when the main vector species is T. citricida was devised and tested. In the alternative procedure, the sampling scheme is operationally identical to that used when the main vector species is A. gossypii, but the calculation of CTV incidence at the scale of the individual tree is based on incidence at the group scale and an effective sample size. The analysis of CTV-incidence data collected from a number of citrus blocks in reasonable geographical and temporal proximity and the use of CTV-detection methods more sensitive than the enzyme-linked immunosorbent assay used here are also discussed.
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Someya, Masanori, Tomokazu Hasegawa, Takaaki Tsuchiya, Mio Kitagawa, Toshio Gocho, Yuuki Fukushima, Masakazu Hori i in. "Retrospective DVH analysis of point A based intracavitary brachytherapy for uterine cervical cancer". Journal of Radiation Research 61, nr 2 (1.02.2020): 265–74. http://dx.doi.org/10.1093/jrr/rrz099.
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ABSTRACT Combining external beam radiotherapy (EBRT) with intracavitary brachytherapy (ICBT) is important for definitive treatment of cervical cancer. In cervical cancer patients receiving radiotherapy, we evaluated treatment outcomes in relation to dose–volume histogram parameters, including the computed tomography (CT)-based high-risk clinical target volume (HR-CTV) for ICBT. Between 2010 and 2015, 89 consecutive cervical cancer patients were mostly treated with 40 Gy of EBRT in 20 fractions and 18 Gy of ICBT prescribed to point A in 3 fractions. CT scans were obtained during ICBT. The HR-CTV D90 was calculated and the total doses of ICBT and EBRT were converted to the equivalent dose in 2 Gy fractions (EQD2). When the patients were divided into four groups according to EQD2 of the HR-CTV D90, the 3-year local recurrence-free survival rates were 95.2, 78.4, 52.7 and 42.9% for patients receiving >80 , 70–80 , 60–70 and <60 Gy, respectively. There was a significant negative correlation between EQD2 of the HR-CTV D90 and the HR-CTV volume at first ICBT (r = −0.713). Local recurrence was more frequent when the HR-CTV volume was ≥22 cc and EQD2 of the HR-CTV D90 was <70 Gy. Multivariate analysis showed that EQD2 of the HR-CTV D90 and concurrent chemotherapy (≥4 cycles) were significant determinants of overall survival. HR-CTV D90 was an important prognostic indicator for local recurrence. HR-CTV D90 >70 Gy is required for the better local control, especially in patients with a larger HR-CTV (≥22 cc at initial ICBT).
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Powell, Charles A., Robert R. Pelosi i Phyllis A. Rundell. "Prevalence of Citrus Tristeza Virus in Florida Citrus Nurseries and Scion Groves". HortScience 38, nr 2 (kwiecień 2003): 244–45. http://dx.doi.org/10.21273/hortsci.38.2.244.
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None of 4190 sweet orange [Citrus sinensis (L.) Osb.] nursery trees of `Hamlin', `Midsweet', `Navel', and `Valencia' sampled from five Florida citrus nurseries were infected with a decline-inducing isolate of citrus tristeza virus (CTV) as judged by enzyme-linked immunosorbent assay (ELISA) using isolate-specific monoclonal antibodies. Two of the nurseries had a relatively high level of infection (37% to 100% of composite samples containing tissue from 10 trees) with nondecline-inducing (mild) isolates of CTV, depending on the cultivar. Three of the nurseries had a lower incidence of mild CTV (0% to 22% of 10 tree composite samples). No nursery was CTV-free. ELISA of individual trees used as budwood sources by the nurseries revealed that one tree out of 260 tested contained decline-inducing CTV, and 83 contained mild CTV. These results suggest that the budwood certification program adopted in 1997 has virtually eliminated decline-inducing CTV from commercial budwood supplies.
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Jones, Christian, Pedro G. R. Teixeira, Kenji Inaba, Sravanthi R. Keesara, Peter Rhee, Carlos Brown, Ali Salim, Timothy Browder i Demetrios Demetriades. "Combined CT Venography and CT Pulmonary Angiography for the Detection of Deep Venous Thrombosis in Injured Patients". American Surgeon 74, nr 10 (październik 2008): 935–38. http://dx.doi.org/10.1177/000313480807401011.
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CT Venography (CTV) performed at the time of CT pulmonary angiography (CTPA) images the central, pelvic, and extremity venous circulation with minimal additional time, radiation, and no added contrast. CTV has been added to CTPA routinely at our Level I trauma center since 2000, and we sought to determine if this addition had increased the diagnostic yield of CTPA in trauma patients. The attending radiologist's interpretation of all CTPA-CTV studies performed over a 5-year period ending in August 2006 were retrospectively reviewed. CTPAs and CTVs were categorized as “positive”, “negative”, or “indeterminate” for pulmonary embolus (PE) and deep venous thrombosis (DVT). During the study period, 3798 patients underwent both a CTPA and CTV; 309 (8%) of these were trauma patients. Forty-four (14%) had a PE diagnosed on CTPA. Seventeen (6%) had a DVT diagnosed on CTV. In eight (3%), the CTV added clinically relevant data, diagnosing a DVT in a patient without PE. As the consequences of a missed pelvic DVT are high and the added time burden, radiation, and contrast required for a CTV are low, further investigation into optimizing the sensitivity of CTV performed at the time of CTPA is warranted.
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Mehta, Prem, R. H. Brlansky, S. Gowda i R. K. Yokomi. "Reverse-Transcription Polymerase Chain Reaction Detection of Citrus Tristeza Virus in Aphids". Plant Disease 81, nr 9 (wrzesień 1997): 1066–69. http://dx.doi.org/10.1094/pdis.1997.81.9.1066.
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A rapid and simple reverse-transcription polymerase chain reaction (RT-PCR) method was developed for the detection of citrus tristeza virus (CTV) in three aphid species. Seven CTV isolates from a worldwide isolate collection were used for aphid acquisition feeding by three aphid species. These included the most efficient CTV vector, the brown citrus aphid, Toxoptera citricida; the melon aphid, Aphis gossypii; and the green peach aphid, Myzus persicae, a non-vector for CTV. A short procedure for nucleic acid extraction from single or groups of aphids was developed. Nucleic acid extracts from 1, 3, 5, and 10 aphids with acquisition-access periods of 24 and 48 h were reverse transcribed and amplified using primers for the coat protein gene of the Florida B3 (T-36) isolate of CTV. PCR-amplified fragments of approximately 670 bp were obtained from all the isolates tested and the amplified product from the aphids fed on citrus infected with isolate B3 was confirmed as the CTV coat protein gene by digesting with various restriction enzymes. This technique will be useful in investigations of CTV-vector-plant interactions and CTV epidemiology.
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Yokomi, Raymond K., Mark S. Sisterson i Subhas Hajeri. "Spread of Citrus Tristeza Virus in Citrus Orchards in Central California". Plant Disease 104, nr 7 (lipiec 2020): 1925–31. http://dx.doi.org/10.1094/pdis-08-19-1791-re.
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In California, citrus tristeza virus (CTV) is regulated by a State Interior Quarantine. In CTV abatement districts in central California, trees with CTV that react to MCA13 (MCA13-positive [MCA13+]), a strain-discriminating monoclonal antibody, are rogued to prevent virus spread. The Tulare County Pest Control District, however, does not participate in this abatement program except for a 1.6-km2 zone around the Lindcove Research and Extension Center, Exeter, CA. To quantify CTV spread under these two disparate management programs, CTV surveys were conducted in abatement plots with mandatory aphid control and nonabatement plots. Abatement plot surveys used hierarchical sampling of 25% of trees with samples pooled from four adjacent trees. Detection of MCA13+ CTV in a sample prompted resampling and testing of individual trees. From 2008 to 2018, incidence of CTV increased by an average of 3.9%, with only two MCA13+ samples detected. In contrast, in nonabatement plots, incidence of CTV increased by an average of 4.6% between 2015 and 2018. Increase in MCA13-negative (MCA−) isolates was 11 times greater than that of MCA13+ isolates, with the number of MCA13+ trees increasing by 19 trees between 2015 and 2018. MCA13− isolates were more randomly distributed, suggesting primary spread, whereas MCA13+ CTV isolates were more aggregated, suggesting some secondary spread. These results suggest that spread of MCA13+ isolates was limited by a combination of tree removal and aphid vector suppression. MCA13+ samples were VT isolates with some mixtures with T30 isolates. Despite the presence of VT isolates, all CTV-infected trees were asymptomatic.
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Lin, Youjian, i Charles A. Powell. "Visualization of the Distribution Pattern of Citrus Tristeza Virus in Leaves of Mexican Lime". HortScience 41, nr 3 (czerwiec 2006): 725–28. http://dx.doi.org/10.21273/hortsci.41.3.725.
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The distribution pattern of citrus tristeza virus (CTV) T-36 isolate in leaves of infected mexican lime [Citrus aurantifolia (Christm.) Swingle] plants was visualized using a whole-leaf-blot immunoassay (WLBIA) procedure in combination with a computer scanning imaging technique and CTV-specific monoclonal antibody 17G11 (CTV MAb 17G11). The distribution pattern of CTV T-36 in leaves varied with the age of the leaves and shoots of infected plants. In the young leaves, especially the about 5-day-old leaves and the completed expanded leaves, CTV T-36 was easily detected in most of the leaf veins, the main veins and the large and small primary veins. In the old leaves, CTV T-36 only was detected in the main veins, sometimes in a few of the large primary veins with weak signals, and seldom in the small primary veins. The distribution density and immunoassay reaction signals of CTV T-36 reacted to CTV MAb 17G11 in leaves from new shoots were much higher than that in leaves from old shoots. ELISA test results using leaves with different ages from different shoots of the same mexican lime plants infected with CTV T-36 supported the visualized-test results obtained by the WLBIA in combination with computer scanning imaging technique. This is the first reported visual analysis of the distribution pattern of CTV in leaves of infected citrus plants. The results indicate that the WLBIA in combination with computer scanning imaging technique is a useful tool for studying the distribution of plant viruses in leaves of virus-infected plants.
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Liu, Jinxiang, Lingdi Li, Hengyan Zhao, Yan Zhou, Hongsu Wang, Zhongan Li i Changyong Zhou. "Titer Variation of Citrus Tristeza Virus in Aphids at Different Acquisition Access Periods and Its Association with Transmission Efficiency". Plant Disease 103, nr 5 (maj 2019): 874–79. http://dx.doi.org/10.1094/pdis-05-18-0811-re.
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Tristeza, caused by citrus tristeza virus (CTV; Closterovirus, Closteroviridae), is of significant economic importance. Tristeza epidemics have caused severe declines in productivity, and even death, of millions of citrus trees on sour orange rootstock in many regions all over the world. In the field, CTV is most efficiently vectored by the brown citrus aphid (Toxoptera citricida (Kirkaldy)) in a semipersistent manner. The transmission efficiency of the vector is influenced by its acquisition access period (AAP) for CTV. A real-time RT-PCR assay using SYBR Green fluorescent dye was used to estimate the CTV titers in groups of 15 aphids under AAPs after 0.5 to 48 h for three CTV isolates (CT11A, CT16-2, and CTLJ). Similar trends for CTV titer in viruliferous aphids were displayed for the three isolates. The maximum CTV titer was at AAP 6 h for isolates CT11A and CT16-2, and at 4 h for isolate CTLJ. During the AAPs from 0.5 to 6 h, the mean CTV titer of CT16-2 increased from 7.8 × 104 to 1.71 × 107 copies per 15 aphids, and was correlated with an increase in transmission rate from 20 to 90.9%. This suggests that the transmission efficiency is positively correlated with viral titer in the insect from 0.5 h until 6 h AAPs. While a downward trend in CTV titer was observed after a 6-h AAP, the transmission rate remained higher than 90% up to 48 h. These results indicate that factors other than the virus titer in the vector contribute to successful transmission under long acquisition conditions. This is the first detailed quantitative analysis of CTV in its main vector species following different AAPs and its association with transmission efficiency, and should enhance our understanding of T. citricida-CTV interactions.
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Brlansky, R. H., Avijit Roy i V. D. Damsteegt. "Stem-Pitting Citrus tristeza virus Predominantly Transmitted by the Brown Citrus Aphid from Mixed Infections Containing Non-Stem-Pitting and Stem-Pitting Isolates". Plant Disease 95, nr 8 (sierpień 2011): 913–20. http://dx.doi.org/10.1094/pdis-10-10-0772.
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Citrus tristeza virus (CTV) is a phloem-limited Closterovirus that produces a variety of symptoms in various Citrus spp. One of these symptoms is stem pitting (SP). SP does not occur in all Citrus spp. but when it does it may cause low tree vigor, decline, and an economic reduction in fruit size and yield. Historically, the first appearance of CTV-SP in a citrus area often occurs after the introduction of the most efficient CTV vector, the brown citrus aphid (BCA), Toxoptera citricida. Hypotheses for this association range from the introduction of these strains in new planting materials to the increased ability of BCA to transmit SP strains from existing CTV sources. It is known that CTV often exists as a complex of isolates or subisolates. Single and multiple BCA transmissions have been used to separate different genotypes or strains of CTV from mixed CTV infected plants. This study was initiated to determine what the BCA transmits when an exotic severe SP CTV isolate B12 from Brazil or B408 from Dominican Republic are mixed with a non-SP (NSP) isolate, FS627 from Florida. Biological and molecular data was generated from grafted mixtures of these isolates and their aphid-transmitted subisolates. Single-strand conformation polymorphism patterns of the 5′ terminal region of open reading frame (ORF) 1a, the overlapping region of ORF1b and ORF2, and the major coat protein gene region of NSP and SP CTV-grafted plants remained unchanged but the patterns of doubly inoculated plants varied. The haplotype diversity within SP isolates B12, B408, and mixtures of NSP and SP isolates (FS627/B12 and FS627/B408) and aphid-transmitted subisolates from doubly inoculated plants was determined by analysis of the haplotype nucleotide sequences. Aphid transmission experiments, symptoms, and molecular analyses showed that SP-CTV was more frequently transmitted with or without NSP-CTV from mixed infections.
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Cook, Glynnis, Stephanus P. van Vuuren, Johannes H. J. Breytenbach, Chanel Steyn, Johan T. Burger i Hans J. Maree. "Characterization of Citrus tristeza virus Single-Variant Sources in Grapefruit in Greenhouse and Field Trials". Plant Disease 100, nr 11 (listopad 2016): 2251–56. http://dx.doi.org/10.1094/pdis-03-16-0391-re.
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Citrus tristeza virus (CTV) is endemic to southern Africa and the stem pitting syndrome that it causes was a limiting factor in grapefruit production prior to the introduction of cross-protection in the Citrus Improvement Scheme. This disease mitigation strategy, using various field-derived CTV sources, has significantly extended the productive lifespan of grapefruit orchards in South Africa. CTV commonly occurs as a population of various strains, masking the phenotypic effect of individual strains. Likewise, current South African CTV cross-protection sources are strain mixtures, obscuring an understanding of which strains are influencing cross-protection. The severity of various CTV strains has mostly been assessed on sensitive indicator hosts, but their effect on commercial varieties has seldom been investigated. Single-variant CTV isolates were used to investigate the phenotypic expression of CTV strains in commercial grapefruit varieties as well as CTV indicator hosts. They were biologically characterized for their ability to cause stem pitting and their rate of translocation and titer in the different hosts, monitored by enzyme-linked immunosorbent assay. Complete genome sequences for three CTV strain variants were generated. Isolates of CTV strains VT, T68, RB, and HA16-5 did not induce severe stem pitting in four grapefruit hosts in a glasshouse trial. Viral titers of the strains differed in the grapefruit hosts, but the RB isolate reached a higher titer in the grapefruit hosts compared with the VT, T68, and HA16-5 isolates. Additionally, horticultural assessment of two grapefruit varieties inoculated with the RB isolate in two field trials demonstrated that mild stem pitting did not negatively influence the horticultural performance of the grapefruit trees over an eight-year assessment period. ‘Star Ruby’ trees containing the CTV source GFMS35 showed less stem pitting than trees inoculated with the RB isolate, but had smaller canopy volumes and lower yields than trees containing the RB isolate. This suggests that the influence of CTV sources on tree performance is not limited to the effect of stem pitting.
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Bhoopathi, Praveen, Anjan K. Pradhan, Santanu Maji, Swadesh K. Das, Luni Emdad i Paul B. Fisher. "Theranostic Tripartite Cancer Terminator Virus for Cancer Therapy and Imaging". Cancers 13, nr 4 (18.02.2021): 857. http://dx.doi.org/10.3390/cancers13040857.
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Combining cancer-selective viral replication and simultaneous production of a therapeutic cytokine, with potent “bystander” anti-tumor activity, are hallmarks of the cancer terminator virus (CTV). To expand on these attributes, we designed a next generation CTV that additionally enables simultaneous non-invasive imaging of tumors targeted for eradication. A unique tripartite CTV “theranostic” adenovirus (TCTV) has now been created that employs three distinct promoters to target virus replication, cytokine production and imaging capabilities uniquely in cancer cells. Conditional replication of the TCTV is regulated by a cancer-selective (truncated PEG-3) promoter, the therapeutic component, MDA-7/IL-24, is under a ubiquitous (CMV) promoter, and finally the imaging capabilities are synchronized through another cancer selective (truncated tCCN1) promoter. Using in vitro studies and clinically relevant in vivo models of breast and prostate cancer, we demonstrate that incorporating a reporter gene for imaging does not compromise the exceptional therapeutic efficacy of our previously reported bipartite CTV. This TCTV permits targeted treatment of tumors while monitoring tumor regression, with potential to simultaneously detect metastasis due to the cancer-selective activity of reporter gene expression. This “theranostic” virus provides a new genetic tool for distinguishing and treating localized and metastatic cancers.
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Toh, Ming Ren, Karthikeyan Damodharan, Han Hui Mervin Nathan Lim i Tjun Yip Tang. "Computed tomography venography versus intravascular ultrasound in the diagnosis of iliofemoral vein stenosis". Vasa 50, nr 1 (1.01.2021): 38–44. http://dx.doi.org/10.1024/0301-1526/a000920.
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Summary: Background: Iliofemoral vein stenosis can cause debilitating chronic venous disease. Diagnostic tools include both computed tomography venography (CTV) and intravascular ultrasonography (IVUS). We aim to compare the diagnostic performance of CTV and IVUS. Patients and methods: We performed a retrospective study of patients with chronic venous disease presenting with iliac vein compression or post-thrombotic limb symptoms, excluding those with acute deep vein thrombosis, high anaesthesia risk, or who had contrast allergy. All patients received CTV before IVUS, as part of the diagnostic work-up and intervention. The cross-sectional area (CSA) of iliofemoral vein segments obtained from both studies were compared against reference CSAs to derive percentage stenosis. A 50% reduction in CSA was considered significant. Results: We studied 50 patients between May 2018 and April 2019. 58% of patients had severe disease CEAP C5-6. 48% of patients had at least one vein segment with significant stenosis. The left proximal common iliac vein was the most commonly stenosed vein segment (n = 12, 24% on IVUS). CSA measurements from CTV were greater than those of IVUS, with a correlation coefficient of 0.57 (p < 0.005). Conversely, percentage stenosis measured on CTV was lower than on IVUS, with approximately one-third of significant stenosis missed on CTV (58 veins from CTV vs. 78 from IVUS, p < 0.005). With IVUS as the gold standard, CTV has low sensitivity (37.2%, 95% CI 26.5–48.9) and high specificity (92.5%, 95% CI 89.3–94.9) in detecting significant stenosis. Conclusions: CTV has limited diagnostic performance in identifying iliofemoral vein stenosis. Patients with normal CTV findings should proceed with IVUS imaging if the clinical features are supportive of iliofemoral vein stenosis.
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Fagoaga, Carmen, Carmelo López, Pedro Moreno, Luis Navarro, Ricardo Flores i Leandro Peña. "Viral-Like Symptoms Induced by the Ectopic Expression of the p23 Gene of Citrus tristeza virus Are Citrus Specific and Do Not Correlate with the Pathogenicity of the Virus Strain". Molecular Plant-Microbe Interactions® 18, nr 5 (maj 2005): 435–45. http://dx.doi.org/10.1094/mpmi-18-0435.
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Ectopic expression of the p23 gene from a severe (T36) strain of Citrus tristeza virus (CTV) induces viral-like symptoms in Mexican lime. Here, we report that expressing the same gene from a mild strain induced similar symptoms that correlated with accumulation of p23 protein irrespective of the source strain. CTV inoculation of transgenic limes showing CTV-like leaf symptoms and high p23 accumulation did not modify symptoms initially, with the virus titer being as in inoculated nontransgenic controls; however, at later stages, symptoms became attenuated. Transformation with p23-T36 of CTV-susceptible sweet and sour orange and CTV-resistant trifoliate orange also led to CTV-like leaf symptoms that did not develop when plants were transformed with a truncated p23 version. In transgenic citrus species and relatives other than Mexican lime, p23 was barely detectable, although symptom intensity correlated with levels of p23 transcripts. The lower accumulation of p23 in sweet and sour orange compared with Mexican lime also was observed in nontransgenic plants inoculated with CTV, suggesting that minimal p23 levels cause deleterious effects in the first two species. Conversely, transgenic expression of p23 in CTV nonhost Nicotiana spp. led to accumulation of p23 without phenotypic aberrations, indicating that p23 interferes with plant development only in citrus species and relatives.
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Lin, Youjian, Phyllis A. Rundell i Charles A. Powell. "In Situ Immunoassay (ISIA) of Field Grapefruit Trees Inoculated with Mild Isolates of Citrus tristeza virus Indicates Mixed Infections with Severe Isolates". Plant Disease 86, nr 5 (maj 2002): 458–61. http://dx.doi.org/10.1094/pdis.2002.86.5.458.
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Ten grapefruit trees that had been inoculated with a mild isolate of Citrus tristeza virus (CTV) and maintained in the field for 18 years were found in a previous study to be declining and infected with severe isolates of CTV, or symptomless and infected with mild isolates of CTV, using enzyme-linked immunosorbent assay (ELISA). They were assayed with an in situ immunoassay (ISIA) procedure using monoclonal antibodies 17G11 (reacts with most Florida isolates of CTV) and MCA13 (reacts with severe, but not Florida mild isolates of CTV). All the grapefruit trees were 17G11 positive by ELISA and ISIA. The five trees that showed moderate decline symptoms were MCA13 positive by ELISA and ISIA. The five symptomless trees were MCA13 negative by ELISA. However, four of the five symptomless trees were MCA13 positive by ISIA, which showed that ISIA with MCA13 had greater sensitivity in detecting severe CTV isolates than ELISA. These results suggested that the cross-protected grapefruit trees, regardless of symptoms, were infected with both mild and severe isolates of CTV.
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Zhang, Hanyi, Shun Lu, Chang Sun i Jin Yi Lang. "Analysis of local control rate and toxicity of radiotherapy dose of cervical cancer." Journal of Global Oncology 5, suppl (7.10.2019): 136. http://dx.doi.org/10.1200/jgo.2019.5.suppl.136.
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136 Background: The standard of care for treatment of advanced cervical cancer is the combination of external beam radiation therapy (EBRT) and intracavitary brachytherapy with cisplatin based concurrent chemotherapy. Radiotherapy plays a crucial role in treatment of cervical cancer. Recent GEC-ESTRO guidelines recommend that the dose to 90% (D90) of the high-risk clinical target volume (HRCTV) in cervical cancer be at least 85Gy with higher doses for poor response to radiotherapy. This study was aim to analyze our institution’s patients with locally advanced cervical cancer in regards to whether higher brachytherapy dose delivery lead to a better outcome, and to investigate the proper dose to balance the local control rate and toxicity. Methods: A total of 262 patients with local advanced cervical cancer treated at a single institution were retrospectively analyzed for the association between dosimetry and outcomes. Youden index was used to identify the optimal cut-off point of continuous tumor parameters and divide patients into subgroups. Significance of radiotherapy dose parameters on OS, PFS, LRFS and DMFS and toxicity was evaluated. Results: In the univariate analysis, for both HR-CTV and LR-CTV, the high dose group (EQD2 D90 >75Gy, LR-CTV>68Gy, respectively) have a better LRFS than low-dose groups (P<0.05). LR-CTV remains significance after adjusted for age and FIGO stage. Moreover, in the high-dose LR-CTV group, there is no association between dose of LR-CTV and LRFS was found, however, higher dose of HR-CTV significant associated with higher ratio of side effect was found. In addition, no association of dose of HR-CTV or LR-CTV and OS were found for all patients. Conclusions: Our results showed that dose of LR-CTV may be a useful prognostic factor of LRFS of patients with cervical cancer. Moreover, after D90 of LR-CTV reaches 68Gy, increasing dose did not show a better LRFS but lead to higher ratio of toxicity, supporting that LR-CTV at 68Gy might be a safety and efficacy dose of radiotherapy to the patients with cervical cancer. However, further improved in dose had no significant benefit on local control rate, and it might increase the risks of toxicity.
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Vidal, E., R. K. Yokomi, A. Moreno, E. Bertolini i M. Cambra. "Calculation of Diagnostic Parameters of Advanced Serological and Molecular Tissue-Print Methods for Detection of Citrus tristeza virus: A Model for Other Plant Pathogens". Phytopathology® 102, nr 1 (styczeń 2012): 114–21. http://dx.doi.org/10.1094/phyto-05-11-0139.
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Citrus tristeza virus (CTV) is one of the most important virus diseases that affect citrus. Control of CTV is achieved by grafting selected virus-free citrus scions onto CTV-tolerant or -resistant rootstocks. Quarantine and certification programs are essential for avoiding the entry and propagation of severe strains of CTV. Citrus nurseries in Spain and central California (United States) maintain zero-tolerance policies for CTV that require sensitive, specific, and reliable pathogen-detection methods. Tissue-print (TP) real-time reverse-transcriptase polymerase chain reaction (RT-PCR) assay was compared with the validated TP enzyme-linked immunosorbent assay (ELISA), using the CTV-specific monoclonal antibodies 3DF1 and 3CA5, for CTV detection. In total, 1,395 samples from healthy and CTV-infected nursery and mature tree plants were analyzed with both methods. The total agreement between both detection methods was substantial (Cohen's kappa index of 0.77 ± 0.03). The diagnostic parameters of each technique (i.e., the sensitivity, specificity, and likelihood ratios) were evaluated in a second test involving 658 Citrus macrophylla nursery plants. Mexican lime indexing was used to evaluate samples with discrepant results in the analysis. For TP-ELISA, a sensitivity of 0.8015, a specificity of 0.9963, and a positive and negative likelihood ratio of 216.42 and 0.199, respectively, were estimated. For TP real-time RT-PCR, a sensitivity of 0.9820, a specificity of 0.8519, and a positive and negative likelihood ratio of 6.63 and 0.021, respectively, were estimated. These diagnostic parameters show that TP real-time RT-PCR was the most sensitive technique, whereas TP-ELISA showed the highest specificity, validating the use of the molecular technique for routine CTV-detection purposes. In addition, our results show that the combination of both techniques can accurately substitute for the conventional biological Mexican lime index for the detection of CTV. The calculation of diagnostic parameters is discussed, as a necessary tool, to validate detection or diagnostic methods in plant pathology. Furthermore, assessment of the post-test probability of disease after a diagnostic result and CTV prevalence allows selection of the best method for accurate and reliable diagnosis.
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Iracheta-Cárdenas, M. M., P. Metheney, M. L. Polek, K. L. Manjunath, R. F. Lee i M. A. Rocha-Peña. "Serological Detection of Citrus tristeza virus with Antibodies Developed to the Recombinant Coat Protein". Plant Disease 93, nr 1 (styczeń 2009): 11–16. http://dx.doi.org/10.1094/pdis-93-1-0011.
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Antibodies specific for the recombinant coat protein (rCP) of the p25 gene of Citrus tristeza virus (CTV) were developed in goats and rabbits and further evaluated as a complete kit for the detection of the virus using healthy and CTV-infected tissue. The combination of goat T1 used as primary (coating) and rabbit C3 as intermediate (detecting) rCP antibodies reacted efficiently, with optical density at 405 nm (OD405) values between 0.250 and 2.000 with samples from an international collection of diverse CTV isolates. The CTV isolates tested cause a broad spectrum of disease syndromes in different citrus hosts. The OD405 values for healthy tissue were less than 0.100. Likewise, the combination of goat T1 and rabbit C3 rCP antibodies gave consistent results for CTV-positive and -negative sample discrimination when directly compared with the Central California Tristeza Eradication Agency (CCTEA) antibodies used for large-scale CTV detection and a commercially available CTV serological detection kit. The combination of goat T1 and rabbit C3 rCP antibodies showed its suitability for large-scale indexing with samples collected in commercial groves as part of the CCTEA's regular monitoring program. The evaluation included 41,195 samples from 301 commercial groves from districts 1, 2, and 3. In total, 26 trees (0.063%) were found to be CTV positive using the T1/C3 rCP antibody combination. Results of this research provide evidence that rCP antibodies can be efficiently used for both capturing and detecting CTV antigens in double-antibody sandwich indirect enzyme-linked immunosorbent assay.
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Nikolaeva, Olga V., Alexander V. Karasev, Stephen M. Garnsey i Richard F. Lee. "Serological Differentiation of the Citrus Tristeza Virus Isolates Causing Stem Pitting in Sweet Orange". Plant Disease 82, nr 11 (listopad 1998): 1276–80. http://dx.doi.org/10.1094/pdis.1998.82.11.1276.
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Citrus tristeza virus (CTV) complex comprises a number of isolates or strains producing several economically important disease syndromes in commercial Citrus spp. The stem pitting syndrome is the most important, and causes substantial losses in many citrus-producing regions of the world. In an attempt to develop a serological tool to rapidly differentiate stem pitting isolates of CTV, we evaluated many combinations of trapping and detecting antibodies in an indirect double-antibody sandwich (I-DAS) enzyme-linked immunosorbent assay (ELISA). Two combinations of trapping and detecting antibodies were found suitable for differentiating stem pitting isolates in extracts of infected sweet orange plants. One used a polyclonal serum raised against bacterially expressed CTV coat protein (CP) for trapping and a conformational monoclonal antibody 3E10 for detection, and the other used two polyclonal antisera generated against bacterially expressed CTV CP. Seventy-six CTV isolates from 20 countries, including 35 that cause stem pitting in sweet orange plants, were analyzed in I-DAS-ELISA using different combinations of polyclonal and monoclonal antibodies for trapping and as intermediate detecting antibodies. The ELISA format developed produces a strong positive signal for CTV isolates that cause stem pitting in sweet orange plants and a negative ELISA signal for CTV isolates that do not cause stem pitting. When combined with data on a universal ELISA format, i.e., reacting with a broad range of CTV isolates, these selective ELISA formats allowed reliable serological differentiation of CTV isolates that caused stem pitting in infected sweet orange plants.
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Fang, D. Q., i M. L. Roose. "A Novel Gene Conferring Citrus Tristeza Virus Resistance in Citrus maxima (Burm.) Merrill". HortScience 34, nr 2 (kwiecień 1999): 334–35. http://dx.doi.org/10.21273/hortsci.34.2.334.
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`Chandler' pummelo [Citrus maxima (Burm.) Merrill] was found to be citrus tristeza virus (CTV)–resistant. The inheritance of this resistance in 84 progeny of two crosses derived from `Chandler' pummelo and trifoliate orange [Poncirus trifoliata (L.) Raf.] was controlled by a single dominant gene designated Ctv2. Progeny analysis of four molecular markers closely linked to the Ctv gene, which confers resistance to CTV in trifoliate orange, demonstrated that Ctv2 was an independently assorting gene from Ctv.
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Cheng, Zhangbo, Hang Wang, Shengmei Lin, Lei Yin, Jiawei Su, Yunhong Lei, Yongrong Lan i in. "Black-blood Venous Imaging (BBVI): A Contrast-Free and High-Resolution Magnetic Resonance Approach for Diagnosing IVCS – a Proof of Concept Study". Clinical and Applied Thrombosis/Hemostasis 28 (styczeń 2022): 107602962211272. http://dx.doi.org/10.1177/10760296221127275.
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Background Iliac vein compression syndrome (IVCS) diagnosis heavily relies on an imaging test. However, non-invasive and contrast-free imaging test for the diagnosis of IVCS remains a big challenge. To address this issue, this prospective study aimed to assess the image quality and diagnostic performance of a magnetic resonance imaging technique, black-blood venous imaging (BBVI), in detecting IVCS by comparing it with contrast-enhanced computed tomography venography (CTV) and using invasive digital subtraction angiography (DSA) as the reference. Methods We enrolled 105 patients, and all patients underwent BBVI, CTV, and DSA examinations. We compared the consistency of CTV and BBVI image quality and their consistency in diagnosing the rate of iliac vein stenosis in IVCS patients. Using the consensus DSA as a reference, the sensitivity, specificity, positive and negative predictive values, and accuracy of BBVI and CTV and their diagnostic agreement with DSA were calculated. Results BBVI demonstrated high sensitivity, specificity, and accuracy for the diagnosis of IVCS, without contrast agents. BBVI and CTV are quite in diagnosis IVCS. Quite SE (67.8% vs 68.3%), SP (94.8% vs 94.8%), PPV (98.0% vs 98.0%), NPV (46.2% vs 46.9%) and ACC (75.3% vs 75.7%) were obtained by BBVI in comparison with CTV. Conclusion BBVI has comparable diagnostic performance with CTV. It may be a viable alternative to CTV techniques in screening the IVCS without contrast agents and free of ionizing radiation.
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Britt, Kellee, Samantha Gebben, Amit Levy, Diann Achor, Peggy Sieburth, Kristian Stevens, Maher Al Rwahnih i Ozgur Batuman. "Analysis of Citrus Tristeza Virus Incidences within Asian Citrus Psyllid (Diaphorina citri) Populations in Florida via High-Throughput Sequencing". Insects 13, nr 3 (10.03.2022): 275. http://dx.doi.org/10.3390/insects13030275.
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The destructive citrus disease, Huanglongbing (HLB) or citrus greening, continues to devastate Florida’s citrus industry. A hemipteran insect, the Asian citrus psyllid (ACP), disperses Candidatus Liberibacter asiaticus, one of the putative bacterial pathogens of HLB. This study builds upon ongoing research utilizing high-throughput sequencing to analyze the virome of ACP populations collected from citrus groves throughout Florida. Following the widespread detection of sequences aligning to the genome of citrus tristeza virus (CTV) across consecutive years in the Florida ACP virome, we continued to detect a pervasive amount of CTV in Florida ACPs during subsequent years. Simultaneously, we also detected mixed infections of CTV strains in pooled ACPs from different Florida regions. Predating the HLB epidemic, CTV has been present in Florida for many years and our results confirm its widespread and diverse persistence in Florida citrus groves through a unique lens, the ACP. CTV presence in the ACP likely results from feeding on CTV-infected citrus trees in Florida citrus groves, which may help to understand an overlapping presence of CTV and HLB, both endemic citrus pathosystems in the state, and their role in future integrated pest management strategies.
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Abbas, M., M. M Khan, S. M Mughal i I. A Khan. "Prospects of classical cross protection technique against Citrus tristeza closterovirus in Pakistan: A review". Horticultural Science 32, No. 2 (23.11.2011): 74–83. http://dx.doi.org/10.17221/3769-hortsci.
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In Pakistan citrus groves in general are facing a serious problem of decline that is attributed to different causes. The major cause, however, is the prevalence of citrus virus and virus-like diseases; Citrus tristeza virus (CTV) is of utmost concern. Although CTV has been identified and characterized on the basis of serological and physical properties, no information is available on the strains of CTV in Pakistan. The identification of CTV strains will be helpful in developing strategies to control the decline of citrus trees to a great extent. Many citrus growing countries have successfully used the technique of cross protection to minimize the drastic effect of severe CTV strains. By pre-immunization of the citrus tree with mild strains, the decline can be controlled to increase the life span of the citrus tree. In this study we focus on the possibility of establishing a cross protection technique in Pakistan against the CTV strains.
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Camps, Rocio, Nicola Fiore, Natalia Riquelme, Wilson Barros-Parada i Ximena Besoain. "Genotype variation of citrus tristeza virus after passage on different hosts, and changes in the virus genotype populations by the vector Aphis gossypii". Phytopathologia Mediterranea 61, nr 1 (25.03.2022): 55–63. http://dx.doi.org/10.36253/phyto-12965.
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Phylogenetic analyses categorize seven genotypes of citrus tristeza virus (CTV). The symptoms caused by this pathogen, their expression and severity are influenced by CTV genotypes, host species, cultivars, and infected host rootstocks. This study aimed to verify how populations of Chilean CTV isolates changed following inoculation from infected sweet orange to Mexican lime trees, and to determine if CTV genotype populations influenced transmission efficiency via Aphis gossypii. Reverse transcription polymerase chain reaction showed variation in genotypes of populations of CTV in Mexican lime, after graft inoculations using infected sweet orange chip-buds. Severe genotypes (VT) were detected after inoculation of mild isolate CTV populations (T30). The T30 donor populations also reduced transmissibility via A. gossypii; however, these results may not be conclusive due to mixture with the VT genotype. There is evidence of high rates of virus acquisition by this aphid species, but also low transmission efficiency, which may partially explain the historical absence of tristeza epidemics in Chile.
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Powell, C. A., R. R. Pelosi, P. A. Rundell, E. Stover i M. Cohen. "Cross-Protection of Grapefruit from Decline-Inducing Isolates of Citrus Tristeza Virus". Plant Disease 83, nr 11 (listopad 1999): 989–91. http://dx.doi.org/10.1094/pdis.1999.83.11.989.
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The ability of three mild isolates of citrus tristeza virus (CTV) to prevent natural infection of 84 Ruby Red grapefruit on sour orange rootstock by aphid-transmitted, decline-inducing isolates of CTV was assessed by symptoms and verified by enzyme-linked immunosorbent assay (ELISA) after 16 years. Of 21 trees in each of four treatments protected by the DD 102 bb, Guettler HS, and DPI 1-12-5-X-E mild CTV isolates, 14, 10, and 14% were infected by severe isolates (MCA13 monoclonal antibody reactive) compared with 67% for unprotected control trees. The health of trees protected by the DD 102 bb CTV isolate was significantly better than that of unprotected control trees as measured by decline, tree ratings, and tree height. These data suggest that infection by certain mild isolates of CTV can cross-protect grapefruit trees on sour orange rootstock from decline-inducing isolates of CTV that are prevalent in the Indian River region of Florida.
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Powell, Charles A., Phyllis A. Rundell i Robert R. Pelosi. "Suppression of Decline-inducing Isolates of Citrus Tristeza Virus by Nondecline-inducing Isolates". HortScience 38, nr 1 (luty 2003): 62–64. http://dx.doi.org/10.21273/hortsci.38.1.62.
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Bark chips from six container-grown citrus trees, infected with nondecline-inducing citrus tristeza virus (CTV) isolates and maintained in a vector-free greenhouse for 10 years, 15 commercial grapefruit (Citrus paradisi Macf.) trees, and 16 commercial sweet orange [C. sinensis (L.) Osbeck] trees were used to inoculate three indicator plants each of `Madam Vinous' sweet orange [C. sinensis (L.) Osbeck], sour orange (C. aurantium L.), `Duncan' grapefruit (C. paradisi Macf.), `Mexican' lime [C. aurantifolia (Christm.)], Swingle citrumelo [C. paradisi Macf. × Poncirus trifoliota (L.) Raf.], and sour orange grafted with `Hamlin' sweet orange [C. sinensis (L.) Osbeck]. All plants providing bark chips had repeatedly tested positive by enzyme-linked immunosorbent assay (ELISA) for CTV [reacted with monoclonal antibody (MAb) 17G11], but tested negative for Florida decline-inducing isolates of CTV (did not react with MAb MCA13). After 6 months in vector-free greenhouses, all in oculated trees (except Swingle citrumelo, which is considered CTV resistant) were positive for CTV by 17G11 ELISA. In addition, some indicator plants inoculated from nine (two container, two commercial grapefruit, and five commercial orange trees) of the 37 bark chip source trees also were positive for decline-inducing CTV by MCA13 ELISA. Some of these positive indicators also showed vein-clearing symptoms characteristic of infection with a severe isolate of CTV. No control, noninoculated indicators in the same greenhouse, became infected with either decline-inducing or nondecline-inducing CTV. These results indicate that decline-inducing isolates of CTV can be present as a minor component of a mixture at levels undetectable by ELISA, and that these decline-inducing isolates can become detectable by ELISA and sometimes by symptoms when inoculated into indicator plants.
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Yamada, Kazuteru, Jun Kaneko, Yoshiyuki Kamio i Yoshifumi Itoh. "Binding Sequences for RdgB, a DNA Damage-Responsive Transcriptional Activator, and Temperature-Dependent Expression of Bacteriocin and Pectin Lyase Genes in Pectobacterium carotovorum subsp. carotovorum". Applied and Environmental Microbiology 74, nr 19 (8.08.2008): 6017–25. http://dx.doi.org/10.1128/aem.01297-08.
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ABSTRACT Pectobacterium carotovorum subsp. carotovorum strain Er simultaneously produces the phage tail-like bacteriocin carotovoricin (Ctv) and pectin lyase (Pnl) in response to DNA-damaging agents. The regulatory protein RdgB of the Mor/C family of proteins activates transcription of pnl through binding to the promoter. However, the optimal temperature for the synthesis of Ctv (23�C) differs from that for synthesis of Pnl (30�C), raising the question of whether RdgB directly activates ctv transcription. Here we report that RdgB directly regulates Ctv synthesis. Gel mobility shift assays demonstrated RdgB binding to the P0, P1, and P2 promoters of the ctv operons, and DNase I footprinting determined RdgB-binding sequences (RdgB boxes) on these and on the pnl promoters. The RdgB box of the pnl promoter included a perfect 7-bp inverted repeat with high binding affinity to the regulator (K d [dissociation constant] = 150 nM). In contrast, RdgB boxes of the ctv promoters contained an imperfect inverted repeat with two or three mismatches that consequently reduced binding affinity (K d = 250 to 350 nM). Transcription of the rdgB and ctv genes was about doubled at 23�C compared with that at 30�C. In contrast, the amount of pnl transcription tripled at 30�C. Thus, the inverse synthesis of Ctv and Pnl as a function of temperature is apparently controlled at the transcriptional level, and reduced rdgB expression at 30�C obviously affected transcription from the ctv promoters with low-affinity RdgB boxes. Pathogenicity toward potato tubers was reduced in an rdgB knockout mutant, suggesting that the RdgAB system contributes to the pathogenicity of this bacterium, probably by activating pnl expression.
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Shilts, Turksen, Choaa El-Mohtar, William O. Dawson i Nabil Killiny. "Citrus tristeza virus P33 Protein Is Required for Efficient Transmission by the Aphid Aphis (Toxoptera) citricidus (Kirkaldy)". Viruses 12, nr 10 (6.10.2020): 1131. http://dx.doi.org/10.3390/v12101131.
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Plant viruses are threatening many valuable crops, and Citrus tristeza virus (CTV) is considered one of the most economically important plant viruses. CTV has destroyed millions of citrus trees in many regions of the world. Consequently, understanding of the transmission mechanism of CTV by its main vector, the brown citrus aphid, Aphis (Toxoptera) citricidus (Kirkaldy), may lead to better control strategies for CTV. The objective of this study was to understand the CTV–vector relationship by exploring the influence of viral genetic diversity on virus transmission. We built several infectious clones with different 5′-proximal ends from different CTV strains and assessed their transmission by the brown citrus aphid. Replacement of the 5′- end of the T36 isolate with that of the T30 strain (poorly transmitted) did not increase the transmission rate of T36, whereas replacement with that of the T68-1 isolate (highly transmitted) increased the transmission rate of T36 from 1.5 to 23%. Finally, substitution of p33 gene of the T36 strain with that of T68 increased the transmission rate from 1.5% to 17.8%. Although the underlying mechanisms that regulate the CTV transmission process by aphids have been explored in many ways, the roles of specific viral proteins are still not explicit. Our findings will improve our understanding of the transmission mechanisms of CTV by its aphid vector and may lead to the development of control strategies that interfere with its transmission by vector.
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Yokomi, R. K., i R. L. DeBorde. "Incidence, Transmissibility, and Genotype Analysis of Citrus tristeza virus (CTV) Isolates from CTV Eradicative and Noneradicative Districts in Central California". Plant Disease 89, nr 8 (sierpień 2005): 859–66. http://dx.doi.org/10.1094/pd-89-0859.
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Growers in 45% (44,100 ha) of the citrus acreage in California stopped eradicating Citrus tristeza virus (CTV)-infected trees from their fields in 1995-96. The impact of leaving infected trees on the rate of CTV spread was determined by comparing temporal incidence of CTV in plots in Strathmore, Tulare County without eradication with incidence in a plot in McFarland, Kern County with eradication. From 1997 to 2003, CTV incidence in the Strathmore plots ranged from 6 to 42%, with annual spread rates from 1.6 to 3.6%. CTV incidence in the McFarland plot increased from 0 to 5% between 2001 and 2003 before infected trees were removed. Using a subplot hierarchical bulk sampling method, virus incidence over a 3-year period in a 6.5 km2 area near McFarland was estimated to range from 0.09 to 0.69%, which indicated that CTV suppression was still being achieved in this area. Vector tests using the cotton aphid, Aphis gossypii, identified highly transmissible isolates (30 to 61% transmission rate) and a larger proportion of highly transmissible isolates were found in the McFarland plots. Thirty-six CTV isolates from recently infected plot trees were obtained and analyzed. None of these isolates reacted with monoclonal antibody MCA13 that detects presumptive CTV severe strains. Molecular analysis using polymerase chain reaction and sequence-specific primers showed that all isolates had a genotype identical to the T30 mild isolate from Florida.
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Takahashi, Shigeo, Takamasa Nishide, Masato Tsuzuki, Hiroki Katayama, Masahide Anada, Toshifumi Kinoshita, Shohei Kozai i Toru Shibata. "Target coverage of daily cone-beam computed tomography in breath-hold image-guided radiotherapy for gastric lymphoma". BJR|Open 3, nr 1 (styczeń 2021): 20200062. http://dx.doi.org/10.1259/bjro.20200062.
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Objectives: We evaluated retrospectively the daily target coverage using cone-beam computed tomography (CBCT) in breath-hold image-guided radiotherapy (BH-IGRT) for gastric lymphoma. Methods: BH-IGRT was performed using a prescribed dose of 30.6 Gy in 17 fractions for the whole stomach. We assessed the target coverage of the whole stomach on daily CBCT images [daily clinical target volume (CTV)], which was delineated individually by two observers. We evaluated V95% (percentage of volume receiving ≥95% of the prescribed dose) of daily CTV. Results: In total, 102 fractions from 6 patients were assessed. The mean V95% of daily CTV was 97.2%, which was over 95%. In two of six patients, the V95% of daily CTV was over 95% for either observer in all fractions. One patient had significant interobserver variation (p = 0.013). In 95 fractions (93%), the V95% of daily CTV was over 95% for either observer. Conclusion: Daily target coverage for CTV in BH-IGRT for gastric lymphoma seems to be favorable, even when using CBCT. Advances in knowledge: A previous study ascertained good daily target coverage in BH-IGRT for gastric lymphoma using in-room CT. Even when using CBCT in our study, daily target coverage for CTV in BH-IGRT for gastric lymphoma seems to be favorable.
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Kang, Sung-Hwan, Yong-Duo Sun, Osama O. Atallah, Jose Carlos Huguet-Tapia, Jerald D. Noble i Svetlana Y. Folimonova. "A Long Non-Coding RNA of Citrus tristeza virus: Role in the Virus Interplay with the Host Immunity". Viruses 11, nr 5 (14.05.2019): 436. http://dx.doi.org/10.3390/v11050436.
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During infection, Citrus tristeza virus (CTV) produces a non-coding subgenomic RNA referred to as low-molecular-weight tristeza 1 (LMT1), which for a long time has been considered as a by-product of the complex CTV replication machinery. In this study, we investigated the role of LMT1 in the virus infection cycle using a CTV variant that does not produce LMT1 (CTV-LMT1d). We showed that lack of LMT1 did not halt virus ability to replicate or form proper virions. However, the mutant virus demonstrated significantly reduced invasiveness and systemic spread in Nicotiana benthamiana as well as an inability to establish infection in citrus. Introduction of CTV-LMT1d into the herbaceous host resulted in elevation of the levels of salicylic acid (SA) and SA-responsive pathogenesis-related genes beyond those upon inoculation with wild-type (WT) virus (CTV-WT). Further analysis showed that the LMT1 RNA produced by CTV-WT or via ectopic expression in the N. benthamiana leaves suppressed SA accumulation and up-regulated an alternative oxidase gene, which appeared to mitigate the accumulation of reactive oxygen species. To the best of our knowledge, this is the first report of a plant viral long non-coding RNA being involved in counter-acting host response by subverting the SA-mediated plant defense.
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Brlansky, R. H., V. D. Damsteegt, D. S. Howd i A. Roy. "Molecular Analyses of Citrus tristeza virus Subisolates Separated by Aphid Transmission". Plant Disease 87, nr 4 (kwiecień 2003): 397–401. http://dx.doi.org/10.1094/pdis.2003.87.4.397.
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Citrus tristeza virus (CTV) exists in field isolates as a complex of virus isolates. This complex may contain both mild and severe CTV. Using single and multiple aphid transmissions, subiso-lates of the various field isolates were separated. Some CTV isolates that tested negative with the monoclonal antibody MCA13 consisted of MCA13-positive subisolates. Using primers to specific and variable regions of the CTV genome, molecular profiles of the isolates and subisolates were generated and compared. The profiles of the subisolates sometimes were very different from the parent field isolates from which they were transmitted.
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Bessarabova, K. S., A. V. Mikhailova, I. M. Lebedenko i T. A. Krylova. "Evaluation of CTV to PTV Margin for Head and Neck Cancer with Daily Setup Using MVCBCT Imaging". Meditsinskaya Fizika 94, nr 2 (12.07.2022): 5–11. http://dx.doi.org/10.52775/1810-200x-2022-94-2-5-11.
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Purpose: Geometrical inaccuracies of setup using MV-CBCT imaging for patients with head and neck cancer were evaluated. Possibility of modifying of CTV to PTV margin while delineation of such tumors was estimated. Materials and methods: Additional adjustment of simulation kV CT pictures with MV-CBCT images received during the implementation of the online protocol was conducted for 35 patients with head and neck cancer. Offline analysis revealed the discrepancy in the results of online correction and offline analyses. CTV to PTV margin considering daily setup was computed. Results: Obtained values of CTV to PTV margin: 2.4 mm in Vrt, 2.1 mm in Lng and 2.5 mm in Lat. Upward variations from 5 mm margin used in unit were registered for 2 patients. Conclusions: Reduction of CTV to PTV margin up to 2.5 mm is precarious because CTV dose coverage is not reasonable for all patients. Implementation of routine work practice in Off-line Review is required for identification of problem cases and determination of individual CTV to PTV margin.
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Nurhadi, Nurhadi, Kamaruzaman Sijam i Inon Sulaiman. "PRODUCTION OF POLYCLONAL ANTIBODY TO THE COAT PROTEIN OF CITRUS TRISTEZA VIRUS IN CHICKEN EGGS". Indonesian Journal of Agricultural Science 4, nr 1 (25.10.2016): 18. http://dx.doi.org/10.21082/ijas.v4n1.2003.18-26.
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Citrus tristeza virus (CTV) is one of the most destructive diseases in many citrus growing areas of Indonesia. Effective strategies for controlling CTV depend on diagnostic procedure namely enzyme-linked immunosorbent assay (ELISA). Study aimed to purify the CTV antigen and produced its polyclonal antibody. Virion of the severe CTV isolate designated UPM/ T-002 was concentrated by polyethylene glycol (PEG) precipitation combined with low speed centrifugation. Semipurified antigen was further purified by sodium dodecyl sulphatepolyacrylamide gel electrophoresis (SDS-PAGE). The specific coat protein (CP) band of CTV with molecular weight of 25 kD was excised and eluted using elution buffer containing 0.25 M Tris-HCl pH 6.8 + 0.1% SDS, then used as antigen for injection into 6-month-old female of White Leghorn chicken. Results, showed than the specific polyclonal antibody raised against the 25-kDa CP had a titer of approximately 104, gave low background reaction with healthy plant sap and reacted specifically with CTV isolates. The reaction was equally strong for a severe, a moderate, a mild, and a symptomless isolate, suggesting a broad reaction range of this antibody toward different CTV isolates. Optimal virus titer can be obtained since virus loss during purification could be minimized and the highly purified antigen as an immunogen could be obtained by cutting out the CP band from SDS-PAGE gels. Large amount of highly titer of CTV antibody can be produced in chicken egg. The simplicity of the procedure makes it economically acceptable and technically adoptable because the antibody can be produced in basic laboratory.
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Nurhadi, Nurhadi, Kamaruzaman Sijam i Inon Sulaiman. "PRODUCTION OF POLYCLONAL ANTIBODY TO THE COAT PROTEIN OF CITRUS TRISTEZA VIRUS IN CHICKEN EGGS". Indonesian Journal of Agricultural Science 4, nr 1 (25.10.2016): 18. http://dx.doi.org/10.21082/ijas.v4n1.2003.p18-26.
Pełny tekst źródłaStreszczenie:
Citrus tristeza virus (CTV) is one of the most destructive diseases in many citrus growing areas of Indonesia. Effective strategies for controlling CTV depend on diagnostic procedure namely enzyme-linked immunosorbent assay (ELISA). Study aimed to purify the CTV antigen and produced its polyclonal antibody. Virion of the severe CTV isolate designated UPM/ T-002 was concentrated by polyethylene glycol (PEG) precipitation combined with low speed centrifugation. Semipurified antigen was further purified by sodium dodecyl sulphatepolyacrylamide gel electrophoresis (SDS-PAGE). The specific coat protein (CP) band of CTV with molecular weight of 25 kD was excised and eluted using elution buffer containing 0.25 M Tris-HCl pH 6.8 + 0.1% SDS, then used as antigen for injection into 6-month-old female of White Leghorn chicken. Results, showed than the specific polyclonal antibody raised against the 25-kDa CP had a titer of approximately 104, gave low background reaction with healthy plant sap and reacted specifically with CTV isolates. The reaction was equally strong for a severe, a moderate, a mild, and a symptomless isolate, suggesting a broad reaction range of this antibody toward different CTV isolates. Optimal virus titer can be obtained since virus loss during purification could be minimized and the highly purified antigen as an immunogen could be obtained by cutting out the CP band from SDS-PAGE gels. Large amount of highly titer of CTV antibody can be produced in chicken egg. The simplicity of the procedure makes it economically acceptable and technically adoptable because the antibody can be produced in basic laboratory.
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Powell, C. A., R. R. Pelosi, M. S. Burton, P. A. Rundell, M. A. Ritenour i R. C. Bullock. "Natural Field Spread of Decline and Nondecline Inducing Isolates of Citrus Tristeza Virus in Florida after the Introduction of the Brown Citrus Aphid". HortScience 40, nr 3 (czerwiec 2005): 691–93. http://dx.doi.org/10.21273/hortsci.40.3.691.
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The effectiveness of seven different aphid control regimes in delaying movement of decline (DI) and nondecline (NDI) inducing isolates of citrus tristeza virus (CTV) into a CTV-free sweet orange scion on sour orange rootstock block was monitored annually for 5 years beginning in 1999, 2 years after the introduction of the brown citrus aphid (BrCA) into the region. After 5 years, the mean percentages of infection with DI CTV were 19, 19, 17, 29, 23, 19, or 14 for trees treated annually with imidocloprid, every 6 months with imidocloprid, every 3 months with imidocloprid, every 2 months with imidocloprid, annually with Temik, annually with Meta Systox-R, or untreated, respectively. The mean percentages of infection (after 5 years) with only NDI isolates of CTV for the seven treatments were 40, 31, 33, 38, 38, 38, or 33. There was no significant difference (after 5 years) among either the DI or NDI CTV treatment means. The overall 5-year infection percentage for DI CTV (20%) was somewhat lower than that reported before the introduction of the BrCA (27%) (11). Aphid densities (Toxoptera citricidus and Aphis spiraecola) varied considerably from year to year. Good aphid control was achieved with all four imidocloprid treatments, but not with Temik or Meta Systox-R. The level of aphid control did not influence overall CTV infection percentages.
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Yang, Zhong-Nan, Xin-Rong Ye, Sandong Choi, Joe Molina, Francis Moonan, Rod A. Wing, Mikeal L. Roose i T. Erik Mirkov. "Construction of a 1.2-Mb contig including the citrus tristeza virus resistance gene locus using a bacterial artificial chromosome library of Poncirus trifoliata (L.) Raf." Genome 44, nr 3 (1.06.2001): 382–93. http://dx.doi.org/10.1139/g01-021.
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The citrus tristeza virus resistance gene (Ctv) is a single dominant gene in Poncirus trifoliata, a sexually compatible relative of citrus. To clone this gene, a bacterial artificial chromosome (BAC) library has been constructed from an individual plant that was homozygous for Ctv. This library contains 45 696 clones with an average insert size of 80 kb, corresponding to 9.6 genome equivalents. Screening of the BAC library with five chloroplast DNA probes indicated that 0.58% of the BAC clones contained chloroplast-derived inserts. The chromosome walk across the Ctv locus was initiated using three closely linked genetic markers: C19, AD8, and Z16. The walk has been completed and a contig of ca. 1.2 Mb was constructed. Based on new data, the genetic map in the Ctv region was revised, with Ctv being located between AD8-Z16 and C19 at distances of 1.2 and 0.6 cM, respectively. Utilizing DNA fragments isolated from the contig as RFLP markers, the Ctv locus was further mapped to a region of ca. 300 kb. This contig contains several putative disease-resistance genes similar to the rice Xa21 gene, the tomato Cf-2 gene, and the Arabidopsis thaliana RPS2 gene. This library will therefore allow cloning of Ctv and other putative disease-resistance genes.Key words: Poncirus, citrus tristeza virus, chromosome walk, resistance gene.
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Muijs, Christina T., Justin K. Smit, Arend Karrenbeld, Jannet C. Beukema, Johannes A. Langendijk i John Theodorus Plukker. "Standardized pathologic evaluation of the esophagus after neoadjuvant chemoradiation." Journal of Clinical Oncology 30, nr 4_suppl (1.02.2012): 136. http://dx.doi.org/10.1200/jco.2012.30.4_suppl.136.
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136 Background: The main objective of this study was to develop and validate a method to reconstruct the gross and clinical tumor volume (GTV and CTV) on the esophageal specimen in order to facilitate a good pathologic examination of the original tumor area after neo-adjuvant chemoradiation (CRT). Methods: The GTV and CTV borders of 25 patients were defined by a radiation oncologist on the planning CT in relation to 5 anatomical reference points. After CRT, the GTV and CTV borders were marked in vivo on the esophagus during surgical resection. Finally, the pathologist evaluated the presence of macroscopic and microscopic tumor in- and outside the GTV and CTV. The radiation tumor response was scored according to the standardized 5-tier Mandard classification. Radiation induced side effects were scored as well. Results: The Mandard classification could be scored on basis of the GTV alone in 68% of the cases (N=17). For the other patients (N=8), the GTV and the CTV should both be incorporated for correct evaluation of the tumor response. Five patients (20%) showed complete tumor response (Mandard 1), 68% (N=17) showed partial response (Mandard 2-3) and 12% (N=3) showed hardly any response (Mandard 4-5). In the partial responders, macroscopic tumor was found within the delineated GTV and microscopic tumor remained within the CTV both in 100% of the cases. In two patients (40%) with hardly any response, microscopic tumor was also found outside the CTV. This might be caused by tumor growth during the neo-adjuvant treatment or by geographical miss. Nine patients turned out to have positive lymph nodes. On average 18 (range 8-30) lymph nodes were evaluated per patients. Giant cell reactions, lymphocyte infiltration, and fibrosis, which indicate tumor regression were seen in the CTV and GTV, and were most pronounced in the GTV. Conclusions: This study suggested that demarcation of the GTV and CTV on the esophagus in vivo is important for standardized pathologic evaluation of the esophagus after neo-adjuvant chemoradiation. Furthermore using this method we determined microscopic tumor outside the CTV in 40% of the cases (N=2) of the bad responders (Mandard 4-5), illustrating the importance of our method in this patient category.
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Saibishkumar, E. P., D. Iupati, J. Borg i K. Fernandes. "Is it possible to get adequate dose coverage of a clinical target volume (CTV) to account for the possible extra capsular extension in early-stage prostate cancer by low dose rate (LDR) brachytherapy?" Journal of Clinical Oncology 29, nr 7_suppl (1.03.2011): 98. http://dx.doi.org/10.1200/jco.2011.29.7_suppl.98.
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98 Background: There is no consensus for the definition and evaluation of CTV in post-implant setting for LDR prostate brachytherapy to account for extra capsular extension in clinically localized prostate cancer. In this study, we defined a CTV and evaluated its dosimetry in the post implant CT/MR scans done at 1 month after the LDR brachytherapy procedure. Methods: The initial consecutive 71 patients who underwent LDR brachytherapy under a single physician at Princess Margaret Hospital from June 2009 to July 2010 were included in this retrospective study. On the post implant MRI, the CTV was created by adding 3mm uniform margins around the prostate but respecting the anatomical boundaries like bone, bladder and rectum. Post implant dosimetry was based on CT/MR fusion using the dosimetric parameters V80, V90, V100, V150, V200, D80, D90 and D100. Implants were qualified as optimal if their V100 was >85% and D90 was >90% for both prostate and CTV. Univariate analysis was performed to evaluate associations of factors with V100 and D90 for the CTV using Wilcoxon rank sum test and Fisher's exact test. Results: The mean (SD) prostate V100 and D90 were 95.5% (4.2) and 117% (10) respectively with only 1 patient having sub optimal implant (V100 <85% and D90 <90%). The mean (SD) V100 and D90 for the CTV were also acceptable at 90.6% (4.9) and 103% (9), respectively. Six patients had V100 <85% and 7 patients had D90 <90% for the CTV. On univariate analysis, edema and seed implantation technique correlated with sub-optimal implant for the CTV. The mean (SD) edema for patients with V100 <85% was 18% (10) and with D90 <90% was 15% (12). The corresponding values for the optimal implants both in terms of V100 and D90 were 3% (13). Patients implanted with exclusively loose seeds (15 patients only) had higher incidence of sub-optimal implants (26%) compared to patients who had strands on the antero-lateral margins (56 patients; 3.5%). Conclusions: In this study, adequate dose coverage of CTV was achieved in most patients with current technique but implants with optimal dosimetry to prostate still may have sub-optimal D90 and V100 for the CTV. No significant financial relationships to disclose.
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Roy, Avijit, Nandlal Choudhary, John S. Hartung i R. H. Brlansky. "The Prevalence of the Citrus tristeza virus Trifoliate Resistance Breaking Genotype Among Puerto Rican Isolates". Plant Disease 97, nr 9 (wrzesień 2013): 1227–34. http://dx.doi.org/10.1094/pdis-01-12-0012-re.
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Citrus tristeza virus (CTV) isolates have been grouped into six genotypes: T3, T30, T36, VT, B165, and resistance breaking (RB) based on symptoms, host range, and genomic sequence data. The RB genotype has recently been identified with the novel property of replicating in trifoliate orange trees, a resistant host for the other five genotypes. Puerto Rican CTV isolate B301 caused mild vein clearing symptoms in Mexican lime but did not induce seedling yellows or stem pitting reactions in appropriate indicator Citrus spp., which are typical host reactions of the isolate T30. The isolate B301 was not detected by the genotype specific primer (GSP), which identifies the CTV-T3, -T30, -T36, -VT, and B165 genotypes. A primer pair for reverse transcription polymerase chain reaction (RT-PCR) amplification of the CTV-RB genotype was designed from the heat shock protein (p65) region based on the complete genomic sequences of trifoliate RB isolates from New Zealand available in the GenBank databases. The amplicon sequence from isolate B301 was 98% identical to that of the other trifoliate RB isolates. In addition, B301 was successfully inoculated into ‘Carrizo citrange’ (a trifoliate hybrid) but did not induce any symptoms. Furthermore, the complete genome sequence of B301 followed by the phylogenetic analysis revealed that the isolate is part of the RB clade with other CTV-RB isolates from New Zealand and Hawaii. Additional CTV isolates obtained from Puerto Rico were tested with the RB-GSP and confirmed the presence of trifoliate RB isolates in mixed infection with known CTV genotypes. Although this is the first report of a CTV trifoliate RB genotype from Puerto Rico, this genotype was present there prior to 1992.
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Vázquez, Carolina, Michele Carmo-Sousa, Joao Roberto Spotti Lopes, Alberto Fereres i Aranzazu Moreno. "Aphids Are Unable to Ingest Phloem Sap from the Peduncles of Lime Fruits". Plants 9, nr 11 (10.11.2020): 1528. http://dx.doi.org/10.3390/plants9111528.
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Citrus exports to Europe are regulated enforcing that fruits shall be free from peduncles and leaves, as they represent an important pathway for the entrance of non-European (non-EU) Citrus tristeza virus (CTV) isolates into the European Community. Aphids, are the vectors of CTV and could potentially feed on peduncles of imported fruits and thus spread non-EU isolates of CTV across Europe. We studied the probing behaviour of the main vectors of CTV (Aphis (Toxoptera) citricidus and Aphis gossypii) on lime leaves and peduncles to assess whether they could potentially transmit the virus. Aphids placed on peduncles rejected probing and feeding, tried to escape and spent most of their time on non-probing activities. Our work demonstrated that both A. citricidus and A. gossypii could not ingest sap from the phloem of lime peduncles, as phloem ingestion was never observed. This implies that aphids would not be able to acquire CTV from an infected fruit peduncle and transmit it to a susceptible plant. Our study supports that citrus exports with fruit peduncles to Europe may not be a real risk for the introduction of non-EU isolates of CTV to the European Community.
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Guarino, Salvatore, Francesco Mercati, Sergio Fatta Del Bosco, Antonio Motisi i Loredana Abbate. "Rootstocks with Different Tolerance Grade to Citrus Tristeza Virus Induce Dissimilar Volatile Profile in Citrus sinensis and Avoidance Response in the Vector Aphis gossypii Glover". Plants 11, nr 24 (8.12.2022): 3426. http://dx.doi.org/10.3390/plants11243426.
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The citrus tristeza virus (CTV) is an agent of devastating epidemics of the citrus plant grafted on Citrus aurantium, one of the main rootstocks still used in the Mediterranean area. Consequently, CTV-tolerant alternative citrus rootstocks are considered necessary to manage this disease and/or its vector; that in Mediterranean countries is the aphid Aphis gossypii. In this study, we analyzed the VOCs emitted from Citrus sinensis plants grafted on the CTV-susceptible C. aurantium and on the CTV-tolerant Volkamer lemon, Forner-Alcaide no. 5, and Carrizo citrange. Furthermore, the aphid preference/avoidance response toward these combinations was evaluated in a semi-field experiment. The VOC profiles recorded on the leaves of C. sinensis grafted on the four rootstocks listed above showed significant differences in the abundances and ratios of the compounds emitted. The behavioral experiments indicated that A. gossypii prefers to orient and establish on the C. sinensis plants grafted on C. aurantium rather than on that grafted on the three CTV-tolerant varieties. The possibility that this avoidance mechanism is triggered by the different profile of the VOC emitted by the different combinations and the consequent susceptibility/tolerance shown toward CTV is discussed.