Relevant bibliographies by topics / Virulent factors

Academic literature on the topic 'Virulent factors'

Author: Grafiati
Published: 10 December 2022
Last updated: 28 January 2023

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Journal articles on the topic "Virulent factors"

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Tan, Y. P., Q. Lin, X. H. Wang, S. Joshi, C. L. Hew, and K. Y. Leung. "Comparative Proteomic Analysis of Extracellular Proteins of Edwardsiella tarda." Infection and Immunity 70, no. 11 (November 2002): 6475–80. http://dx.doi.org/10.1128/iai.70.11.6475-6480.2002.

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ABSTRACT A comparison of extracellular proteins of virulent and avirulent Edwardsiella tarda strains revealed several major, virulent-strain-specific proteins. Proteomic analysis identified two of the proteins in the virulent strain PPD130/91 as flagellin and SseB, which are virulence factors in bacterial pathogens. PCR amplification and DNA sequencing confirmed the presence of the genes that encode these proteins. Our results clearly demonstrated the potency of the proteomic approach in identifying virulence factors.
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ERDENLIG, SEVIL, A. JERALD AINSWORTH, and FRANK W. AUSTIN. "Pathogenicity and Production of Virulence Factors by Listeria monocytogenes Isolates from Channel Catfish." Journal of Food Protection 63, no. 5 (May 1, 2000): 613–19. http://dx.doi.org/10.4315/0362-028x-63.5.613.

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Pathogenicity of four channel catfish Listeria monocytogenes isolates (CCF1, CCF4, HCC7, and HCC23) was examined in a comparative manner with virulent type strains L. monocytogenes ATCC 19115 and EGD and avirulent type strain ATCC 15313 in BDF and A/J mice. Isolates HCC7 and CCF1 (both serovar 1) caused similar percent mortalities and 50% lethal concentration values when compared with virulent type strains and were therefore considered pathogenic. The presence of the virulence factors listeriolysin (LLO), phosphotidylcholine-phospholipase (PC-PLC), and phosphotidylinositol-phospholipase (PI-PLC) was determined using specific activity tests. The virulent catfish isolates were positive for production of LLO, PCPLC, and PI-PLC. However, catfish isolate HCC23 was not virulent in mice despite being hemolytic, suggesting that not every hemolytic L. monocytogenes strain is virulent. With the exception of HCC7, all virulent strains displayed enhanced LLO production in a special stress medium, whereas almost undetectable LLO activity was present when catfish isolates and virulent type strain L. monocytogenes were grown in a rich medium such as brain heart infusion. Avirulent strains were found to lack or have decreased expression of LLO, PC-PLC, or PI-PLC.
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Grim, Christopher J., Elena V. Kozlova, Duraisamy Ponnusamy, Eric C. Fitts, Jian Sha, Michelle L. Kirtley, Christina J. van Lier, et al. "Functional Genomic Characterization of Virulence Factors from Necrotizing Fasciitis-Causing Strains of Aeromonas hydrophila." Applied and Environmental Microbiology 80, no. 14 (May 2, 2014): 4162–83. http://dx.doi.org/10.1128/aem.00486-14.

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ABSTRACTThe genomes of 10Aeromonasisolates identified and designatedAeromonas hydrophilaWI, Riv3, and NF1 to NF4;A. dhakensisSSU;A. jandaeiRiv2; andA. caviaeNM22 and NM33 were sequenced and annotated. Isolates NF1 to NF4 were from a patient with necrotizing fasciitis (NF). Two environmental isolates (Riv2 and -3) were from the river water from which the NF patient acquired the infection. While isolates NF2 to NF4 were clonal, NF1 was genetically distinct. Outside the conserved core genomes of these 10 isolates, several unique genomic features were identified. The most virulent strains possessed one of the following four virulence factors or a combination of them: cytotoxic enterotoxin, exotoxin A, and type 3 and 6 secretion system effectors AexU and Hcp. In a septicemic-mouse model, SSU, NF1, and Riv2 were the most virulent, while NF2 was moderately virulent. These data correlated with high motility and biofilm formation by the former three isolates. Conversely, in a mouse model of intramuscular infection, NF2 was much more virulent than NF1. Isolates NF2, SSU, and Riv2 disseminated in high numbers from the muscular tissue to the visceral organs of mice, while NF1 reached the liver and spleen in relatively lower numbers on the basis of colony counting and tracking of bioluminescent strains in real time byin vivoimaging. Histopathologically, degeneration of myofibers with significant infiltration of polymorphonuclear cells due to the highly virulent strains was noted. Functional genomic analysis provided data that allowed us to correlate the highly infectious nature ofAeromonaspathotypes belonging to several different species with virulence signatures and their potential ability to cause NF.
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França, Angela, Vânia Gaio, Nathalie Lopes, and Luís D. R. Melo. "Virulence Factors in Coagulase-Negative Staphylococci." Pathogens 10, no. 2 (February 4, 2021): 170. http://dx.doi.org/10.3390/pathogens10020170.

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Coagulase-negative staphylococci (CoNS) have emerged as major pathogens in healthcare-associated facilities, being S. epidermidis, S. haemolyticus and, more recently, S. lugdunensis, the most clinically relevant species. Despite being less virulent than the well-studied pathogen S. aureus, the number of CoNS strains sequenced is constantly increasing and, with that, the number of virulence factors identified in those strains. In this regard, biofilm formation is considered the most important. Besides virulence factors, the presence of several antibiotic-resistance genes identified in CoNS is worrisome and makes treatment very challenging. In this review, we analyzed the different aspects involved in CoNS virulence and their impact on health and food.
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Mroczyńska, Martyna, and Anna Brillowska-Dąbrowska. "Virulence of Clinical Candida Isolates." Pathogens 10, no. 4 (April 12, 2021): 466. http://dx.doi.org/10.3390/pathogens10040466.

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The factors enabling Candida spp. infections are secretion of hydrolytic enzymes, adherence to surfaces, biofilm formation or morphological transition, and fitness attributes. The aim of this study was to investigate the correlation between known extracellular virulence factors and survival of Galleria mellonella larvae infected with clinical Candida. The 25 isolates were tested and the activity of proteinases among 24/24, phospholipases among 7/22, esterases among 14/23, hemolysins among 18/24, and biofilm formation ability among 18/25 isolates was confirmed. Pathogenicity investigation using G. mellonella larvae as host model demonstrated that C. albicans isolates and C. glabrata isolate were the most virulent and C. krusei isolates were avirulent. C. parapsilosis virulence was identified as varied, C. inconspicua were moderately virulent, and one C. palmioleophila isolate was of low virulence and the remaining isolates of this species were moderately virulent. According to our study, virulence of Candida isolates is related to the expression of proteases, hemolysins, and esterases.
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de Leeuw, Olav S., Guus Koch, Leo Hartog, Niek Ravenshorst, and Ben P. H. Peeters. "Virulence of Newcastle disease virus is determined by the cleavage site of the fusion protein and by both the stem region and globular head of the haemagglutinin–neuraminidase protein." Journal of General Virology 86, no. 6 (June 1, 2005): 1759–69. http://dx.doi.org/10.1099/vir.0.80822-0.

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Virulence of Newcastle disease virus (NDV) is mainly determined by the amino acid sequence surrounding the fusion (F) protein cleavage site, since host proteases that cleave the F protein of virulent strains are present in more tissues than those that cleave the F protein of non-virulent strains. Nevertheless, comparison of NDV strains that carry exactly the same F protein cleavage site shows that significant differences in virulence still exist. For instance, virulent field strain Herts/33 with the F cleavage site 112RRQRRF117 had an intracerebral pathogenicity index of 1·88 compared with 1·28 for strain NDFLtag, which has the same cleavage site. This implies that additional factors contribute to virulence. After generating an infectious clone of Herts/33 (FL-Herts), we were able to map the location of additional virulence factors by exchanging sequences between FL-Herts and NDFLtag. The results showed that, in addition to the F protein cleavage site, the haemagglutinin–neuraminidase (HN) protein also contributed to virulence. The effect of the HN protein on virulence was most prominent after intravenous inoculation. Interestingly, both the stem region and the globular head of the HN protein seem to be involved in determining virulence.
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Uzelac, Aleksandra, Ivana Klun, Vladimir Ćirković, and Olgica Djurković-Djaković. "In Vivo and In Vitro Virulence Analysis of Four Genetically Distinct Toxoplasma gondii Lineage III Isolates." Microorganisms 8, no. 11 (October 31, 2020): 1702. http://dx.doi.org/10.3390/microorganisms8111702.

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Toxoplasma gondii archetypes II and III are mildly virulent, yet virulence of variant strains is largely unknown. While lineage II dominates in humans in Europe, lineage III strains are present in various intermediate hosts. In Serbia, lineage III represents 24% of the population structure and occurs most frequently in domestic animals, implying a significant presence in the human food web. In this study, the virulence of four genetically distinct lineage III variants was assessed in vivo and in vitro. In vivo, two strains were shown to be intermediately virulent and two mildly virulent, with cumulative mortalities of 69.4%, 38.8%, 10.7%, and 6.8%, respectively. The strain with the highest mortality has previously been isolated in Europe and may be endemic; the strain with the lowest mortality matches ToxoDB#54, while the remaining two represent novel genotypes. Identical alleles were detected at ROP5, ROP16, ROP18, and GRA15. A set of in vitro analyses revealed proliferation and plaque formation as virulence factors. Higher levels of expression of ENO2 in intermediately virulent strains point to enhanced metabolism as the underlying mechanism. The results suggest that metabolic attenuation, and possibly stage conversion, may be delayed in virulent strains.
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Chiu, Yi-Chun, Wei-Chen Tai, Seng-Kee Chuah, Ping-I. Hsu, Deng-Chyang Wu, Keng-Liang Wu, Chao-Cheng Huang, Ji-Chen Ho, Johannes Ring, and Wen-Chieh Chen. "The Clinical Correlations ofHelicobacter pyloriVirulence Factors and Chronic Spontaneous Urticaria." Gastroenterology Research and Practice 2013 (2013): 1–6. http://dx.doi.org/10.1155/2013/436727.

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Background and Study Aims. The association betweenHelicobacter pylori(H. pylori) and chronic spontaneous urticaria (CSU) remains controversial. This study explored the role ofH. pyloriin CSU among different virulent genotypes patients.Patients and Methods. Patients infected byH. pyloriwere sorted into two groups as group A (with CSU) and group B (without CSU). The tissue materials were taken via endoscopy for polymerase chain reaction study to determine virulence factors.AfterH. pylorieradication therapy, the eradication rate and response of urticaria were evaluated by using C13-UBT and a three-point scale (complete remission, partial remission, or no improvement).Results. The results were comparable between patients of groups A and B in terms ofH. pyloriinfection rates and eradication rate. Longitudinal follow-up of 23.5 months showed complete remission of urticaria in 63.6% but no improvement in 36.4% of the patients afterH. pylorieradication.H. pyloriinfected patients with different virulence factors such as cytotoxin-associated gene A, vacuolating cytotoxin gene A signal region and middle region have similar remission rates for CSU.Conclusions. Current study suggests thatH. pylorimay play a role in the development and disease course of CSU but may be irrelevant to different virulent genotypes.
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Beach, Nathan M., Robert B. Duncan, Calvert T. Larsen, Xiang-Jin Meng, Nammalwar Sriranganathan, and F. William Pierson. "Comparison of 12 turkey hemorrhagic enteritis virus isolates allows prediction of genetic factors affecting virulence." Journal of General Virology 90, no. 8 (August 1, 2009): 1978–85. http://dx.doi.org/10.1099/vir.0.010090-0.

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Turkey hemorrhagic enteritis virus (THEV) is a member of the genus Siadenovirus and causes disease in turkey poults characterized by splenomegaly, bloody diarrhoea and death. The mechanism responsible for intestinal lesion formation and mortality is not known, although there is strong evidence that it is immune-mediated. All strains of THEV are serologically indistinguishable, although there are naturally occurring avirulent strains of THEV that replicate efficiently in turkeys without the intestinal haemorrhage or mortality associated with more virulent strains. The purpose of this study was to determine which viral genes are involved in virulence. The full-length genome of an avirulent vaccine strain was sequenced and compared with the genome of a virulent field isolate from Israel that was sequenced in 1998. Comparison of the two 26.3 kb genomes revealed 49 nucleotide differences resulting in 14 putative amino acid changes within viral proteins. Sequencing of the regions surrounding the 14 missense mutations revealed variations in ORF1, E3 and the fiber (fib) knob domain in five additional strains with varying degrees of virulence. Complete sequences of these genes were determined in a total of 11 different strains of THEV. All strains had at least one missense mutation in ORF1, and all but two of the strains had one missense mutation in E3. At least one missense mutation was found in the fiber knob domain in six out of seven virulent strains. Sequence variation of ORF1, E3 and fib in strains of THEV with different phenotypes strongly indicates that these genes are the key factors affecting virulence.
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Susič, Nik, Sandra Janežič, Maja Rupnik, and Barbara Gerič Stare. "Whole Genome Sequencing and Comparative Genomics of Two Nematicidal Bacillus Strains Reveals a Wide Range of Possible Virulence Factors." G3: Genes|Genomes|Genetics 10, no. 3 (January 9, 2020): 881–90. http://dx.doi.org/10.1534/g3.119.400716.

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Bacillus firmus nematicidal bacterial strains are used to control plant parasitic nematode infestation of crops in agricultural production. Proteases are presumed to be the primary nematode virulence factors in nematicidal B. firmus degrading the nematode cuticle and other organs. We determined and compared the whole genome sequences of two nematicidal strains. Comparative genomics with a particular focus on possible virulence determinants revealed a wider range of possible virulence factors in a B. firmus isolate from a commercial bionematicide and a wild type Bacillus sp. isolate with nematicidal activity. The resulting 4.6 Mb B. firmus I-1582 and 5.3 Mb Bacillus sp. ZZV12-4809 genome assemblies contain respectively 18 and 19 homologs to nematode-virulent proteases, two nematode-virulent chitinase homologs in ZZV12-4809 and 28 and 36 secondary metabolite biosynthetic clusters, projected to encode antibiotics, small peptides, toxins and siderophores. The results of this study point to the genetic capability of B. firmus and related species for nematode virulence through a range of direct and indirect mechanisms.
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Dissertations / Theses on the topic "Virulent factors"

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Keller, Ninette. "Hypoglycaemia in virulent canine babesiosis prevalence and risk factors /." Diss., University of Pretoria, 2004. http://upetd.up.ac.za/thesis/available/etd-03082005-092252/.

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Kitahara, Nao. "Study on screening of novel pathogenic factors of Candida albicans by proteome analysis and its putative virulent mechanism." Kyoto University, 2016. http://hdl.handle.net/2433/215600.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第19774号
農博第2170号
新制||農||1040(附属図書館)
学位論文||H28||N4990(農学部図書室)
32810
京都大学大学院農学研究科応用生命科学専攻
(主査)教授 植田 充美, 教授 栗原 達夫, 教授 矢﨑 一史
学位規則第4条第1項該当
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Yang, Guowei. "Photorhabdus virulence factors." Thesis, University of Bath, 2005. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425889.

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Guttmann, Daniel Mark. "Bacillus thuringiensis virulence factors." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621944.

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Wright, K. "Genomics and virulence factors of Fusobacterium necrophorum." Thesis, University of Westminster, 2016. https://westminsterresearch.westminster.ac.uk/item/9ywy3/genomics-and-virulence-factors-of-fusobacterium-necrophorum.

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Fusobacterium necrophorum, a Gram negative, anaerobic bacterium, is a common cause of acute pharyngitis and tonsillitis and a rare cause of more severe infections of the head and neck. At the beginning of the project, there was no available genome sequence for F. necrophorum. The aim of this project was to sequence the F. necrophorum genome and identify and study its putative virulence factors contained using in silico and in vitro analysis. Type strains JCM 3718 and JCM 3724,F. necrophorum subspecies necrophorum (Fnn) and funduliforme (Fnf), respectively, and strain ARU 01 (Fnf), isolated from a patient with LS, were commercially sequenced by Roche 454 GS-FLX+ next generation sequencing and assembled into contigs using Roche GS Assembler. Sequence data was annotated semi-automatically, using the xBASE pipeline, BLASTp and Pfam. The F. necrophorum genome was determined to be approximately 2.1 – 2.3 Mb in size, with an estimated 1,950 ORFs and includes genes for a leukotoxin, ecotin, haemolysin, haemagglutinin, haemin receptor, adhesin and type Vb and Vc secretion systems. The prevalence of the leukotoxin gene was investigated in strains JCM 3718, JCM 3724 and ARU 01, as well as a clinical collection of 25 Fnf strains, identified using biochemical and molecular tests. The leukotoxin operon was found to be universal within the strain collection by PCR. HL-60 cells subjected to aliquots of concentrated high molecular weight culture supernatant, predicted to contain the secreted leukotoxins of strains JCM 3718, JCM 3724 and ARU 01, were killed in a dose-dependent manner. The cytotoxic effect of the leukotoxin against human donor white blood cells was also tested to validate the HL-60 assay. The differences in the results between the two assays were not statistically significant. Ecotin, a serine protease inhibitor, was found to be present in 100 % of the strain collection and had a highly conserved sequence with primary and secondary binding sites exposed on opposing sides of the protein. During enzyme inhibition studies, a purified recombinant F. necrophorum ecotin protein inhibited human neutrophil elastase, a protease that degrades bacteria at inflammation sites, and human plasma kallikrein, a component of the host clotting cascade. The recombinant ecotin also prolonged human plasma clotting times by up to 7-fold for the extrinsic pathway, and up to 40-fold for the intrinsic pathway. The genome sequence data provides important information about F. necrophorum type strains and enables comparative study between strains and subspecies. Results from the leukotoxin and ecotin assays can be used to build up an understanding of how the organism behaves during infection.
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Monteil, Vanessa. "Analyses phénotypiques et génotypiques de différentes souches de dengue : applications en épidémiologie et recherche de facteurs de virulence." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM5038.

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De 50 à 100 millions de cas de maladie de dengue sont recensés chaque année dans le monde. Le virus de la dengue présente aujourd’hui un problème de santé publique avec son émergence en Europe et particulièrement en France. L’infection par le virus peut être asymptomatique ou être responsable de trois pathologies: l’une avec des symptômes grippaux (DF), une autre avec des hémorragies modérées (DHF) et une dernière avec des hémorragies sévères entraînant un syndrome de choc (DSS).Les facteurs de l’hôte jouent un rôle important dans le développement de formes sévères mais les facteurs viraux impliqués restent peu décrits. Le but de ce travail de thèse était de mieux comprendre ces facteurs viraux au travers de l’étude des dynamiques de circulation de souches de dengue 3 génotype III en Afrique et de la caractérisation de trois souches de dengue de sérotype I du Cambodge. Ce travail nous a permis de mettre en évidence la circulation de variants pendant les épidémies, permettant de supposer que la présence de variants permet une meilleure dissémination, ainsi que des caractéristiques génotypiques et phénotypiques particulières in vitro aux souches associées aux formes hémorragiques et aux formes avec syndrome de choc chez l’homme. Ces travaux ont été complétés par le développement d’un système original de détection du virus de la dengue et des autres virus du genre Flavivirus. Ce travail de thèse a permis d’identifier de potentiels facteurs de virulence propres au virus, ouvrant la voie à la recherche sur le rôle de certaines protéines virales dans la pathogénicité
From 50 to 100 million cases of dengue illness occurred every year in the world. Today, dengue virus is a public health problem with its emergence in Europe, particularly in France. DENV infection can be asymptomatic or be responsible for three distinct pathologies: one with flu-like symptoms (DF), another with moderate hemorrhage (DHF) and the last one with severe bleeding leading to shock syndrome (DSS). Host factors have an important role in the development of severe forms but implicated viral virulence factors stay not well described. The aim of this research work was to better understand these viral factors through study of dengue serotype 3 genotype III dynamics of circulation in Africa and through the characterization of three dengue serotype 1 strains in Cambodia. This work highlighted the circulation of variants during epidemics, allowing us to suppose that the presence of variants permits a better dissemination, as well as specific phenotypic and genotypic characteristics in vitro of strains associated with hemorrhagic forms or forms with shock syndrome in humans. These works were completed by the development of an original system of detection of dengue virus and other viruses of genus Flavivirus. This research work allowed identifying potential virulence factor specific to virus, opening the way for research on the role of certain viral proteins in pathogenicity
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Ranc, Anne-Gaëlle. "Phenol Soluble Modulins et lipopolysaccharide de Legionella pneumophila : rôle dans la réponse immunitaire innée." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1010/document.

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Legionella pneumophila (Lp) est une bactérie ubiquitaire dans les environnements aqueux et responsable d’une pneumopathie potentiellement sévère : la légionellose. La majorité des souches impliquées appartiennent au sérogroupe 1 (Lp1) et à un sous- groupe spécifique de souches portant un épitope particulier dites mAb3/1+. Cependant, la différence de distribution entre les souches retrouvées dans l’environnement et celles impliquées en clinique n’est pas clairement élucidée. Notre travail a porté sur la détection de deux facteurs de virulence de Lp. Nous avons voulu mettre en évidence l’existence de Phenols Soluble Modulines (PSMs), peptides uniquement décrit chez Staphylocoques et avons ainsi pu démontrer l’activité de peptides prédits par analyse in silico chez Lp capables d’activer la réponse inflammatoire par la voie du NF-?B et sont dotés d’une action cytotoxique. Notre deuxième axe d’étude a porté sur le lipopolysaccharide (LPS) de Lp. Afin de vérifier si la prédominance de certaines souches était liée à un biais diagnostique, nous avons voulu tout d’abord vérifier la sensibilité de 3 tests urinaires diagnostiques envers le LPS extrait de souches de différents sous- groupes de Lp1 et sérogroupes de Lp et avons ainsi pu montrer que ces tests sont capables de détecter tous les LPS de Lp1. La sensibilité envers le LPS des autres sérogroupes est très variable mais reste insuffisante pour permettre leur détection. Nous avons ensuite utilisé ces LPS extraits pour vérifier la réponse immunitaire innée en fonction des souches de Lp1. Ainsi les souches mAb3/1+ activent moins le système immunitaire que les souches mAb3/1-, ce qui pourrait expliquer alors une moins bonne clairance de ces souches permettant leur multiplication à l’origine d’une infection. Au final, notre travail a permis d’étudier deux facteurs de virulence potentiels au sein de Lp, pouvant expliquer partiellement la prédominance de certaines souches en pathologie humaine
Legionella pneumophila (Lp) is a ubiquitous intracellular bacterium found widely in the environment and is the cause of an opportunistic infection named legionellosis. The majority of the strains involved belong to serogroup 1 (Lp1) and to a specific subgroup named mAb3/1+, linked to a specific epitope expressed at the cell membrane. However the distribution difference between the strains found in the environment and the ones involved in pathology is not fully understood. We here studied two virulence factors of Lp. We first demonstrated the existence of Phenols Soluble Modulines (PSMs), smalls peptides that only have been described for Staphylococcus and found that the peptides that were predicted for Lp by in silico analysis were able to activate the innate immune response by NF-?B pathway and were able to have a cytotoxic activity. We also studied the lipopolysaccharide (LPS) of Lp. To found out if the predominance of some strains was linked to a diagnosis biais, we first evaluated the sensitivity of 3 urinary antigens tests against extracted LPS of strains belonging to all the sous-groups of Lp1 and serogroups of Lp. We then demonstrated that those tests are able to detect all LPS of Lp1, independently of mAb3/1 character. The sensitivities of the 3 tests were very variable for the other serogroups of Lp, but were too low to be able to detect those LPS in practice. We then used these extracted LPS to evaluate the innate immune response for different strains of Lp1. We demonstrated that mAb3/1- strains needed lower dose of LPS to activate the innate immune response than mAb3/1+ strains, which could be linked to a better clearance of the bacteria from the host, which doesn’t develop an infection. This work has studied two potentially virulent factors of Lp, which could partially explain the predominance of some strains of Lp in human pathology
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Seixas, Rui Emanuel Antunes de. "Virulence of Salmonella typhimurium 1,4,[5],12:i:- : the new emergent strain." Doctoral thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2017. http://hdl.handle.net/10400.5/13925.

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Tese de Doutoramento em Ciências Veterinárias na Especialidade Sanidade Animal
Salmonella serovar 1,4,[5],12:i:- is presently considered one of the major serovars responsible for human salmonellosis worldwide. A multidisciplinary approach, including the fields of epidemiology, spatial statistics, clinical and applied microbiology was used to perform an extensive characterization of Salmonella 1,4,[5],12:i:- isolates obtained by the National Health Institute Dr. Ricardo Jorge, which was lacking due to the recent emergence. It was observed that cases are reported in most districts, being more frequent in the Portuguese coastland. Spatial statistical analysis showed a significant geographic clustering, pointing out for the importance of evaluating these areas to identify risk factors, in order to establish adequate prevention programs. The most relevant antimicrobial profile in this serovar is the tetra-resistance pattern (R-type ASSuT), displaying resistance to ampicillin, streptomycin, sulphonamides and tetracyclines. A high occurrence of R-type ASSuT isolates was observed in the isolates under study, with the majority harboring the resistance genes frequently associated with the European clone, namely blaTEM, sul2, straA-straB, tetB. Additionally, resistance to quinolones and 3rd generation cephalosporin was also detected. In Portugal, the rapid spread of Salmonella 1,4,[5],12:i:- R-type ASSuT might be related with the diversity of pulsotypes and also the presence of a core of virulence factors, including biofilm production. Biofilm-forming ability varied between sample locations and collection year, and can be one of the virulence features related with the rise of this serovar. Furthermore, biofilm formation was evaluated in vitro using a simulated human intestinal environment. In such conditions was observed an impairment of biofilm production, revealing that conditions mimicking the human intestinal tract can influence the biofilm-forming ability of the isolates under study. This research highlight the critical importance of close surveillance of Salmonella 1,4,[5],12:i:- in Portugal, including R-type ASSuT isolates. Information gathered may unravel Salmonella 1,4,[5],12:i:- features, prevent the dissemination to other regions and also benefit the medical community in order to rationalize salmonellosis antimicrobial therapeutics.
RESUMO - Virulência de Salmonella Typhimurium 1,4,[5],12:i:-, a nova estirpe pandémica* - Salmonella é uma bactéria Gram-negativa pertencente à família Enterobacteriaceae, sendo uma das principais responsáveis pela morbilidade e mortalidade associadas a toxinfecções alimentares. Pode manifestar-se num espectro de sintomatologia variado, incluindo a gastroenterite, a bacteriémia e a infecção focal. Este género incluí mais de 2600 serovares descritos, distribuídos por apenas duas espécies: Salmonella enterica que inclui todos os serovares patogénicos para os humanos e Salmonella bongori. Actualmente, um dos principais serovares responsáveis pela salmonelose humana em todo o mundo é o 1,4,[5],12:i:-. Este serovar é uma variante monofásica de Salmonella Typhimurium, muito semelhante a nível molecular, sendo caracterizado pela ausência da expressão do gene fljB. Devido à sua recente emergência, estudos que avaliem este serovar são escassos, particularmente em Portugal, o que definiu o âmbito desta investigação, que teve como objectivo a caracterização epidemiológica e microbiológica, tanto do ponto de vista fenotípico e genotípico, de isolados de Salmonella 1,4,[5],12:i:- obtidos em Portugal a partir de diferentes origens, incluindo amostras humanas, animais e ambientais. Numa primeira fase foi realizada uma caracterização demográfica, epidemiológica e espacial de todos os casos de Salmonelose 1,4,[5],12:i:- humana notificados em Portugal pelo Instituto Nacional de Saúde Dr. Ricardo Jorge (INSA), durante um período de 10 anos, desde 2001 a 2011. Foram recolhidos dados sobre a origem, ano e mês de amostragem, género, idade, distrito e município de residência dos pacientes. Foi realizada a análise estatística descritiva, bem como, a análise estatística espacial através do software SaTScan™, combinada com análise através de software de georeferenciação, o QGIS™, de forma a caracterizar a epidemiologia e identificar agrupamentos espaciais de risco superior de infecção por Salmonella 1,4,[5],12:i:- em Portugal. Globalmente, observou-se que em Portugal, a maioria dos distritos tem casos notificados de infecção por Salmonella 1,4,[5],12:i:-. Verificou-se também um aumento da incidência durante o intervalo de 2004 a 2011, com um maior número de casos na região litoral do país, incluindo distritos como Porto, Lisboa e Aveiro, o que pode ser explicado pela maior densidade populacional nestas áreas. A maioria das infecções ocorreu durante Maio e Outubro, e o menor número em Fevereiro, afectando principalmente indivíduos jovens.[...]*O autor escreve segundo o antigo Acordo Ortográfico
This work was supported by National Health Institute Doutor Ricardo Jorge (INSA) and funded by Centre for Interdisciplinary Research in Animal Health (CIISA)
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Scott, David Albert. "Virulence factors of oral anaerobic spirochetes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0001/NQ30378.pdf.

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Scott, David 1964 Jan 11. "Virulence factors of oral anaerobic spirochetes." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34446.

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The research work presented in this thesis involved the examination of several fundamental questions concerning the role of oral anaerobic spirochetes (OAS) in the etiology of periodontal disease (PD). OAS are unusual, helical, Gram-negative bacteria that are considered putative periodontopathogens due to numerical association with diseased sites and the enzymatic arsenal available to OAS that appears consistent with disease symptoms. T. denticola is the most commonly isolated OAS from periodontal pockets and as such is the focus of most investigations into the role of OAS in PD.
As free iron is severely limited in humans the means by which OAS may obtain sufficient iron to prosper in the sub-gingiva was examined. The resultant model suggests T. denticola obtains iron through the $ beta$-hemolysis of erythrocytes and the binding of liberated hemin by a 47-kDa outer membrane sheath (OMS) protein. The kinetics of the ligand-receptor interaction are presented and the receptor has been purified to apparent homogeneity from T. denticola. $ sp3$H-labeled hemin is not transported into the cell. Evidence is presented to show that T. denticola produces an iron reductase, which may facilitate the transport of ferrous iron across biological membranes. It is also shown that T. denticola (Td), T. vincentii (Tv) and T. socranskii (Ts) do not produce siderophores. In growth assays, under conditions of iron-limitation, T. denticola may use inorganic iron, a source unlikely to be available in vivo.
Hyaluronidase (Hase) activity is elevated in the gingival crevice during episodes of disease. Hase, when injected into the periodontal cavity under experimental conditions has been shown to result in connective tissue degradation. It is also known that T. pallidum, the agent of syphilis, produces a Hase that is critical to pathogenesis. Evidence is presented herein to show that Td, Tv and Ts all produce a hyauronoglucosaminidase (HGase). The identity and specificity of the Td HGase is confirmed through the use of enzyme inhibitors and activators, by electron microscope observations of the enzyme using the Hase inhibitor gold sodium thiomalate and anti-Apis mellifera venom antibodies and examination of the purity of the HA substrate using other polysaccharide degrading enzymes. As the HGase of these OAS would not migrate through a substrate-SDS PAGE system, we have employed hyaluronate (HA)- and chondroitin sulfate (CS)-absorbed nitrocellulose membranes to visualize HGase activity. The 59 kDa HGase of Td has been purified to apparent homogeneity through the conjugation of HA and CS to Affigel 701 beads.
The last subject to be addressed by this thesis pertains to the ultrastructure of oral spirochetes. Using the copper-containing dye, Alcian blue, we have shown that T. denticola produces an exopolysaccharide layer, in an electron microscopy investigation. The development of a stain for dark-field microscopy has simplified the observation of this layer. The exopolysaccharide layer may have relevance to the evasion of phagocytosis, to protection against colicins, immunoglobulins and bacteriophages, to adherence and perhaps to the immunogenicity of OAS inhabiting the sub-gingiva.
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Books on the topic "Virulent factors"

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Crowley, Dolores. Cloning virulence factors of clostridium difficile. [S.l: The Author], 1991.

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Johnson, Douglas I. Bacterial Pathogens and Their Virulence Factors. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-67651-7.

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Boquet, Patrice, and Emmanuel Lemichez, eds. Bacterial Virulence Factors and Rho GTPases. Berlin, Heidelberg: Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/3-540-27511-8.

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Regulation of bacterial virulence. Washington, DC: ASM Press, 2012.

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Urabi, Iftikhar. Virulence factors of verotoxin-producing Escherichia coli O157:H7. [s.l.]: typescript, 1993.

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Bacterial pathogenesis: Molecular and cellular mechanisms. Norfolk, UK: Caister Academic Press, 2012.

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Baloda, Suraj B. Potential salmonella virulence factors: Studies on toxins and cell-surface adhesins. Uppsala: Sveriges Lantbruksuniversitet, 1987.

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Cookson, Adrian Lawrence. The adherence and virulence factors of Prevotella intermedia and Prevotella nigrescens. Manchester: University of Manchester, 1996.

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Elwyn, Evans. Staphylococcus epidermidis: Effect of growth rate on surface properties and production of extracellular virulence factors. Manchester: University of Manchester, 1992.

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Patrick, S. Immunological and molecular aspects of bacterial virulence. Chichester: J. Wiley & Sons, 1995.

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Book chapters on the topic "Virulent factors"

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Gupta, Akshat, Anmol Srivastava, and Vishnu Agarwal. "Biofilm Detachment and Its Implication in Spreading Biofilm-Related Infections." In Proceedings of the Conference BioSangam 2022: Emerging Trends in Biotechnology (BIOSANGAM 2022), 3–13. Dordrecht: Atlantis Press International BV, 2022. http://dx.doi.org/10.2991/978-94-6463-020-6_2.

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AbstractBiofilms are a community of microorganisms formed on both abiotic and biotic surfaces. These colonies play a vital role in the virulent life cycle of bacteria. Bacteria communicate intrinsically and extrinsically to grow and eventually disperse their virulent factors, ultimately leading to diseases. Biofilm dispersion is the last stage in this life cycle; at this stage, the biofilm has completed maturation. The microorganism then disperses as the biofilm ruptures and assumes a planktonic lifestyle until they find a new surface to attach to and repeat the cycle. This mechanism plays a vital role in the pathogenicity of the microorganism and can be triggered prematurely to disrupt the microorganism's virulent nature. In this mini-review, we have summarized biofilm dispersion, its mechanisms, and the factors influenced by, focusing on their effect on the pathogen's virulence. We have also discussed the significance of quorum sensing and the modern methods used to develop quorum sensing inhibitors through in-silico approaches.
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Gooch, Jan W. "Virulence Factor." In Encyclopedic Dictionary of Polymers, 932. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_15100.

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Heilmann, Christine, and Friedrich Götz. "Staphylococcal Virulence Factors." In Biomaterials Associated Infection, 57–85. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-1031-7_3.

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Delden, Christian. "Virulence Factors in." In Pseudomonas, 3–45. Boston, MA: Springer US, 2004. http://dx.doi.org/10.1007/978-1-4419-9084-6_1.

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O’Donnell, Lindsay E., Douglas Robertson, and Gordon Ramage. "Candida Virulence Factors." In Oral Candidosis, 7–19. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-47194-4_2.

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Johnson, Douglas I. "Bacterial Virulence Factors." In Bacterial Pathogens and Their Virulence Factors, 1–38. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-67651-7_1.

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Johnson, Douglas I. "Anti-Virulence Factor Therapeutics." In Bacterial Pathogens and Their Virulence Factors, 439–61. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-67651-7_34.

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Wake, Akira, and Herbert R. Morgan. "Virulence Factors of Yersinia pestis." In Host-Parasite Relationships and the Yersinia Model, 185–234. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-71344-6_21.

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Bliven, Kimberly A., and Keith A. Lampel. "Shigella: Virulence Factors and Pathogenicity." In Foodborne Pathogens, 169–208. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-56836-2_7.

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Bhattacharya, Sayak, and Joydeep Mukherjee. "Microbial Infections and Virulence Factors." In Model Organisms for Microbial Pathogenesis, Biofilm Formation and Antimicrobial Drug Discovery, 1–18. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-1695-5_1.

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Conference papers on the topic "Virulent factors"

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"Virulent Factors Of Coral Pathogen Serratia Marcescens Associated With White Pox Disease Acropora formosa, Palk Bay, Southeast Coast Of India." In International Conference on Plant, Marine and Environmental Sciences. International Institute of Chemical, Biological & Environmental Engineering, 2015. http://dx.doi.org/10.15242/iicbe.c0115018.

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Crook, A. N., A. V. Domenican, N. E. Gogolev, Yu V. Gogolev, and E. A. Nikolaychik. "Two transcription factors of the LuxR family determine the virulent properties of Pectobacterium spp. through transcriptional control of one gene of the global regulator." In IX Congress of society physiologists of plants of Russia "Plant physiology is the basis for creating plants of the future". Kazan University Press, 2019. http://dx.doi.org/10.26907/978-5-00130-204-9-2019-239.

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Suntres, Z. E., and K. L. Kachur. "The Effect of Thymol on Pseudomonas Aeruginosa Virulence Factors." In American Thoracic Society 2019 International Conference, May 17-22, 2019 - Dallas, TX. American Thoracic Society, 2019. http://dx.doi.org/10.1164/ajrccm-conference.2019.199.1_meetingabstracts.a3690.

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Vychyk, P. V., and Y. A. Nikolaichik. "Identification of bacterial virulence factors based on an integration of experimental and in silico transcription factor target discovery." In 2nd International Scientific Conference "Plants and Microbes: the Future of Biotechnology". PLAMIC2020 Organizing committee, 2020. http://dx.doi.org/10.28983/plamic2020.278.

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Fernandez, Mark, Robert Suchland, and Kevin Hybiske. "P854 Interspecies chimeras: a tool to identify chlamydial virulence factors." In Abstracts for the STI & HIV World Congress (Joint Meeting of the 23rd ISSTDR and 20th IUSTI), July 14–17, 2019, Vancouver, Canada. BMJ Publishing Group Ltd, 2019. http://dx.doi.org/10.1136/sextrans-2019-sti.896.

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Naik, Deepak, Supriya Tilvi, and Lisette D’Souza. "Flavonoids from Rhizophora conjugata fruit extract blocks virulence factors of Pseudomonas aeruginosa." In Annual International Conference on Advances in Biotechnology. Global Science & Technology Forum (GSTF), 2015. http://dx.doi.org/10.5176/2251-2489_biotech15.72.

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MOXON, RICHARD, and CHRISTOPH TANG. "CHALLENGE OF INVESTIGATING BIOLOGICALLY RELEVANT FUNCTIONS OF VIRULENCE FACTORS IN BACTERIAL PATHOGENS." In The Activities of Bacterial Pathogens in Vivo - Based on Contributions to a Royal Society Discussion Meeting. IMPERIAL COLLEGE PRESS, 2001. http://dx.doi.org/10.1142/9781848161610_0009.

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Ebeling, Julia. "Characterization of virulence factors in the fatal honey bee disease American foulbrood." In 2016 International Congress of Entomology. Entomological Society of America, 2016. http://dx.doi.org/10.1603/ice.2016.112492.

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Rodrigues, M. V. Pimenta, C. Sena Martins de Souza, N. B. Teixeira, C. M. Castelo Branco Fortaleza, and M. L. Ribeiro de Souza da Cunha. "Methicillin-resistant Staphylococcus aureus in Brazil: classification of SCCmec and virulence factors." In Proceedings of the III International Conference on Environmental, Industrial and Applied Microbiology (BioMicroWorld2009). WORLD SCIENTIFIC, 2010. http://dx.doi.org/10.1142/9789814322119_0111.

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Baruel Vieira, Tais, Domingos Da Silva Leite, and Taila dos Santos Alves. "Shiga toxin-producing Escherichia coli and their associated serotypes and virulence factors." In XXV Congresso de Iniciação Cientifica da Unicamp. Campinas - SP, Brazil: Galoa, 2017. http://dx.doi.org/10.19146/pibic-2017-78593.

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Reports on the topic "Virulent factors"

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Splitter, Gary A., Menachem Banai, and Jerome S. Harms. Brucella second messenger coordinates stages of infection. United States Department of Agriculture, January 2011. http://dx.doi.org/10.32747/2011.7699864.bard.

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Aim 1: To determine levels of this second messenger in: a) B. melitensiscyclic-dimericguanosinemonophosphate-regulating mutants (BMEI1448, BMEI1453, and BMEI1520), and b) B. melitensis16M (wild type) and mutant infections of macrophages and immune competent mice. (US lab primary) Aim 2: To determine proteomic differences between Brucelladeletion mutants BMEI1453 (high cyclic-dimericguanosinemonophosphate, chronic persistent state) and BMEI1520 (low cyclicdimericguanosinemonophosphate, acute virulent state) compared to wild type B. melitensisto identify the role of this second messenger in establishing the two polar states of brucellosis. (US lab primary with synergistic assistance from the Israel lab Aim 3: Determine the level of Brucellacyclic-dimericguanosinemonophosphate and transcriptional expression from naturally infected placenta. (Israel lab primary with synergistic assistance from the US lab). B. Background Brucellaspecies are Gram-negative, facultative intracellular bacterial pathogens that cause brucellosis, the most prevalent zoonosis worldwide. Brucellosis is characterized by increased abortion, weak offspring, and decreased milk production in animals. Humans are infected with Brucellaby consuming contaminated milk products or via inhalation of aerosolized bacteria from occupational hazards. Chronic human infections can result in complications such as liver damage, orchitis, endocarditis, and arthritis. Brucellaspp. have the ability to infect both professional and non-professional phagocytes. Because of this, Brucellaencounter varied environments both throughout the body and within a cell and must adapt accordingly. To date, few virulence factors have been identified in B. melitensisand even less is known about how these virulence factors are regulated. Subsequently, little is known about how Brucellaadapt to its rapidly changing environments, and how it alternates between acute and chronic virulence. Our studies suggest that decreased concentrations of cyclic dimericguanosinemonophosphate (c-di-GMP) lead to an acute virulent state and increased concentrations of c-di-GMP lead to persistent, chronic state of B. melitensisin a mouse model of infection. We hypothesize that B. melitensisuses c-di-GMP to transition from the chronic state of an infected host to the acute, virulent stage of infection in the placenta where the bacteria prepare to infect a new host. Studies on environmental pathogens such as Vibrio choleraeand Pseudomonas aeruginosasupport a mechanism where changes in c-di-GMP levels cause the bacterium to alternate between virulent and chronic states. Little work exists on understanding the role of c-di-GMP in dangerous intracellular pathogens, like Brucellathat is a frequent pathogen in Israeli domestic animals and U.S. elk and bison. Brucellamust carefully regulate virulence factors during infection of a host to ensure proper expression at appropriate times in response to host cues. Recently, the novel secondary signaling molecule c-di-GMP has been identified as a major component of bacterial regulation and we have identified c-di-GMP as an important signaling factor in B. melitensishost adaptation. C. Major conclusions, solutions, achievements 1. The B. melitensis1453 deletion mutant has increased c-di-GMP, while the 1520 deletion mutant has decreased c-di-GMP. 2. Both mutants grow similarly in in vitro cultures; however, the 1453 mutant has a microcolony phenotype both in vitro and in vivo 3. The 1453 mutant has increased crystal violet staining suggesting biofilm formation. 4. Scanning electron microscopy revealed an abnormal coccus appearance with in increased cell area. 5. Proteomic analysis revealed the 1453 mutant possessed increased production of proteins involved in cell wall processes, cell division, and the Type IV secretion system, and a decrease in proteins involved in amino acid transport/metabolism, carbohydrate metabolism, fatty acid production, and iron acquisition suggesting less preparedness for intracellular survival. 6. RNAseq analysis of bone marrow derived macrophages infected with the mutants revealed the host immune response is greatly reduced with the 1453 mutant infection. These findings support that microlocalization of proteins involved in c-di-GMP homeostasis serve a second messenger to B. melitensisregulating functions of the bacteria during infection of the host.
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Glazer, Itamar, Alice Churchill, Galina Gindin, and Michael Samish. Genomic and Organismal Studies to Elucidate the Mechanisms of Infectivity of Entomopathogenic Fungi to Ticks. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7593382.bard.

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The overall goal of this research was to elucidate the factors affecting early development of Metarhizium spp. (previously named M. anisopliae) on ticks or tick cuticle extracts and the molecular basis of these early infection processes. The original objectives were: 1. Characterize the pre-penetration events (adhesion, germination and appressorium formation) of spores of M. anisopliae strains with high or low virulence during tick infection. 2. Create GFP-expressing strains of M. anisopliae tick pathogens having high and low virulence to compare their progress of infection by microscopy. 3. Use microarray analyses, primarily with existing M. anisopliae EST sequences in GenBank, to identify and characterize fungal genes whose expression is regulated in response to host cuticle extracts. Objective 3 was later modified (as approved by BARD) to use RNAseq to characterize the early stages of fungal gene expression during infection of intact host cuticles. This new method provides a massively larger and more informative dataset and allows us to take advantage of a) recently published genomes of Metarhizium robertsii and M. acridum for RNAseq data analysis, and b) newly developed and highly efficient cDNA sequencing technologies that are relatively low cost and, therefore, allow deep sequencing of multiple transcriptome samples. We examined pre-penetration and penetration events that differentiate high and low virulence strains of Metarhizium spp., focusing on spore adhesion, germination, appressorium formation, and penetration of tick integuments. Initiation of fungal infection was compared on susceptible and resistant tick species at different tick developmental stages. In vitro studies comparing the effects of protein and fatty acid profiles from tick cuticle extracts demonstrated that resistant tick cuticles contain higher concentrations of specific lipids that inhibit fungal development than do susceptible tick cuticles, suggesting one mechanism of Ixodidae resistance to fungal entomopathogens (Objective 1). We used molecular markers to determine that the three M. anisopliae strains from Israel that we studied actually were three distinct species. M. brunneum is highly virulent against the tick Rhipicephalus annulatus, M. pingshaense and M. robertsii are intermediate in virulence, and M. majus is of low virulence. We transformed all four Metarhizium species to express GFP and used them in pathogenicity assays against diverse tick species. Key findings were that a) resistant ticks inhibit Metarhizium infection prior to hemocoel invasion by reducing fungal viability on the cuticle surface (Objective 2), as was supported by the in vitro studies of Objective 1, and b) Metarhizium kills susceptible ticks after cuticle penetration but prior to hemocoel colonization. Transcriptome studies of the most virulent species, M. brunneum, are in progress and include analyses of ungerminated conidia and conidia germination and development on a low nutrient medium or on susceptible R. annulatus exoskeleton (Objective 3). We anticipate these studies will contribute to identifying fungal genetic factors that increase virulence and speed of kill and may help reveal tick chemistries that could be included in biocontrol formulations to increase efficacy. Methodologies developed to screen tick cuticle extracts for ability to support conidia germination and development may help in the selection of wild fungi with increased virulence against resistant ticks. The overall knowledge gained should contribute not only to the improvement of tick control but also to the control of other blood-sucking arthropods and related plant pests. Use of bio-based agents for controlling arthropods will contribute to a healthier, more sustainable environment and serve a growing number of organic food farmers.
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Liddington, Robert C. Structural Genomics of Bacterial Virulence Factors. Fort Belvoir, VA: Defense Technical Information Center, May 2004. http://dx.doi.org/10.21236/ada425660.

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DelVecchio, Vito G. Rapid Identification of Bacterial Virulence Factors. Fort Belvoir, VA: Defense Technical Information Center, April 2014. http://dx.doi.org/10.21236/ada625389.

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Samish, Michael, K. M. Kocan, and Itamar Glazer. Entomopathogenic Nematodes as Biological Control Agents of Ticks. United States Department of Agriculture, September 1992. http://dx.doi.org/10.32747/1992.7568104.bard.

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This research project was aimed to create a basis for the use of entomopathogenic nematodes (Steinernematidae an Heterorhabditidae) for biological control of ticks. The specific objectives were to determinate: 1) Nematode virulence to various. 2) Host-parasite interactions of nametodes and ticks. 3) Effect of environmental factors of tick habitats on nematode activity. 4) To test nematodes (anti tick activity) in defined field trials. Throughout the project 12 nematode strains from five species were tested in laboratory assays against all developmental stages of eight tick species. All tick species were found susceptible to nematode infection. The nematode strains the IS-5 and IS-12 of Heterorhabditis bacteriophora were found to be the most virulent. Engorged adults, particularly females, were the most susceptible stages. Despite the high susceptibility, ticks are not suitable hosts for nematode development and propagation. Entomopathogenic namatodes enter ticks and kill them by releasing the symbiotic bacteria from their foregut. Under favorable conditions, i.e. moist soil, moderate temperature (22-27oC) and sandy soil, nematode efficacy against B. annulatus engorged females was very high (>5% w/w) and high animal manure concentration in soil adversely effect nematode efficacy. In field trails, nematodes were effective when soil moisture was maintained at high levels. The results indicate that under favorable conditions the nematodes show promise as a biological control method for ticks. However, we still face several potential obstacles to the use of nematodes under less favorable conditions.
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Alagarsamy, Jeyashree, Ramya Seetharaman, Chandramouli Sivanandham, Karthickeyan Chella Krishnan, and Ross Overbeek. Connecting Sequence Data to Virulence Factors in Streptococcus Genomes. Office of Scientific and Technical Information (OSTI), March 2014. http://dx.doi.org/10.2172/1171190.

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Jones, Kathy R. Heliobactor pylori Virulence Factors and Their Role in Pathogenesis. Fort Belvoir, VA: Defense Technical Information Center, February 2011. http://dx.doi.org/10.21236/ad1013348.

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Swaminathan, Subramanyam. Structural Studies on Toxins and Virulence Factors of Yersinia pestis. Fort Belvoir, VA: Defense Technical Information Center, July 2004. http://dx.doi.org/10.21236/ada426839.

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Swaminathan, S. Structural Studies on Toxins and Virulence Factors of Yersinia Pestis. Fort Belvoir, VA: Defense Technical Information Center, July 2006. http://dx.doi.org/10.21236/ada466156.

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Swaminathan, Subramanyam. Structural Studies on Toxins and Virulence Factors of Yersinia Pestis. Fort Belvoir, VA: Defense Technical Information Center, July 2005. http://dx.doi.org/10.21236/ada466704.

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