Academic literature on the topic 'Virus-free'

Abstract Development of a simple, fast, and safe method to detect neutralizing antibody levels to a pathogen is urgent to help understand the immune status of convalescent patients and the immune responses after vaccine. Here we report the development of a cell-free and virus-free beads-based virus neutralization assay. We focused on the detection of neutralization antibody (nAb) in blood circulation to SARS-Cov-2 spike protein receptor binding domain (RBD). This assay uses histidine tagged recombinant RBD protein to replace living virus and uses streptavidin coated polystyrene beads as a carrier of human angiotensin-converting enzyme 2 (hACE2). This bead serves as a surrogate for target cells. Neutralization was detected by the decrease or absence of fluorescence signal associated with RBD. The assay was compared to a cell-based neutralization assay and ELISA, and these results are reported. The bead-based assay is simple, fast, safe and importantly, can truly reflect the immune status of individuals. The result of the assay can help assess the response of vaccine recipients and assist in selecting serum from convalescent patients for therapeutic purposes.

BR6/Icrf mice carrying a milk-transmitted mammary tumour virus (MMTV) develop tumours after several pregnancies. If the mice are freed from MMTV, no tumours develop. In the experiments described in this paper, MMTV was reintroduced into MMTV-free mice by foster nursing, which was least effective if the pups were exposed to the virus only during the first week of life. Exposure for even a short time after that age led to a tumour incidence similar to that found in normally infected mice. Reinfection was also achieved by injection of MMTV-containing milk into weanling or pregnant mice, and was then transmitted naturally to the next generation.

A method for the efficient production of RNA-free particles of Cowpea mosaic virus (CPMV) has been developed. These are generated by co-expression of the precursor of the coat proteins (VP60) and the viral proteinase (24K) using the highly-efficient plant expression system, CPMV-HT, in the model plant Nicotiana benthamiana. Particles thus produced were shown to be identical to CPMV on the outside and devoid of RNA on the inside and were hence named CPMV empty virus-like particles (eVLPs). The availability of large quantities of purified eVLPs represents a significant milestone in the development of CPMV-based particle technologies and their potential applications in nanotechnology have been investigated. eVLPs were shown be genuinely empty unlike other VLPs which package random cellular RNAs from the host. The high specificity of CPMV in packaging led to the investigation of the requirements for efficient packaging in CPMV where the functional coupling of replication and encapsidation was identified. Methods have been presented to extend this approach for packaging heterologous nucleic acids in eVLPs for their application as delivery vehicles. To obtain a continuous supply of eVLPs, methods for its stable expression were developed for which the suppressor of silencing deployed in the CPMV-HT system, P19, was modified as the use of wt P19 inhibits regeneration of leaf tissue. A mutant form of P19, R43W, with reduced but still substantial suppressor activity was shown to permit the regeneration of transgenic plants. P19/R43W was used for the stable expression of a variety of heterologous proteins showing the broad applicability of this system. To reduce the possibility of homologous recombination, an alternative to the CPMV-HT system was developed by deploying the UTRs from CPMV RNA-1. Expression with RNA-1 UTRs was rapid as compared to CPMV-HT and hence, the expression system was named Rapid-Trans.

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.
Includes bibliographical references (leaves 106-124). Also available in electronic version. Access restricted to campus users.

This dissertation reports on the technology of cell-free protein synthesis (CFPS) including 1) stabilized lyophilized cell-free systems and 2) enhanced heterogeneous cell extracts. This work further considers applications of CFPS systems in 1) rapid vaccine development, 2) functional virus-based nanoparticles, 3) site-specific protein immobilization, and 4) expanding the language of biology using unnatural amino acids. CFPS technology is a versatile protein production platform that has many features unavailable in in vivo expression systems. The primary benefit cell-free systems provide is the direct access to the reaction environment, which is no longer hindered by the presence of a cell-wall. The “openness” of the system makes it a compelling candidate for many technologies. One limitation of CFPS is the necessity of freezing for long-term viable storage. We demonstrate that a lyophilized CFPS system is more stable against nonideal storage than traditional CFPS reagents. The Escherichia coli-based CFPS system in this work is limited by the biocatalytic machinery found natively in E. coli. To combat these limitations, exogenous biocatalysts can be expressed during fermentation of cells prepared into extract. We demonstrate that simple adjustments in the fermentation conditions can significantly increase the activity of the heterogeneous extract. Towards virus-based particles and vaccines, we demonstrate that the open nature of CFPS can be utilized for coexpression of virus proteins and self-assembly of virus particles. This technique allows for the rapid production of potential vaccines and novel functional virus-based nanoparticles. Unnatural amino acids expand the effective language of protein biology. Utilizing CFPS as an expression system, we demonstrated that the incorporation of a single specific unnatural amino acid allows for site-specific immobilization, thus stabilizing the protein against elevated temperatures and chemical denaturants. Current unnatural amino acid incorporation technologies are limited to one or few simultaneous incorporations and suffer from low efficiency. This work proposes a system that could potentially allow for upwards of 40 unnatural amino acids to be simultaneously incorporated, effectively tripling the protein code. These projects demonstrate the power and versatility of CFPS technologies while laying the foundation for promising technologies in the field of biotechnology.

Human respiratory syncytial virus (HRSV) is a known cause of severe lower respiratory tract infection (LRTI) in infants and young children worldwide. HRSV can cause illness in all ages especially those people at high risk including the immunocompromised and the elderly. Globally, HRSV infection leads to a significant healthcare and economic burden due to the lack of an approved vaccine and costly antiviral therapies that are potentially ineffective in some cases. Ribavirin is the only therapeutic licensed for the treatment of severe HRSV infection. It is a synthetic nucleoside with broad spectrum of antiviral activity encompassing both DNA and RNA viruses. The mechanism of action of ribavirin is unclear. It is thought to inhibit the replication of HRSV and lead to a reduction in viral load. How it does this is unknown and the subject of this thesis. This study focused on investigating the effect of the anti-viral ribavirin on cells in general and then infected with HRSV using both label free quantitative proteomics and transcriptomics. This allowed the investigation of the mutation frequency in HRSV and cellular protein abundance, which encompass several mechanisms by which ribavirin is postulated to work. This study was demonstrated that treatment of cells with ribavirin resulted in the increased transcription of selected cellular mRNAs including those involved in mediating anti-viral signalling. Additionally, ribavirin treatment caused a decrease in viral mRNA and proteins. In the absence of ribavirin, HRSV specific transcripts accounted for up to one third of total RNA reads from the infected cell RNA population. Ribavirin treatment resulted in a greater than 90% reduction in reads mapping to viral mRNA, while at the same time no such drastic reduction was detected for the abundance of cellular transcripts. The presented data revealed that ribavirin significantly increased the frequency of HRSV-specific RNA mutations in the viral genome, suggesting direct influence on the fidelity of the HRSV polymerase. The presented data shows transition and transversion substitutions occur during HRSV replication, and that these changes occurred in 'hot spots' along the HRSV genome. Examination of nucleotide substitution rates in the viral genome indicated an increase in the frequency of transition but not transversion mutations in the presence of ribavirin. In addition, the data indicated that in the continuous cell types used, and at the time points analyzed, the abundance of some HRSV mRNAs did not reflect the order in which the mRNAs were transcribed. Overall, the work describes a mechanism of action for ribavirin in the context of viral infection, that has not previously been elucidated for HRSV.

Cryptophlebia leucotreta is an economically important agricultural pest throughout Sub-Saharan Africa. CrleGV has been considered as an alternative to chemical control of this pest due to its host specificity and innocuous nature towards vertebrates. A CrleGV free laboratory colony of C. leucotreta would be useful for the isolation of genotypically pure strains of the CrleGV and for virulence comparisons between isolates. It is preferable to have a full characterisation of CrleGV prior to its registration and release into the environment as a biopesticide. A laboratory colony of C. leucotreta, set up at Rhodes University, containing a low level of infection indicated that CrleGV is vertically transmitted. To establish a virus free laboratory colony of C. leucotreta, a solution of 3.5% sodium hypochlorite and 1% Tween 20 was used to surface decontaminate C. leucotreta eggs for removal of transovum CrleGV from the laboratory colony. No apparent infection by CrleGV was induced by subjecting larvae to stress. PCR of DNA extracted from larvae using CTAB failed to detect virus in the laboratory colony. This detection protocol was able to detect down to 60 fg (480 genome copies of CrleGV). The possibility of low-level virus remaining in the colony requires monitoring of genotypic purity of virus manipulated in the colony. Sequencing of Bam HI/KpnI fragments produced a preliminary sequence of the granulin region of CrleGV. This preliminary sequence supports the trend that the gene organisation of the granulin region of the granuloviruses infecting the family Tortricidae is conserved.

Orientador : Prof. Dr. Carlos Ricardo Soccol
Coorientadora : Profa. Dra. Vanete Thomaz Soccol
Dissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia de Bioprocessos e Biotecnologia. Defesa: Curitiba, 29/10/2012
Inclui referências : f.53-55
Área de concentração: Saúde humana e animal
Resumo: Soro animal é usado em cultivo celular por causa de seus fatores nutricionais, porém, seu uso é um risco potencial à saúde, devido a possível presença de agentes adventícios, tais como vírus e príons, e também é um dos principais responsáveis por reações alérgicas em cães. Células BHK-21 adaptadas à suspensão crescendo em meio de cultura padrão com 3% de soro fetal bovino foram submetidas à adaptação em meio de cultura livre de soro. Os meios de cultura livre de soro usados neste estudo foram VP-SFM, Ex-Cell 302 e Cellvento BHK-200. As células foram adaptadas ao VP por trocada direta do meio de cultura, ao Ex-Cell por troca direta e gradual do meio. Adaptação a Cellvento só foi possível usando células previamente adaptada a VP-SFM. As células adaptadas ao meio de cultura Ex Cell 302 apresentaram melhores resultados de crescimento. Todas as células adaptadas são capazes de produzir vírus da raiva. Porém, células adaptadas em VP-SFM apresentaram a melhor produtividade viral. Entretanto, produção de vírus utilizando Cellvento BHK-200 apresenta o melhor potencial econômico. Palavras chaves: vacina antirrábica veterinária, meio de cultura livre de soro, BHK-21, adaptação celular.
Abstract: Animal serum is used in cell culture because of its nutritional factors, however, their use not only is a potential risky for health, due to possible presence of adventitious agents, such as virus and príons, but also is the major responsible of allergic reactions in dogs. BHK-21 cells adapted to suspension growing in standard culture media with 3% of fetal bovine serum were submitted to adaptation to serum free culture media. Serum free culture media used in this study were VP-SFM, EX-CELL 302 and Cellvento BHK-200. Cells were adapted to VP by direct media change, to Ex Cell by direct and gradual media change. Adaptation to Cellvento was only possible by using cells priory adapted to VP-SFM. Cells adapted to Ex Cell culture media presented best growth results. All adapted cells have ability to produce rabies virus. Although, cells adapted to VP-SFM presented best virus productivity. However, virus production using Cellvento BHK-200 presents best economic potential. Keywords: veterinary rabies vaccine, serum free media, BHK-21, cell adaptation.

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O alho (Allium sativum L.) não possui semente verdadeiramente botânica, sendo assim, sua única via de propagação se dá vegetativamente, fato este que implica regularmente numa infecção viral mista, se tornando uma das principais causas da redução de produtividade. Alguns produtores já possuem acesso a semente de alho ‘Livre de Vírus’, no entanto, ainda utilizam de vernalização antiquada, preconizada pela pesquisa para alho semente infectada por vírus (material comum para maioria dos produtores nacionais), e quando utilizada pelos produtores em alho-semente ‘Livre de Vírus’, vem acarretando problemas principalmente para os produtores do cerrado, onde o plantio é antecipado. Neste estudo foi avaliado o efeito da temperatura de vernalização a 4ºC combinada por diferentes períodos (30, 40, 50 e 60 dias) em bulbilho-semente livre de vírus. O experimento foi conduzido de acordo coma a safra da cultura na região (março à outubro), em fazendas localizadas nos municípios de Santa Juliana (MG) e Campo Alegre de Goiás (GO): regiões de cerrado que se destacam atualmente pela produção de alho nobre no Brasil. Foram avaliadas três das principais cultivares existentes no mercado, sendo elas: Caçador, Quitéria e Ito. As maiores produtividades de bulbos comerciais para as cultivares Caçador em Campo Alegre de Goiás (GO) 2014 e Santa Juliana (MG) 2014 foram nos tratamentos de 30 e 40 dias de vernalização, respectivamente, conciliando produtividades de 11,3 t.ha-¹ e 12,4 t.ha-¹, com boa qualidade de bulbo. A cultivar Quitéria em Campo Alegre de Goiás (GO) 2014 alcançou melhor resultado com tratamento de 51 dias de vernalização, atingindo produtividade de 16,8 t.ha-¹. ‘Ito’ 2015 em Campo Alegre de Goiás (GO) e Santa Juliana (MG) atingiu produtividades interessantes do ponto de vista comercial aos 30 e 40 dias de vernalização, respectivamente, atingindo 16,7 e 17,1 t.ha-¹. Também foi avaliado que para bulbilhos livre de vírus ‘Caçador’, se demonstraram menos susceptíveis à formação de bulbos ‘charutos’ em baixos períodos de vernalização, do que bulbilhos convencionais. Em longos períodos de vernalizações, ‘Caçador’ livre de vírus é mais sensíveis ao aparecimento de brotações laterais do que o convencional. Verificou-se ainda que o efeito dos tratamentos de vernalização teve influência direta no IVD na semeadura, tempo de diferenciação (dias), número de folhas na diferenciação, ciclo da cultura (dias), incidência de bulbos charutos e brotações laterais em todas as cultivares avaliadas. Observou-se que do ponto de vista prático, que não é recomendável a utilização de extensos períodos de vernalização para produção de semente, já que esta possui notável relação com o estímulo à produção de bulbilhos com mais de uma gema.
Garlic (Allium sativum L.) does not really have truly botanic seeds; therefore, its only way of propagation is vegetatively, which regularly implies in a mixed viral infection that becomes the major cause of reduced productivity. Some producers already have access to garlic seed 'Virus Free', however, still use old-fashioned vernalization, recommended by the search for seed infected garlic virus (common material for most domestic producers), and when used by producers in garlic-seed 'Virus Free', has been causing problems especially for the cerrado producers, where planting is anticipated. This study evaluated the effect of vernalization temperature of 4 ° C combined for different periods (30, 40, 50 and 60 days) in virus free bulbil seed. The experiment was conducted in accordance eat the harvest of culture in the region (march to october), in farms located in the cities of Santa Juliana (MG) and Campo Alegre de Goiás (GO): cerrado regions which are currently out for garlic production noble in Brazil. Were evaluated three of the main existing cultivars on the market, which are: Caçador, Quiteria and Ito. The highest commercial bulbs for Caçador in Campo Alegre de Goiás (GO) 2014 and Santa Juliana (MG) in 2014 were the treatments of 30 and 40 days of vernalization, respectively, combining yields of 11.3 t ha-¹ and 12.4 t ha-¹, with good quality bulb. Quitéria in Campo Alegre de Goiás (GO) in 2014 achieved a better result with treatment of 51 days of vernalization, reaching productivity of 16.8 t ha-¹. 'Ito' 2015 Campo Alegre de Goiás (GO) and Santa Juliana (MG) reached interesting productivities commercial point of view at 30 and 40 days of vernalization, respectively, reaching 16.7 and 17.1 t ha-¹. It was also reported that for virus free bulbils of "Caçador", have proved less susceptible to the formation of bulbs 'cigar' in low periods of vernalization than conventional bulbils. Over long periods of vernalizações 'Caçador ' virus free is more sensitive to the onset of side shoots than conventional. It was also found that the effect of vernalization had a direct influence on the IVD during sowing, differentiation time (days) number of leafs in the differentiation, culture cycle (days), the incidence of ‘cigars’ bulbs and side shoots in all cultivars evaluated. It was observed that from a practical point of view, it is not recommendable to use long periods of vernalization for seed production, since it has remarkable relationship to stimulate production of bulbils over a gem.

In this study, a PCR free technique for effective detection of hepatitis B virus (HBV) DNA obtained directly from clinical samples was presented. The honeycomb-like barrier layer of an anodic aluminum oxide (AAO) film having a uniform nanohemisphere array was used as the substrate of the sensing electrode. A gold thin film about 30 nm thick was radio-frequency (RF) magnetron sputtered onto the AAO barrier-layer surface as the electrode for the successive deposition of gold nanoparticles (GNPs) on the hemisphere surface. A specially designed single-strand 96-mer gene fragment of the target genomic DNA of HBV based on the genome sequences of HBV from the National Center for Biotechnology Information (NCBI) was immobilized on the nanostructured electrode as the capture probe. Complementary target HBV DNA (3020–3320 mer) obtained from clinical samples were further hybridized to the sensing probes. Detection results through electrochemical impedance spectroscopy (EIS) illustrate that two dynamic linear ranges, 0–103 and 103–105 copies/mL, having R2 values of 0.973 and 0.998, respectively, could be obtained. A detection limit of 186 copies/mL could be achieved. The proposed simple and high performance HBV DNA detection technique in this study is highly feasible for future clinical applications.

Abstract In this study, a label-free detection approach for effective detection of the odontoglossum ringspot virus (ORSV) infected orchids has been developed. We used semiconductor fabrication process to fabricate 1,810 micro/nano hybrid structured sensing electrodes on a 8 inch reclaimed wafer. The self-assembled monolayer (SAM) process was then employed to sequentially modify the electrode surface with 11-mercaptoundecanoic acid (11-MUA), 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC)/ N-hydroxysuccinimide (NHS), anti-ORSV, and ORSV. EIS was conducted for the ORSV concentration detection. Experimental results demonstrated that the ORSV concentration in a virus infected orchid leaf could be effectively detected. When compared with the ELISA kit, our device possesses a wider linear detection range (0.5–50,000 ng/mL) and a higher sensitivity. The specificity of our device on ORSV detection was also confirmed. Our sensing device retains advantages, such as label-free, lower amounts of the antibody and target sample required, low detection time, and a wider linear detection range. Those results imply the feasibility of our sensing device in field applications.

Based on the type of relationship with the host, plant viruses can be grouped as acute or persistent. Acute viruses are well studied and cause disease. In contrast, persistent viruses do not appear to affect the phenotype of the host. The genus Endornavirus contains persistent viruses that infect plants without causing visible symptoms. Infections by endornaviruses have been reported in many economically important crops, such as avocado, barley, common bean, melon, pepper, and rice. However, little is known about the effect they have on their plant hosts. The long term objective of the proposed project is to elucidate the nature of the symbiotic interaction between Bell pepper endornavirus (BPEV) and its host. The specific objectives include: a) to evaluate the phenotype and fruit yield of endornavirus-free and endornavirus-infected bell pepper near-isogenic lines under greenhouse conditions; b) to conduct gene expression studies using endornavirus-free and endornavirus-infected bell pepper near-isogenic lines; and c) to study the interactions between acute viruses, Cucumber mosaic virus Potato virus Y, Pepper yellow leaf curl virus, and Tobacco etch virus and Bell pepper endornavirus. It is likely that BPEV in bell pepper is in a mutualistic relationship with the plant and provide protection to unknown biotic or abiotic agents. Nevertheless, it is also possible that the endornavirus could interact synergistically with acute viruses and indirectly or directly cause harmful effects. In any case, the information that will be obtained with this investigation is relevant to BARD’s mission since it is related to the protection of plants against biotic stresses.

Pelargonium (Geranium) is the number one pot plant in many areas of the United States and Europe. Israel and the U.S. send to Europe rooted cuttings, foundation stocks and finished plants to supply a certain share of the market. Geraniums are propagated mainly vegetatively from cuttings. Consequently, viral diseases have been and remain a major threat to the production and quality of the crop. Among the viruses isolated from naturally infected geraniums, 11 are not specific to Pelargonium and occur in other crops while 6 other viruses seem to be limited to geranium. However, several of these viruses are not sufficiently characterized to conclude that they are distinct agents and their nomenclature and taxonomy are confusing. The ability to separate, distinguish and detect the different viruses in geranium will overcome obstacles te developing effective detection and certification schemes. Our focus was to further characterize some of these viruses and develop better methods for their detection and control. These viruses include: isolates of pelargonium line pattern virus (PLPV), pelargonium ringspot virus (PelRSV), pelargonium flower break virus (PFBV), pelargonium leaf curl (PLCV), and tomato ringspot virus (TomRSV). Twelve hybridoma cell lines secreting monoclonal antibodies specific to a geranium isolate of TomRSV were produced. These antibodies are currently being characterized and will be tested for the ability to detect TomRSV in infected geraniums. The biological, biochemical and serological properties of four isometric viruses - PLPV, PelRSV, and PFBV (and a PelRSV-like isolate from Italy called GR57) isolated from geraniums exhibiting line and ring pattern or flower break symptoms - and an isolate ol elderbeny latent virus (ELV; which the literature indicates is the same as PelRSV) have been determined Cloned cDNA copies of the genomic RNAs of these viruses were sequenced and the sizes and locations of predicted viral proteins deduced. A portion of the putative replicase genes was also sequenced from cloned RT-PCR fragments. We have shown that, when compared to the published biochemical and serological properties, and sequences and genome organizations of other small isometric plant viruses, all of these viruses should each be considered new, distinct members of the Carmovirus group of the family Tombusviridae. Hybridization assays using recombinant DNA probes also demonstrated that PLPV, PelRSV, and ELV produce only one subgenomic RNA in infected plants. This unusual property of the gene expression of these three viruses suggests that they are unique among the Carmoviruses. The development of new technologies for the detection of these viruses in geranium was also demonstrated. Hybridization probes developed to PFBV (radioactively-labeled cRNA riboprobes) and to PLPV (non-radioactive digoxigenin-labeled cDNAs) were generally shown to be no more sensitive for the detection of virus in infected plants than the standard ELISA serology-based assays. However, a reverse transcriptase-polymerase chain reaction assay was shown to be over 1000 times more sensitive in detecting PFBV in leaf extracts of infected geranium than was ELISA. This research has lead to a better understanding of the identity of the viruses infecting pelargonium and to the development of new tools that can be used in an improved scheme of providing virus-indexed pelargonium plants. The sequence information, and the serological and cloned DNA probes generated from this work, will allow the application of these new tools for virus detection, which will be useful in domestic and international indexing programs which are essential for the production of virus-free germplasm both for domestic markets and the international exchange of plant material.

On 8 June 2020, the Government of Tanzania officially declared the country to be free of COVID-19 and all restrictions have since been lifted. As of 3 December 2020, Tanzania had only 509 confirmed cases of the virus and 21 deaths. Nevertheless, neighbouring countries are still facing the threat of the pandemic, all of which are key trading partners. Their continuing COVID-19 control measures have disrupted regional and domestic agricultural markets and affected local livelihoods and food systems. This study analysed the resulting impacts in those systems in several rice-producing communities in Morogoro Region, south-western Tanzania.

1. Original Objectives. The original broad objectives of the grant were to determine A) the impact of CAV on the generation of cytotoxic T lymphocytes (CTL) to reticuloendotheliosis virus (REV) (CU), B). the interactions between chicken anemia virus (CAV) and Marek’s disease virus (MDV) with an emphasis on horizontal spread of CAV through feathers (KVI), and C) the impact of CAV infection on Salmonella typhimurium (STM) (HUJI). During the third year and the one year no cost extension the CU group included some work on the development of an antigen-antibody complex vaccine for CAV, which was partially funded by the US Poultry and Egg Association. 2. Background to the topic. CAV is a major pathogen causing clinical disease if maternal antibody-free chickens are infected vertically or horizontally between 1 and 14 days of age. Infection after 3 weeks of age when maternal antibodies are not longer present can cause severe subclinical immunosuppression affecting CTL and cytokine expression. The subclinical immunosuppression can aggravate many diseases including Marek’s disease (MD) and several bacterial infections. 3. Major conclusions and achievements. The overall project contributed in the following ways to the knowledge about CAV infection in poultry. As expected CAV infections occur frequently in Israel causing problems to the industry. To control subclinical infections vaccination may be needed and our work indicates that the development of an antigen-antibody complex vaccine is feasible. It was previously known that CAV can spread vertically and horizontally, but the exact routes of the latter had not been confirmed. Our results clearly show that CAV can be shed into the environment through feathers. A potential interaction between CAV and MD virus (MDV) in the feathers was noted which may interfere with MDV replication. It was also learned that inoculation of 7-day-old embryos causes growth retardation and lesions. The potential of CAV to cause immunosuppression was further examined using CTL responses to REV. CTL were obtained from chickens between 36 and 44 days of age with REV and CAV given at different time points. In contrast to our earlier studies, in these experiments we were unable to detect a direct impact of CAV on REV-specific CTL, perhaps because the CTL were obtained from older birds. Inoculation of CAV at one day of age decreased the IgG antibody responses to inactivated STM administered at 10 days of age. 4. Scientific and Agricultural Implications The impact of the research was especially important for the poultry industry in Israel. The producers have been educated on the importance of the disease through the many presentations. It is now well known to the stakeholders that CAV can aggravate other diseases, decrease productivity and profitability. As a consequence they monitor the antibody status of the breeders so that the maternal antibody status of the broilers is known. Also vaccination of breeder flock that remain antibody negative may become feasible further reducing the negative impact of CAV infection. Vaccination may become more important because improved biosecurity of the breeder flocks to prevent avian influenza and Salmonella may delay the onset of seroconversion for CAV by natural exposure resulting in CAV susceptible broilers lacking maternal antibodies. Scientifically, the research added important information on the horizontal spread of CAV through feathers, the interactions with Salmonella typhimurium and the demonstration that antigen-antibody complex vaccines may provide protective immunity.

Background The tomato yellow leaf curl disease (TYLCV) has been a major deterrent to tomato production in Israel for the last 20 years. This whitefly-transmitted viral disease has been found in the Caribbean Island in the early 1990s, probably as an import from the Middle East. In the late 1990s, the virus has spread to the US and is now conspicuous in Florida and Georgia. Objectives Because of the urgency facing the TYLCV epidemics, there was a compelling need to mobilize scientists to develop tomato variety resistant to TYLCV. The major goal was to identify the virus movement protein (MP) and to express a defective from of MP in a cultivar that contained the natural Ty-1 resistance gene. The research included 1. cloning of the TYLCV isolate from the Dominican Republic (DR) which is (or a close variant) also present in the continental USA; 2. ddefining the role of the MP; 3. mutating the putative MP gene; 4. introducing the modified gene into an advance Ty-1 line; 5. testing the transgenic plants in the field. The pressing threat to tomato production in the US resulted in an extension of the objectives: more emphasis was placed on characterization of TYLCV i the DR, on determination of the epidemiology of the virus in the DR, and on using new TYLCV resistance sources for tomato breeding. Achievements and signification 1. The characterization of TYLCV-DR allowed for more effective TYLCV management strategies that are now implemented in the DR. 2. The identification of the TYLCV MPs and, more importantly, insight into their function has provided a model for how these proteins function in TYLCV movement and support the targeting of one or more of these proteins in a dominant lethal strategy to engineer plants for TYLCV resistance. 3. The transgenic plants that are being generated with wild-type and mutated TYLCV MPs will serve to test the hypothesis that interference with one or more of the TYLCV movement proteins will be a strategy for generating TYLCV-resistant plants. 4. The fine mapping of the resistance Ty-1 gene allowed eliminating deleterious chromosome segments from the wild tomato genitor L. chilense. It may in a near future allow the cloning of the first geminivirus resistance gene. 5. Another resistance source from the wild tomato species L. hirsitum was introgressed into the domesticated tomato, resulting in the production of resistant breeding lines. Implications 1. The monitoring of TYLCV in whiteflies has been applied in the DR. These tools are presently being used to assist in the evaluation of the host-free period and to help select the appropriate locations for growing tomatoes in the DR. 2. An overall strategy to obtain resistance against TYLCV has been used. The expression of wild-type or mutated TYLCV MPs in transgenic tomato is another addition to the arsenal used to fight TYLCV, together with marker assisted breeding and mobilization of additional resistant genes from the wild.

The coordination and regulation of growth and development in multicellular organisms is dependent, in part, on the controlled short and long-distance transport of signaling molecule: In plants, symplastic communication is provided by trans-wall co-axial membranous tunnels termed plasmodesmata (Pd). Plant viruses spread cell-to-cell by altering Pd. This movement scenario necessitates a targeting mechanism that delivers the virus to a Pd and a transport mechanism to move the virion or viral nucleic acid through the Pd channel. The identity of host proteins with which MP interacts, the mechanism of the targeting of the MP to the Pd and biochemical information on how Pd are alter are questions which have been dealt with during this BARD project. The research objectives of the two labs were to continue their biochemical, cellular and molecular studies of Pd composition and function by employing infectious modified clones of TMV in which MP is fused with GFP. We examined Pd composition, and studied the intra- and intercellular targeting mechanism of MP during the infection cycle. Most of the goals we set for ourselves were met. The Israeli PI and collaborators (Oparka et al., 1999) demonstrated that Pd permeability is under developmental control, that Pd in sink tissues indiscriminately traffic proteins of sizes of up to 50 kDa and that during the sink to source transition there is a substantial decrease in Pd permeability. It was shown that companion cells in source phloem tissue export proteins which traffic in phloem and which unload in sink tissue and move cell to cell. The TAU group employing MP:GFP as a fluorescence probe for optimized the procedure for Pd isolation. At least two proteins kinases found to be associated with Pd isolated from source leaves of N. benthamiana, one being a calcium dependent protein kinase. A number of proteins were microsequenced and identified. Polyclonal antibodies were generated against proteins in a purified Pd fraction. A T-7 phage display library was created and used to "biopan" for Pd genes using these antibodies. Selected isolates are being sequenced. The TAU group also examined whether the subcellular targeting of MP:GFP was dependent on processes that occurred only in the presence of the virus or whether targeting was a property indigenous to MP. Mutant non-functional movement proteins were also employed to study partial reactions. Subcellular targeting and movement were shown to be properties indigenous to MP and that these processes do not require other viral elements. The data also suggest post-translational modification of MP is required before the MP can move cell to cell. The USA group monitored the development of the infection and local movement of TMV in N. benthamiana, using viral constructs expressing GFP either fused to the MP of TMV or expressing GFP as a free protein. The fusion protein and/or the free GFP were expressed from either the movement protein subgenomic promoter or from the subgenomic promoter of the coat protein. Observations supported the hypothesis that expression from the cp sgp is regulated differently than expression from the mp sgp (Szecsi et al., 1999). Using immunocytochemistry and electron microscopy, it was determined that paired wall-appressed bodies behind the leading edge of the fluorescent ring induced by TMV-(mp)-MP:GFP contain MP:GFP and the viral replicase. These data suggest that viral spread may be a consequence of the replication process. Observation point out that expression of proteins from the mp sgp is temporary regulated, and degradation of the proteins occurs rapidly or more slowly, depending on protein stability. It is suggested that the MP contains an external degradation signal that contributes to rapid degradation of the protein even if expressed from the constitutive cp sgp. Experiments conducted to determine whether the degradation of GFP and MP:GFP was regulated at the protein or RNA level, indicated that regulation was at the protein level. RNA accumulation in infected protoplast was not always in correlation with protein accumulation, indicating that other mechanisms together with RNA production determine the final intensity and stability of the fluorescent proteins.

This report has been written to serve as a history of the U.S. Aujeszky’s Disease (Pseudorabies) Eradication Program and as a guide when future disease eradication programs are considered. The report provides an overview of the program and its history and is generally nontechnical, with specific sections written by subject matter experts. The information was compiled during 2007, three years after the last four States qualified for Stage V (Free) Status. This eradication effort was formally initiated in 1989. The contents of this report include a variety of information that represents the viewpoints of individuals participating in the eradication effort. To introduce the challenge of pseudorabies (PRV), the report covers characteristics of the virus and the history of the disease in the United States, followed by the emergence of virulent strains in the 1970s that coincided with management changes in the swine industry. The report also discusses early attempts at PRV control, vaccines, and diagnostic tools, and then reviews various pilot projects, individual State experiences, and national debate on the pros and cons of eradication versus control. In addition, the report offers details on the evolution and acceptance of a national eradication program, including debate among industry and State/Federal officials, funding, testing protocols, cleanup plans, and the development of gene-deleted vaccines and their complementary tests. The ongoing threat of reintroduction from feral swine and emergency response plans are also included. Lastly, the technical coordinators have included a chapter on lessons learned from our various viewpoints on the eradication effort.

This brief summarises key considerations concerning cross-border dynamics between South Sudan and Uganda in the context of the 2022 outbreak of Ebola in Uganda, and the risk of the spread of the virus into South Sudan. It is one of four briefs exploring cross-border dynamics in the context of the outbreak, alongside Kenya, Rwanda and Tanzania. The outbreak is of the Sudan strain of Ebola (Sudan Virus Disease, SVD). SVD is used in this paper to refer to the current outbreak in East Africa, whereas outbreaks of Zaire Ebolavirus disease or general references to Ebola are referred to as EVD. The outbreak of SVD began in Mubende, Uganda, on 19 September 2022. At the time of writing (25 November), there had been 141 confirmed cases and 55 deaths, including seven health workers. Infections had been confirmed in nine districts in Uganda, including in Kampala – a major transport hub. Vaccines used in previous Ebola outbreaks are effective against the Zaire strain of Ebola, and vaccines that could work against the Sudan strain remain under investigation. As of November 2022, there have been no confirmed cases of SVD imported into South Sudan, although several alerts have been investigated. However, the fear that travellers from Uganda might bring the disease into South Sudan has spurred preparations by government institutions and partner organisations, building on the experiences acquired during past outbreaks, particularly Ebola and COVID-19. An EVD High Level Taskforce has been formed, chaired by the Minister for Cabinet Affairs and co-chaired by the Minister of Health. The South Sudan Ministry of Health (MoH) has activated the Public Health Emergency Operation Centre (PHEOC) and Incident Management System (IMS). A national EVD Readiness Plan has been developed and endorsed by the government. A free hotline (number 6666) is in place, which can be used either to report suspected cases or for information on Ebola. Training of staff at border entry points has started. This brief is based on a rapid review of published and grey literature, and informal discussions with the South Sudan Red Cross, IOM, academics from University of Juba, and the PHEOC. It was requested by the Collective Service and was written by Leben Nelson Moro (University of Juba) and Alice Robinson (London School of Economics). It was reviewed by colleagues at the University of Bath, the PHEOC, Internews, Anthrologica, the Institute of Development Studies and the Collective Service. The brief is the responsibility of the Social Science in Humanitarian Action Platform (SSHAP).

Abstract. Tomato yellow leaf curl virus (TYLCV), a monopartitebegomovirus, is one of the most devastating viruses of cultivated tomatoes and poses increasing threat to tomato production worldwide. Because all accessions of the cultivated tomato are susceptible to these viruses, wild tomato species have become a valuable resource of resistance genes. QTL controlling resistance to TYLCV and other begomoviruses (Ty loci) were introgressed from several wild tomato species and mapped to the tomato genome. Additionally, a non-isogenic F₁diallel study demonstrated that several of these resistance sources may interact with each other, and in some cases generate hybrid plants displaying lower symptoms and higher fruit yield compared to their parental lines, while their respective resistance genes are not necessarily allelic. This suggests that pyramiding genes originating from different resistance sources can be effective in obtaining lines and cultivars which are highly resistant to begomoviruses. Molecular tools needed to test this hypothesis have been developed by our labs and can thus significantly improve our understanding of the mechanisms of begomovirus resistance and how to efficiently exploit them to develop wider and more durable resistance. Five non-allelic Ty loci with relatively major effects have been mapped to the tomato genome using molecular DNA markers, thereby establishing tools for efficient marker assisted selection, pyramiding of multiple genes, and map based gene cloning: Ty-1, Ty-2, Ty-3, Ty-4, and ty-5. This research focused on Ty-3 and Ty-4 due to their broad range of resistance to different begomoviruses, including ToMoV, and on ty-5 due to its exceptionally high level of resistance to TYLCV and other begomoviruses. Our aims were: (1) clone Ty-3, and fine map Ty-4 and Ty-5 genes, (2)introgress each gene into two backgroundsand develop semi isogenic lines harboring all possible combinations of the three genes while minimizing linkage-drag, (3) test the resulting lines, and F₁ hybrids made with them, for symptom severity and yield components, and (4) identify and functionally characterize candidate genes that map to chromosomal segments which harbor the resistance loci. During the course of this research we have: (1) found that the allelic Ty-1 and Ty-3 represent two alternative alleles of the gene coding DFDGD-RDRP; (2) found that ty-5is highly likely encoded by the messenger RNA surveillance factor PELOTA (validation is at progress with positive results); (3) continued the map-based cloning of Ty-4; (4) generated all possible gene combinations among Ty-1, Ty-3 and ty-5, including their F₁ counterparts, and tested them for TYLCV and ToMoV resistance; (5) found that the symptomless line TY172, carrying ty-5, also carries a novel allele of Ty-1 (termed Ty-1ⱽ). The main scientific and agricultural implications of this research are as follows: (1) We have developed recombination free DNA markers that will substantially facilitate the introgression of Ty-1, Ty-3 and ty-5 as well as their combinations; (2) We have identified the genes controlling TYLCV resistance at the Ty-1/Ty-3 and ty-5 loci, thus enabling an in-depth analyses of the mechanisms that facilitate begomovirus resistance; (3) Pyramiding of Ty resistance loci is highly effective in providing significantly higher TYLCV resistance.

1.1 Macroeconomic summary Economic recovery has consistently outperformed the technical staff’s expectations following a steep decline in activity in the second quarter of 2020. At the same time, total and core inflation rates have fallen and remain at low levels, suggesting that a significant element of the reactivation of Colombia’s economy has been related to recovery in potential GDP. This would support the technical staff’s diagnosis of weak aggregate demand and ample excess capacity. The most recently available data on 2020 growth suggests a contraction in economic activity of 6.8%, lower than estimates from January’s Monetary Policy Report (-7.2%). High-frequency indicators suggest that economic performance was significantly more dynamic than expected in January, despite mobility restrictions and quarantine measures. This has also come amid declines in total and core inflation, the latter of which was below January projections if controlling for certain relative price changes. This suggests that the unexpected strength of recent growth contains elements of demand, and that excess capacity, while significant, could be lower than previously estimated. Nevertheless, uncertainty over the measurement of excess capacity continues to be unusually high and marked both by variations in the way different economic sectors and spending components have been affected by the pandemic, and by uneven price behavior. The size of excess capacity, and in particular the evolution of the pandemic in forthcoming quarters, constitute substantial risks to the macroeconomic forecast presented in this report. Despite the unexpected strength of the recovery, the technical staff continues to project ample excess capacity that is expected to remain on the forecast horizon, alongside core inflation that will likely remain below the target. Domestic demand remains below 2019 levels amid unusually significant uncertainty over the size of excess capacity in the economy. High national unemployment (14.6% for February 2021) reflects a loose labor market, while observed total and core inflation continue to be below 2%. Inflationary pressures from the exchange rate are expected to continue to be low, with relatively little pass-through on inflation. This would be compatible with a negative output gap. Excess productive capacity and the expectation of core inflation below the 3% target on the forecast horizon provide a basis for an expansive monetary policy posture. The technical staff’s assessment of certain shocks and their expected effects on the economy, as well as the presence of several sources of uncertainty and related assumptions about their potential macroeconomic impacts, remain a feature of this report. The coronavirus pandemic, in particular, continues to affect the public health environment, and the reopening of Colombia’s economy remains incomplete. The technical staff’s assessment is that the COVID-19 shock has affected both aggregate demand and supply, but that the impact on demand has been deeper and more persistent. Given this persistence, the central forecast accounts for a gradual tightening of the output gap in the absence of new waves of contagion, and as vaccination campaigns progress. The central forecast continues to include an expected increase of total and core inflation rates in the second quarter of 2021, alongside the lapse of the temporary price relief measures put in place in 2020. Additional COVID-19 outbreaks (of uncertain duration and intensity) represent a significant risk factor that could affect these projections. Additionally, the forecast continues to include an upward trend in sovereign risk premiums, reflected by higher levels of public debt that in the wake of the pandemic are likely to persist on the forecast horizon, even in the context of a fiscal adjustment. At the same time, the projection accounts for the shortterm effects on private domestic demand from a fiscal adjustment along the lines of the one currently being proposed by the national government. This would be compatible with a gradual recovery of private domestic demand in 2022. The size and characteristics of the fiscal adjustment that is ultimately implemented, as well as the corresponding market response, represent another source of forecast uncertainty. Newly available information offers evidence of the potential for significant changes to the macroeconomic scenario, though without altering the general diagnosis described above. The most recent data on inflation, growth, fiscal policy, and international financial conditions suggests a more dynamic economy than previously expected. However, a third wave of the pandemic has delayed the re-opening of Colombia’s economy and brought with it a deceleration in economic activity. Detailed descriptions of these considerations and subsequent changes to the macroeconomic forecast are presented below. The expected annual decline in GDP (-0.3%) in the first quarter of 2021 appears to have been less pronounced than projected in January (-4.8%). Partial closures in January to address a second wave of COVID-19 appear to have had a less significant negative impact on the economy than previously estimated. This is reflected in figures related to mobility, energy demand, industry and retail sales, foreign trade, commercial transactions from selected banks, and the national statistics agency’s (DANE) economic tracking indicator (ISE). Output is now expected to have declined annually in the first quarter by 0.3%. Private consumption likely continued to recover, registering levels somewhat above those from the previous year, while public consumption likely increased significantly. While a recovery in investment in both housing and in other buildings and structures is expected, overall investment levels in this case likely continued to be low, and gross fixed capital formation is expected to continue to show significant annual declines. Imports likely recovered to again outpace exports, though both are expected to register significant annual declines. Economic activity that outpaced projections, an increase in oil prices and other export products, and an expected increase in public spending this year account for the upward revision to the 2021 growth forecast (from 4.6% with a range between 2% and 6% in January, to 6.0% with a range between 3% and 7% in April). As a result, the output gap is expected to be smaller and to tighten more rapidly than projected in the previous report, though it is still expected to remain in negative territory on the forecast horizon. Wide forecast intervals reflect the fact that the future evolution of the COVID-19 pandemic remains a significant source of uncertainty on these projections. The delay in the recovery of economic activity as a result of the resurgence of COVID-19 in the first quarter appears to have been less significant than projected in the January report. The central forecast scenario expects this improved performance to continue in 2021 alongside increased consumer and business confidence. Low real interest rates and an active credit supply would also support this dynamic, and the overall conditions would be expected to spur a recovery in consumption and investment. Increased growth in public spending and public works based on the national government’s spending plan (Plan Financiero del Gobierno) are other factors to consider. Additionally, an expected recovery in global demand and higher projected prices for oil and coffee would further contribute to improved external revenues and would favor investment, in particular in the oil sector. Given the above, the technical staff’s 2021 growth forecast has been revised upward from 4.6% in January (range from 2% to 6%) to 6.0% in April (range from 3% to 7%). These projections account for the potential for the third wave of COVID-19 to have a larger and more persistent effect on the economy than the previous wave, while also supposing that there will not be any additional significant waves of the pandemic and that mobility restrictions will be relaxed as a result. Economic growth in 2022 is expected to be 3%, with a range between 1% and 5%. This figure would be lower than projected in the January report (3.6% with a range between 2% and 6%), due to a higher base of comparison given the upward revision to expected GDP in 2021. This forecast also takes into account the likely effects on private demand of a fiscal adjustment of the size currently being proposed by the national government, and which would come into effect in 2022. Excess in productive capacity is now expected to be lower than estimated in January but continues to be significant and affected by high levels of uncertainty, as reflected in the wide forecast intervals. The possibility of new waves of the virus (of uncertain intensity and duration) represents a significant downward risk to projected GDP growth, and is signaled by the lower limits of the ranges provided in this report. Inflation (1.51%) and inflation excluding food and regulated items (0.94%) declined in March compared to December, continuing below the 3% target. The decline in inflation in this period was below projections, explained in large part by unanticipated increases in the costs of certain foods (3.92%) and regulated items (1.52%). An increase in international food and shipping prices, increased foreign demand for beef, and specific upward pressures on perishable food supplies appear to explain a lower-than-expected deceleration in the consumer price index (CPI) for foods. An unexpected increase in regulated items prices came amid unanticipated increases in international fuel prices, on some utilities rates, and for regulated education prices. The decline in annual inflation excluding food and regulated items between December and March was in line with projections from January, though this included downward pressure from a significant reduction in telecommunications rates due to the imminent entry of a new operator. When controlling for the effects of this relative price change, inflation excluding food and regulated items exceeds levels forecast in the previous report. Within this indicator of core inflation, the CPI for goods (1.05%) accelerated due to a reversion of the effects of the VAT-free day in November, which was largely accounted for in February, and possibly by the transmission of a recent depreciation of the peso on domestic prices for certain items (electric and household appliances). For their part, services prices decelerated and showed the lowest rate of annual growth (0.89%) among the large consumer baskets in the CPI. Within the services basket, the annual change in rental prices continued to decline, while those services that continue to experience the most significant restrictions on returning to normal operations (tourism, cinemas, nightlife, etc.) continued to register significant price declines. As previously mentioned, telephone rates also fell significantly due to increased competition in the market. Total inflation is expected to continue to be affected by ample excesses in productive capacity for the remainder of 2021 and 2022, though less so than projected in January. As a result, convergence to the inflation target is now expected to be somewhat faster than estimated in the previous report, assuming the absence of significant additional outbreaks of COVID-19. The technical staff’s year-end inflation projections for 2021 and 2022 have increased, suggesting figures around 3% due largely to variation in food and regulated items prices. The projection for inflation excluding food and regulated items also increased, but remains below 3%. Price relief measures on indirect taxes implemented in 2020 are expected to lapse in the second quarter of 2021, generating a one-off effect on prices and temporarily affecting inflation excluding food and regulated items. However, indexation to low levels of past inflation, weak demand, and ample excess productive capacity are expected to keep core inflation below the target, near 2.3% at the end of 2021 (previously 2.1%). The reversion in 2021 of the effects of some price relief measures on utility rates from 2020 should lead to an increase in the CPI for regulated items in the second half of this year. Annual price changes are now expected to be higher than estimated in the January report due to an increased expected path for fuel prices and unanticipated increases in regulated education prices. The projection for the CPI for foods has increased compared to the previous report, taking into account certain factors that were not anticipated in January (a less favorable agricultural cycle, increased pressure from international prices, and transport costs). Given the above, year-end annual inflation for 2021 and 2022 is now expected to be 3% and 2.8%, respectively, which would be above projections from January (2.3% and 2,7%). For its part, expected inflation based on analyst surveys suggests year-end inflation in 2021 and 2022 of 2.8% and 3.1%, respectively. There remains significant uncertainty surrounding the inflation forecasts included in this report due to several factors: 1) the evolution of the pandemic; 2) the difficulty in evaluating the size and persistence of excess productive capacity; 3) the timing and manner in which price relief measures will lapse; and 4) the future behavior of food prices. Projected 2021 growth in foreign demand (4.4% to 5.2%) and the supposed average oil price (USD 53 to USD 61 per Brent benchmark barrel) were both revised upward. An increase in long-term international interest rates has been reflected in a depreciation of the peso and could result in relatively tighter external financial conditions for emerging market economies, including Colombia. Average growth among Colombia’s trade partners was greater than expected in the fourth quarter of 2020. This, together with a sizable fiscal stimulus approved in the United States and the onset of a massive global vaccination campaign, largely explains the projected increase in foreign demand growth in 2021. The resilience of the goods market in the face of global crisis and an expected normalization in international trade are additional factors. These considerations and the expected continuation of a gradual reduction of mobility restrictions abroad suggest that Colombia’s trade partners could grow on average by 5.2% in 2021 and around 3.4% in 2022. The improved prospects for global economic growth have led to an increase in current and expected oil prices. Production interruptions due to a heavy winter, reduced inventories, and increased supply restrictions instituted by producing countries have also contributed to the increase. Meanwhile, market forecasts and recent Federal Reserve pronouncements suggest that the benchmark interest rate in the U.S. will remain stable for the next two years. Nevertheless, a significant increase in public spending in the country has fostered expectations for greater growth and inflation, as well as increased uncertainty over the moment in which a normalization of monetary policy might begin. This has been reflected in an increase in long-term interest rates. In this context, emerging market economies in the region, including Colombia, have registered increases in sovereign risk premiums and long-term domestic interest rates, and a depreciation of local currencies against the dollar. Recent outbreaks of COVID-19 in several of these economies; limits on vaccine supply and the slow pace of immunization campaigns in some countries; a significant increase in public debt; and tensions between the United States and China, among other factors, all add to a high level of uncertainty surrounding interest rate spreads, external financing conditions, and the future performance of risk premiums. The impact that this environment could have on the exchange rate and on domestic financing conditions represent risks to the macroeconomic and monetary policy forecasts. Domestic financial conditions continue to favor recovery in economic activity. The transmission of reductions to the policy interest rate on credit rates has been significant. The banking portfolio continues to recover amid circumstances that have affected both the supply and demand for loans, and in which some credit risks have materialized. Preferential and ordinary commercial interest rates have fallen to a similar degree as the benchmark interest rate. As is generally the case, this transmission has come at a slower pace for consumer credit rates, and has been further delayed in the case of mortgage rates. Commercial credit levels stabilized above pre-pandemic levels in March, following an increase resulting from significant liquidity requirements for businesses in the second quarter of 2020. The consumer credit portfolio continued to recover and has now surpassed February 2020 levels, though overall growth in the portfolio remains low. At the same time, portfolio projections and default indicators have increased, and credit establishment earnings have come down. Despite this, credit disbursements continue to recover and solvency indicators remain well above regulatory minimums. 1.2 Monetary policy decision In its meetings in March and April the BDBR left the benchmark interest rate unchanged at 1.75%.