Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

For baculoviruses and herpesviruses, integration of transposons or retroviruses into the virus genome has been documented. We report here that field and vaccine strains of fowlpox virus (FPV) carry integrated sequences from the avian retrovirus, reticuloendotheliosis virus (REV). Using PCR and hybridization analysis we observed that vaccine and field strains of FPV carry REV sequences integrated into a previously uncharacterized region of the right 1/3 of the FPV genome. Long-range PCR, hybridization, and nucleotide sequence determination demonstrated that one vaccine strain (FPV S) and recently isolated field strains carry a near-full-length REV provirus. For another vaccine strain (FPV M) a rearranged remnant of the LTR was found at the same insertion site. By Western blotting and reverse transcriptase assays we were unable to demonstrate free REV in supernatants of FPV S cultures. The near-full-length REV provirus integrated into the FPV genome is infectious since FPV S DNA gave rise to REV upon transfection into chicken embryo fibroblasts. Upon infection of chickens with FPV S, all chickens developed high-titered antibodies to REV, and REV was isolated from the blood of half of the inoculated chickens. Our observations add to the list of targets for retrovirus integration into DNA virus genomes. The integration of a near-full-length, and apparently infectious, REV provirus into FPV provides additional transmission routes for the retrovirus by way of the infectious cycle of FPV, including the possibility of mechanical transmission by biting insects since FPV is believed to be transmitted by this route. For large DNA viruses, including the poxviruses, retrovirus integration with attendant possibilities of gene transduction may be an important mechanism for virus evolution, including the acquisition of cellular genes with the potential to modify virus virulence and pathogenicity.
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PMID:Field and vaccine strains of fowlpox virus carry integrated sequences from the avian retrovirus, reticuloendotheliosis virus. 928 17

Infection with chicken anaemia virus (CAV), a circovirus, can result in immunosuppression and subsequent increased susceptibility to secondary infections. This is the first report of impairment of pathogen-specific cytotoxic T lymphocytes (CTL) after natural and experimental infection of chickens with CAV and Marek's disease virus (MDV) or reticuloendotheliosis virus (REV). MDV- and REV-specific CTL were generated at 7 days post infection by 9-30-day-old-chickens that were positive for maternal antibodies to CAV at 9-17 days of age. Replication of CAV could not be demonstrated in these chickens using quantitative real-time polymerase chain reaction (PCR) and reverse transcriptase (RT)-PCR assays. In contrast, REV-specific CTL failed to develop when chickens negative for maternal antibodies at 9-17 days of age were infected. Infection with CAV at 45 days of age after CAV maternal antibodies had waned also caused a decreased REV-specific CTL response. In these chickens increased levels of CAV DNA of up to 107 copy numbers per micro g DNA and increased relative transcript levels of CAV by up to a factor of 106 were detected by quantitative real-time PCR and RT-PCR. Interleukin (IL)-1beta and IL-2 mRNA levels were not significantly affected by CAV infection at 7 or 14 days p.i. Similar assays for interferon-gamma (IFN-gamma) transcripts demonstrated a 10-fold increase in IFN-gamma mRNA levels at 7 days post infection following REV or REV + CAV infection, while CAV alone caused a two- to fourfold increase. These results show a strong link between CAV antibody status, CAV replication, and the ability to generate REV-specific CTL. It is likely that the immunosuppressive effects of subclinical infection have previously been underestimated.
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PMID:Infection with chicken anaemia virus impairs the generation of pathogen-specific cytotoxic T lymphocytes. 1275 24

Reticuloendotheliosis virus (REV) is widespread in the world. No related data has been reported in Taiwan. To determine the REV infection status, antibody determination and virus isolation were performed on chickens in Taiwan. The results revealed that serological flock prevalence for the REV antibody reached 92.8% (39/42) amongst breeders (> 16 weeks old). Two different REV isolates were identified by reverse transcriptase-polymerase chain reaction, electron microscopic, immunofluorescent, and western blot assays after isolation. One of these viruses was isolated from a broiler breeder farm and the other was isolated from a Taiwan Country Chicken farm. Despite their different origins, the percent identity of the nucleotide sequences of the env gene of these two isolates was 99.7%. These two strains were similar to the FPV-UI-REV strain, featuring 99.7% and 99.8% percent identity. Indeed, REV infection would appear to be quite common amongst chickens.
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PMID:Serological and virological surveys of reticuloendotheliosis in chickens in Taiwan. 1721

A reverse transcriptase assay was applied as a diagnostic test for lymphoproliferative disease (LPD) of turkeys. The assay differentiates LPD from reticuloendotheliosis (RE) on the basis of a different divalent cation-requirement of the exogenous-templated reverse transcriptase activity associated with the causative viruses. The test requires small volumes of blood, is rapid, sensitive and appropriate for the detection of LPD virus in the blood of field or experimentally infected turkeys.
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PMID:A reverse transcriptase assay for the diagnosis of lymphoproliferative disease (LPD) of turkeys. 1877 Feb 89

The successful reintroduction of Wild Turkeys ( Meleagris gallopavo) to Ontario, Canada, has led to established populations in southern portions of the province and currently allows for biannual hunting seasons. These populations geographically overlap Domestic Turkey farms, an important sector of the provincial agri-food industry. Potential pathogen transmission between Wild Turkeys and Domestic Turkeys ( Meleagris gallopavo) is a concern, because they are susceptible to infection with many of the same pathogens and have direct and indirect contact in outdoor or open farm settings and contaminated environmental substrates. However, data concerning potential poultry pathogens in Wild Turkeys in Canada are scarce. Thus, we assessed the prevalence and geographic distribution of geographically relevant viruses in Ontario Wild Turkeys. Oropharyngeal and cloacal swabs were tested for avian influenza viruses (AIV) by real-time reverse transcriptase (RT)-PCR ( n=207), pooled tissues for lymphoproliferative disease virus (LPDV; n=183) and reticuloendotheliosis virus ( n=119) by PCR, and gross skin lesions by real-time RT-PCR for avian poxvirus ( n=8). We sequenced a fragment of the gag polyprotein (p31) gene of LPDV on a subset ( n=10) of LPDV-positive samples for phylogenetic analysis and tested additional upland game bird species ( n=39) and domestic fowl for LPDV ( n=17). To the best of our knowledge, we document the first detection of LPDV in Wild Turkeys in Canada, with a prevalence of 65% (119/183). Phylogenetic analysis revealed that LPDV sequences from Ontario were genetically similar to other North American strains and did not group into separate clades. Reticuloendotheliosis virus was detected in 4% (5/119) of LPDV-positive Wild Turkeys. Grossly evident skin lesions from five Wild Turkeys tested positive for poxvirus, and all turkeys tested negative for AIV. This study provides evidence of LPDV circulation in Canada and provides a baseline for comparison with future Wild Turkey pathogen surveillance and monitoring in Ontario and elsewhere.
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PMID:DETECTION OF LYMPHOPROLIFERATIVE DISEASE VIRUS IN CANADA IN A SURVEY FOR VIRUSES IN ONTARIO WILD TURKEYS ( MELEAGRIS GALLOPAVO). 3012 93


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