| Avian Leukosis Viruses (ALV) belong to Alpharetrovirus genus of the family Retroviridae and was first recognized as a tumor-inducing virus. According to antigenicty of its envelope protein gp85 related to host specificity, ALV have 10 subgroups of A to J, but only subgroups A, B, C, D, E, and J infect chickens. Since 1988, the White Boilers in the UK found a J-sub-group of ALV, with fast speed spread to the world of poultry and has also brought huge losses. In the past decade, the prevalence of leukemia in chickens has also been extensive coverage in our country. Because of its more serious losses, international and domestic poultry industry is also more focus more on the ALV-J. In the past two years, reports of start laying hens occur vascular tumors were significantly increased. It has become the first major epidemic that affect the egg industry in China. It gives farmers great economic losses. Virus isolation and identification showed that tumor blood vessels is mainly subgroup J avian leukosis virus, but also some from A, B subsets of leukemia virus infection. This is not just the main problems of layers, which is the main problem of the local strains chicken. As our country has never been purified classic leukemia, in our local strains classical chicken leukemia virus may be widely popular, and even a new mutation has occurred, resulting in a new subtype. So our local strains of chickens in the epidemiology of leukemia may be more complex.In this study, the fertilized eggs were collected from a local breed chicken flock and incubated for 9-11 days, chicken fibroblast cells (CEF) were prepared from these embryos one by one and incubated for 7-9 days. The supernatant was collected from each CEF cultlures and inoculated into DF1 cells. The inoculated DF1 cell cultures were incubated for another 9 days and tested for avian leukosis virus (ALV) group specific p27 antigen in ELISA. Each of the positive samples was vaccination to 3 42 days old SPF chickens breast muscle. Started from the second week, every two weeks collect blood samples once, separation of serum, respectively use ALV-J, ALV-ab antibody kit detection antibody, and continuous measurement for 16 weeks. Test results showed that four of SPF chickens inoculated showed a transient or persistent ALV-AB-positive, and the remaining samples of SPF chickens inoculated with neither a positive nor a J AB positive. Cloacal swab collected at the same time, with ALVp27 antigen ELISA assay kit detox situation, showed that some attack chickens had transient drug detoxification, and some are not detected detoxification.By PCR, its env gene was amplified, cloned and sequenced. Comparison of env amino acid sequences between the virus we isolates and other ALV strains of different subgroups published indicated that we have got an A sub-group of leukemia viruses, a subgroup B leukemia viruses, and a new subtype of leukemia virus.
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