Pathogenicity And Genomic Cloning Of A Chicken Infectious Anemia Virus Isolated From Beijing

Chicken infectious anemia virus (Chicken infectious anemia virus,CIAV) is the pathogen which cause chicken infectious anemia (Chicken infectious anemia,CIA), belong to Circoviridae (Circoviridae). The disease can damage blood system, and make the lymphoid organs shrink, causing immunosuppression in chickens. Immunosuppressed of CAV often make chicken infected by other pathogens of multiple infections.The whole genome of strain of chicken anemia virus (CAV) from the Beijing was cloned using PCR method , and sequenced named BJ0924, the virus genome is circular negative strand DNA, the whole genomic sequence 2298 bp,containing three overlapping open reading frame and a control region. Compared the BJ0924 strain and the other CAV genome in GenBank genome with homology 93.3% to -96.8%, with the German isolate (strain pattern) Cux-l homology is 95.5%. Compared the BJ0924 strain with other strains on the VP1, VP2 and VP3 protein, VP1 has largest variation, VP3 second, while the highest VP2 conservative. Drawn the phylogenetic tree between the BJ0924 strain genome sequence and the CAV genome sequence in GenBank . From the view of phylogenetic tree,the BJ0924 strains was a separate one . From this information we can speculate that the isolated strain BJ0924 of chicken anemia virus may be a new virus genotype.In this paper, based on the system study of 1 day-old SPF chickens poison attack experimental that the CAV field isolates Beijing (BJ0924) to the pathogenicity of SPF chickens. After attacking by 7,14,21 days, BJ0924 SPF can cause chickens weight loss, immune organs (thymus, bursa) atrophy, chicken femur and tibia bone marrow color pale yellow, and the number of red blood cells significantly decreased and such clinical symptoms, on the study of thymus , bursa, spleen, liver, pathological changes and antigen localization. The results show the virus to a virulent CAV, and the virus antigens obtained mainly in the thymus, bursa of Fabricius and spleen, while small amount of antigen expression in liver.Detected by flow cytometry of 1 day old chicks infected by CAV-BJ0924 , after the infection of 7,14,21 days, we get peripheral blood and thymus, bursa, spleen, bone marrow, and made them into lymphocytes , then using the three flow cytometry to detection dynamics change of CD4 ~+ and CD8 ~+ T cell subsets in tissue. The results showed that: after 7 days of infection,peripheral blood,bone marrow,CD3~+,CD4~+,CD8~+, CD4~+/CD8~+ T lymphocyte levels in bursa of each experimental chickens did not have significant difference with the control group,whileCD4~+,CD8~+,CD4~+/CD8~+in the thymus,and CD8~+T lymphocyte levels in spleen have significantly different with control group. At 14 days age of infection, the differences between peripheral blood, bone marrow, spleen and in CD3~+,CD4~+,CD8~+, CD4~+/CD8~+T lymphocyte levels in thymus of each experimental chickens and control group were significant, and in the bursa,only CD4~+/CD8~+T lymphocyte levels were significantly different from control group, and in peripheral blood and spleen, CD3~+,CD4~+,CD8~+,CD4~+/CD8~+T lymphocyte levels and the control group was significantly different. At 21 days age of infection, except the differences of CD3~+,CD4~+,CD8~+,CD4~+/CD8~+T lymphocyte levels in Bursa with the control group was not significant, other differences were significant, but differences between CD3~+,CD4~+,CD8~+,CD4~+/CD8~+ T lymphocytes content with uninfected control chicks decreased.