| Chicken infectious anemia virus (CIAV), belonging to Gyrovirus genus of Circoviridae family, is an important immunosuppressive disease hazardous to chicken industry, and the etiologic agent of which is chicken infectious anemia (CIA). CIAV could infects the chickens of all age groups. But the clinical disease is mainly noticed in young chicks of 10-14 days of age, which usually acquire the infection vertically. The disease is characterized by increased mortality, reduced weight gain, anaemia, aplasia of bone marrow and atrophy of thymus.Between 2013 and 2014,138 suspected samples were collected from diseased broilers at different chicken flocks located in ten administrative area of Sichuan province, China, and detected by PCR with CIAV-specific primers. The positive samples were then used for CIAV isolation and the complete genome sequence of CIAV isolates was determined. The delegate of CIAV isolates were then selected to infect one-day-old SPF chickens to observe its pathogenicity. The result showed that 28.26%(39/138) of samples were positive by PCR, and eleven CIAV strains were isolated from the positive samples. The sequence analysis indicated that the nucleotide homology of complete genome sequence of this eleven isolates was 98.1%-99.7%. while those between this 11 isolates and other CIAVs was 96.2%-98.4%; the amino acid homology of VP1 protein of 11 CIAV isolates was 99.1%-100%. while those between this 11 isolated and other CIAVs was 96.9%-99.3%. Phylogenetic analysis showed that 11 isolates formed a separate cluster and were relatively closely related to American Del Ross strain. The pathogenicity study showed that all chickens infected by CIAVs display severe anaemia, reduced weight gain, swelling of spleen, atrophy of thymus and aplasia of bone marrow on 15th day post-infection.In order to study the IB and ND vaccines and pathogenicity effect of co-infection of Chicken infectious anemia virus(CIAV) and Subgroup J ALV(ALV-J) in chicks. CIAV-MZ isolates of CIAV and ALV-J were used to infect 1-day-old chicks. ALV-J infection exacerbates the degree of anemia caused by CIAV on 15 days post-infection. ALV-J also extended the time to recover from anemia. Anemia persists in chickens on 40 days post-infection. Although ALV-J can induce high levels of antibody titers after immuned the IB vaccine, CIAV can significantly weaken the capacity of ALV-J. CIAV infection alone has little effect on the generation of HI antibody titer after immunization ND vaccine, ALV-J infection could obviously decreased antibody titers in the fourth week of ND vaccine immunization. It was found that CIAV with ALV-J of co-infection can lead to decreased HI antibody titer in advance. In addition, CIAV co-infected with ALV-J interaction will be enhanced pathogenicity. Chickens showed atrophy of the thymus, glandular stomach bleeding nipples, myocardial hemorrhage, intestinal and pancreas bleeding. These results suggest that CIAV with ALV-J synergistic effects on immune suppression and enhanced pathogenicity. |
