Immune Changes Of Chicks Infected With Chicken Infectious Anemia Virus And Immune Response And Mechanism To Newcastle Disease Vaccine Immunity

The dynamic changes of the number of T or B lymphocytes and the content of immunoglobulin (Ig) G, IgM, IgA in peripheral blood, the number of CD4+, CD8+ lymphocyte subpopulation , TANAE+ cells and IgG, IgM, IgA antibody-producing cells, the ratios of CD4+ and CDg+ T cells in immune organs (thymus, bursa of Fabricius and spleen) and immune tissues (cecal tonsils and Harderian glands), the content of IgA, IgM, IgG in local fluid (tear, tracheal fluid, intestinal fluid and bile) of one-day chicks infected with chicken infectious anemia virus (CIAV) and CIAV-infected chicks immunized with Newcastle disease (ND) vaccine were determined respectively by immunohistochemistry, immunogold-silves and immunoenzyme staining in order to reveal mechanism of immunopathogenesis of chicks infected with CIAV and influence of immune responses of CIAV-infected chicks to ND vaccine. The results were as follows:1. The numbers of T,B lymphocytes and the content of IgG, IgM, IgA in peripheral blood of chicks infected with CIAV were significantly decreased compared with controls 7-28 days postinfection (PI). The results showed that cellular and humoral immune function in peripheral blood of chicks infected with CIAV were lowered.2. The number of CD4+, CDg+ lymphocyte subpopulation , ANAE+ T cells and IgG, IgM, IgA antibody-producing cells in immune organs (thymus, bursa of Fabricius and spleen) of chicks infected with CIAV were significantly decreased compared with control 7~35 days PI. Especially, the ratios of CD4+ and CD8+ T cells of CIAV-infected chicks were markedly lowered compared with chicks no-infected with CIAV. The results indicated that the cellular immune function in immune organs of CIAV-infected chicks not only was repressed but humoral immune function was lowered.3. The number of CD4+ and CD8+ lymphocytes subpopulation , ANAE+ T cells and IgG, IgM, IgA antibody-producing cells in the local immune tissues (cecal tonsils and Harderian glands), the content of IgA, IgM, IgG in the local fluid (tear, tracheal fluid, intestinal fluid and bile) of chicks infected with CIAV were significantly decreased compared with controls 7-28 days PI. The results showed that the both cellular andhumoral immune function of local mucous membrane in the digestive and respiratory duct of CIAV-infected chicks was lowered.4. The number of CD/ lymphocytes subpopulation in the immune organs and tissues of CIAV-infected chicks decreased lower than CD8+ T cells. The results indicated that CIAV infection destroyed CD4+ T-cell subsets more serious than CDg+.5. The content of IgG, IgM, IgA and HI titer in serum were significantly lower in infected-vaccinated chicks than vaccinated control chicks 7-28 days postvaccination (PV). These indicated that humoral immune response in peripheral blood of CIAV-infected chicks to ND vaccine were markedly lowered.6. The number of CD4+ and CDg+ lymphocytes subpopulation and IgA, IgM, IgG antibody-producing cells , the ratios of CD4+ and CDg+ T-cell subsets in immune organs (thymus, bursa of Fabricius and spleen) of CIAV-infected chicks vaccinated ND vaccine were significantly decreased compared with vaccinated control chicks 7-28 days PV. The results showed that immune responses in immune organs of chicks infected with CIAV to ND vaccine were lowered.7. The number of CD4+ and CD8+ lymphocytes subpopulation and IgA, IgM, IgG antibody-producing cells, the ratios of CD4+ and CD8+ T-cell in the cecal tonsils and Harderian glands, the content of IgA, IgM, IgG in tear, tracheal fluid, intestinal fluid and bile of CIAV-infected chicks vaccinated with ND vaccine were significantly decreased compared with vaccinated control chicks 7-28 days PV. The results showed that immune responses of local mucous membrane of CIAV-infected chicks to ND vaccine were lowered.8. The immune protective rates of CIAV-infected chicks vaccinated with ND vaccine (60%) were markedly lower than that of the ND-vaccinated control birds (100%) after challenge with vND...