Impact Of Reticuloendotheliosis Virus And Uve Infectious Bursi Bl Disease Vacdne On The Avian Influenza Vaccine

Highly pathogenic avian influenza(HPAI) induced by H5 subtype avian influenza virus(AIV) has caused huge economic losses for the poultry industry and threaten public health. China takes measures of culling plus vaccination and the implement of AI vaccines has played a major role in controlling HPAI. However, HPAI still occurred sometimes, with the reason of big difference between clinical application and experimental results. Many factors may contribute to the decreased immune efficacy. In this study, we investigated the immunosuppression caused by reticuloendotheliosis virus(REV) and live infectious bursal disease(IBD) vaccine in order to give reference for analyzing the reason of immune failure and choosing suitable IBD vaccine.To evaluate the impact of REV on AI vaccines, we chosed REV HLJR0901 to infect one-day-old SPF chickens and immunized AI vaccines, then evaluated the influence of REV on AI vaccines from aspects of HI antibody titers, stimulation index(SI) of peripheral blood monouclear cells(PBMCs) and splenic lymphocytes, CD4+/CD8+ of PBMCs and splenic lymphocytes, cytokine content and protective efficacy. The results showed that REV suppressed the HI antibody titers, lymphocytes prolification and CD4+/CD8+ significantly. The peak of average HI antibody titers could be more than fourfold, with the biggest difference being 64 times on the same day after immunizing with AI vaccine. Inactivated AI vaccine(Re-6) could only provide 70% protection and single live AI vaccine(rLH5-6) and twice rLH5-6 vaccine could provide 60% and 80% protection respectively after REV infection.To evaluate the impact of live IBD vaccine on AI vaccines, we chosed two live IBD vaccines with virulence of weakness and medium, and immunized these two vaccines with AI vaccines respectively, then evaluated the influence of live IBD vaccines on AI vaccines from the same aspects with the study about the influence of REV on AI vaccines. The results showed that HI antibody titers in groups of IBD vaccine(Gt strain), IBD vaccine(MB strain) were 5.9 log2, 2.1 log2 on 21 days post-vaccinated with inactivated AI vaccine(Re-6), while the HI antibody titer of the control group of Re-6 vaccinated was 7.7 log2, and the survival rate of these three groups were 10/10, 8/10, 10/10 respectively, and the virus shedding were 1/10, 7/10, 0/10 respectively. HI antibody titers in groups of IBD vaccine(Gt strain), IBD vaccine(MB strain) were 2.2log2, 1.6 log2 on 21 days post-vaccinated with live AI vaccine(rLH5-6), while the HI antibody titer of the control group of rLH5-6 vaccinated was 2.5 log2, and the survival rate of these three groups were 10/10, 7/10, 10/10 respectively, and the virus shedding were 1/10, 3/10, 0/10 respectively. Neither of these two IBD vaccines showed significant impact on celluar immune response.Our study demonstrated that both REV and live IBD vaccine(MB strain) had significant impact on AI vaccines, while live IBD vaccine(Gt strain) had no significant impact on the protective efficacy of AI vaccines.