Immuno-Suppression of Reticuloendotheliosis Virus Infection on Antibody Responses to Different Vaccines in SPF chickens

Avian reticuloendotheliosis virus (REV) infection was reported to be very common in chicken flocks in China, but its economic impact on the poultry industry was not clear. The results in this study indicated that REV infection in 1-day-old SPF chickens could severely suppressimmune reactions to inactivated vaccines against Newcastle disease virus (NDV) and Avian influenza virus (AIV). Hemagglutination inhibition (HI) antibody titers to NDV, AIV-H9 and AIV-H5 in REV-infected birds were significantly lower than that in the control group 3, 4, and 5 weeks after vaccination at the age of 7 days. REV infection of high doses caused more severely immuno-suppression than that with low doses, but the difference between high and low doses was not significant. REV infection also caused severe atrophy of central immune organs, the ratios of thymus and the Bursa to body weight in REV-infected birds were significantly lower than that in thecontrol birds. This study demonstrated that the early REV-infection interfered vaccinations to NDV and AIV.