The Negative Impact of Chicken Infectious Anemia Virus Infection on Immune Responses to Different Newcastle Disease Virus Vaccination Programs

Chicken infectious anemia virus (CIAV) is among the naturally occurring viruses that cause immunosuppression in chickens. In the present study, the impact of CIAV infection on both NDV vaccination immune responses and bird performance were demonstrated. Post CIAV infection, the mean live body weights of the ND-vaccinated groups showed improvement compared with the non-NDV vaccinated groups. The immunosuppressive effects of CIAV infection was higher and more obvious on live ND vaccinated group compared with the other vaccinated groups. The vaccination with combination of live and inactivated vaccines showed better HI-NDV Ab responses especially when inactivated vaccine was administrated at 9 days (group II). In consistent, both the phagocytic Percent and Index were lower in case of vaccination with live NDV vaccine only and CIAV infection. Birds were vaccinated with both live and inactivated NDV vaccines at different time points showed superior protection rate (100%) compared with the other groups. Microscopically, CIAV infection led to severe deterioration in the lymphoid tissues (thymus, bursa, spleen and bone marrow) such as focal to diffuse depletion of lymphocytes and hematopoietic cells. This study highlights the negative impact of CIAV infection on both bird performance and immune status.