Despite the infectious nature of Angara Disease (AD), the disease has also been clinically observed in association with other infectious diseases of poultry, which alone may not be capable to cause high mortality. The present study was designed to evaluate the pathology of co-infection of Avian Adenovirus-4 (AAV-4) and Avian Influenza virus (AIV) serotype H9N2 on the health of broiler chicken. In this regard, 12-day old chicks were first experimentally infected with AAV-4 followed by re-infection with AIV H9N2. The chickens infected only with AAV-4 showed virus detection from primary and secondary lymphoid organs up to 7 days post-infection. However, the duration of detection was extended up to 28 days post AIV-H9N2 infection when these birds were co-infected with Avian Influenza serotype H9N2. Moreover, a reduced serological response was observed against AIV-H9N2 in the presence of AAV-4 infection in chicken in comparison with the serological response against AIV H9N2 from healthy birds.

Key words: Avian Adenovirus-4 (AAV-4), Avian Influenza virus (AIV-H9N2), Immunosuppression, Persistence, Polymerase Chain Reaction (PCR)