EFFECT OF AVIAN INFLUENZA-VIRUS INFECTION ON THE PHAGOCYTIC FUNCTION OF SYSTEMIC PHAGOCYTES AND PULMONARY MACROPHAGES OF TURKEYS

The effects of avian influenza virus (AIV) infection on systemic phago cytes and pulmonary, macrophages of turkeys were studied. There was a significant increase (P < 0.0001) in oxidative burst in systemic phago cytes of AIV-inoculated turkeys on 2, 4, 6, and 8 days postinoculation (PI), as measured by chemiluminescence. There was also a significant increase (P < 0.02) in oxidative burst in pulmonary macrophages on day 4 PI. The chemiluminescence response was depressed on 6, 8, and 10 da ys PI in AIV-inoculated turkeys compared with controls. The increase i n oxidative response in both systemic phagocytes and pulmonary macroph ages correlated with the peak virus titer in the lungs and trachea of AIV-inoculated turkeys. Bacterial killing by pulmonary macrophages fro m AIV-inoculated turkeys was reduced on days 6 and 10 PI compared with uninoculated controls. Histopathological changes in trachea were more pronounced on days PI in AIV-inoculated turkeys; no significant chang es were detected in the lungs. These data indicate that compromised fu nctional capacity of pulmonary macrophages predisposes turkeys to seco ndary bacterial infections.