PATHOGENESIS OF PANCREATIC ATROPHY BY AVIAN INFLUENZA-A VIRUS-INFECTION

Specific-pathogen-free (SPF), 2-day-old chicks were inoculated with ty pe A influenza virus (A/whistling swan/Shimane/499/83/(H5N3)) into the ir caudal thoracic air sac. The original isolate of the virus was of l ow virulence (ICPI 0.20 to 0.40), and was passaged 10 times through th e respiratory organs of SPF chicks. Most of the chicks inoculated with the passaged virus (strain 499) showed respiratory and alimentary sig ns. Three of 30 chicks died on days 2, 6 and 7 post-inoculation (p.i.) . Almost half of the infected chicks showed poor growth, and the varia tion of body size in the flock became prominent from day 10 p.i. Infec ted chicks consistently had pathological changes in the pancreas, live r, kidneys and respiratory tracts, and occasionally in the brain, duod enum and bone marrow. Positive immunoreaction to avian influenza virus (AIV) antigen and recovery of the virus persisted for longer period i n the pancreas than in other organs. The pancreatic lesions were cause d by a direct, lyric virus infection of the acinar cells and contribut ed to poor growth of the chicks.