COMPARATIVE PATHOLOGY OF INTRAVENOUSLY INOCULATED WILD DUCK-ORIGIN AND TURKEY-ORIGIN TYPE-A INFLUENZA-VIRUSES IN CHICKENS

Five-week-old specific-pathogen-free chickens were inoculated intraven ously with one of 16 low-pathogenicity type A influenza virus isolates ; 14 were of wild duck origin, and two were of turkey origin. Tubuloin terstitial nephritis was the most frequent specific histopathologic ch ange. The frequency and severity of kidney lesions were independent of the virus hemagglutinin-neuraminidase subtype or titer of the challen ge virus. Influenza nucleoprotein was most frequently demonstrated in the kidney and was consistently localized to necrotic proximal and/or distal renal tubule epithelium. Common nonspecific histopathologic cha nges were lymphoid hyperplasia of the spleen and cecal tonsils, as wel l as lymphocyte depletion in the cloacal bursa. Uncommon histopatholog ic changes, in decreasing order of frequency, were interstitial pneumo nia, lymphoid follicular hyperplasia in the myocardium, and lymphocyti c tracheitis. Histopathologic changes were rare or absent in the jejun um, duodenum, pancreas, and brain.The low-pathogenicity avian-origin t ype A influenza virus isolates were epitheliotropic in chickens, prima rily nephrotropic. Such findings were dissimilar from Endings with hig hly pathogenic avian-origin type A influenza virus isolates both in se verity and in tissue distribution of histopathologic changes and influ enza viral antigen.