TISSUE TROPISM AND REPLICATIVE PROPERTIES OF WATERFOWL ORIGIN INFLUENZA-VIRUSES IN CHICKENS

Waterfowl-origin influenza (WFOI) viruses were evaluated for their tis sue tropism and replicative properties in chickens. The 14 WFOI isolat es used in this study represented 13 different hemagglutinin-neuramini dase combinations recovered during 1987 and 1988 and included isolates possessing the H5 and H7 hemagglutinin subtypes and one isolate posse ssing the H5N2 combination. Following intravenous challenge, the frequ encies of virus recovery within individual experiments were generally higher for the lower digestive tract and kidney samples. Virus titers ranged up to 10(8.5) mean embryo infective doses per gram of kidney ti ssue in clinically normal chickens. Differences in frequencies of viru s recovery and virus titers in tissues indicated that some of these un iformly nonpathogenic and low-pathogenicity WFOI virus isolates replic ated more extensively in chickens than did others. This enhanced abili ty to replicate in chickens should be further evaluated as a potential factor associated with the threat WFOI viruses present to poultry.