PATHOLOGICAL-STUDIES OF A CHICKEN ALABAMA 7395 75 (H4N8) INFLUENZA-VIRUS IN SPECIFIC-PATHOGEN-FREE LAYING HENS/

Specific-pathogen-free laying hens were inoculated with avian influenz a virus (AIV) A/chicken/Alabama/7395/75 (H4N8) either intratracheally (IT) or intravenously (IV). IT inoculation produced a localized infect ion of the upper and lower respiratory tracts with lesions of tracheit is, bronchitis, airsacculitis, and pneumonia around the secondary bron chi. IV inoculation produced a systemic infection with major lesions o f nephritis, interstitial pneumonia, salpingitis, and splenic and hepa tic necrosis. In IV-inoculated hens, AIV nucleoprotein was demonstrate d within renal tubule epithelium, in luminal surface and glandular ovi duct epithelium, and in mononuclear cells within pulmonary blood capil laries. However, no virus was recovered from internal contents of eggs laid between days 1.5 and 5 postinfection. These data indicate that A /chicken/Alabama/7395/75 has tissue tropism and pathogenicity for the respiratory and urogenital systems of reproductively active laying hen s. Site and severity of lesion development are determined by the local ized or systemic nature of AIV infection.