PATHOLOGICAL FEATURES OF ACQUIRED IMMUNODEFICIENCY-LIKE SYNDROME IN CATS EXPERIMENTALLY INFECTED WITH FELINE IMMUNODEFICIENCY VIRUS

Five specific pathogen free cats were inoculated with feline immunodef iciency virus (FIV) isolated in Japan to observe changes toward develo pment of acquired immunodeficiency syndrome (AIDS)-like disease. All i noculated cats had lymphadenopathy and mild respiratory disease shortl y after inoculation. Following the initial acute phase lasting for mor e than 40 weeks, the clinical signs gradually diminished in three anim als, and the asymptomatic carrier (AC) stage was observed at 45 (1 cat ) and 70 (2 cats) weeks postinoculation (p.i.). Two of the three cats developed respiratory signs and diarrhea at 105 or 106 weeks p.i. One cat died at 121 weeks p.i. with severe wasting, with necropsy findings consistent with AIDS-related complex (ARC). The others were surviving at 150 weeks p.i. with mild clinical signs or asymptomatic. Another g roup of two cats developed more severe illness without the AC phase. O ne died at 48 weeks p.i. with the ARC illness. The other cat developed marked emaciation with dearrhea at 75 weeks p.i., and died at 100 wee ks p.i. with a histologic diagnosis suggestive of terminal immunodefic iency. Hstologically, the lymph nodes showed serial changes toward the terminal illness, from follicular hyperplasia at the acute phase to t he lymphoid depletion at the ARC and AIDS-like terminal stages. The FI V antigen was demonstrated in the lymph nodes. The virus was isolated from peripheral blood mononuclear cells of all the inoculated animals. These data demonstrated possible etiologic association of FIV with de velopment of AIDS-like disorders in the cat.