AIDS-associated encephalopathy with experimental feline immunodeficiency virus infection.

Experimental intravenous challenge of 8-week-old kittens with the feline immunodeficiency virus Maryland isolate (FIV-MD) was investigated for its ability to infect the central nervous system (CNS) and induce neurologic abnormalities. Six cats were inoculated with 1,000 TCID50 units of FIV-MD isolate, with six age-matched cats serving as uninfected controls. Clinical and immunological evaluation documented that challenged cats developed immunodeficiency and growth delay. Neurologic examination revealed an abnormal stereotypic motor behavior consisting of repetitive, compulsive roaming that developed as early as 4 weeks postinfection (PI) and persisted throughout the 16-month study in three cats. Serial neuroelectrodiagnostic evaluation revealed persistent abnormal electroencephalographic recordings in three infected cats. Serial evoked potential (EP) recordings at 3, 8, and 12 months PI demonstrated significantly prolonged interpeak latencies III-V at 3 months PI and I-III at 12 months PI for brainstem EP recordings. Alterations of visual EPs were detected only at the 3-month time period. Retinocortical time, however, was significantly different from that in control cats at 3 and 12 months PI. Magnetic resonance imaging evaluation of FIV-MD-infected cats at 12 months PI revealed cortical atrophy, mild ventricular enlargement, and discrete white matter lesions. At 16 months PI, however, histopathological examination of brain tissue indicated only mild lesions limited to satellitosis and perivascular lymphocytic infiltrates. Virus was detected in the CNS by reverse transcriptase, immunofluorescence, and antigen capture. Evaluation of the cerebrospinal fluid revealed intrathecal anti-FIV-MD antibody despite lack of detectable viremia in five challenged cats. Collectively, these findings demonstrate the induction of virus-associated neurologic disease following parenteral FIV challenge in conjunction with an immunodeficiency state. The nature of the nervous system infection is analogous to HIV-1 pediatric encephalopathy.