AIDS-ASSOCIATED ENCEPHALOPATHY WITH EXPERIMENTAL FELINE IMMUNODEFICIENCY VIRUS-INFECTION

Experimental intravenous challenge of 8-week-old kittens with the feli ne immunodeficiency virus Maryland isolate (FIV-MD) was investigated f or its ability to infect the central nervous system (CNS) and induce n eurologic abnormalities. Six cats were inoculated with 1,000 TCID50 un its of FIV-MD isolate, with six age-matched cats serving as uninfected controls. Clinical and immunological evaluation documented that chall enged cats developed immunodeficiency and growth delay. Neurologic exa mination revealed an abnormal stereotypic motor behavior consisting of repetitive, compulsive roaming that developed as early as 4 weeks pos tinfection (PI) and persisted throughout the 16-month study in three c ats. Serial neuroelectrodiagnostic evaluation revealed persistent abno rmal electroencephalographic recordings in three infected cats. Serial evoked potential (EP) recordings at 3, 8, and 12 months PI demonstrat ed significantly prolonged interpeak latencies III-V at 3 months PI an d I-III at 12 months PI for brainstem EP recordings. Alterations of vi sual 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 ventric ular 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 infi ltrates. Virus was detected in the CNS by reverse transcriptase, immun ofluorescence, and antigen capture. Evaluation of the cerebrospinal fl uid revealed intrathecal anti-FIV-MD antibody despite lack of detectab le viremia in five challenged cats. Collectively, these findings demon strate 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 ped iatric encephalopathy.