Natural variants of human immunodeficiency virus from patients with neurological disorders do not kill T4+ cells

Human immunodeficiency virus (HIV) has selective T4-cell tropism and is cytocidal to cells with the helper-inducer phenotype. Central nervous system dysfunctions can complicate full-blown acquired immunodeficiency syndrome (AIDS) but can also be present either in isolation or in the context of AIDS-related complex. Remarkably bland histopathological findings have been reported in some patients with AIDS dementia in the presence of severe clinical dysfunction. Thus, to understand the cytopathic properties of HIV, we recovered five viral isolates from 4 patients with neurological symptoms of AIDS and identified them as HIVs. The replication and cytocidal properties of these isolates were compared with lymphadenopathy-associated virus in vitro. All five isolates exhibited replication efficiency equivalent to lymphadenopathy-associated virus, but four isolates did not kill CD4 (T4+) cells. These findings provide evidence for the existence of replication-competent noncytocidal natural variants of HIV and raise the possibility that, in some AIDS patients, neurological disorders might be caused by HIV variants that are noncytocidal to T4 cells.