HIV-1 infection of human brain-derived microvascular endothelial cells in vitro

We examined the ability of human immunodeficiency virus (HIV) type 1 (HIV-1) to infect in vitro, primary brain-derived human microvascular endothelial cells (HMEC) that constitute the blood-brain barrier (BBB). Immunofluorescence (IFA) and antigen capture assays failed to demonstrate p24 antigen from HIV inoculated endothelial cells and supernatants did not contain detectable levels of reverse transcriptase (RT). HIV could be rescued by cocultivation of infected HMEC with a susceptible T-lymphocyte line (CEM-SS), which were then shown to form syncytia and produce RT activity and p24 Ag (IFA, antigen captive assay). Polymerase chain reaction (PCR) was successfully used to amplify HIV-specific gag and env gene sequences from HMEC. CD4 expression was not identified on these cells by IFA. These results suggest that HIV infection of BBB endothelium occurs, but that viral replication is minimal. Infection of the BBB by HIV may give the virus a foothold in the CNS and suggests that the brain might be infected directly and may not be limited to just the passage of infected mononuclear cells.