Analysis of human endothelial cells and cortical neurons for susceptibility to HIV-1 infection and co-receptor expression

Neuronal cell death is believed to be the underlying cause of neurological diseases and AIDS dementia often seen in human immunodeficiency virus (HIV) infected patients. The means by which HIV invades the brain is still unknown and the mechanism of neuronal cell death remains to be elucidated. The aim of this study was to determine if direct infection of human brain endothelial cells and neurons play a role in viral invasion of the brain and neuronal cell death, respectively. To this effect, we evaluated human brain microvascular endothelial cells (HBMEC) and human cortical neurons (HCN) for the expression of HIV co-receptors and their susceptibility to HIV-1 infection. While both HBMEC and HCN failed to express any CXCR4 and CCR5 on their cell surface, as assessed by flow cytometry, RT-PCR revealed the presence of CXCR4 and CCR5 mRNA in HBMEC but not in HCN, Two dual tropic HIV-1 primary isolates failed to infect both cell types as determined by p24 antigen capture ELISA, RT-PCR and DNA PCR. These data support the hypothesis that no productive infection of HBMEC and HCN occurs in vitro and suggest that other cell types are the primary focus of HIV-1 infection in the brain.