Binding of HIV-2 envelope glycoprotein to CD8 molecules and related chemokine production.

We recently found that human immunodeficiency virus (HIV)-2 envelope glycoprotein, but not that of HIV-1, could bind to CD4 and CD8 molecules on T cells, and that the binding site of HIV-2 envelope glycoprotein was located on the alpha-chain (but not the beta-chain) of CD8. This study showed that the binding of HIV-2 envelope glycoprotein could induce phosphorylation of protein tyrosine kinase p56lck in CD8+ T cells. We also found that production of beta-chemokines in response to HIV-2 envelope glycoprotein was significantly higher than that in response to HIV-1 envelope glycoprotein, and that CD8+ T cells were the main source of beta-chemokines production among the T-cell population. These findings indicate the possibility that the binding of envelope glycoprotein to CD8 molecules are related to signal transduction into CD8+ T cells and the resultant beta-chemokine production in HIV-2 infection. Our results may help to explain the differences in disease manifestations between HIV-1 and HIV-2, including the lower virulence of HIV-2 and the longer survival of HIV-2-infected individuals.