Differences of HIV Envelope Protein between HIV-1 and HIV-2: Possible Relation to the Lower Virulence of HIV-2

Although a decade has passed since human immunodeficiency virus (HIV)-2 was first reported, both basic and clinical research involving HIV-2 have been less extensive when compared with the more widespread and earlier described HIV-1, despite both being causative agents of acquired immunodeficiency syndrome (AIDS). Investigation of the mechanisms behind the lower virulence of HIV-2 may provide useful information on the pathogenesis of HIV-1, which is a more widespread and more harmful virus than HIV-2. In this article, we report on and review the different effects of envelope glycoproteins of HIV-1 and HIV-2 on the immune responses induced by these viruses, and discuss possible mechanisms of the lower virulence of HIV-2 based on our experimental results and the relevant literature.