Complexity and dynamics of HIV-1 quasispecies.

The human immunodeficiency virus type 1 (HIV-1) envelope glycoproteins mediate virus entry into target cells by binding receptors of the cell membrane and fusing viral and cellular structures. In particular, recent crystallographic studies have clarified the complex role of the glycoprotein gp120 in the early phase of the infection. In this context the inter- and intra-host variability of the HIV-1 gp120 poses a major problem for the development of effective methods of immunization against this virus. In the present report, the relevant aspects emerging from the study of HIV-1 variability are addressed and several methodological approaches to evaluate HIV-1 diversity discussed.