The antigenic tip GPGRAFY of the V3 loop on HIV-1 gp120: genetic variability and subtypes

Significant genetic and antigenic variability within the env gene of systemic human immunodeficiency virus type 1 group O populations during the natural course of a heterosexual infection: a pilot study

We assessed the genetic and the antigenic variability within the env gene of peripheral blood human immunodeficiency virus (HIV) type 1 (HIV-1) group O populations during the natural course of a female heterosexual infection. Our data revealed the existence of a significant increase in amino acid sequence variability within the C2-V3 and gp41 regions (P = 0.023 and P < 0.001, respectively) in association with substitutions within neutralizing epitope sequences usually selected for HIV serological assays. These antigenic variations might significantly decrease the sensitivity of classical HIV enzyme-linked immunosorbent assays with blood samples of subjects heterosexually infected by HIV-1 group O strains. These findings may be of significant use both to devise diagnostic tools and to pursue suitable therapeutic modalities in cases of heterosexual infection by outlier HIV-1 strains.

Neutralizing epitopes in the membrane-proximal region of HIV-1 gp41: genetic variability and co-variation

Recent investigations on the passive immunization have proved that neutralizing antibodies directed to the membrane-proximal region of HIV-1 gp41 are potent anti-viral components, so this region is thought to be an attractive target for AIDS vaccine. Three key neutralizing epitopes, ELDKWA (aa662-667), NWFDIT (aa671-676) and ERDRDR (aa739-744) have been mapped in this region. In this study, their genetic variability and co-variation was evaluated. There exists marked shift in the predominant sequence patterns on these three neutralizing epitopes over time. Compared with subtype B, non-B clades exhibit significant genetic variability and co-variation on these three epitopes. Among HIV-1 strains isolated in recent 5 years, about one third displays epitope variants simultaneously on three epitopes. The newly isolated strains with co-variations on several neutralizing epitopes ought to be of strict surveillance in clinical treatment, and those frequent epitope variants should also be considered in vaccine design.