J Virol. 2015 Apr; 89(7):3619-29.

PubMed ID: 25589663

Conserved molecular signatures in gp120 are associated with the genetic bottleneck during simian immunodeficiency virus (SIV), SIV-human immunodeficiency virus (SHIV), and HIV type 1 (HIV-1) transmission

Gonzalez MW, DeVico AL, Lewis GK, Spouge JL

Human immunodeficiency virus (HIV) transmission typically results from infection by a single transmitted/founder (T/F) variant. Are T/F variants chosen uniformly at random from the donor pool, or are they selected based on advantageous traits facilitating transmission? Finding evidence for selection during transmission is of particular interest, because it would indicate that phenotypic and/or genetic properties of the viruses might be harnessed as potential vaccine targets or immunotherapies. Here, we systematically evaluated the differences between the Env proteins of simian immunodeficiency virus/simian HIV (SIV/SHIV) stock and T/F variants in search of ""signature"" sites of transmission. We also surveyed residue preferences in HIV at the SIV/SHIV signature sites. Four sites of gp120 showed significant selection, and an additional two sites showed a similar trend. Therefore, the six sites clearly differentiate T/F viruses from the majority of circulating variants in the stocks. The selection of SIV/SHIV could be inferred reasonably across both vaccinated and unvaccinated subjects, with infections resulting from vaginal, rectal, and intravenous routes of transmission and regardless of viral dosage. The evidence for selection in SIV and SHIV T/F variants is strong and plentiful, and in HIV the evidence is suggestive though commensurate with the availability of suitable data for analysis. Two of the signature residues are completely conserved across the SIV, SHIV, and HIV variants we examined. Five of the signature residues map to the C1 region of gp120 and one to the signal peptide. Our data raise the possibility that C1, while governing the association between gp120 and gp41, modulates transmission efficiency, replicative fitness, and/or host cell tropism at the level of virus-cell attachment and entry.