Editors' ChoiceGlobal Health

Transmission Favors HIV’s Ancestors

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Science Translational Medicine  17 Oct 2012:
Vol. 4, Issue 156, pp. 156ec187
DOI: 10.1126/scitranslmed.3005117

HIV is a master at evading the human immune system. Every day, every single base-pair changes, making the virus virtually unrecognizable. This massive diversity in HIV strains makes vaccine development challenging because the optimal target is ever-changing. HIV vaccine design has focused on conserved regions of the virus, but these are usually tucked away inside the virus, protecting them from immune cells. In a recent paper, Redd and colleagues demonstrated that previously transmitted HIV strains are preferentially selected during heterosexual transmission, opening the door to new avenues of vaccine design.

In a study among couples followed in the Rakai Community Cohort Study in Uganda between 1994 and 2002, interhost and intrahost HIV diversity was analyzed by using HIV sequencing. The authors were able to compare the diversity within an individual over time and identify the strain with which his or her partner was infected. The diversity was greater intrahost than interhost. Further, for the majority of couples, the newly infected partner’s HIV strain was more closely related to HIV found earlier in the infectious partner as compared with those strains circulating at the time of infection. The authors’ findings suggest that, at a population level, ancestral strains of HIV are preferentially transmitted compared with contemporary circulating strains.

This work by Redd et al. has important implications for HIV prevention, specifically HIV vaccine development. Once it is confirmed that ancestral strains are preferentially transmitted, further studies can identify molecular determinants for HIV transmission, and vaccine development can focus on a narrower range of targets.

A. D. Redd et al., Previously transmitted HIV-1 strains are preferentially selected during subsequent sexual transmissions. J. Infect. Dis. 206, 1433–1442 (2012). [Abstract]

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