HIV This Week

Butler IF, Pandrea I, Marx PA, Apetrei C. HIV genetic diversity: biological and public health consequences. Curr HIV Res 2007;5:23-45.

The devastating consequences of the HIV pandemic will probably only be controlled when a vaccine is developed that is safe, effective, affordable, and simple enough to permit implementation in developing countries where the impact of HIV is most severe. However, the major obstacle for the control of the spread of HIV lies in the diversity of HIV and its enormous evolutionary potential. Butler and colleagues in this review article describe the numerous HIV forms that contribute to the HIV pandemic. Two viral types (HIV-1 and HIV-2), numerous groups (M, N and O for HIV-1 and A through H for HIV-2) and numerous subtypes, sub-subtypes and circulating recombinant forms (CRF) have emerged during the last 50 years. At least nine different genetic HIV-1 subtypes and over 20 CRFs were defined within group M, which accounts for the majority of cases in the HIV pandemic. Even though HIV-1 subtype C and A predominate globally, the other viral forms co-circulate all over the world and may have a major impact for the strategies of pandemic control. The authors review the distribution of these divergent viral forms worldwide and they discuss the potential consequences of such a tremendous viral diversity for diagnostic, monitoring, treatment and the development of an effective vaccine.

Editors’ note: This overview describes HIV viral diversity and the continuing rapid evolution of this wily virus. When two subtypes encounter each other in the same individual, they swap and trade gene segments, creating new ‘recombinants’ – yet another reason, beyond the personal risk, to avoid getting a second HIV infection.