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NLM AIDSLINE
Molecular epidemiology of HIV.
Hahn RH
November 30, 1996
3rd Conf Retro and Opportun Infect. 1996 Jan 28-Feb 1;:166. Unique

Globally circulating strains of HIV-1 and HIV-2 are known to exhibit considerable genetic diversity and this variability is believed to pose a formidable challenge to AIDS vaccine development efforts. Phylogenetic analysis of viral sequences have shown that HIV-1 can be classified into two groups (M and O). group M comprises the great majority of HIV-1 isolates and can be further subdivided into at least nine sequence subtypes (A-I). Similarly, HIV-2 can be classified into five sequence subtypes (A-E), although these are based on the analysis of considerably fewer viruses. Importantly, the majority of HIV-1 and HIV-2 isolates cluster consistently in phlyogenetic trees derived from different regions of the genome. Nevertheless, recent studies have noted several viruses which occupy different positions in phylogenetic trees, depending on which genes or part of their genome is used for analysis. Further examination of these cases revealed mosaic HIV-1 and HIV-2 pro-viruses. Moreover, a recent survey of near full-length gag and env sequences from the database suggested that approximately 10% of HIV-1 viruses originated from probable recombinants. These results indicate that co-infection with highly divergent viral strains can occur in HIV-1 infected humans and that intersubtype recombination can be expected to increase in geographic regions where multiple sequence subtypes co-circulate. In addition, these results have immediate consequences for our understanding of HIV-1 pathogenesis, vaccine development, and the methods that should be employed to monitor the molecular epidemiology of HIV-1 worldwide.

AIDS Vaccines HIV-1/CLASSIFICATION/*GENETICS HIV-2/CLASSIFICATION/*GENETICS Mosaicism Phylogeny Recombination, Genetic Variation (Genetics) ABSTRACT

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