12th International AIDS Conference Geneva, Switzerland - June 28-July 3, 1998

Int Conf AIDS 1998 Jun 28-Jul 3; 12:18 (abstract no. 11181)

McCutchan FE, Birx DL
Henry M. Jackson Foundation, Rockville, MD 20850, USA.

BACKGROUND: The identification of globally prevalent HIV-1 strains is an important element of HIV-1 diagnosis, therapy and prevention. The pandemic is composed of multiple subtypes and a variety of inter-subtype recombinant forms that are not easily distinguished by partial genome sequencing. An increasing proportion of international HIV-1 strains are now characterized by full-genome sequencing, and the resultant database has prompted revisions of subtype classification and new awareness of several inter-subtype recombinant forms that are undergoing epidemic spread. Frequent compilation and review of a rapidly expanding database of HIV-1 sequences will be required to fully integrate new findings and to focus research on HIV-1 subtypes and recombinants of global importance.

METHODS: Virtually full-length HIV-1 genomes are amplified using polymerase chain reaction from primary virus cultures on peripheral blood mononuclear cells and are sequenced using fluorescent dye terminators and automated DNA sequencers. Data analysis is with maximum likelihood or maximum parsimony with bootscanning for identification and mapping of recombinants.

RESULTS: Some HIV-1 "subtypes" identified by partial genome sequencing are actually recombinants and some recombinants are more globally prevalent than subtypes. In some recently completed regional studies in Africa, even partial genome sequencing was sufficient to establish that inter-subtype recombinant strains outnumber subtypes. The identification of multiple recombinant strains, each recovered from more than one individual, suggests that the spread of recombinants is a major facet of the HIV-1 epidemic in some locations.

CONCLUSION: The contribution of inter-subtype recombination to HIV-1 diversity is currently underestimated, particularly in parts of sub-Saharan Africa. The epidemic spread of several intersubtype recombinant HIV-1 should be considered, along with the subtypes, in planning for diagnosis, treatment, and prevention. Characterization of globally prevalent strains by full-length genome sequencing should be continued and expanded.

Copyright © 1998 - International AIDS Society (IAS). Reproduction of this abstract (other than one copy for personal reference) must be cleared through the IAS.