Recombination in HIV-1: Update and Implications
Miguel E. Quiñones-Mateu 1, Eric J. Arts 1
1 NULL
*Correspondence: Eric J. Arts, Email not available
Abstract
Recombination is a common feature of retroviruses first described in the early 1970s. Although recognized as mutagenic strategy for rapid evolution and adaptation for avian and murine retroviruses, the implications or even possibility of recombination between heterogeneous HIV isolates was unclear until a few years ago. It is obvious that recombination can occur between HIV-1 quasispecies in a host, initially infected with single HIV-1 strain. However, the principal of retroviral interference and HIV-specific host immune response was thought to block any superinfection of a human host by a second HIV-1 isolate. Recent identification of individuals infected with HIV-1 isolates from two subtypes and intersubtype HIV-1 recombinants suggests that superinfections do occur at some low frequency in the population. It is not surprising that HIV-1 recombinants are detected with the greatest frequency in Africa, specifically in regions where many subtypes (or clades) co-circulate. However, a continual introduction of new subtypes (e.g. clade A, C, D, and F) worldwide could increase the occurrence of HIV-1 recombination outside of Africa. For example, intersubtype recombinants have now been identified in Brazil, Argentina, Russia, and India. In contrast to the A/E recombined HIV-1 in Thailand, these chimeric viruses are not related to recombined HIV-1 strains in Africa but are the result of recent recombinations between clades co-circulating in that country. Analysis of a limited set of HIV-1 chimeric genomes reveals no selection for specific recombination sites in the HIV-1 genome. Even though âhot spotsâ? for recombination may occur in vitro, it is apparent that viral fitness may be a deciding factor in the selection and transmission of specific recombined viruses in the population. Increases in intersubtype recombination and transmission of recombined isolates can lead to major antigenic shifts and will undoubtedly effect the development of new vaccine and chemotherapeutic strategies.
