Significance of HIV-1 genetic subtypes.

HIV is the most significant new pathogen that emerged during the twentieth century. Since the recognition of AIDS in 1981, HIV has caused a worldwide epidemic. HIV-1 mutates extensively and shows high genetic diversity and thereby poses significant challenges for effective surveillance and disease control. At the beginning of the 1990s phylogenetic analyses of HIV-1 sequences from different sources of the world epidemic revealed that HIV-1 can be divided into different clades or subtypes. However, most of the knowledge from that time was based on information from western countries, where subtype B predominated. Important questions were raised about the possibility that genetic and phenotypic differences in HIV-1 may affect transmissibility, infectivity and pathogenicity, in addition to responses to therapy and vaccines. On this basis this study was initiated in 1994, and presented as a thesis in 1999. This paper gives an overview of the results from this thesis (based on 6 original papers) and the conclusions drawn. In summary, determination of the genetic subtype of HIV-1 probably has little value for routine clinical care of individual patients, but provides a powerful tool for monitoring changes in local and global transmission patterns.