HIV-1 intrasubtype diversification originates from the moment of introduction of virulent HIV-1 strains into current AIDS risk groups in the 1960s and 1970s.
Int Conf AIDS 1998 Jun 28-Jul 3; 12:21 (abstract no. 11197)
Lukashov V, Goudsmit J University of Amsterdam, Dept. of Human Retrovirology, The Netherlands.
Phylogenetic analysis indicates that the considerable genetic variation within each HIV-1 subtype is a result of an intrasubtype diversification of a more recent date than the separation of HIV-1 subtype lineages. Two issues concerning the history of HIV-1 subtypes are still unresolved: (i) when did lineages of HIV-1 subtypes separated from each other and (ii) when did the diversification observed within subtypes emerge? To study the origin of intrasubtype diversification, we designed a new method to trace the divergence of a virus population without using estimates for the evolution rates of the individual genomes. Analysis of the longitudinal HIV-1 subtype B sequence data from several epidemics, including those in the US and among homosexual men and drug users in The Netherlands, revealed significant relationships between the sampling year of individual sequences and their synonymous distances to the common node of the HIV-1 population, which allowed us to estimate the moment of intrasubtype diversification. Based on our observation of the clock-like diversification of HIV-1, we dated the onset of the HIV-1 intrasubtype A and B diversification to the mid 1960s and 1970s, respectively. The extension of our results to the HIV-1 subtypes C and D suggests their diversification in the early 1960s. Our results indicate that the diversification within HIV-1 subtypes occurs at a constant rate. We estimated the moment that the HIV-1 strains of the same subtype could be distinguished, which is dated significantly later than the moment that subtype lineages separated from each other.
CONCLUSIONS: The onset of intrasubtype diversification coincided with the introduction of virulent HIV-1 strains into current AIDS-risk groups and the beginning of the global AIDS epidemic in the 1960s-1970s.
