Abstract
The Congo Basin region is believed to be the site of the cross-species transmission event that yielded HIV-1 group M (HIV-1M). It is thus likely that the virus has been present and evolving in the region since that cross-species transmission. As HIV-1M was only discovered in the early 1980s, our directly observed record of the epidemic is largely limited to the past four decades. Nevertheless, by exploiting the genetic relatedness of contemporary HIV-1M sequences, phylogenetic methods provide a powerful framework for investigating simultaneously the evolutionary and epidemiologic history of the virus. Such an approach has been taken to find that the currently classified HIV-1 M subtypes and Circulating Recombinant Forms (CRFs) do not give a complete view of HIV-1 diversity. In addition, the currently identified major HIV-1M subtypes were likely genetically predisposed to becoming a major component of the present epidemic, even before the events that resulted in the global epidemic. Further efforts have identified statistically significant hot- and cold-spots of HIV-1M subtypes sequence inheritance in genomic regions of recombinant forms. In this review we provide ours and others recent findings on the emergence and spread of HIV-1M variants in the region, which have provided insights into the early evolution of this virus.
Highlights
Accepted: 26 March 2021The simian ancestors of HIV-1 group M (HIV-1M) have been transmitted to humans from Chimpanzees (SIVcpz) in south eastern Cameroon in the Congo Basin (CB) near the beginning of last century [1,2]
Among the HIV-1M genomes circulating at that time, four of them led to the HIV-1M subtype A, B, C and D lineages that today are the dominant drivers of the global AIDS epidemic [9,10,11]
In one of the most extensive studies performed to date throughout Angola, Bartolo et al (2009) characterized 159 HIV-1M sequences collected from HIV-infected individuals and found that 8% of these sequences could not be classified within any known HIV-1M lineages [20]
Summary
The simian ancestors of HIV-1 group M (HIV-1M) have been transmitted to humans from Chimpanzees (SIVcpz) in south eastern Cameroon in the Congo Basin (CB) near the beginning of last century [1,2]. The second factor implies that the demographic composition of HIV-1M populations in different parts of the world may reflect the timing and frequency of HIV-1M dispersal or founder events [6,8]. Beside these unpredictable stochastic processes, it is possible that there were some viral features and host factors that may have influenced the rise of some variants in, and their spread out of the CB. The recent development of computational sequence analysis tools and the accumulation of contemporary sequences from the CB region have greatly improved our understanding of viral genetic events that may have made this epidemic possible This review provides an overview of the key findings pertaining to the early evolution of HIV-1 M in the CB region
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