Emerging trends of HIV epidemiology in Asia.

The main molecular trait of HIV-1 is the inherent capacity to vary, recombine, and diversify, which gives it a clear edge to evade the human immune system and survive through the generation of complex molecular forms, termed recombinants. In a setting of coinfection, molecular and biological interactions between diverse HIV-1 subtypes may promote the emergence of circulating recombinant forms through the shuffling of viral genomes, which results in increased intra- and inter- host viral variation and altered biological properties. The focus of this review is on Asia, which has the highest proportion of HIV-1 recombinants circulating worldwide, with the top in South and Southeast Asia, amounting to 89% of its total HIV-1 infection. The HIV-1 strains which are spreading in this geographic area are CRF01_AE, subtypes B and C. Given the rapid spread and active establishment of some of the recombinant forms in Asia, it is essential to understand how they differ from their parental strains, the acquisition of certain molecular traits, and their biological attributes upon recombination, which give these strains an epidemiologic edge. The current epidemic provides strong evidence that the parental subtypes are being replaced via competition with possibly more versatile HIV-1 recombinant forms. This appears to be an ongoing phenomenon and has resulted in an HIV-1 epidemic shift, with the expansion and dissemination of a wide variety of HIV-1 forms within this geographic region.