Global HIV-1 molecular epidemiology with special reference to genetic analysis of HIV-1 subtypes circulating in North India: functional and pathogenic implications of genetic variation.

HIV-1 displays extensive genetic diversity globally which poses challenge in designing a suitable antigen/immunogen to provoke desired protective immune response in host. HIV-1 mediated pathogenesis is complex and involves host genes, virus genes and other factors. A number of genetic subtypes have been identified based on sequence variations, largely in envelope region. Different genetic subtypes display variation in amino acid sequences with increasing incidence of subtype B, C, D and mosaic recombinants in India. They can potentially alter the functions of several proteins like Rev, Tat ,Vpr, Vif etc and thereby, influence HIV-1 mediated pathogenesis. Recent study has shown that LTR promoter region exhibits novel mosaic structures with segments from B/C Myanmar and India. This indicates rapid evolving nature of HIV-1 and causing epidemics due to existence of multiple subtypes in Indian region. These multiple subtypes show significant differences in various functions (gene activation, cell cycle arrest, RNA binding activities) compared to prototype subtype B genes. These differences may help in better understanding of unique features of HIV-1 epidemic in India.