HIV-1 strains from India are highly divergent from prototypic African and US / European strains but are linked to a South African isolate.

The authors report their findings from the analysis of nucleotide sequences derived from the env region of four HIV-1 strains in an attempt to gain molecular insights into different HIV-1 strains present in Maharashtra and Goa India. HIV-1 was isolated from 22 patients from Bombay and one from Goa. The subjects were mainly prostitutes. The molecular analysis of the env region encompassed all variable domains of the external glycoprotein gp120. Genomic DNA from cultured cells infected with each of the four Indian HIV-1 strains independently was amplified by polymerase chain reaction (PCR). PCR fragments were cloned and sequenced and a phylogenetic tree constructed. All four Indian HIV-1 sequences were found to be closely related to each other with the closest related sequence being from a South African isolate HIV-1 (NOF) with an homology of 85-87%. In the phylogenetic tree the Indian and South African HIV-1 sequences cluster together and constitute a subtype different from the North American/European Central African Uganda/Rwanda and Northern Thailand subtypes. The viruses of this subtype are characterized by an additional potential N-glycosylation site C-terminal to the CD4-binding domain. HIV is spreading rapidly in India most probably through heterosexual sexual intercourse. Consideration must be given to the existence of these varied HIV-1 strains when developing a vaccine.