title: Distribution of HIV-1 subtypes in female sex workers of Calcutta, India.
abstract: OBJECTIVE
  Different routes for the transmission of HIV-1 in India have been reported and the majority of infections occurred through heterosexual route of transmission. In order to understand the dynamics of HIV-1 transmission, a systematic study was undertaken to determine the viral subtypes circulating among the female sex workers in Calcutta, India.
  
  
  METHODS
  Peptide enzyme immunoassay (PEIA), heteroduplex mobility assay (HMA) and DNA sequence analysis were used to ascertain the HIV-1 subtypes.
  
  
  RESULTS
  V3 serotyping of 52 HIV-1 seropositive samples identified 33 (60%) to be subtype C. A DNA fragment within C2-V3/C2-V5 regions of HIV-1 gp120 was amplified directly from the lymphocyte DNA to avoid any bias in selecting viral variants and used in HMA. Of the 40 samples analyzed, 38 (95%) belonged to subtype C and 2 were found to be non-typable. Further analysis of these 38 samples revealed that 26 (68%) had maximum homology to the C3-Indian reference strain (IND868), 11 (29%) were most homologous to C2-Zambian strain (ZM18) and 1 (3%) showed close resemblance to C1-Malawi strain (MA959). Nucleotide sequence of 11 subsamples encompassing about 325 base pairs was aligned for the Indian and other geographically distinct isolates. On distance and parsimony trees, most of the samples (8/11) clustered together as subtype C.
  
  
  CONCLUSIONS
  Subtype C was the major circulating HIV-1 strain in this geographical region, although variation within this subtype was also noticed. DNA sequence analysis was found to be the best method in determining the nature of the HIV-1 subtype followed by HMA and peptide enzyme immunoassay. These findings may have important implications for the design of effective vaccines in India and emphasizes the need for constant monitoring of the HIV-1 subtypes in different parts of India.
authors.affiliation: National Institute of Cholera & Enteric Diseases (ICMR), Calcutta.
authors.forename: D
authors.initials: D
authors.lastname: Mandal
authors.forename: S
authors.initials: S
authors.lastname: Jana
authors.forename: S
authors.initials: S
authors.lastname: Panda
authors.forename: S
authors.initials: S
authors.lastname: Bhattacharya
authors.forename: T C
authors.initials: TC
authors.lastname: Ghosh
authors.forename: S K
authors.initials: SK
authors.lastname: Bhattacharya
authors.forename: S
authors.initials: S
authors.lastname: Chakrabarti
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D017931:DNA Primers; D004279:DNA, Viral / Q000235:genetics; D005260:Female; D015699:HIV Envelope Protein gp120 / Q000737:chemistry; D015658:HIV Infections / Q000453:epidemiology / Q000821:virology*; D015497:HIV-1 / Q000145:classification* / Q000235:genetics; D006801:Humans; D007124:Immunoenzyme Techniques; D007194:India / Q000453:epidemiology; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D011477:Sex Work
chemical_list: D017931:DNA Primers; D004279:DNA, Viral; D015699:HIV Envelope Protein gp120; C059762:HIV envelope protein gp120 (305-321); D010446:Peptide Fragments