Distribution of CCR5Δ32, CCR2-64I and SDF1-3′A and plasma levels of SDF-1 in HIV-1 seronegative North Indians

Host genetic factors play an important role in susceptibility to HIV-1 infection and progression to AIDS. Mutations in genes encoding chemokine receptors and their ligands, viz., CCR5Δ32, CCR2-64I and SDF1-3′A are implicated to have protective effects against HIV-1 infection and/or disease progression. The distribution of these gene polymorphisms and their role in the course of the disease varies between individuals of different racial, ethnic and risk groups. We have examined the allelic frequencies of CCR5Δ32, CCR2-64I and SDF1-3′A in 500 healthy North Indians tested seronegative for HIV-1, by PCR-RFLP. The plasma levels of stromal derived factor (SDF-1) protein were estimated in 75 individuals using ELISA kit. Frequencies of CCR5Δ32, CCR2-64I and SDF1-3′A alleles in 500 individuals were 1.5%, 9.1% and 20.4%, respectively. The SDF1-3′A homozygosity was confirmed by PCR product cloning and sequencing. The relative hazard values calculated on the basis of the three locus genotype of each individual revealed high relative hazard values (>0.9). The plasma levels of SDF-1 ranged from 1.77 to 3.42 ng/ml and were comparable between the three genotypes of SDF-1. This is the first study to assess the plasma level of SDF-1 protein in Asian Indians. Low frequency of the protective allele CCR5Δ32 observed in this study suggests high vulnerability of North Indians to HIV-1 infection. The precise role of SDF1-3′A in HIV-1 infection needs to be elucidated.