ABSTRACT
Objective:To investigate the subtype distribution of HIV-1 strains prevalent in four areas of China,and to study the characteristics of gag gene variation and changes in antigen epitopes under the host immune pressures. Methods:The plasma of HIV-1 infected people from Henan, Guangdong, Sichuan and Beijing in China were collected. Virion RNA was extracted directly from plasma after the virion was condensed. The gag gene was amplified by RT-PCR and nested-PCR.Sequences were subtyped by Genotyping Tool software, and phylogenetic analysis of gag gene were performed using the MEGA 4.1 software.The gene distances intra each subtype were calculated by Distance program. The Ks/Ka ratios were calculated using SNAP program. The variation analysis of CTL antigen epitopes restricted by main HLA-Ⅰ specificities in China was performed.Results:Six subtypes or circulating recombinant forms(CRFs)of HIV-1,including B',CRF07_BC,CRF01_AE,B,CRF08_BC and CRF02_AG,were identified in four areas of China.The gene distances intra each subtype were CRF01_AE>B>CRF08_BC> CRF07_BC>B' listed in order of size, meanwhile the order of Ks/Ka ratios was CRF01_AE>B>CRF08_BC>B'>CRF07_BC. Far more diversity of antigen epitopes in P17 region was observed than that in P24.Epitope mutations intra subtypes were CRF01_AE>B>B'>CRF07_BC listed in order of size. Conclusion:Itseems that CRF01_AE is under the strongest immune pressures,and displays the most diversity of gene and variation of epitopes intra subtypes prevalent in China, followed by subtype B, B' and CRF07_BC. The discrepancy of epitope mutations intra the subtypes is significant.