Epidemiology and Genetic Background of HIV-1 Strains Circulating in Shandong, China

Shandong is a relatively developed coastal province in China with 17 cities, a population of 91.23 million, and increasing numbers of HIV/AIDS cases. We investigated the epidemiology of circulating HIV-1 strains from 97 HIV-1 infected cases from 1992 to 2004 in Shandong. Fragments of HIV-1 env C2-V3, gag P17/P24, 1st exon of tat and adjacent region were PCR amplified and sequenced, followed by phylogenetic, homology and recombination analysis. We found 7 circulating HIV-1 subtypes/CRFs, which are B' (75.3%), CRF01_AE (10.3%), CRF07_BC, CRF08_BC (i.e. B'/C, 4.1% respectively), B, C and CRF02_AG (2.1% respectively). Subtype B' was found mostly in paid blood donors, while B'/C recombinants were primarily in injecting drug users. The remaining subtypes distributed mainly in sexually transmitted subjects. Genetic divergence and amino acid sequence analysis showed that B' strains are closely related to B.CN.RL42; B'/C strains to 97CN54A and 97CNGX6F; CRF01_AE strains to 01_ae.th.90.cm2; CRF02_AG, C and B strains were related to standard strains from Cameroon, Ethiopia and America, respectively. Genetic divergence of env of B' strain showed that it started circulating in Shandong 7–10 years ago. The large strain variation and occurrence of CRFs signify the rapidly increasing HIV-1 epidemic in Shandong, and have implications for vaccine design.