OBJECTIVETo investigate the distribution and proportion of subtypes of pol gene in HIV-1 epidemic strains in Guangxi Autonomous Region.

METHODS152 HIV-1 patients were enrolled from 11 cities in Guangxi Autonomous Region from 2010 to 2012 by convenient sampling. Inclusion criterias were listed as the fdlowing: HIV-1 infection was confirmed by Western blot, HIV-1 viral load >1 000 copies/ml, > 18 year-old, and without any serious illnesses. 5 ml of peripheral blood samples were obtained from each patient. The viral RNA was isolated from plasma and used for amplification of full-length pol gene by nested RT-PCR. The amplified products were sequenced. After editing and modification, all sequences were characterized for preliminary subtyping by genotyping and confirmed with phylogenetic tree constructed by MEGA 5.03 software. The recombinant identification of 2 unknown recombinant strains was determined by RIP and jpHMM at GOBICS.

RESULTSAmong 152 patients, 137 full-length pol genes were successfully amplified and 127 HIV-1 subtypes were identified. The distribution and proportion of subtypes was summarized as the following 71 cases of CRF01_AE, accounting for 55.9% (71/127), 38 CRF08_BC, 29.9% (38/127), 13 CRF07_BC, 10.2% (13/127), and 3 B (B'), 2.4% (3/127), 2 unknown recombinant strains, 1.6% (2/127). In 11 cites of Guangxi Autonomous Region, subtype CRF01_AE was the dominant strain. Among heterosexual transmitted patients and drug abusers, the proportions of subtype CRF01_AE were 67.4% (58/86) and 34.1% (14/41), respectively. There was a significance different in the distribution of CRF01_AE in different routes of transmission (χ(2)=15.07, P<0.001). In age 21- 35, age 36- 60 and age>60 groups, the proportions of CRF01_AE was 43.6% (17/39), 57.6% (38/66), 77.3% (17/22), and CRF08_BC was 43.6% (17/39), 28.8% (19/66), 9.1% (2/22), respectively, the difference in proportions was significant(χ(2)=8.48, P= 0.014). The patterns of two unknown recombinant strains were found to be CRF01_AE/B (B') and CRF01_AE/C/B(B'), respectively.

CONCLUSIONCRF01_AE was the dominant HIV-1 subtype in Guangxi Autonomous Region from 2010 to 2012, with heterosexual transmission as its main spreading route. The two unknown recombinant strains in Guangxi Autonomous Region were reconstructed by subtype CRF01_AE and CRF_BC.