[Transition and evolution of HIV-1 subtype among HIV-1 infections in Wuxi city, 2013-2016].

Objective: To understand the distribution of HIV-1 subtype in Wuxi city, to predict the local HIV-1 epidemics. Methods: Samples were collected from the 'CD(4)(+) T lymphocyte monitoring cohort study' in Wuxi from April 2013 to July 2016. HIV-1 gene was amplified, sequenced and with HIV-1 sequence database constructed, using both the ChromasPro 1.6 and MEGA 7.0 softwares. Bayesian phylogenetic inference was used to rebuild the history of HIV-1 transmission, while BEAST 1.7.2 and FastTree 2.1.10 software were used for data analysis. Statistical analysis using SPSS 22.0 software. Results: Among the 205 subjects of HIV-1 infection, 32.68 % (67/205) of them were over 50 years old. Seven subtypes (including CRF01_AE, CRF07_BC, CRF67_01B, B, CRF08_ BC, CRF68_0B, CRF78_cpx) and one of the unique recombinant forms (URFs) were detected. The main subtypes were CRF01_ AE (51.67 % , 93/180) and CRF07_BC (17.22 % , 31/180). Differences between subtypes and ways of transmission were statistically significant ( χ (2)=16.99, P ≤0.05). The proportion of CRF67_01B (12.78 % , 23/180) was higher than before. Results from Bayesian phylogenetic inference analysis showed that the evolution rate was 2.29×10(-3) and Time to the Most Recent Common Ancestor (tMRCA) was 2 003.10. CRF67_01B was probably related to the reference strains from Jiangsu and Anhui provinces, and had been spreading in Wuxi since 2003. Conclusions: HIV-1 subtypes seemed complex and diverse in Wuxi city in 2013-2016, with CRF67_01B being pervasive. Continuous molecular monitor program was still needed to provide reference for the prediction of epidemics, from the molecular perspective.