The sexually driven epidemic in youths in China's southwestern border region was caused by dynamic emerging multiple recombinant HIV-1 strains

Abstract

Dehong prefecture, Yunnan province on China's southwestern border was the gateway of the country's AIDS epidemic. Studies on HIV-1 molecular epidemiology will provide key information on virus transmission dynamics and help to inform HIV prevention strategies. HIV-1 infected youths (age 16-25 years) diagnosed in the continuous 3 months in 2009 to 2012 were enrolled. By means of phylogenetic and statistical analyses, It was showed that two thirds (133/205) of youths in Dehong, of which 74.1% were infected sexually, were infected by uncharacterized recombinant HIV-1 strains. Among them about 59.4% (79/131) were unique recombinant forms (URFs) and 40.6% (54/131) formed 11 transmission clusters, termed potential circulating recombinant forms (pCRFs). The emergence of recombinants was statistically significant related with people of low education, residents outside the capital city of Dehong and being Myanmar residents. It was the first report with ongoing HIV-1 recombinant strains in a sexually driven epidemic area in China. Great efforts should be put on reducing multiple risk exposures behavior in local young people, containing the spread of pCRFs to other regions, and preventing the URFs from evolving into future CRFs. Collaborative prevention across border is needed to better control the local AIDS epidemic.

Figure 1. Phylogenetic analysis of the 1.2 kb pol gene fragments of 205 samples.

Sequences were aligned and phylogenetic tree constructed using the maximum-likelihood method in PhyML. Strain designations are marked with different colors. Clusters with high bootstrap values and potential circulating recombinant clades (pCRFs, n = 11) are marked with vertical lines and labeled accordingly. Markers on the individual sequences indicate the route of transmission: ■, heterosexual sex; ▲, MSM sex; •, intravenous drug use; and ♦, not available. The proportion of each subtype is also shown in the figure.

Figure 2. Characteristics of potential circulating recombinant forms.

The recombinant patterns of the 11 pCRFs were listed, with brief summary of demographic information of each cluster. Patient IDs in bold indicate samples with NFLG sequences, and all other IDs indicate 1.2 kb pol gene fragments.