Trends of HIV subtypes and phylogenetic dynamics among young men who have sex with men in China, 2009-2014

Abstract

To investigate the origins of HIV transmission and phylogenetic dynamics among men who have sex with men (MSM), a total of 1205 newly diagnosed HIV-infected 16-25 year-olds were recruited in 13 provinces across China between 2009 and 2014. Based on phylogenetic analyses of partial pol sequences, HIV-1 subtypes including CRF01_AE (45.3%), CRF07_BC (37.8%), subtype B (6.1%), and B' (3.7%), as well as some other recombinants (7.1%) were identified. In addition to two distinct CRF01_AE clusters [cluster 4 (33.7%, 406/1205) and cluster 5 (7.1%, 85/1205)], we identified a new CRF07_BC cluster (cluster 1) (36.0%, 434/1205), which entered Chinese MSMs in 2004, and had been rapidly spreading since about 2004, which indicating the third wave of the HIV epidemic among the population. Moreover, two new clusters of CRF_01B recombinants were found in this study. The complexities of HIV subtypes and recombinants strongly supports the necessity for a comprehensive study about risk behaviors and their relationship with increasing HIV epidemic subtypes among the MSM group. Implementation and evaluation of comprehensive harm reduction strategies in Chinese MSM are urgently needed.

Figure 1

The phylogenetic tree constructed by PhyML 3.0 with the Maximum likelihood method, based on partial pol fragment. The geographic origin of each sequence is color-coded (see inset). The branch significance was analyzed by bootstrap with 500 replicates and inter-subject distances were calculated. Only bootstrap values above or equal to 70 are shown at the corresponding nodes. The map was generated by ArcGIS (http://www.esri.com/software/arcgis/arcgis-for-desktop/free-trial).

Figure 2. Baysian skyline plot was estimated to reconstruct the demographic history of the five major clusters (n ≥ 45) among MSM in China.

The x axis is the time in units of years, and the y axis is equal to the effective population size. The thick solid line is the mean estimate and the 95% HPD credible region is shown by blue areas.