北京市男男性行为者中人类免疫缺陷病毒1的流行亚型及其变化趋势

The prevalence and dynamics of human immunodeficiency virus-1 subtypes among men who have sex withmen in Beijing

目的了解北京市2005-2011年间男男性行为（MSM）人群HIV-1的流行亚型分布及其变化趋势。方法2005-2006、2007、2008、2009和2010-2011年通过5次横断面调查，对北京市朝阳区MSM人群进行HIV-1抗体阳性筛查，采集阳性者的外周血，提取RNA，通过反转录及套式PCR扩增HIV-1的gag基因，并采用系统进化树来确定其亚型。结果系统进化树分析发现，MSM人群中HIV-1的主要流行亚型为欧美B、CRF01-AE和CRF07-BC亚型。从2008年开始发现了CRFl5-01B亚型，且2005-2011年此类人群中HIV-1主要流行亚型中欧美B亚型所占比例显著下降，而CRF01-AE亚型所占比例显著上升，CRF07-BC亚型所占比例逐年增加。结论2005-2011年间北京市MSM人群中，HIV-1的流行亚型逐渐呈多元性，出现新的重组亚型，且主要亚型的流行趋势已发生改变。

Objective To investigate the subtype distribution and changing trend of human immunodeficiency virus （HIV）-I strains among men who have sex with men （MSM） during 2005- 2011 in Beijing. Methods Five serial cross-sectional surveys of MSM were conducted in the year of 2005-2006, 2007, 2008, 2009, and 2010-2011 in Chaoyang district of Beijing. Whole blood samples were collected and then RNA was extracted. HIV-1 gag gene was characterized by reverse transcriptase and nested polymerase chain reaction （RT-PCR） amplification, DNA sequencing, and phylogenetic analysis of viral sequences to determine the HIV-1 subtypes. Results Phylogenetic analysis of the sequences revealed that the predominant subtypes of HIV-1 gag gene included subtype B, CRF01_AE and CRF07_BC. And CRF15_01B was detected from the year of 2008. In addition, significant changes of the distributions of subtypes and CRFs occurred from 2005 to 2011 in HIV＋ MSM. Subtype B showed a significant decreased trend, while the proportions of CRF01_AE and CRF07_BC significantly increased in the 7-year period, particularly that of CRF01_AE. Conclusions The substantial changes are observed in the diversity of HIV-1 strains circulating among MSM in Beijing during a 7-year period.