Objective: To understand HIV-1 subtype characteristics and transmission clusters in elderly male clients and female sex workers (FSWs) of low-cost commercial sex venues in Guangxi Zhuang Autonomous Region, China. Methods: A cross sectional survey was conducted in FSWs and elderly male clients (≥50 years) of low-cost commercial sex venues in 4 cities and 9 counties in Guangxi Zhuang Autonomous Region by convenient sampling in 2012. The blood sample was collected from each case for HIV-1 antibody detection. The pol gene fragments were amplified and sequenced from viral RNA template extracted from plasma samples. The phylogenetic tree was constructed and the subtypes were identified. Results: A total of 4 048 elderly male clients and 784 FSWs were surveyed, and 116 HIV-1 infections were detected, the positive rate was 2.5% (103/4 048) in the clients and 1.7% (13/784) in FSWs. The gene amplification and sequencing of HIV-1 detected in 84 blood samples indicated that 53 pol gene sequences were successfully determined (48 blood samples from elderly male clients and 5 blood samples from FSWs). Among 53 pol sequences, 48(90.6% ), 4(7.5% ), and 1(1.9% ) sequences were identified as CRF01_AE, CRF08_BC, and CRF07_BC, respectively. Two transmission clusters were identified among CRF01_AE, including 4 sub-clusters. One transmission cluster was identified among CRF08_BC. The transmission cluster or sub-cluster were from the infected individuals at same low-cost commercial sex venue, or different low-cost commercial sex venues in the same town, or same place, or adjacent villages and towns. Conclusions: CRF01_AE was the predominant HIV-1 subtype among elderly male clients and FSWs of low-cost commercial sex venues in Guangxi Zhuang Autonomous Region, circulating in same venue or adjacent villages and towns. The HIV-1 positive male clients and FSWs might play an important role in the spread of the strains.
目的： 了解广西壮族自治区低档场所中老年嫖客与暗娼的HIV-1感染者病毒基因亚型特征及传播规律。 方法： 采用方便抽样的方法，于2012年对广西壮族自治区4个城市和9个县（区）低档场所的嫖客（年龄≥50岁）与暗娼开展分子流行病学调查，进行HIV-1抗体筛查，对HIV-1抗体阳性者血浆进行pol区基因片段扩增和序列测定，对获得的基因序列进行系统进化树构建并鉴定毒株的基因亚型，分析毒株亚型分布特征及传播规律。 结果： 共招募4 048例中老年嫖客和784例低档暗娼，共发现116例HIV-1抗体阳性，中老年嫖客与暗娼的HIV-1抗体阳性检出率分别为2.5%（103/4 048）、1.7%（13/784 ），对其中84例HIV-1抗体阳性者进行基因扩增和序列测定，53例获得基因序列（中老年嫖客48例、暗娼5例）。发现3种基因亚型，均为重组株，CRF01_AE占90.6%（48/53），CRF08_BC占7.5%（4/53），CRF07_BC占1.9%（1/53 ）。经系统进化树分析发现，48例CRF01_AE流行毒株聚集成2个传播簇Cluster 1和2; 4例CRF08_BC聚集成1个传播簇。在CRF01_AE Cluster 1中又形成4个亚簇C1-SC1、2、3、4，各亚簇对象来源于同一处或相邻低档场所、或与同一省道毗邻乡镇的低档场所。 结论： 广西壮族自治区低档场所中老年嫖客与暗娼HIV-1感染者流行毒株仍以CRF01_AE为主，以同一处或相邻低档场所或毗邻乡镇呈小范围聚集，当地HIV-1阳性的中老年嫖客与暗娼可能是该人群易感者毒株快速传播的重要传染源。.
Keywords: Female sex worker; Human immunodeficiency virus; Male client; Subtype; Transmission cluster.