Molecular transmission characteristics of human immunodeficiency virus type 1 in northern Zhejiang Province / 中华传染病杂志

ABSTRACT

Objective:To construct the molecular transmission network of human immunodeficiency virus type 1 (HIV-1) epidemic strains in northern Zhejiang Province (Jiaxing City and Huzhou City) and to explore the HIV-1 transmission characteristics in this region.Methods:A total of 371 newly diagnosed human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) patients in Jiaxing City and Huzhou City in 2017 were included as study subjects, and the blood samples were collected and the basic demographic and epidemiological information were obtained. RNA in plasma was extracted, and the pol region gene sequence was amplified by reverse transcriptase polymerase chain reaction (RT-PCR) and nested polymerase chain reaction (PCR) to construct phylogenetic tree for identifying subtypes. The pairwise genetic distances were calculated, and the optimal threshold of genetic distance was selected, and finally the molecular transmission network was constructed. Chi-square test was used for statistical analysis. Results:The pol region gene sequences of 336 samples were successfully obtained, and 11 subtypes were detected, mainly including circulating recombinant form (CRF)07_BC (40.8%, 137/336) and CRF01_AE (31.2%, 105/336). Based on the 1.0% genetic distance threshold, the molecular transmission network of HIV-1 was plotted. A total of 38 transmission clusters (cluster sizes ranging from two to 28) including 119 patients were found, with males predominantly (82.4%, 98/119) and most of the patients aged over 40 (include 40) years old (52.9%, 63/119), mainly infected with CRF07_BC subtype (57.1%, 68/119) and CRF01_AE (24.4%, 29/119). The clustering rate of CRF07_BC (49.6%, 68/137) was significantly higher than that of CRF01_AE (27.6%, 29/105), the difference was statistically significant ( χ2=5.27, P=0.022). Two large clusters C1 (28 cases) and C2 (11 cases) were identified, the majority of which were men who have sex with men (17 cases and seven cases, respectively). High-risk cases generally sought sexual partners in local or nearby cities through mobile phone dating software, of which the infected sequences mostly had high homology with other economic developed regions (Guangdong Province, Beijing City and Hangzhou City, etc.). Conclusions:The HIV-1 subtypes are diverse in Jiaxing City and Huzhou City, mainly CRF07_BC and CRF01_AE. The HIV-1 transmission networks are complex, among which high-risk cases may be the key factor leading to the HIV-1 epidemic in the region. Therefore, it is urgent to deepen the transmission network monitoring and formulate timely precise intervention and prevention strategies.