title: Prospective cohort study of HIV incidence and molecular characteristics of HIV among men who have sex with men(MSM) in Yunnan Province, China.
abstract: BACKGROUND
  Yunnan has the largest number of reported HIV/AIDS cases among all Chinese provinces, the reported prevalence of HIV among Yunnan men who have sex with men (MSM) passed 10%, while HIV incidence epidemic and molecular characteristics of new infected Yunnan MSM were not evaluated before.
  
  
  METHODS
  An 18 months prospective followed up with a frequency of 3 month per visit were conducted among HIV seronegative MSM in Kunming cityduring 2009-2011. Interviewer-administrated questionnaires were carried out. Blood specimens were obtained to test for syphilis and HIV, in which HIV were evaluated by standard HIV enzyme immunoassay (EIA) and HIV nucleic acid amplification testing (NAAT). Near full-length regions of the HIV-1 were evaluated for subtyping, primary drug resistance mutations.
  
  
  RESULTS
  During the follow-up 70.1% of the recruited 378 MSM retained in the cohort. Eleven MSM seroconverted to HIV and fifteen MSM seroconverted to syphilis. The HIV incidence and syphilis incidence was 3.5 (95% CI 1.8-6.2) cases /100 person year(PY) and 5.3 (95% CI 3.0-8.7) cases/100 PY, respectively. Multivariate analysis showed that baseline syphilis infection (aHR, 17.7), occupation (students vs. others [aHR, 5.7], retirees vs. others [aHR, 4.1]), bleeding experience after receptive anal intercourse (aHR,7.6), and minority ethnic(vs. Han) [aHR, 5.7] were independent risk factors for HIV seroconversion(each P<0.05). Among the 7/11 successfully amplified near full-length sequences, 71.4% (5/7) were CRF01_AE, and 28.6% (2/7) were CRF07_BC. Two HIV transmission pairs were detected among seroconverted minority ethnic MSM.
  
  
  CONCLUSIONS
  HIV incidence was moderately high among Yunnan MSM. Yunnan province need to strengthen both HIV and syphilis screening among MSM population. Some subpopulations of MSM, such as students, retirees and minority ethnic groups require more HIV epidemic surveillance and strengthened behavior interventions. HIV subtypes and primary drug resistance should be continually monitored to track cross-group transmission of HIV strains.
authors.affiliation: Key Laboratory of AIDS Immunology of Ministry of Health, Department of Laboratory Medicine, No,1 Hospital of China Medical University, Nanjing north street 155#, Heping district, Shenyang 110001, China.
authors.forename: Junjie
authors.initials: J
authors.lastname: Xu
authors.forename: Minghui
authors.initials: M
authors.lastname: An
authors.forename: Xiaoxu
authors.initials: X
authors.lastname: Han
authors.forename: Manhong
authors.initials: M
authors.lastname: Jia
authors.forename: Yanling
authors.initials: Y
authors.lastname: Ma
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.forename: Qinghai
authors.initials: Q
authors.lastname: Hu
authors.forename: Zhenxing
authors.initials: Z
authors.lastname: Chu
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Jiang
authors.forename: Wenqing
authors.initials: W
authors.lastname: Geng
authors.forename: Lin
authors.initials: L
authors.lastname: Lu
authors.forename: Hong
authors.initials: H
authors.lastname: Shang
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002681:China / Q000453:epidemiology; D005500:Follow-Up Studies; D005838:Genotype; D015658:HIV Infections / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission / Q000821:virology*; D015497:HIV-1 / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D018451:Homosexuality, Male; D006801:Humans; D015994:Incidence; D008297:Male; D010802:Phylogeny; D011446:Prospective Studies; D013587:Syphilis / Q000453:epidemiology / Q000821:virology