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Background Men who have sex with men (MSM) have become one of the most risky populations for HIV infection in China. Though several cross-sectional sero-prevalence studies have been conducted, the annual HIV incidence remains unknown in this population. Methods We applied IgG-capture BED-enzyme immunoassay (BED-CEIA) to define the recent HIV-1 infections among MSM in Beijing in the years 2005 and 2006 and the annual HIV incidence was estimated. Results Overall, 1067 MSM samples were collected, including 526 samples in the year 2005 and 541 in 2006. In 2005, of 17 HIV seropositive samples, 7 were identified as recent HIV-1 infections and the estimated HIV infection incidence was 2.9% per year (95% CI, 0.8% - 5.0%). In 2006, of 26 HIV seropositive samples, 9 were identified as recent HIV-1 infections and the estimated annual incidence was 3.6% (95% CI, 1.3% - 5.9%), which was 0.7% higher than that in 2005. Individuals engaging in male group sexual intercourse (5.17% vs 0.87%, P = 0.019) and having receptive anal sexual intercourse more than five times (2.79% vs 0.33%, P = 0.047) in the past 6 months significantly increase the risk of being infected by HIV-1. Conclusions A high level of annual HIV-1 infection incidence was observed among MSM in Beijing for the consecutive years 2005 and 2006 with a continuous increasing trend. The rising incidence and related high risk behavior among MSM alarmed the health authorities and calls for more effective intervention strategies among this population.

Man who has sex with man (MSM) is one of the high risk groups for spreading HIV/AIDS. It was reported that the most prevalent human immunodeficiency virus type 1 (HIV-1) strain among MSM is subtype B; however T cell immunity remains unknown across the HIV-1 B genome in this population. Using Elispot assay with synthetic peptides spanning the sequence of HIV-1 consensus B HIV-1-specific cytotoxic T-cell lymphocyte responses were quantified among 3 treated and 19 untreated HIV-1 infected MSM from Beijing China. Cross-sectional association between viral loads and cellular immune responses were analyzed. Peptide pools corresponding to each HIV-1 protein were used for Env Gag Pol Nef Tat/Rev Vpr/Vpu and Vif. The results showed that the magnitude of T cell responses in the 3 treated HIV+ MSM group [median 770 spot forming cells (SFCs) per 10/6 peripheral blood mononuclear cells (PBMCs)] might be significantly lower than that in the 19 untreated HIV+ MSM group (median 6175 SFCs per 10/6 PBMCs).Nef Gag and Pol are the most frequently targeted HIV-1 antigens; and 16 subjects (73%) were identified with vigorous T cell immunity against each of these three proteins. The overall magnitude of T cell immunity closely related to its breadth (r=0.72 P

Following the increased human immunodeficiency virus (HIV) notification (infection) rates via sexual transmission and increased abuse of new synthetic drugs instead of heroin in China, a study on HIV infections and risk factors among synthetic drugs and heroin users in Beijing was conducted to provide a cue for further development of targets and strategies of HIV/AIDS control and prevention for different drug populations.A total of 428 subjects including 224 heroin users and 204 new synthetic drug users was recruited from communities in Beijing by convenience sampling. A χ(2) test was used to compare HIV and syphilis infections between the two subpopulations. Logistic regression models were used to evaluate factors related to HIV, syphilis infections and abuse of synthetic drugs.Unbalanced distributions of demographics were detected between the two subpopulations. Compared with heroin users, most users of synthetic drugs were migrants, single and of younger age (age ≤ 30 years). Ten HIV infections and twenty-four syphilis infections were confirmed among 428 subjects. No significant difference in HIV infection was found between the two subpopulations (crude odds ratio (OR) = 0.46, 95% confidence interval (CI): 0.07 - 15.80 and adjusted odds ratio (AOR) = 1.26, 95%CI: 0.09 - 18.28) while four times as many syphilis infections were identified among users of synthetics drugs (AOR = 3.92, 95%CI: 1.06 - 14.56). HIV and syphilis infections appeared to work synergistically. The migrants who were of Han ethnicity, single and who had stayed in Beijing for more than six months were more likely to abuse synthetics drugs.The new synthetic drug users and heroin users are different subpopulations. We optimistically speculate that HIV has not yet been introduced into the former in Beijing, but considering higher syphilis infections in synthetic drug users and the role of syphilis in HIV infection, synthetic drug users, as a possible and important driver of the HIV/AIDS epidemic in Beijing, should be paid more attention in HIV prevention and control strategies.

Men who have sex with men (MSM) have become one of the most risky populations for HIV infection in China. Though several cross-sectional sero-prevalence studies have been conducted, the annual HIV incidence remains unknown in this population.We applied IgG-capture BED-enzyme immunoassay (BED-CEIA) to define the recent HIV-1 infections among MSM in Beijing in the years 2005 and 2006 and the annual HIV incidence was estimated.Overall, 1067 MSM samples were collected, including 526 samples in the year 2005 and 541 in 2006. In 2005, of 17 HIV seropositive samples, 7 were identified as recent HIV-1 infections and the estimated HIV infection incidence was 2.9% per year (95% CI, 0.8% - 5.0%). In 2006, of 26 HIV seropositive samples, 9 were identified as recent HIV-1 infections and the estimated annual incidence was 3.6% (95% CI, 1.3% - 5.9%), which was 0.7% higher than that in 2005. Individuals engaging in male group sexual intercourse (5.17% vs 0.87%, P = 0.019) and having receptive anal sexual intercourse more than five times (2.79% vs 0.33%, P = 0.047) in the past 6 months significantly increase the risk of being infected by HIV-1.A high level of annual HIV-1 infection incidence was observed among MSM in Beijing for the consecutive years 2005 and 2006 with a continuous increasing trend. The rising incidence and related high risk behavior among MSM alarmed the health authorities and calls for more effective intervention strategies among this population.

Man who has sex with man (MSM) is one of the high risk groups for spreading HIV/AIDS. It was reported that the most prevalent human immunodeficiency virus type 1 (HIV-1) strain among MSM is subtype B; however, T cell immunity remains unknown across the HIV-1 B genome in this population.Using Elispot assay with synthetic peptides spanning the sequence of HIV-1 consensus B, HIV-1-specific cytotoxic T-cell lymphocyte responses were quantified among 3 treated and 19 untreated HIV-1 infected MSM from Beijing, China. Cross-sectional association between viral loads and cellular immune responses were analyzed.Peptide pools corresponding to each HIV-1 protein were used for Env, Gag, Pol, Nef, Tat/Rev, Vpr/Vpu and Vif. The results showed that the magnitude of T cell responses in the 3 treated HIV(+) MSM group [median, 770 spot forming cells (SFCs) per 10(6) peripheral blood mononuclear cells (PBMCs)] might be significantly lower than that in the 19 untreated HIV(+) MSM group (median, 6175 SFCs per 10(6) PBMCs). Nef, Gag and Pol are the most frequently targeted HIV-1 antigens; and 16 subjects (73%) were identified with vigorous T cell immunity against each of these three proteins. The overall magnitude of T cell immunity closely related to its breadth (r = 0.72, P0.05) and was inversely but weakly associated with viral loads (r = -0.15). Further analysis showed that both Gag (r = -0.24) and Pol specific T cells (r = -0.12) contributed to this inverse association whereas Nef specific T cells showed no association with viral loads.The magnitude of HIV-1 specific T cells is inversely but weakly associated with viral loads among MSM; HIV-specific T cell responses against conservative sequences (Gag and Pol) are the main contributors to this association among Chinese HIV(+) MSM. These findings have important implications for vaccine design.