Detection of recent HIV-1 infections among men who have sex with men in Beijing during 2005 - 2006 / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSIONS</b>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.</p>

HIV-specific T cell immunity across the entire HIV genome in Chinese men who have sex with men / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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 < 0.05) 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.</p><p><b>CONCLUSIONS</b>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.</p>