Objective To characterize HIV-1 specific CTL responses to regulatory proteins Tat and Rev in HIV-B＇/C virus-infected ART-naive individuals. Methods HIV-1-specific CTL responses were analyzed by IFN-7 ELISPOT assay using overlapping peptides spanning the consensus sequences of HIV-1 clade C Tat and Rev proteins. Statistical analysis and graphical presentation were performed using SIGMAPLOT 10.0 and SIGMASTAT 3.5. For samples with a positive response, the magnitude of CTL responses was compared between HIV-1 C proteins by Wilcoxon rank sum test, and the significance threshold was P〈0.05. Results Tat and Rev were frequently recognized, with 23% and 52% of the tested individuals having detectable responses to these proteins, respectively. Several immunodominant regions were detected in Rev. No significant correlation was observed between the magnitude and breadth of CTL responses to regulatory proteins and the control of virus replication in this study. Conclusion Tat and Rev can serve as targets for HIV-l-specific CTL, and several immunodominant regions are detectable in Rev. Further characterization of epitopes and their role in virus control may shed light on pathogenesis of HIV- 1 natural infection and also be useful for the design and testing of candidate vaccines.
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.
LI Shen-weiZHANG Xiao-yanLI Xin-xuWANG Min-jieLI Dong-liangRUAN Yu-huaZHANG Xiao-xiSHAO Yi-ming
Background 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 irnmunodeficiency 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. Methods Using Elispot assay with synthetic peptides spanning the sequence of HIV-1 consensus B, HIV-l-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. Results 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 106 peripheral blood mononuclear cells （PBMCs）] might be significantly lower than that in the 19 untreated HIV^＋ MSM group （median, 6175 SFCs per 106 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. Conclusions 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.
