Yuanzhi Zhang

Characterization of a Virtually Full-Length Human Immunodeficiency Virus Type 1 Genome of a Prevalent Intersubtype (C/B′) Recombinant Strain in China

ABSTRACT A molecular epidemiology study was conducted among more than 100 human immunodeficiency virus type 1 (HIV-1) subtype C seropositive intravenous drug users (IDUs) from China. Genotyping based on the envelope C2V3 coding region revealed the highest homology of the most prevalent virus strains circulating throughout China to subtype C sequences of Indian origin. Based on these results, a virtually full-length genome representing the most prevalent class of clade C strains circulating throughout China was directly amplified from peripheral blood mononuclear cells of a selected HIV-infected IDU and subcloned. Sequence analysis identified a mosaic structure, suggesting extensive intersubtype recombination events between genomes of the prevalent clade C and (B′)-subtype Thai virus strains of that geographic region. Recombinant Identification Program analysis and phylogenetic bootstrapping suggested that there were 10 breakpoints (i) in the gag-pol coding region, (ii) in vpr and at the 3′ end of the vpu gene, and (iii) in thenef open reading frame. (B′)-sequences therefore include (i) several insertions in the gag-pol coding region; (ii) 3′-vpr, the complete vpu gene, and the first exons of tat and rev; and (iii) the 5′ half of the nef gene. Breakpoints located in thevpr/vpu coding region as well as in the nefgene of 97cn54 were found at almost identical positions of all subtype C strains isolated from IDUs living in different areas of China, suggesting a common ancestor for the C/B′ recombinant strains. More than 50% of well-defined subtype B-derived cytotoxic T-lymphocyte epitopes within Gag and Pol and 10% of the known epitopes in Env were found to exactly match sequences within in this clade C/B′ chimeric reference strain. These results may substantially facilitate a biological comparison of clade C-derived reference strains as well as the generation of useful reagents supporting vaccine-related efforts in China.

Willingness of Chinese injection drug users to participate in HIV vaccine trials

BACKGROUND Chinese injection drug users (IDUs) may be a proper candidate population for HIV vaccine trials. OBJECTIVE To evaluate willingness to participate (WTP) in HIV vaccine trials among Chinese IDUs. METHODS Questionnaire interviews were completed among 401 IDUs in Urumqi City in northwestern China in 2005. RESULTS Overall 74.3% of participants said that they would be definitely willing to participate in HIV vaccine trials, 17.7% were probably willing, 6.2% were probably not willing, and remaining 1.8% were definitely not willing to join. Multivariate logistic regression analysis demonstrated that WTP was positively associated with having ever had sex with a drug use partner (adjusted odds ratio [AOR]: 1.8; 95% confidence interval [CI]: 1.04, 3.2), sharing needle and syringe with a new drug use partner in the past 3 months (AOR: 3.8; 95% CI: 1.2, 11.7), perceived family support for participation (AOR: 7.4; 95% CI: 4.3, 12.7), and perceived vaccine protection against HIV infection (AOR: 16.1; 95% CI: 3.7, 70.8), and was negatively associated with perceived risk of social stigma and isolation for participation (AOR: 0.3; 95% CI: 0.2, 0.5). CONCLUSIONS The stated WTP in hypothetical HIV vaccine trials was high among Chinese IDUs. Further studies are needed to evaluate actual enrollment into the trials.

Increased NKG2A found in cytotoxic natural killer subset in HIV-1 patients with advanced clinical status.

Objectives:To investigate the expression of NKG2A on cytotoxic natural killer (NK) cells in HIV-1-infected patients. Design:A cross-sectional study was conducted to investigate the NKG2A expression on NK cell subsets among HIV-infected individuals at different clinical stages and HIV negative controls. Methods:113 HIV-1 infected and 43 uninfected individuals were enrolled in this study. The HIV-1 infected patients were further categorized into three groups, CD4 cell count > 500 cells/μl (n = 44), CD4 cell count of 200–500 cells/μl (n = 49) and CD4 cell count < 200 cells/μl (n = 20). Flow cytometry was used to determine the expression of NKG2A on NK cell subsets. A flow-based assay was employed to quantify the NK cytotoxicity. Results:Fewer cytotoxic NK cells and more dysfunctional NK cells were observed in patients with advanced clinical conditions. Higher NKG2A expression level in cytotoxic NK subset were found in later stages HIV infection, 25.6% in groups with CD4 cell count > 500 cells/μl, 40.9% in groups with CD4 cell count 200–500 cells/μl and 48.3% in groups with CD4 cell count < 200 cells/μl. Lower NK mediated cytotoxicity, which was associated with the decrease in cytotoxic NK cell number and higher NKG2A expression on cytotoxic NK subsets, was found in AIDS patients compared with patients at early stage of infection. A reverse association between the percentage of NKG2A positive cells in cytotoxic NK subset and CD4 cell count was observed in all HIV-1 infected groups. Conclusion:Fewer cytotoxic NK cells and higher NKG2A expression in cytotoxic NK subset was found in patients in late stage HIV infection. Such a phenomenon may relate to the escape of HIV-1-infected CD4+ T cells from being attacked by NK cells.

Genetic and temporal dynamics of human immunodeficiency virus type 1 CRF07_BC in Xinjiang, China

To explore the temporal genetic variation of human immunodeficiency virus type 1 CRF07_BC and reconstruct its epidemic in Xinjiang, China, we studied 216 C2-V4 fragments of env genes sampled from 1996 to 2008. Phylogenetic analysis indicates that the viruses prevailing in Xinjiang form a large monophyletic cluster and may have originated from a common ancestor. The epidemic in Xinjiang was probably established around 1995 (95% confidence interval, 1994-1996). We noted an increased diversity of CRF07_BC over time, with a rapid evolutionary rate we estimated to be 8.3x10(-3) substitutions per site per year in the env gene. After 5-6 years of the epidemic (1997-2002), the transmission rate of CRF07_BC in Xinjiang slowed down, although CRF07_BC infection remained at a high prevalence.

High HIV risk among Uigur minority ethnic drug users in northwestern China

Objective  To assess differences of HIV risk between ethnicities in northwestern China.

Human immunodeficiency virus type 1 specific cytotoxic T lymphocyte responses in Chinese infected with HIV-1 B'/C Recombinant (CRF07_BC)

BackgroundThe characterization of HIV-1-specific T cell responses in people infected with locally circulating HIV-1 strain will facilitate the development of HIV-1 vaccine. Sixty intravenous drug users infected with HIV-1 circulating recombinant form 07_BC (CRF07_BC), which has been spreading rapidly in western China from north to south, were recruited from Xinjiang, China to assess the HIV-1-specific T cell responses at single peptide level with overlapping peptides (OLP) covering the whole concensus clades B and C proteome.ResultsThe median of the total magnitude and total number of OLPs recognized by CTL responses were 10925 SFC/million PBMC and 25 OLPs, respectively, when tested by clade C peptides, which was significantly higher than when tested by clade B peptides. The immunodominant regions, which cover 14% (58/413) of the HIV-1 proteome, are widely distributed throughout the HIV-1 proteome except in Tat, Vpu and Pol-PR, with Gag, Pol-RT, Pol-Int and Nef being most frequently targeted. The subdominant epitopes are mostly located in p24, Nef, integrase, Vpr and Vif. Of the responses directed to clade C OLPs, 61.75% (972/1574) can be observed when tested with corresponding clade B OLPs. However, Pol-PR and Vpu tend to be targeted in the clade B sequence rather than the clade C sequence, which is in line with the recombinant pattern of CRF07_BC. Stronger and broader CTL responses in subjects with CD4 cell counts ranging from 200 to 400/mm3 were observed when compared to those with less than 200/mm3 or more than 400/mm3, though there have been no significant correlations identified between the accumulative CTL responses or overall breadth and CD4 cell count or plasma viral load.ConclusionThis is the first study conducted to comprehensively address T cell responses in Chinese subjects infected with HIV-1 CRF07_BC in which subtle differences in cross-reactivity were observed, though similar patterns of overall immune responses were demonstrated with clade B infected populations. The immunodominant regions identified in this population can facilitate future HIV-1 vaccine development in China.

Analysis of putative N-linked glycosylation sites and variable region of envelope HIV-1 CRF07_BC recombinant in intravenous drug users in Xinjiang Autonomous Region, China.

To investigate more closely the determinants of transmission and escape in HIV-1 internal proteins, we analyzed the characterization of putative N-linked glycosylation sites (PNGSs) and the variable loop of CRF07_BC recombinant human immunodeficiency virus type 1 (HIV-1), isolated from intravenous drug users (IDUs). We studied the characterization of PNGSs and the variable loop in the C1-C5 and V1-V4 regions of the HIV-1 env gene in 12 intravenous drug users (IDUs) who were divided into two groups according to the length of infection time. In addition, two IDUs were longitudinally monitored from the time of seroconversion for 1.5 and 2.5 years. The longitudinal characterization within the individuals on PNGSs and the variable loop in the C1-C5 and V1-V4 region were also observed. Based on the above analysis, we found that PNGSs and the variable loop appeared to increase over time within IDU transmission of CRF07_BC recombinant HIV-1. We argue that limited PNGSs and the length of variable loops may be involved in selective transmission and escape.