Molecular characterization of HIV-1 CRF01_AE in Mekong Delta, Vietnam, and impact of T-cell epitope mutations on HLA recognition (ANRS 12159).

BACKGROUND: To date, 11 HIV-1 subtypes and 48 circulating recombinant forms have been described worldwide. The underlying reason why their distribution is so heterogeneous is not clear. Host genetic factors could partly explain this distribution. The aim of this study was to describe HIV-1 strains circulating in an unexplored area of Mekong Delta, Vietnam, and to assess the impact of optimal epitope mutations on HLA binding. METHODS: We recruited 125 chronically antiretroviral-naive HIV-1-infected subjects from five cities in the Mekong Delta. We performed high-resolution DNA typing of HLA class I alleles, sequencing of Gag and RT-Prot genes and phylogenetic analysis of the strains. Epitope mutations were analyzed in patients bearing the HLA allele restricting the studied epitope. Optimal wild-type epitopes from the Los Alamos database were used as reference. T-cell epitope recognition was predicted using the immune epitope database tool according to three different scores involved in antigen processing (TAP and proteasome scores) and HLA binding (MHC score). RESULTS: All sequences clustered with CRF01_AE. HLA class I genotyping showed the predominance of Asian alleles as A*11:01 and B*46:01 with a Vietnamese specificity held by two different haplotypes. The percentage of homology between Mekong and B consensus HIV-1 sequences was above 85%. Divergent epitopes had TAP and proteasome scores comparable with wild-type epitopes. MHC scores were significantly lower in divergent epitopes with a mean of 2.4 (±0.9) versus 2 (±0.7) in non-divergent ones (p<0.0001). CONCLUSIONS: Our study confirms the wide predominance of CRF01_AE in the Mekong Delta where patients harbor a specific HLA pattern. Moreover, it demonstrates the lower MHC binding affinity among divergent epitopes. This weak immune pressure combined with a narrow genetic diversity favors immune escape and could explain why CRF01_AE is still predominant in Vietnam, particularly in the Mekong area.

HSV-2 antibodies in female sex workers in Vietnam.

Little information is available on the prevalence of herpes simplex type-2 (HSV-2) antibodies among groups at potential high risk of HIV in Asia. This study was carried out to determine the prevalence of HSV-2 antibodies and correlates of HSV-2 infection in female sex workers (FSWs) in border provinces of Vietnam. Nine hundred and four FSWs in five border provinces of Vietnam were interviewed about selected sociodemographic and behavioural characteristics, and information about partners by a standard interview schedule. Serological samples were collected for HSV-2 antibodies, syphilis and HIV. The overall prevalence of HSV-2 antibodies was 27.7% (95% confidence interval [CI]: 24.8-30.7%). The prevalence of HSV-2 in southern provinces (Dong Thap 32.3%, An Giang 33.3% and Kien Giang 29.9%) was higher than that in the central (Quang Tri 20.8%) and northern border areas (Lai Chau 5.0%). In multivariate analysis, Kinh ethnicity (odds ratio [OR] = 2.59, P = 0.02), direct sex work (OR = 1.61, P = 0.01), >/=9 clients/week (OR = 2.11, P = <0.001), ever worked outside Vietnam (OR = 2.12, P = 0.05), >1 pregnancy termination (OR = 1.58, P = 0.05), syphilis (OR = 5.19, P = <0.001) and HIV (OR = 2.68,P = 0.01) were associated with HSV-2. Age