Chemokine co-receptor usage in HIV-1-infected treatment-naïve voluntary counselling and testing clients in Southern Taiwan.

Objective: The goal of this present study was to determine the proportion of CCR5-tropic and CXCR4-tropic viruses and impact of tropism test on clinical presentation, CD4 cell counts, viral load and genotypic drug resistance from drug-naïve, voluntary counselling and testing (VCT) clients in southern Taiwan.
Design: This was a cross-sectional study. Plasma samples were collected from HIV-1-infected patients from January 2013 to December 2013; subjects were recruited from free VCT centres in southern Taiwan.
Setting: Taiwan.
Participants: Plasma samples from 108 HIV-1-infected, treatment-naïve, VCT clients were analysed. HIV-1 strains were sequenced, genotype resistance was determined by a commercial kit (Viro-seq) and co-receptor tropism (CRT) was predicted by an internet tool geno2pheno[coreceptor], with a 10% false-positive rate as the cut-off. Differences in progression markers, patient characteristics, VCT questionnaires and HIV subtype distribution were evaluated statistically.
Results: All the 108 VCT clients were male with 90% between the ages of 20 and 40 years. Eighty-eight per cent of the patients were men who have sex with men (MSM). The median (IQR) CD4 cell count was 342 cells/µL (221-454) and the viral load was 4.6 log (4.0-5.0). HIV-transmitted drug resistance was found in 9.3% (10/108) of the patients. CRT predictions indicated that 74% of the patients had only R5-tropic strains. CRT was not associated with CD4 cell counts, patient characteristics, VCT questionnaire and transmitted drug resistance. There was a significant difference with regard to viral load at the time of presentation, showing that patients with R5 more often had a higher viral load as compared with those with X4/DM strains (4.6±0.6 log vs 4.33±0.7 log, p=0.036).
Conclusions: We found that 74% of the VCT clients were infected with R5-tropic virus strains. HIV-transmitted drug resistance was not associated with CRT predictions. Higher viral load at presentation was predictive of R5 co-receptor usage.
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