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Prevalence of CCR5-tropic HIV-1 among treatment-experienced individuals in South Africa infected with Clade C virus

Purpose of the study

HIV-1 enters target cells by binding to the CD4 molecule and a co-receptor (CCR5 [R5] and/or CXCR4 [X4]). HIV-1 may be classified as R5-tropic, X4-tropic, or dual/mixed (D/M) tropic depending on the co-receptor(s) used. Little is known about the prevalence of R5-tropic HIV-1 in regions of the world where non-clade B virus predominates. The objectives of this study were to determine the prevalence of R5-tropic HIV-1 amongst treatment-experienced (TE) individuals in South Africa infected with Clade C virus (the predominant Clade in South Africa) and to ascertain variables associated with R5 tropism.

Methods

At a single study visit, in this cross-sectional study conducted at three sites in South Africa, a brief questionnaire elicited information on demographics, HIV clinical history, and antiretroviral regimens. Blood was drawn from subjects and analyzed for CD4 cell count, HIV-1 RNA load (VL), and HIV-1 genotype to ascertain clade. Clade C samples with a VL of >1,000 copies/mL were tested for tropism via the original phenotypic Trofile™ assay.

Summary of results

Of the 353 subjects recruited for this study, 294 (84.2%) had a VL of >1,000 copies/mL; 276 (93.9%) of these were infected with Clade C HIV-1. Tropism results were obtained for 206 (74.6%) subjects with Clade C HIV-1. Mean age at study entry was 37 years; 40.8% of subjects were male, and the majority (97.6%) were of African race/ethnicity. Most (98.1%) subjects reported a heterosexual mode of HIV-1 transmission. Mean VL was 122,978 copies/mL and mean CD4 cell count was 208 cells/μL. R5, D/M and X4-tropic HIV-1 was present in 146 (70.9%), 52 (25.2%) and 8 (3.9%) of TE subjects, respectively. A multivariate logistic model was fitted including age, sex, CD4 cell count, VL, time since HIV diagnosis, and mode of HIV transmission. Backward selection from a saturated model with all two-way interactions yielded three variables significantly associated with R5 tropism: age, VL, and CD4 cell count.

Conclusion

R5-tropic HIV-1 was the predominant variant detected in this TE South African population infected with Clade C HIV-1. In a multivariate model, older age, higher CD4 cell count, and higher VL were all associated with the presence of R5 co-receptor usage.

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Open Access This article is published under license to BioMed Central Ltd. This is an Open Access article is distributed under the terms of the Creative Commons Attribution 2.0 International License (https://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Eng, S., Sanne, I., Badal-Faesen, S. et al. Prevalence of CCR5-tropic HIV-1 among treatment-experienced individuals in South Africa infected with Clade C virus. JIAS 11, P198 (2008). https://doi.org/10.1186/1758-2652-11-S1-P198

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  • DOI: https://doi.org/10.1186/1758-2652-11-S1-P198

Keywords

  • South African Population
  • Multivariate Logistic Model
  • Predominant Variant
  • Enter Target Cell
  • Tropism Result