Comparison of dynamics of HIV-1 coreceptor usage in a long-term antiretroviral treatment adolescent by genotypic and phenotypic assays

• Main Authors: Sayamon Hongjaisee, Sartsin Chaipong, Tanawan Samleerat
• Format: Article
• Language: English
• Published: Chaing Mai University 2018-10-01
• Series: Journal of Associated Medical Sciences
• Subjects: HIV; coreceptor usage; tropism; CCR5; genotypic predictors
• Online Access: https://www.tci-thaijo.org/index.php/bulletinAMS/article/view/116543
• ISSN: 2539-6056; 2539-6056

Background: Based on coreceptor usage, HIV-1 variants can be classified as R5, X4, and dual/mixed viruses. Currently, the determination of HIV-1 coreceptor usage can be performed by both phenotypic and genotypic assays. Although, the accessibility, simple, and low cost makes those genotypic assays a more feasible alternative to phenotypic assays, but they are not always accurate. Here, we discussed the coreceptor usage obtained by both assays in HIV-infected patient who acquired HIV-1 CRF01_AE and received antiretroviral therapy for at least 10 years. Objectives: To determine the HIV-1 coreceptor usage by both genotypic and phenotypic assays at different three times in long-term antiretroviral treatment adolescent. Materials and methods: The remained RNA was collected at different three times to determine the HIV-1 coreceptor usage by both phenotypic and genotypic assays. Firstly, HIV-1 V3 region was amplified, sequenced, and then V3 amino acid sequences were used as templates for prediction of coreceptor usage by genotypic predictors. Secondly, the entire gp160 envelope fragment was amplified from the same remained RNA to produce env-pseudotyped virus. The viruses were tested for coreceptor usage using U373.R5 and U373.X4 cells, and viral entry was assessed with luciferase activity measurement. Results: From all time points at which coreceptor usage was determined, the genotypic results showed that the coreceptor usage trend to be more X4 phenotype using genotypic predictors, but it contrasted with phenotypic result which only voted to R5 phenotype. Although, the genotypic results showed the evolution of V3 amino acid sequences but it still not sufficient for coreceptor changed when confirmed with phenotypic assay. The presence of positively charged amino acid in V3 sequences causes a high net charge which can lead to mis-prediction by genotypic predictors. Conclusion: This finding suggested that the predictions are not always accurate; a false prediction of X4 variants may lead to unnecessarily precluding patients who could have benefited from receiving CCR5 inhibitors whereas a false prediction of R5 variants may lead to the reemergence of X4-strains under CCR5 inhibitors pressure. Thus, the utilization of genotypic predictors should be carefully considered.