No selection of CXCR4-using variants in cell reservoirs of dual-mixed HIV-infected patients on suppressive maraviroc therapy

Existence of Replication-Competent Minor Variants with Different Coreceptor Usage in Plasma from HIV-1-Infected Individuals

Cell entry by HIV-1 is mediated by its principal receptor, CD4, and a coreceptor, either CCR5 or CXCR4, with viral envelope glycoprotein gp120. Generally, CCR5-using HIV-1 variants, called R5, predominate over most of the course of infection, while CXCR4-using HIV-1 variants (variants that utilize both CCR5 and CXCR4 [R5X4, or dual] or CXCR4 alone [X4]) emerge at late-stage infection in half of HIV-1-infected individuals and are associated with disease progression. Although X4 variants also appear during acute-phase infection in some cases, these variants apparently fall to undetectable levels thereafter. In this study, replication-competent X4 variants were isolated from plasma of drug treatment-naive individuals infected with HIV-1 strain CRF01_AE, which dominantly carries viral RNA (vRNA) of R5 variants. Next-generation sequencing (NGS) confirmed that sequences of X4 variants were indeed present in plasma vRNA from these individuals as a minor population. On the other hand, in one individual with a mixed infection in which X4 variants were dominant, only R5 replication-competent variants were isolated from plasma. These results indicate the existence of replication-competent variants with different coreceptor usage as minor populations.IMPORTANCE The coreceptor switch of HIV-1 from R5 to CXCR4-using variants (R5X4 or X4) has been observed in about half of HIV-1-infected individuals at late-stage infection with loss of CD4 cell count and disease progression. However, the mechanisms that underlie the emergence of CXCR4-using variants at this stage are unclear. In the present study, CXCR4-using X4 variants were isolated from plasma samples of HIV-1-infected individuals that dominantly carried vRNA of R5 variants. The sequences of the X4 variants were detected as a minor population using next-generation sequencing. Taken together, CXCR4-using variants at late-stage infection are likely to emerge when replication-competent CXCR4-using variants are maintained as a minor population during the course of infection. The present study may support the hypothesis that R5-to-X4 switching is mediated by the expansion of preexisting X4 variants in some cases.

CD4 T cell decline following HIV seroconversion in individuals with and without CXCR4-tropic virus

Background

The natural clinical and immunological courses following HIV seroconversion with CXCR4-tropic or dual-mixed (X4/DM) viruses are controversial. We compared spontaneous immunological outcome in patients harbouring an X4/DM virus at the time of seroconversion with those harbouring a CCR5-tropic (R5) virus.

Methods

Data were included from patients participating in CASCADE, a large cohort collaboration of HIV seroconverters, with ≥2 years of follow-up since seroconversion. The HIV envelope gene was sequenced from frozen plasma samples collected at enrolment, and HIV tropism was determined using Geno2Pheno (false-positive rate 10%). The spontaneous CD4 T cell evolution was compared by modelling CD4 kinetics using linear mixed-effects models with random intercept and random slope.

Results

A total of 1387 patients were eligible. Median time between seroconversion and enrolment was 1 month (range 0-3). At enrolment, 202 of 1387 (15%) harboured an X4/DM-tropic virus. CD4 decrease slopes were not significantly different according to HIV-1 tropism during the first 30 months after seroconversion. No marked change in these results was found after adjusting for age, year of seroconversion and baseline HIV viral load. Time to antiretroviral treatment initiation was not statistically different between patients harbouring an R5 (20.76 months) and those harbouring an X4/DM-tropic virus (22.86 months, logrank test P = 0.32). Conclusions: In this large cohort collaboration, 15% of the patients harboured an X4/DM virus close to HIV seroconversion. Patients harbouring X4/DM-tropic viruses close to seroconversion did not have an increased risk of disease progression, estimated by the decline in CD4 T cell count or time to combined ART initiation.