Impact of the mutational load on the virological response to a first-line rilpivirine-based regimen

HIV-1 resistance genotyping by ultra-deep sequencing and 6-month virological response to first-line treatment

OBJECTIVES

To evaluate the routine use of the Sentosa ultra-deep sequencing (UDS) system for HIV-1 polymerase resistance genotyping in treatment-naïve individuals and to analyse the virological response (VR) to first-line antiretroviral treatment.

METHODS

HIV drug resistance was determined on 237 consecutive samples from treatment-naïve individuals using the Sentosa UDS platform with two mutation detection thresholds (3% and 20%). VR was defined as a plasma HIV-1 virus load <50 copies/mL after 6 months of treatment.

RESULTS

Resistance to at least one antiretroviral drug with a mutation threshold of 3% was identified in 29% and 16% of samples according to ANRS and Stanford algorithms, respectively. The ANRS algorithm also revealed reduced susceptibility to at least one protease inhibitor (PI) in 14.3% of samples, to one reverse transcriptase inhibitor in 12.7%, and to one integrase inhibitor (INSTI) in 5.1%. For a mutation threshold of 20%, resistance was identified in 24% and 13% of samples according to ANRS and Stanford algorithms, respectively. The 6 months VR was 87% and was similar in the 58% of patients given INSTI-based treatment, in the 16% given PI-based treatment and in the 9% given NNRTI-based treatment. Multivariate analysis indicated that the VR was correlated with the baseline HIV virus load and resistance to at least one PI at both 3% and 20% mutation detection thresholds (ANRS algorithm).

CONCLUSIONS

The Vela UDS platform is appropriate for determining antiretroviral resistance in patients on a first-line antiretroviral treatment. Further studies are needed on the use of UDS for therapeutic management.

Long-Acting Rilpivirine (RPV) Preexposure Prophylaxis Does Not Inhibit Vaginal Transmission of RPV-Resistant HIV-1 or Select for High-Frequency Drug Resistance in Humanized Mice

The antiretroviral drug rilpivirine was developed into a long-acting formulation (RPV LA) to improve adherence for preexposure prophylaxis (PrEP) to prevent HIV-1 transmission. A concern is that RPV LA will not inhibit transmission of drug-resistant HIV-1 and may select for drug-resistant virus. In female humanized mice, we found that RPV LA inhibited vaginal transmission of WT or 3-fold RPV-resistant HIV-1 but not virus with 30-fold RPV resistance. In animals that became infected despite RPV LA PrEP, WT HIV-1 dissemination was delayed until genital and plasma RPV concentrations waned. RPV resistance was detected at similar low frequencies in untreated and PrEP-treated mice that became infected. These results indicate the importance of maintaining RPV at a sustained threshold after virus exposure to prevent dissemination of HIV-1 after vaginal infection and low-frequency resistance mutations conferred low-level resistance, suggesting that RPV resistance is difficult to develop after HIV-1 infection during RPV LA PrEP.

As a long-acting formulation of the nonnucleoside reverse transcriptase inhibitor rilpivirine (RPV LA) has been proposed for use as preexposure prophylaxis (PrEP) and the prevalence of transmitted RPV-resistant viruses can be relatively high, we evaluated the efficacy of RPV LA to inhibit vaginal transmission of RPV-resistant HIV-1 in humanized mice. Vaginal challenges of wild-type (WT), Y181C, and Y181V HIV-1 were performed in mice left untreated or after RPV PrEP. Plasma viremia was measured for 7 to 10 weeks, and single-genome sequencing was performed on plasma HIV-1 RNA in mice infected during PrEP. RPV LA significantly prevented vaginal transmission of WT HIV-1 and Y181C HIV-1, which is 3-fold resistant to RPV. However, it did not prevent transmission of Y181V HIV-1, which has 30-fold RPV resistance in the viruses used for this study. RPV LA did delay WT HIV-1 dissemination in infected animals until genital and plasma RPV concentrations waned. Animals that became infected despite RPV LA PrEP did not acquire new RPV-resistant mutations above frequencies in untreated mice or untreated people living with HIV-1, and the mutations detected conferred low-level resistance. These data suggest that high, sustained concentrations of RPV were required to inhibit vaginal transmission of HIV-1 with little or no resistance to RPV but could not inhibit virus with high resistance. HIV-1 did not develop high-level or high-frequency RPV resistance in the majority of mice infected after RPV LA treatment. However, the impact of low-frequency RPV resistance on virologic outcome during subsequent antiretroviral therapy still is unclear.

IMPORTANCE The antiretroviral drug rilpivirine was developed into a long-acting formulation (RPV LA) to improve adherence for preexposure prophylaxis (PrEP) to prevent HIV-1 transmission. A concern is that RPV LA will not inhibit transmission of drug-resistant HIV-1 and may select for drug-resistant virus. In female humanized mice, we found that RPV LA inhibited vaginal transmission of WT or 3-fold RPV-resistant HIV-1 but not virus with 30-fold RPV resistance. In animals that became infected despite RPV LA PrEP, WT HIV-1 dissemination was delayed until genital and plasma RPV concentrations waned. RPV resistance was detected at similar low frequencies in untreated and PrEP-treated mice that became infected. These results indicate the importance of maintaining RPV at a sustained threshold after virus exposure to prevent dissemination of HIV-1 after vaginal infection and low-frequency resistance mutations conferred low-level resistance, suggesting that RPV resistance is difficult to develop after HIV-1 infection during RPV LA PrEP.

Time to eligibility for antiretroviral therapy in adults with CD4 cell count > 500 cells/μL in rural KwaZulu-Natal, South Africa

OBJECTIVES

Understanding of progression to antiretroviral therapy (ART) eligibility and associated factors remains limited. The objectives of this analysis were to determine the time to ART eligibility and to explore factors associated with disease progression in adults with early HIV infection.

METHODS

HIV-infected adults (≥ 18 years old) with CD4 cell count > 500 cells/μl were enrolled in the study at three primary health care clinics, and a sociodemographic, behavioural and partnership-level questionnaire was administered. Participants were followed 6-monthly and ART eligibility was determined using a CD4 cell count threshold of 350 cells/μl. Kaplan - Meier and Cox proportional hazard regression modelling were used in the analysis.

RESULTS

A total of 206 adults contributed 381 years of follow-up; 79 (38%) reached the ART eligibility threshold. Median time to ART eligibility was shorter for male patients (12.0 months) than for female patients (33.9 months). Male sex [adjusted hazard ratio (aHR) 3.13; 95% confidence interval (CI) 1.82-5.39], residing in a household with food shortage in the previous year (aHR 1.58; 95% CI 0.99-2.54), and taking nutritional supplements in the first 6 months after enrolment (aHR 2.06; 95% CI 1.11-3.83) were associated with shorter time to ART eligibility. Compared with reference CD4 cell count ≤  559 cells/μl, higher CD4 cell count was associated with longer time to ART eligibility [aHR 0.46 (95% CI 0.25-0.83) for CD4 cell count 560-632 cells/μl; aHR 0.30 (95% CI 0.16-0.57) for CD4 cell count 633-768 cells/μl; and aHR 0.17 (95% CI 0.08-0.38) for CD4 cell count > 768 cells/μl].

CONCLUSIONS

Over one in three adults with CD4 cell count > 500 cells/μl became eligible for ART at a CD4 cell count threshold of 350 cells/μl over a median of 2 years. The shorter time to ART eligibility in male patients suggests a possible need for sex-specific pre-ART care and monitoring strategies.