# Characterization of drug resistance mutations in people living with HIV with low-level viremia on antiretroviral therapy in Chongqing, China

## TL;DR

This study finds that many HIV patients with low virus levels in Chongqing have drug resistance mutations, especially to a common HIV treatment class.

## Contribution

The study introduces a combined RNA/DNA genotyping strategy that improves detection of drug resistance mutations in low-level viremia patients.

## Key findings

- 26.32% of low-level viremia patients had drug resistance mutations, with most resistance against non-nucleoside reverse transcriptase inhibitors.
- The combined RNA/DNA genotyping approach significantly increased detection of resistance mutations in low viral load cases.
- Low baseline CD4+ T-cell counts were linked to higher resistance mutation rates in patients with isolated low-level viremia.

## Abstract

To investigate the prevalence and patterns of drug resistance mutations (DRMs) and associated risk factors among ART-experienced people living with HIV (PLWH) exhibiting low-level viremia (LLV; 50–999 copies/mL) in Chongqing, China, and to evaluate the utility of a combined plasma RNA and proviral DNA genotyping strategy.

In this cross-sectional study (September 2023–February 2024), we screened 4,941 ART-treated individuals, identifying 210 with LLV. Genotypic resistance testing targeting the protease, reverse transcriptase, and integrase regions was successfully performed for 133 participants (63.33%) using a dual-source (plasma RNA and/or proviral DNA) approach. HIV-1 subtyping and DRM analysis were conducted using the Stanford HIVdb algorithm and phylogenetic methods.

The overall prevalence of LLV was 4.25%. CRF07_BC was the predominant HIV-1 subtype (76.69%). DRMs were detected in 26.32% (35/133) of the cohort. Resistance to non-nucleoside reverse transcriptase inhibitors (NNRTIs) was most common (19.55%), primarily driven by V179D/E and G190A/S/E mutations. Resistance to nucleoside reverse transcriptase inhibitors (NRTIs) and integrase strand transfer inhibitors (INSTIs) was observed in 12.03 and 3.76% of participants, respectively, with M184V/I being the predominant NRTI mutation. No significant differences in DRM prevalence were observed across viral subtypes. In multivariate analysis, baseline CD4+ T-cell count <100 cells/μL was significantly associated with DRMs specifically in the isolated LLV subgroup.

This study reveals a considerable prevalence of drug mutations (DRMs), predominantly against NNRTIs, among ART-experienced PLWH with LLV in Chongqing. The combined RNA/DNA genotyping strategy significantly enhanced DRM detection sensitivity in this low viral load cohort, underscoring its value for resistance surveillance and guiding clinical management in resource-limited settings.