Defective HIV-1 DNA pol sequences are not associated with HIV-1 DNA levels and drive most APOBEC-context drug resistance mutations.

Introduction: The specificity of HIV-1 DNA genotypic resistance tests (GRTs) is hampered by the detection of the APOBEC-context drug resistance mutations (AC DRMs), usually harboured by replication-incompetent proviruses. We sought factors associated with defective sequences in the HIV-1 pol region. In addition, AC DRMs and their link with defective sequences were investigated.

Methods: We included ART-treated patients with viral suppression or plasma viral load (VL) lower than 200 copies/mL, who underwent HIV-1 DNA genotyping, with successful sequencing of protease (PR), reverse transcriptase (RT) and integrase (IN) regions. Sequencing was performed using either the Sanger method or the Sentosa® NGS approach with a 20% cut-off. All hypermutated sequences and/or those containing at least one stop codon were considered defective.

Results: A total of 613 HIV-1 DNA GRTs were analysed. Defective sequences were identified for 186 samples (30.3%) including 65 PR sequences, 92 RT sequences and 65 IN sequences. No association, including HIV-1 DNA levels, was found with the detection of defective pol sequences. A total of 226 AC DRMs were recorded in all sequences. Most of these mutations (78%) were harboured by defective sequences. AC DRMs did not emerge in the plasma viral population, and likely do not impact the virological response to ART.

Conclusions: Defectives pol sequences were not associated with HIV-1 DNA levels and harboured most of the AC DRMs. Such mutations likely have no clinical impact, and should not be reported in routine practice. Consensus guidelines for reporting HIV-1 DNA GRTs are needed, especially for the assessment and management of AC DRMs.