Detection of antiretroviral drug-resistant mutations and HIV-1 subtypes in circulation among men who have sex with men, SEM females and female sex workers: results of Vietnam's HIV Sentinel Surveillance Plus (HSS+) system, 2018 - 2020.

Background: HIV drug resistance (HIVDR) can reduce the effectiveness of antiretroviral (ARV) drugs in preventing morbidity and mortality, limit options for treatment, and prevention. Our study aimed to assess HIV-1 subtypes and HIVDR among key populations in HIV Sentinel Surveillance Plus Behavior (HSS+) in 2018 and 2020.

Methods: One-stage venue-based cluster sampling was used to recruit participants at hotspots identified for Men who have sex with men (MSM) in 7 provinces and SEM females and female sex worker (FSW) in 13 provinces. Participants completed a standard questionnaire about risk and preventive behaviors, and ART history, and provided intravenous blood for HIV testing. HIVDR testing was conducted on HIV-positive samples with VL >1,000 copies/ml.

Results: A total of 185/435 (42.5%) HIV-positive samples had viral load ≥1,000 copies/ml, of which 130/136 from MSM and 26/49 from FSW, were successfully sequenced. Six HIV-1 subtypes were detected (CRF01_AE, A, CRF07/08_BC, B, C, CRF25_cpx), with CRF01_AE (82.7%, 129/156) the most common. Drug resistance mutations were detected in 16.7% of participants overall (26/156), in 15.4% (20/130) of MSM, and in 23.1% (6/26) of FSW. Mutations associated with resistance to NNRTI were the most frequently detected (73.1%, 19/26). The high level of resistance was presented in NNRTI and NRTI classes. There are 10 major resistance mutations detected with NRTI (M184VI-25.0%, K65KR-50.0%, Y115F-25%), NNRTI (K103N-21.1%, E138A-10.5%, V106M-5.3%, K101E-5.3%, G190A-5.3%) PI (L33F-40.0%, M46L-20.0%).

Conclusions: Vietnam's HSS+ system identified an emerging strain of HIV-1 and mutations associated with resistance to multiple drug classes among MSM and FSW.