Characterizing HIV drug resistance in cases of vertical transmission in the VESTED randomized antiretroviral treatment trial.

Introduction: VESTED (NCT03048422) compared the safety and efficacy of three antiretroviral treatment () regimens in pregnant and postpartum women: dolutegravir+emtricitabine/tenofovir alafenamide fumarate; dolutegravir+emtricitabine/tenofovir disoproxil fumarate (); efavirenz/emtricitabine/TDF. Vertical HIV transmission () occurred to 4/617 (0.60%) live-born infants, who were evaluated for HIV drug resistance () and other risk factors.

Setting: In 2018-2020, pregnant (weeks-14-28) women living with HIV and ≤14 days of ART were enrolled at 22 international sites and followed with their infants through 50 weeks postpartum.

Methods: HIV sequences derived by single genome amplification () from longitudinally collected specimens were assessed from VT Cases for HIVDR in protease, reverse transcriptase, integrase, and the 3'polypurine tract ().

Results: The four Case mothers were prescribed efavirenz-based-ART for 1-7 days prior to randomization to study ART. Their infants received postnatal nevirapine+/-zidovudine prophylaxis and were breastfed. A total of 833 SGA sequences were derived. The "major" (Stanford HIVDR Score ≥60) non-nucleoside reverse transcriptase inhibitor () mutation (K103N) was detected persistently in one viremic mother, and likely contributed to VT of HIVDR. Major NNRTI HIVDR mutations were detected in all three surviving infants. No integrase, nor high frequencies of 3'PPT mutations conferring dolutegravir HIVDR were detected. The timing of HIV infant diagnosis, plasma HIV RNA levels and HIVDR suggests one , one peripartum, one early, and one late breastfeeding transmission.

Conclusions: VT was rare. New-onset NNRTI HIVDR in Case mothers was likely from efavirenz-ART prescribed prior to study dolutegravir-ART, and in one case appeared transmitted to the infant despite nevirapine prophylaxis.