AbstractBackgroundThe time at which the protective effect of starting ART is achieved in male rectal and genital reservoirs is not clearly established.ObjectivesTo quantify HIV-1 RNA decay towards virological suppression in rectal mucosa and semen in MSM starting dolutegravir/abacavir/lamivudine (DTG/ABC/3TC).MethodsA longitudinal cohort study of ART-naive HIV-positive MSM was performed. HIV-1 RNA was quantified in rectal mucosa and seminal plasma samples at day 1 of ART initiation (baseline) and every 4 weeks until week 20 (w20; all participants) and week 64 (w64; 6 of 12 participants).ResultsTwelve MSM, with median (IQR) age 36 (33–40) years and baseline CD4+ count 449 (411–503) cells/mm3, were included. At baseline, HIV-1 RNA was detectable in all plasma and seminal samples and 10/12 rectal samples. All participants achieved plasma virological suppression by w20, whereas HIV-1 RNA was detectable in 42% and 50% of seminal and rectal samples, respectively. At w64, HIV-1 RNA was detectable in 1/6 seminal and 1/6 rectal samples. A relationship of baseline seminal and rectal HIV-1 RNA levels with viral shedding in reservoirs (HIV-1 RNA >200 copies/mL or copies/swab) was found. In addition, a significant association of baseline plasma viral load with time to rectal HIV-1 RNA <200 copies/swab was found (P=0.025).ConclusionsViral decay after initiating DTG/ABC/3TC is slower in rectal mucosa and semen than in plasma. Approximately half of patients achieved undetectable HIV-1 RNA levels in rectal and genital secretions at w20 and in some patients viral shedding persisted for up to 1 year. Initial plasma viral load influences time to rectal suppression.