Discordance of HIV-1 viral load from paired blood and seminal plasma samples in a Chinese MSM population.

The alarming spread of HIV among men who have sex with men (MSM) has become a national concern in China. Estimating men's sexual HIV infectiousness from blood plasma viral load (BPVL) depends on the association between BPVL and semimal plasma viral load (SPVL). However, previous studies were controversial and few concentrated on MSM. Twenty antiretroviral therapy (ART) naive MSM and 54 MSM under ART were recruited between July and September 2015 in the city of Hangzhou, China. Blood and semen were collected in pairs at the same visit for each individual. BPVL and SPVL were measured by COBAS AmpliPrep/COBAS TaqMan HIV-1 Test ver2.0. The mean viral load in blood plasma was higher than that in semen (4.5± 0.9 log10 vs 3.4±1.3 log10) in 20 ART-untreated MSM, and a positive correlation was found between BPVL and SPVL, as evaluated by linear regression (R2=0.565, P<0.001). 96.3% (52/54) of ART-treated patients had successful viral suppression (<400 cps/ml) according to the BPVL. Fourteen subjects (25.9%, 14/54) presenting undetectable SPVL showed detectable BPVL, ranging from 20.4 to 7470 copies/ml. Three subjects (5.6%, 3/54) presented detectable SPVL although BPVL was undetectable. MSM could pose a transmission risk despite undetectable BPVL. Consistent use of condoms and other risk reduction strategies should be strongly advocated in MSM throughout all stages of HIV infection, regardless of ART.