ABSTRACT
BACKGROUND: To focus interventions, biomarkers of HIV-1 exposure could help in identifying subpopulations at highest risk of acquisition. We assessed whether Y-chromosome single tandem repeat (YSTR) mixtures obtained from rectal swabs could serve as a biomarker of condomless receptive anal intercourse (CRAI) among men who have sex with men and transgender women and evaluated the feasibility of detecting HIV-1 virions to assess exposures. METHODS: Twenty-nine sexually active HIV-seronegative men who have sex with men and one transgender woman from New York City answered on-site and mobile app sexual behavior questionnaires. They were randomized to collecting self-administered rectal swabs every morning or after receptive anal intercourse (RAI). YSTR profiles were assessed from blood sample and swabs; HIV-1 exposure was measured by conducting quantitative polymerase chain reaction in swabs. RESULTS: After 2 months, the daily mobile survey had 135%-201% more instances of anal sex acts and 170%-193% more RAI than on-site surveys. Daily mobile reporting had 11%-35% less CRAI events than those reported on-site (Pdaily = 0.001; Pper-sex = 0.047). The daily swabbing arm reported less RAI (P < 0.001) and CRAI (P < 0.038) and had 2.95 lower odds of detecting YSTR mixtures (P = 0.021) than the per-sex-event arm. Surprisingly, YSTR detection was not significantly modified by report of bowel movements and lubricant, enema, or condom use. No participant became HIV-1 infected, yet HIV-1 total nucleic acids were detected in 6 independent episodes of CRAI in 2 participants taking pre-exposure prophylaxis. CONCLUSIONS: YSTR mixtures demonstrated 80% specificity but only 30% sensitivity as a biomarker of CRAI in self-collected rectal swabs. However, detection of HIV-1 exposures in self-collected swabs may help in identifying those needing further HIV risk reduction strategies.
Subject(s)
Condoms , HIV Infections/diagnosis , HIV Seronegativity , HIV-1/genetics , Sexual Behavior , Adolescent , Adult , Biomarkers , Condoms/statistics & numerical data , Female , HIV-1/isolation & purification , Homosexuality, Male , Humans , Male , Nucleic Acids , Tandem Repeat Sequences , Young AdultABSTRACT
Emerging SARS-CoV-2 variants have raised concerns about resistance to neutralizing antibodies elicited by previous infection or vaccination. We examined whether sera from recovered and naive donors collected prior to, and following immunizations with existing mRNA vaccines, could neutralize the Wuhan-Hu-1 and B.1.351 variants. Pre-vaccination sera from recovered donors neutralized Wuhan-Hu-1 and sporadically neutralized B.1.351, but a single immunization boosted neutralizing titers against all variants and SARS-CoV-1 by up to 1000-fold. Neutralization was due to antibodies targeting the receptor binding domain and was not boosted by a second immunization. Immunization of naïve donors also elicited cross-neutralizing responses, but at lower titers. Our study highlights the importance of vaccinating both uninfected and previously infected persons to elicit cross-variant neutralizing antibodies.
ABSTRACT
Emerging SARS-CoV-2 variants have raised concerns about resistance to neutralizing antibodies elicited by previous infection or vaccination. We examined whether sera from recovered and naïve donors collected prior to, and following immunizations with existing mRNA vaccines, could neutralize the Wuhan-Hu-1 and B.1.351 variants. Pre-vaccination sera from recovered donors neutralized Wuhan-Hu-1 and sporadically neutralized B.1.351, but a single immunization boosted neutralizing titers against all variants and SARS-CoV-1 by up to 1000-fold. Neutralization was due to antibodies targeting the receptor binding domain and was not boosted by a second immunization. Immunization of naïve donors also elicited cross-neutralizing responses, but at lower titers. Our study highlights the importance of vaccinating both uninfected and previously infected persons to elicit cross-variant neutralizing antibodies.
