RV144 Vaccine Induced IgA mediated Infectious HIV-1 Virion Capture. Purified plasma IgA at visit 1 (pre-vaccination) and visit 8 (2 weeks post last vaccination) from 22 (CM244 or WITO) and 29 (NL4-3) vaccinees with detectable HIV-1 Env binding antibody responses were selected and measured in infectious HIV-1 capture assays using micro-plate based assay . Relative light units (RLU) produced by infected target cells quantify the amount of infectious virus bound. Dashed line (RLU ≥ 1000) indicates positive samples. The percentage of tested vaccinees with virion capture capacity are 34.5% (10/29) NL4-3, and 60.9% (14/23) for lab adapted strain NL4-3 and CM244, respectively. The transmitted/founder WITO was captured by 31.8% (7/22) vaccinees. Dashed line indicates positivity threshold, defined by the background levels of capture (≥1000).