B cells were antigen specific single-cell sorted or isolated from memory B cell culture. The antibody VH and VL chain genes were RT-PCR amplified, Sanger sequenced, and analyzed with Cloanalyst (45). Env reactivity and epitope specificity was determined by transiently expressing mAbs and assaying by ELISA. MAbs were isolated from 8 RV144 vaccinees, 14 RV305 vaccinees, and 5 RV305a vaccinees, of which 5 were studied in all 3 clinical trials. All PBMCs used for mAb isolation were collected 2 weeks after the final boost in each clinical trial. Dashed line indicates 2% VH chain gene mutation frequency. Numbers of mAbs analyzed are in parentheses.