Report of the Cent Gardes HIV Vaccine Conference: The B-cell response to HIV Part 2: Non-neutralizing antibodies: Fondation Mérieux Conference Center, Veyrier du Lac, France 5–7 November 2012

• Protection in the RV144 efficacy trial was associated with HIV non-neutralizing antibodies.
• Non-neutralizing HIV IgGs mediate antibody-dependent cellular cytotoxicity (ADCC).
• Vaginal HIV IgAs, especially dIgA1, block virus transcytosis across monocellular epithelia.
• HIV transcytosis is favored by acidic pH and the neonatal FcRn receptor.

The Cent Gardes Conference on HIV Vaccines took place on November 5–7, 2012 at the Fondation Mérieux Conference Center, Annecy, France. The aim of the meeting was to review the B cell response to human immunodeficiency virus-1 (HIV-1) infection and immunization, from broadly neutralizing antibodies (bnAbs) to non-neutralizing antibodies (n-nAbs). This paper, Part 2 of the report, focuses on potentially protective n-nAbs. Evidence was presented that n-nAbs may effectively contribute to protection against HIV, as illustrated by the recent RV144 efficacy trial. They can either act as IgGs by mediating antibody-dependent cellular cytotoxicity (ADCC) involving Fc effector functions, or as IgAs, particularly dimeric IgA1s, which can inhibit virus transcytosis through monocellular epithelia and could play an important role in mucosal immunity.