Surender Khurana, Olivia Posadas, Lela Kardava, Elizabeth M. Coyle, Supriya Margabandhu Ravichandran, Gabrielle Grubbs, Rosemary McConnell, Nadine Rouphael, Guillaume Poliquin, Joanne M. Langley, Eric Chun‐Pu Chu, Dean A. Follmann, Xiaoran Shang, Yuxing Li, Susan Moir, Richard T. Davey
Short-term boosting of the currently licensed rVSV∆G-ZEBOV-GP vaccine does not generate lasting antibody respones to Ebola virus (EBOV), prompting interest in strategies that elicit more durable immunity. Here, we elucidated the longitudinal humoral immune repertoire over 3 years following prime and boost rVSV∆G-ZEBOV-GP vaccinations administered 18 months apart in healthy adults compared to participants randomized to no boost. This delayed booster vaccination induced long-lasting EBOV-neutralizing antibodies that persisted up to 36 month at levels similar to peak titers after a single dose. Phage display libraries, expressing linear and conformational epitopes of EBOV glycoprotein (GP), demonstrated a highly diverse and durable antibody epitope repertoire following prime boost vaccination. Delayed booster vaccination recalled memory B cells, promoted anti-GP IgG class switching and induced antibodies specific to GP with Fcγ receptor interaction and functional antibody-dependent cellular cytotoxicity and phagocytosis. The 18-month interval led to 13-fold higher antibody affinity maturation than a single dose, maintained up to 36 months. Overall, delayed rVSV∆G-ZEBOV-GP booster vaccination promoted a diverse, stronger, durable, predominant IgG, highly affinity-matured antibody response to GP.