Fig. 3: Memory B cell (MBC) and antibody responses in EILV/CHIKV- vaccinated macaques.
A–C CHIKV-specific MBC responses by ELISPOT analysis. PBMCs of day 30 (A) and day 350 (B-C) vaccinated NHPs were stimulated for 5 d with R848 plus rIL-2 and seeded onto ELISPOT plates coated with CHIKV capsid, E3, E2 and E1 peptide pools (A), total IgG or CHIKV recombinant E2 protein (B,C). A–C Frequencies of CHIKV-specific antibody secreting cells (ASC)s per 106 input cells in MBC cultures from the subject. B Images of total IgG-ASCs, CHIKV peptide-specific or CHIKV E2 protein- specific MBCs, are shown. D Serum neutralizing activity against CHIKV 181/25 was measured by a plaque reduction neutralization test (PRNT). E CHIKV E2 binding IgG responses at indicate time points by ELISA. F,G Passive immunization study. Pooled sera collected at day 350 PV of macaques were diluted 1:2 in PBS and transferred to 6 week-old AB6 mice 24 h before infection with a LD100 dose of WT CHIKV. Mice were monitored daily for morbidity. F Survival rate. G Percent weight loss compared to prior infection. ***P < 0.001, **P < 0.01, or *P < 0.05 compared to mock. ####P < 0.001, ##P < 0.01, or #P < 0.05 compared to CHIKV 181/25.
