Figure 4: Durability of Neutralizing Antibody Response.

PRNT₈₀ titers for EEEV (Panel A), VEEV (Panel B), and WEEV (Panel C) up to 28 weeks post second product administration. Participants received 6, 30, or 60 mcg WEVEE VLP without alum (open circles) or with alum (closed circles) administered at day 0 and study week 8 indicated by black arrows. The reciprocal of the serum dilution which neutralizes 80% of the input virus is shown as the geometric mean PRNT₈₀ titers by study group, with 95% confidence intervals indicated by error bars. A positive response was defined as a PRNT₈₀ value ≥ 10 as indicated by dotted horizontal line, and n = 5 for all dose groups with the exception of 6 mcg WEVEE (n = 4). Peak neutralizing responses were seen at 2 weeks (EEEV, VEEV) and 4 weeks (WEEV) post second vaccination. The dosing effect is observed out to the last study time point, and an alum-dependent response is seen in the 6 and 30 mcg dosing groups throughout the study time course.