A Multiagent Alphavirus DNA Vaccine Delivered by Intramuscular Electroporation Elicits Robust and Durable Virus-Specific Immune Responses in Mice and Rabbits and Completely Protects Mice against Lethal Venezuelan, Western, and Eastern Equine Encephalitis Virus Aerosol Challenges

Figure 4

EEEV-specific antibody responses and survival of vaccinated mice. Female BALB/c mice ( per group) were vaccinated on days 0, 21, and 42 with 5 μg of empty vector DNA, 5 μg of the EEEV DNA vaccine, or 5 μg each of the VEEV, WEEV, and EEEV DNA vaccines (3-EEV DNA vaccine) delivered by IM EP or 0.5 ml of the formalin-inactivated EEEV IND vaccine delivered by subcutaneous injection. Serum samples obtained on days 21, 42, and 63 were assayed for total IgG anti-EEEV antibodies by ELISA and for EEEV-neutralizing antibodies by PRNT. The group mean log₁₀ ELISA (a) and PRNT₈₀ (b) titers along with the SEM are shown. for comparison of titers between groups. Four weeks after the final vaccination, the mice were challenged with 1 × 10⁵ PFU (~3000 LD₅₀) of EEEV strain FL91-4679 by the aerosol route. Kaplan-Meier survival curves indicating the percentage of surviving mice at each day of the 28-day postchallenge observation period are shown (c). for survival rate as compared to negative control group.

(a)

(b)

(c)