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 2

VEEV-specific cellular immune responses of vaccinated mice. Female BALB/c mice ( per group) were vaccinated twice at a 3-week interval with 5 μg of empty vector DNA, 5 μg of the VEEV DNA vaccine, or 5 μg each of the VEEV, WEEV, and EEEV DNA vaccines (3-EEV DNA vaccine) delivered by IM EP. Two weeks after the second vaccination, splenocytes were isolated and restimulated with no peptide, a peptide from the unrelated β-galactosidase protein, or pools of overlapping peptides spanning the VEEV IAB E2 or E1 envelope glycoproteins and analyzed by IFN-γ ELISpot assay. The mean spot forming units (SFU) per 10⁶ cells along with the SEM are shown for each group. for comparison of spot counts between groups.