FIG. 2.

Detection of CVB3-specific antibody levels induced by DNA vaccine. BALB/c mice were injected twice i.m. with plasmid DNA at 28-day intervals. Four weeks after every injection, sera were obtained and analyzed for the presence of CVB3-specific antibodies by Western blot analysis. (A) After the first immunization, no virus-specific antibodies were detectable. (B) After the second immunization, antibodies which were present in sera of pCMV/VP1 (lanes 2 to 6)- and pCMV/VP4-2 (lanes 12 to 16)-immunized mice were able to bind virus-specific proteins with the same molecular weight as the capsid protein VP1 or VP2 of CVB3 (lane 1, as a positive control). Only a few or no virus-specific antibodies were present in samples of pCMV/VP3-1 (lanes 7 to 11)- and pCMV/VP4-1 (lanes 17 to 21)-treated mice. The serum dilution was 1:25. The results are representative of three different experiments.