Figure 2.

DNA vaccines induce similar patterns of antibody responses in adults and in early life. Young and adult BALB/c (A) and C57BL/6 (B) mice were immunized i.m. with DNA plasmids encoding either the C fragment of tetanus toxin (TetC-DNA, A), or Sendai virus nucleoprotein (SV-NP DNA, B). Vaccine-specific serum IgG antibodies were measured by ELISA at various time intervals after immunization. Serum vaccine-specific IgG1 and IgG2a antibodies were measured by ELISA >6 weeks after priming. Results are expressed as mean vaccine-specific antibody titers (in log₁₀) obtained in groups of 6–10 immunized mice.