Table 2.
Serum IgG titersb in offspring | |||||||
Plasmid | ELISA (2n)c | NI assay (2n)c | Lung virus titersb (log10 TCID50) | Survival offspring/Tested offspring (3 weeks) | |||
Plasmid for female mice | Plasmid for offspring | 21 days after primary immunization | 7 days after booster | 21 days after primary immunization | 7 days after booster | ||
30 μg HA | 30 μg HA | 15.0 ± 0.00 | 13.3 ± 0.60 | 4.3 ± 0.35 | 0/7 | ||
Unimmunized | 30 μg HA | 11.3 ± 0.50 | 14.3 ± 0.50 | 4.0 ± 0.58* | 5/7* | ||
30 μg NA | 30 μg NA | 5.6 ± 0.90 | 3.3 ± 0.60 | 4.0 ± 0.70 | 2/7 | ||
Unimmunized | 30 μg NA | 4.6 ± 0.60 | 8.5 ± 0.70 | 2.8 ± 0.35* | 7/7* | ||
Unimmunized | Unimmunized | <1 | <1 | <3 | <3 | 5.7 ± 0.00 | 0/7 |
a Female mice were immunized twice, 3 weeks apart, with 30 μg HA DNA or 30 μg NA DNA. The offspring were immunized at ages of 1 and 4 weeks, respectively, with the same vaccine as their mothers. Serum samples from offspring were collected 3 weeks after primary immunization and 1 week after booster. The anti-HA antibody titers were measured by ELISA. The anti-NA antibody titers were measured by NI assay. One week after booster, the offspring were challenged with a lethal dose of A/PR/8/34 (20 × LD50). Lungs were taken out from at least three mice in each group 3 days after challenge for virus titration by standard MDCK assay. Survival rates of mice were measured 3 weeks after challenge.
b Values represent mean ± S.D. of each group.
c The serum samples were diluted 2-fold serially and "n" represents the dilution factor.
*Significant difference (p < 0.05)