Vaccination with hemagglutinin or neuraminidase DNA protects BALB/c mice against influenza virus infection in presence of maternal antibody

Table 4 Protection against a lethal influenza virus challenge in offspring immunized with different DNA vaccine from that for their mothers ^a

		Serum IgG titers^b in offspring
Plasmid for female mice	Plasmid for offspring	ELISA (2ⁿ)^c		NI assay (2ⁿ)^c		Lung virus titers^b (log₁₀ TCID₅₀)	Survival offspring/Tested offspring (3 weeks)
		21 days after primary immunization	7 days after booster	21 days after primary immunization	7 days after booster
30 μg HA	30 μg NA			4.3 ± 0.60	7.0 ± 1.40	1.2 ± 0.57*	7/7*
30 μg NA	30 μg HA	12.0 ± 0.60	15.7 ± 0.60			3.8 ± 0.23*	7/7*
Unimmunized	Unimmunized	<1	<1	<3	<3	5.5 ± 0.16	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 with the different vaccines from that for their mothers at ages of 1 and 4 weeks respectively. 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)

ISSN: 1471-2334