A single immunization with HA DNA vaccine by electroporation induces early protection against H5N1 avian influenza virus challenge in mice

BMC Infectious Diseases

Table 1 Protection of mice immunized with HA DNA vaccine against lethal H5N1 virus challenge^a

		Lung virus titer^b (log₁₀ TCID₅₀/ml)			Survival rate (No. of survivors/no. tested)
Plasmid DNA	Dose (μg)	3 days	5 days	7 days	3 days	5 days	7 days
HA DNA	10	6.25 ± 0.35	4.80 ± 0.28^c	4.25 ± 0.35^c	0/12	0/12	6/12
	50	5.75 ± 0.35	4.55 ± 0.07^c	4.00 ± 0.70^c	0/12	4/12	10/12^d
	100	5.75 ± 0.35	4.55 ± 0.07^c	3.25 ± 0.35^c	0/12	6/12	12/12^d
Control		6.25 ± 0.35			0/12

^a Mice were immunized once with HA DNA 3, 5 and 7 days, respectively, before the challenge and at various dosages. Then all the mice were challenged under anesthesia with 5 LD₅₀ of homologous A/Chicken/Henan/12/2004(H5N1) virus. Three days after the viral challenge, the mice were sacrificed. The trachea and lungs were taken out and washed twice by injecting 2 ml of PBS containing 0.1% BSA. The bronchoalveolar wash was used for virus titration after removing cellular debris by centrifugation. The survival of mice 3 weeks after the challenge was measured.
^bValues represent means ± SD of 4 mice from each group.
^c Significantly different from the control groups (p < 0.05) by ANOVA.
^d Significantly different from the control groups (p < 0.05) by Fisher's exact test.