Table 3.

Specific Ab titers in unexposed and pre-exposed mice after immunization^§

		Ab titer by ELISA (log2)
Group	Subgroup (DNA vaccine)	Anti-NP	Anti-M1
Unexposed to H1N1	NP DNA	12.5 ± 1.0	Not done
	M1 DNA	Not done	10.0 ± 0.81
	NP + M1 DNAs	12.5 ± 0.58	10.5 ± 1.29
Pre-exposed to H1N1	NP DNA	22.0 ± 0.57a, b	Not done
	M1 DNA	Not done	12.7 ± 1.15a, b
	NP + M1 DNAs	22.3 ± 1.15a, b	13.3 ± 0.57a, b
	Unimmunized control	17.0 ± 1.0	9.33 ± 0.57

^§Mice were grouped and treated as described in Table 2. Three days after the lethal H5N1 challenge, six mice from each subgroup were sacrificed for specific IgG Ab detection by ELISA. NP and M1 proteins obtained by prokaryotic expression were used to coat the microtiter plate. Values represent means ± SD of each group.

^aSignificant difference (p < 0.05), compared with the corresponding unexposed mice.

^bSignificant difference (p < 0.05), compared with the pre-exposed but unimmunized control.