Table 1. Protective efficacy of the recombinant his-tag OmpA in the mouse pulmonary infection model (data representing 16 mice from each group).

Antigena	Challengeb	#Survivors/totalc	% Protectiond	P-valuec
Recombinant his-tag OmpA	S. flexneri 2a	16/16	100	<0.001
0.9% saline	S. flexneri 2a	3e/16	0	-

^aThe protective efficacy of the recombinant his-tag OmpA was evaluated with the mouse lethal lung model. Groups of 20 mice were immunized intranasally with the recombinant his-tag OmpA or normal saline. Table showing the data for 16 mice from each group, as 4 mice from each group were sacrificed within 24 h after challenge for histopathology and cytokine assay.

^bThree weeks after the final immunization, mice were challenged with virulent S. flexneri 2a (N.Y-962/92).

^cDeaths were recorded daily for 14 days after challenge.

^d% of protection was calculated by the following formula: [(percent deaths of controls) - (percent deaths of immunized mice)]/[percent deaths of controls] ×100.

^cP values were determined by the Fisher’s exact test.

^eThree saline immunized control mice did not die after challenge.