TABLE 1.

Efficacy of immunization with various soluble immunogens

Immunogen	Challenge strain	Challenge routea	Challenge dose (CFU)	No. of protected rabbits/total no. challenged	Corresponding figure
PA	Vollum	s.c.	2 × 103	4/4	2
	Vollum	i.v.	7 × 106	1/5	2
	Vollum Δpag Δlef Δcya	i.v.	1 × 107	0/6	2
TF-SPF	Vollum Δpag Δlef Δcya	i.v.	1.3 × 107	4/4	3
	Vollum	i.v.	1.1 × 107	0/4	3
PA+TF-SPF	Vollum	i.v.	1.4 × 107	4/4	NAb

^aThe s.c. challenge was carried out with spores, while for the i.v. challenge, vegetative cells were used.

^bNA, not applicable.