TABLE 2.

Total IgG anti-PA and antispore antibody responses to either PA-FIS or PA alone in the sera from immunized mice and guinea pigs^a

Animal model	Antigen(s)	Immunization protocol	No. of animals	Anti-PA antibody titer				Antispore antibody titer
				ELISA		TNAb
				Median ± SD	P	Median ± SD	P	Median ± SD	P
Mouse	PA+FIS	(s.c.+i.n.)×3	24	17.85 ± 1.07		14.75 ± 1.04		14.03 ± 1.23
	PA	(s.c.+i.n.)×3	4	18.08 ± 0.44	NS	15.08 ± 0.27	NS
	PA+FIS	i.n.×2	4	16.40 ± 1.10	0.0186*	12.79 ± 0.54	0.0012†	13.23 ± 0.78	NS
	PA+FIS	i.n.×3	8	16.86 ± 1.92	NS	13.66 ± 0.99	0.0148*	13.40 ± 1.43	NS
	PA+FIS	s.c.×2	12	17.95 ± 1.10	NS	11.64 ± 1.75	0.0001‡	13.10 ± 1.45	NS
Guinea pig	PA+FIS	(s.c.+i.n.)×3	7	18.76 ± 0.10		14.31 ± 0.45		16.14 ± 0.49
	PA	(s.c.+i.n.)×3	2	17.43 ± 1.49	0.0224*	13.24 ± 0.19	0.0160*
	PA+FIS	i.n.×3	4	15.83 ± 0.86	0.0001‡	10.61 ± 0.74	0.0001‡	11.02 ± 0.59	0.0001‡
	PA+FIS	s.c.×2	6	18.65 ± 1.12	NS	14.16 ± 1.35	NS	14.31 ± 0.36	0.0001‡

^aIn each column of values (ELISA anti-PA, anti-PA-TNA, and ELISA antispore), an unpaired Student t test (5%, two-tailed P value) was used to compare the medians obtained with each of the protocols (rows) to the median of PA-FIS [(s.c.+i.n.)×3] in the same column. A P value of ≤0.05 was considered to indicate a statistically significant difference between the means. According to the P value, the difference was significant (*), very significant (†), extremely significant (‡), or not significant (NS). Median ± SD values are log₂ ± the standard deviation. Antibody titers were measured in the sera from immunized animals as described in Materials and Methods.

^bTNA, lethal TNA titer.