Table 2.

Survival, mean time-to-death (MTD), and serological response of mice vaccinated simultaneously with rPA plus recombinant spore protein and challenged s.c.

Group	Immunization		Survival^a	MTD	Mean anti-PA response (OD₄₅₀)^b	Mean anti-spore protein response (OD₄₅₀)^c
	Day 1	Day 15
1	PBS	PBS	0/5	4.2	0.07	N/A
2	PBS	PA (50 ng)	2/5	8.0	1.29^*	N/A
3	CotZ1 (10 μg)	PA (50 ng) + CotZ1 (10 μg)	0/5	4.5	0.31	1.12
4	BxpB (10 μg)	PA (50 ng) + BxpB (10 μg)	0/5	5.3	0.11	2.65
5	SOD15 (10 μg)	PA (50 ng) + SOD15 (10 μg)	0/5	5.2	0.15	2.88
6	p2366 (10 μg)	PA (50 ng) + p2366 (10 μg)	0/5	4.6	0.24	0.18
7	p3957 (10 μg)	PA (50 ng) + p3957 (10 μg)	0/5	4.0	0.13	0.58
8	SODA1 (10 μg)	PA (50 ng) + SODA1 (10 μg)	0/5	4.8	0.30	3.10
9	YwdL (10 μg)	PA (50 ng) + YwdL (10 μg)	0/5	4.6	0.20	3.05
10	p5303 (10 μg)	PA (50 ng) + p5303 (10 μg)	0/5	5.8	0.19	2.94

Mice were challenged on Day 28 with 10 LD₅₀s Sterne spores. The 50% lethal dose of Sterne strain is approximately 1.13 × 10³ spores.

Optical density measurement at 450 nm for a 1:300 antiserum dilution. OD₄₅₀ for positive control (monoclonal anti-PA antibody) was 1.68. OD₄₅₀ for negative control (NRS) was 0.04.

Optical density measurement at 450 nm for a 1:200 antiserum dilution. OD₄₅₀ for positive controls (polyclonal anti-spore protein IgGs) ranged from 3.23 to 3.43. OD₄₅₀ for negative control (NRS) was 0.04.

P ≤ 0.002 compared to all other groups.