TABLE 1.

Effect of age on anti-PT IgG antibody response following primary immunization

Age (days) of mice at immunization	Vaccine	Type of challenged	Levele of anti-PT IgG in serum (μg/ml) on day of life:
			18a	25b
5	PTxc	0.5 μg of PT	0.3	3.3
	PTx	Saline	0.7	8.1
	AlPO4	0.5 μg of PT	0.3	0.5
7	PTx	0.5 μg of PT	0.6	5.4
	PTx	Saline	0.4	6.4
	AlPO4	0.5 μg of PT	0.4	0.7
9	PTx	0.5 μg of PT	0.3	4.7
	PTx	Saline	0.4	5.3
	AlPO4	0.5 μg of PT	0.2	0.4

^aNo statistical difference between any of the groups (P > 0.05).

^bApproximately 10-fold rise in antibody for all PTx-immunized groups (P < 0.05).

^cTNM-inactivated PTx vaccine.

^dOn day 18 of life.

^eGeometric mean.