TABLE 1.

Survival of naïve and immunized A/J and C57B1/6 mice following inoculation of L. monocytogenes Scott A

Mouse type	Challenge dose (CFU)	No. of deaths/no. inoculated
		A/J mice	C57B1/6 mice
Naïvea	109	NT	4/6
	108	NT	4/6
	107	6/6	1/6
	106	2/6	NT
	105	1/6	NT
Immunizedb	1010	NT	2/7
	108	2/8	NT

^aNaïve mice were anesthetized with sodium pentobarbital and inoculated i.g. with the indicated dose of L. monocytogenes Scott A. Deaths were recorded for a 10-day period after challenge.

^bMice that survived the experimental infection were challenged i.g. 2 weeks later with the indicated dose of L. monocytogenes Scott A, and deaths were recorded for a 7-day period.