Expression of NADPH oxidase-dependent resistance to listeriosis in mice occurs during the first 6 to 12 hours of liver infection

Abstract

Wild-type mice inoculated with Listeria monocytogenes intravenously were capable of reducing the bacterial load in their livers by 90% within 6 h. In contrast, mice with deletions of the gene for NADPH oxidase were incapable of expressing this early oxygen-dependent anti-Listeria defense and consequently showed higher levels of liver infection at later times.

FIG. 1.

Growth of an inoculum of 2 × 10³ CFU of L. monocytogenes, given i.v., in the livers and spleens of WT and phox^−/− mice over 48 h of infection. The bacterial load in the liver was reduced by approximately 1 log (P = 0.001, according to Student's t test) during the first 6 h in the livers of WT mice but not in the livers of phox^−/− mice. There was no immediate reduction in bacterial number in the spleens of mice of either type. Values are means ± standard deviations for five mice.

FIG. 2.

Growth of inocula of 8 × 10³ and 8 × 10⁴ CFU of L. monocytogenes in the livers and spleens of WT and phox^−/− mice, showing an increased level of infection in the liver, but not in the spleen, at 12 h of infection. Values are means ± standard deviations for five mice.