Dietary stress and development of resistance ot Listeria monocytogenes in mice.

The native and acquired cell-mediated immune resistance against Listeria monocytogenes steadily developed in young mice after weaning and reached maximum activity at 6 and 12 weeks of age, respectively. Mice fed a high fat (20% corn oil) diet from 3 weeks of age had a significantly more rapid development of resistance against L. monocytogenes. Mice fed the high fat diet beginning at 6 and 12 weeks of age had significantly lower native preimmune resistance against L. monocytogenes after 3 weeks on the diet. On the other hand, 3-week-old mice fed a low protein (4% casein) diet had a significantly retarded development of native and acquired resistance against L. monocytogenes. However, mice consuming the low protein diet at 6, 12 or 24 weeks of age did not exhibit an impairment in this resistance. Therefore age at which the dietary stress, either low protein or high fat, was initiated had an important effect on native and acquired resistance of mice against L. monocytogenes.