EFFECTS OF CONTINUOUS IRRADIATION OF MICE ON THE IMMUNE RESPONSE TO LIVE LISTERIA MONOCYTOGENES VACCINE
NAVAL RADIOLOGICAL DEFENSE LAB SAN FRANCISCO CA SAN FRANCISCO United States
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Mice exposed continuously to radiation delivered at 1.0-1.5 radhour were exposed to a respiratory infection with a midlethal dose of a live avirulent strain of Listeria monocytogenes immediately after accumulating either 1700-2200 rad or 2800-3000 rads. The surviving mice were challenged two weeks later with a second aerosol containing the organism in order to determine their immune state. All of the nonirradiated mice exposed to the two aerosol infections survived while 24 of the 1700-2200 rad irradiated mice and 54 of the 2800-3000 rad groups succumbed to the second infection. If the irradiated mice were immunized with two aerosol exposures at a two week interval both the irradiated 2200 rad and the non-irradiated animals survived. Immunity following a single exposure was of short duration. If the challenge was postponed until 4 weeks after the immunizing exposure, 90 of the irradiated mice died. Clearance of L. monocytogenes from the lungs, liver and spleen was rapid in the non-irradiated immune group. By the fourth day after challenge, few organisms could be isolated. If the mice were irradiated prior to immunization, clearance was delayed. Bacteria could still be found in all organs. Large numbers of bacteria could be isolated from both groups of non-immune mice.
- Anatomy and Physiology