Delay of Fatal Pneumonia in X-Irradiated Mice Inoculated with Mouse-Adapted Influenza Virus, PR8 Strain

Adult male albino mice were infected by intranasal and airborne routes with highly adapted Type A influenza virus, PR8 strain, one day after whole-body X-irradiation. Graded amounts of X-rays had little effect, if any, on susceptibility to this virus as measured by infectivity and mortality. However, pretreatment with 350 R reduced the frequency of early deaths due to influenzal pneumonia but did not prevent later deaths. The findings demonstrate that the number of days to death in irradiated mice inoculated with influenza virus is independent of the mortality rate and should not be ignored in evaluating radiation effects in infectious processes.