Effect of Acclimatization to Altitude on Susceptibility of Mice to Influenza A Virus Infection. ∗ †

Abstract

Summary

1. Mice acclimatized to a simulated altitude of approximately 20,000 feet for 3 weeks are more resistant to artificially induced infection with the PR8 strain of influenza A virus than (a) normal control mice, (b) mice similarly exposed to altitude but given three weeks of recovery at normal atmospheric pressures prior to infection, and (c) mice made anemic by standardized hemorrhage, the latter 3 groups showing no significant difference in susceptibility. 2. Altitude acclimatized mice maintained at simulated altitude for the postinfection period are significantly more resistant than those maintained at normal atmospheric pressures. 3. There is some indication that these results are due to a metabolic disturbance which accompanies adaptation to altitude as shown by a reduction in the citric acid content of lung tissue of these animals compared to that of normal mice which reduces the animal's capacity for virus synthesis.