Susceptibility of Hamsters to Peripherally Inoculated Japanese B and St. Louis Viruses Following Cortisone,X-Ray,Trauma. ∗

Abstract

Summary

1) Brain irritation and intraperitoneal glycerin were tried to enhance susceptibility of hamsters to subcutaneous inoculation of JBE virus. Both of these methods have a slight enhansive effect, but not of the degree desired for the purposes of this study. 2) A total dose of 0.2 mg cortisone/g body weight, when given to hamsters as described, rendered them highly susceptible to subcutaneous inoculation of JBE virus and to only a slightly less degree to SLE virus. 3) It was found that a dose of 450 r of X-ray detectably increased susceptibility of hamsters to subcutaneous inoculation of JBE virus. This was the maximum dose of X-ray tolerated, and increase in susceptibility observed was less marked than with cortisone. 4) Combined treatment of hamsters with the maximum tolerated combined doses of X-ray and cortisone (150 r of X-ray and 0.15 mg cortisone) rendered them much more highly susceptible than X-ray alone; however, the combination tested was not as effective as cortisone alone in a subtoxic dose. Cortisone at a dosage of 0.2 mg/g body weight was adopted as a standard procedure for subsequent work. The increase in susceptibility to JBE virus was in excess of 100,000 fold, rendering the animals almost as susceptible to peripheral inoculation as to intracerebral.