Effect of Estrogen and Other Steroids on MM Virus Infection in Mice

The effect of several steroid hormones on the susceptibility of mice to infection with MM virus was studied. Estrone, cortisone, and hydrocortisone increased mortality, whereas progesterone, prednisolone, and testosterone had no effect. The viral infection-enhancing (VIE) activity of estrone was maximal when the hormone was given 24 to 72 hr prior to viral inoculation. Less VIE activity was seen when the estrone was administered at the same time as the virus, and hormone treatment 24 hr after inoculation had no significant effect on mortality. Virus was found in the blood 24 hr before it appeared in the brain, regardless of estrone treatment. However, viremia was demonstrated in estrone-treated mice 48 hr before it occurred in control animals. There was no significant difference in the respective titers reached in the sera or the brains of the two groups.