A study was made of the pathogenesis of infection due to the Conn.-5 strain of Coxsackie virus in 4 to 5 day old infant mice, untreated adult mice, and adult mice treated with cortisone. The quantitative distribution of virus and the evolution of lesions in different tissues were followed for the first 7 days of the infection. Virus dissemination was prompt and widespread via the blood in all groups. In 4 to 5 day old infant mice viral multiplication and cellular injury occurred in many organs and tissues, while in untreated adult mice these processes were largely limited to the pancreas, even though infecting virus appeared to be equally available to other tissues from the blood. Treatment of adult mice with a single injection of 2.5 mg. cortisone resulted in viral multiplication and tissue damage in several sites in addition to the pancreas, the most marked occurring in the liver and heart.
In a consideration of possible mechanisms involved, it was thought unlikely that the differences in the course of the disease in the three groups could be attributed solely to differences in the specific immune response. It is suggested that developmental changes in cells and tissues, perhaps related to cellular metabolism and alterable by cortisone administration, are the major factors determining the location and extent of viral multiplication and tissue injury in this infection in mice.