Protection of Mice Against the Vaccinia Virus by the Administration of Phenoxythiouracils

Open Access
Publisher Website
Google Scholar
Abstract
Summary: Certain 5-phenoxythiouracils, although only moderately active inhibitors of vaccinia virus in chick embryonic tissue culture, have a significant protective effect in vivo. A reduction in the mortality of mice as a result of treatment could be demonstrated with the IHD strain inoculated intracerebrally and nasally and with the WR strain inoculated intracerebrally. The protective effect of therapy could be demonstrated only when treatment was begun soon after infection was initiated. Treated animals appeared to have a lower titer of virus in the brain than untreated animals. These facts suggest that these substances directly or indirectly diminish the rate of viral multiplication without, however, having a virucidal action. 5-(2′4′-Dichlorophenoxy)-4-hydroxy-2-mercaptopyrimidine was found to be the most effective compound tested. This substance protected mice against the vaccinia virus when administered parenterally or in the diet. It shows no demonstrable antibacterial activity at concentrations which inhibit growth of the vaccinia virus nor has a protective effect against other viruses been demonstrated.