Heterogeneity in evolutive patterns of inbred mice infected with a cloned substrain of mouse hepatitis virus type 3.

F1 hybrid mice, resulting from a cross between a susceptible and a resistant parent, were infected with a cloned substrain of mouse hepatitis virus type 3 (MHV3). Results showed various evolutive patterns ranging from fulminant hepatitis to persistent infection and excluded virus variation as an explanation for different disease types. Since host resistance to MHV3 has been previously shown to be under the genetic influence of 1 or 2 genes only rather than a polygenic phenomenon, these results strongly suggest that nongenetic factors play a major role in the determination of evolutive patterns.