Interaction of minute virus of mice with differentiated cells: strain-dependent target cell specificity is mediated by intracellular factors.

The prototype strain of minute virus of mice and the immunosuppressive strain are unable to grow lytically in each other's murine host cell type. To characterize these strain-dependent virus-host cell interactions further, we have compared the early events of both productive and restrictive infections. Each virus binds to specific receptors on the surface of both productive and restrictive cell types. Competition experiments show that both viruses recognize the same receptor on each cell type. Penetration and uncoating are presumed to be similar in both productive and restrictive infections, since incoming viral genomes are converted to parental replicative form DNA independent of the final outcome of the virus-host cell interaction. In contrast to the majority of other systems studied to date, these differences in minute virus of mice target cell specificity are not mediated at the cell surface, but by the interaction of a strain-specific viral determinant with intracellular host factors that are expressed in particular cell types as a function of differentiation. These cellular factors catalyze a step in viral replication which occurs after the initiation of viral DNA synthesis, but before the detectable expression of the viral capsid polypeptide genes.