Key words: Autonomous parvoviruses / MVM/host range Developmental-dependent Replication of Minute Virus of Mice in Differentiated Mouse

The replication of the autonomous parvovirus, minute virus of mice (MVM), requires mitotically active cells and depends on certain factors expressed by ceils of particular differentiated phenotype. As an approach to the understanding of these helper functions, we studied the interaction of the fibrotropic [MVM(p)] and the lymphotropic [MVM(i)] strains of MVM with two differentiated cell lines from mouse testicular epithelial origins. The relative support given to viral expression by these cell lines varied extensively. Cells from Sertoli origin (TM4) were permissive to MVM(p) but were mostly restrictive to MVM(i). The other cell line, of Leydig cell origin (TM3), was highly restrictive to both viral strains, but the blocks to their growth in these cells were localized at different stages of their growth cycle, suggesting that the replication of MVM in these cells requires tissue-specific helper functions during at least two stages of viral replication. Autonomously replicating parvoviruses infect a wide spectrum of animal species ranging from mice to humans (Berns, 1984). Their limited genetic capacity, and their inability to induce cellular functions, makes them highly dependent on cellular helper functions for their ow