Localization of the Restrictive Event of EMC Virus Replication in Semi-permissive Monkey and Monkey-Mouse Hybrid Cells

Encephalomyocarditis (EMC) virus replication was investigated in permissive mouse MKS cells, semi-permissive monkey CV₁ cells, and in somatic monkey-mouse MKCV_III hybrid cells whose permissiveness is under the negative control of the simian genome. We found that in CV₁ cells the synthesis of both single- and double-stranded virus RNAs was restricted. In contrast, in semi-permissive hybrid Cl_4/3 cells only the single-stranded virus RNA was synthesized in small amounts, whereas the double-stranded virus RNA accumulated late after infection. The synthesis of virus polyribosomes and virus polypeptides was lowered in semi-permissive conditions. In the presence of quaternary ammonium ions, the synthesis of EMC virus was partially relieved in CV₁ cells. Thus, it can be postulated that a defective function in the replication complex is involved in the restrictive event.