Transmission of viral persistence by transfection of human cultured cells with RNA of a persistent strain of echovirus 6.

A cloned line of persistently infected (PI) human cells has been established with a strain of the normally lytic, echovirus 6. All of the cells contained non-lytic viral RNA and synthesized defective viral particles. The present study was undertaken to determine whether replication of non-lytic viral RNA occurred after transfection. Uninfected human WISH cells were transfected with viral RNA recovered either directly from persistently infected PI cells or from virus particles produced by PI cells. Cytoplasmic extracts were prepared at various times after transfection and examined for presence of viral RNA and protein. The viral RNA was detected by hybridization of Northern blots of cellular RNA extracts with a cDNA clone of wild-type, lytic echovirus 6. Viral proteins were isolated by immunoprecipitation with specific anti-viral serum and analysed by polyacrylamide gel electrophoresis. Increased concentrations of viral RNA were detectable in cellular extracts at 48 h after transfection. Replicate transfected cultures retained viral RNA and produced viral proteins after cultivation for 287 days. RNA extracts from the transfected cells did not produce cytopathology or lytic virus. Thus, conversion of uninfected cells into a persistently infected cell line was accomplished by transfection with the non-lytic genome of echovirus 6.