Establishment of persistent reovirus infection in SC1 cells: absence of protein synthesis inhibition and increased level of double-stranded RNA-activated protein kinase.

In the present study we report the establishment and characterization of an SC1 cell line persistently infected by reovirus. We observed that a significant percentage of SC1 cells was resistant to cell lysis upon infection with non-defective reovirus stocks. The apparent resistance of SC1 cells to the virus-induced inhibition of protein synthesis is probably an important factor favoring the establishment of such a persistence. The remaining cells, obtained following reovirus infection at a high multiplicity of infection, were kept as a continuous cell line and shown to have normal growth rate. They also released a high titer of virus that did not appear to differ from the original stock in neither infectivity nor genomic pattern. Electron microscopic examination further confirmed the presence of well-developed viral inclusions in the persistently infected cells. These cells were resistant to viral superinfection and exhibited a high constitutive level of the double-stranded RNA-activated protein kinase that might be involved in this resistance. We suggest that this cell line might be an interesting, and possibly more natural system than most previously used cell lines, for the continuing study of virus-host cell interactions during establishment of viral persistence using the much-studied model of reovirus infection.