Constitutive expression of (2′–5′) oligo A synthetase confers resistance to picornavirus infection

Abstract

Study of the mechanisms by which interferon (IFN) treatment of cells induces resistance to virus infections has been complicated by the multiple biochemical changes induced. Over 20 proteins are increased by IFN, including the double-stranded (ds) RNA-activated protein kinase, (2'–5') oligo A synthetase, surface proteins such as the major histocompatibility complex (MHC) proteins, and various proteins with unknown functions1–3. The availability of cloned complementary DNAs for several IFN-induced proteins3–8 now allows us to probe their roles in IFN action. For instance, the murine MX protein has been shown to confer resistance to influenza virus7. We studied Chinese hamster ovary (CHO) cell clones expressing high constitutive levels of (2'–5') A synthetase as a result of transfection with the cDNA encoding the enzyme form8 which has a relative molecular mass (M r) of 40K. Elevated enzyme correlates directly with resistance to infection by a picornavirus such as Mengo, but does not make the cells resistant to vesicular stomatitis virus (VSV).