Interferon lambda induces antiviral response to herpes simplex virus 1 infection

Lambda interferons (IFN-λ) are known to induce potent antiviral response in a wide variety of target cells. They activate the same intracellular signalling pathways and have similar biological activities as IFN-α/β, including antiviral activity, but signal via distinct receptor complex, which is expressed in a cell- and species-specific manner. IFN-λ was reported to induce in vitro marked antiviral activity against various RNA viruses, but corresponding data on DNA viruses are sparse. Therefore we examined the IFN-λ1 induced antiviral activity against two strains of herpes simplex virus 1, a highly pathogenic ANGpath and moderately pathogenic KOS. The antiviral response was determined in vitro in Vero cells, known as deficient in production of type I IFNs and in Vero E6 cells, responding to viral infection with abundant IFN-λ production, although deficient in production of type I IFNs. The results showed that IFN-λ1 induced in Vero cells higher antiviral activity against ANGpath strain than against KOS strain. In Vero E6 cells endogenous IFN-λ induced higher antiviral activity against ANGpath strain than against KOS strain, but because of the virus induction of IFN-λ expression the antiviral activity was detected later. The observed differences between the IFN-λ1-induced antiviral activities against viral strains of various pathogenicity suggest that virus attributes may play role in the antiviral state of cells induced by IFN-λ.