RNASEL and viral infectious disease: Although the antiviral activity of the OAS family and 2-5A-RNase L is well characterized,1, 2, 3 it was reported recently that not all of the OAS antiviral function is mediated by the RNase L-dependent pathway.4, 5 This indicates that the OAS family proteins may be involved in pathways for regulating viral infection other than the pathway involving RNase L activation.