Non-canonical proteolytic activation of RNase L by SARS-CoV-2 3CLpro offsets inactivation of OAS1 antiviral signaling

A non-cleavable RNase L (Gln409Ala) mutant lacks antiviral activity in p46-null cells, confirming this non-canonical activation mechanism. RNA-seq revealed that the proteolytically activated RNase exhibits altered specificity toward cellular mRNA targets and that 3CL pro indirectly suppresses OAS3 transcripts without directly cleaving OAS3. We propose that the conserved 3CL pro -sensitive motif in RNase L functions as a failsafe tripwire that constrains complete loss of antiviral restriction despite simultaneous evasion of OAS1 p46.

Thus, SARS-CoV-2 replication dynamics are intrinsically balanced by viral proteolysis within the OAS–RNase L axis, sufficient for polyprotein processing but countered by protease-triggered activation of RNase L and downstream antiviral restriction.