Figure 7.

Open-loop lethality generates an antiviral effect against SARS-CoV-2

(A) Schematic of the putative SARS-CoV-2 transcriptional negative-feedback circuit. Nsp15 proteins, which are transcribed from a sub-genomic RNA, cleave genomic RNAs (gRNAs) at the transcriptional regulatory sequences (TRS), thereby suppressing genomic and sub-genomic RNA levels. Feedback can be disrupted by supplying excess TRS encoding RNAs (FD^TRS) as decoys to titrate nsp15, thereby leading to the accumulation of genomic RNAs and increased synthesis of non-structural, structural, and accessory proteins, including cytotoxic viral proteins above cytotoxic levels.

(B) Vero cells were nucleofected with 25 μM FD^TRS or FD^Scram, followed by infection with SARS-CoV-2 (WA-1 strain, MOI = 0.05) and quantification of nsp15, ORF1a, and Spike RNA by qRT-PCR within the first round of replication (i.e., 8 hpi).

(C) Apoptosis analysis at 12 hpi by qRT-PCR for annexin V.

(D) Apoptosis analysis at 48 hpi by TUNEL assay.

(E) Virus titer for SARS-CoV-2 after treatment with either FD^TRS or FD^Scram. p values derived from Student’s t test: ^∗<0.05, ^∗∗<0.01, ^∗∗∗<0.001.

See also Figure S7.