Stability of RNA sequences derived from the coronavirus genome in human cells

Most viruses inhibit the innate immune system and/or the RNA degradation processes of host cells to construct an advantageous intracellular environment for their survival. Characteristic RNA sequences within RNA virus genomes or RNAs transcribed from DNA virus genomes contribute toward this inhibition. In this study, we developed a method called "Fate-seq" to comprehensively identify the RNA sequences derived from RNA and DNA viruses, contributing RNA stability in the cells. We examined the stabilization activity of 5,924 RNA fragments derived from 26 different viruses (16 RNA viruses and 10 DNA viruses) using next-generation sequencing of these RNAs fused 3' downstream of GFP reporter RNA. With the Fate-seq approach, we detected multiple virus-derived RNA sequences that stabilized GFP reporter RNA, including sequences derived from severe acute respiratory syndrome-related coronavirus (SARS-CoV). Comparative genomic analysis revealed that these RNA sequences and their predicted secondary structures are highly conserved between SARS-CoV and the novel coronavirus, SARS-CoV-2, which is responsible for the global outbreak of the coronavirus-associated disease that emerged in December 2019 (COVID-19). These sequences have the potential to enhance the stability of viral RNA genomes, thereby augmenting viral replication efficiency and virulence.