Contribution of host an viral small non-coding RNAs to SARS-CoV lung pathology

Severe acute respiratory syndrome coronavirus (SARS-CoV) causes lethal disease in humans, with viral E protein promoting the exacerbated inflammatory response. By deep sequencing RNAs from the lungs of infected mice, we have addressed the relevance of small, non-coding RNAs in SARS-CoV pathology. Host microRNAs (miRNAs) expressed during infection by a virulent virus encoding the E protein were significantly enriched for cytokine-mediated inflammatory pathways when compared with attenuated SARS-CoV-?E, suggesting contribution of miRNAs to E protein-induced inflammation. The discovery of three 18-22 nt small viral RNAs (svRNAs) derived from the nsp3 and N genomic regions of SARS-CoV in mouse lung and cell cultures is also described. Depletion of these svRNAs significantly reduced viral titers and genomic RNA levels, indicating their positive contribution to virus growth. Remarkably, svRNA-N antagomirs significantly reduced in vivo lung pathology and pro-inflammatory cytokine expression, indicating that svRNAs contribute to SARS-CoV pathogenesis and highlighting the potential of these antagomirs as antivirals. Overall design: Strand-specific, single-end, reads were generated for detecting smallRNAs (18 nts or more) in lungs (mouse). Three or four replicates were prepared per sample type.