Multiple novel non-canonically transcribed sub-genomic mRNAs produced by avian coronavirus infectious bronchitis virus

Keep, Sarah, Oade, Michael S., Lidzbarski-Silvestre, Filip, Bentley, Kirsten ORCID: https://orcid.org/0000-0002-6619-2098, Stevenson-Leggett, Phoebe, Freimanis, Graham L., Tennakoon, Chandana, Sanderson, Nicholas, Hammond, John A., Jones, Richard C., Britton, Paul and Bickerton, Erica 2020. Multiple novel non-canonically transcribed sub-genomic mRNAs produced by avian coronavirus infectious bronchitis virus. Journal of General Virology 101 (10) , pp. 1103-1118. 10.1099/jgv.0.001474

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Abstract

Coronavirus sub-genomic mRNA (sgmRNA) synthesis occurs via a process of discontinuous transcription involving complementary transcription regulatory sequences (TRSs), one (TRS-L) encompassing the leader sequence of the 5′ untranslated region (UTR), and the other upstream of each structural and accessory gene (TRS-B). Several coronaviruses have an ORF located between the N gene and the 3′-UTR, an area previously thought to be non-coding in the Gammacoronavirus infectious bronchitis virus (IBV) due to a lack of a canonical TRS-B. Here, we identify a non-canonical TRS-B allowing for a novel sgmRNA relating to this ORF to be produced in several strains of IBV: Beaudette, CR88, H120, D1466, Italy-02 and QX. Interestingly, the potential protein produced by this ORF is prematurely truncated in the Beaudette strain. A single nucleotide deletion was made in the Beaudette strain allowing for the generation of a recombinant IBV (rIBV) that had the potential to express a full-length protein. Assessment of this rIBV in vitro demonstrated that restoration of the full-length potential protein had no effect on viral replication. Further assessment of the Beaudette-derived RNA identified a second non-canonically transcribed sgmRNA located within gene 2. Deep sequencing analysis of allantoic fluid from Beaudette-infected embryonated eggs confirmed the presence of both the newly identified non-canonically transcribed sgmRNAs and highlighted the potential for further yet unidentified sgmRNAs. This HiSeq data, alongside the confirmation of non-canonically transcribed sgmRNAs, indicates the potential of the coronavirus genome to encode a larger repertoire of genes than has currently been identified.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Medicine
Publisher:	Microbiology Society
ISSN:	0022-1317
Date of First Compliant Deposit:	24 February 2021
Date of Acceptance:	1 July 2020
Last Modified:	04 May 2023 07:33
URI:	https://orca.cardiff.ac.uk/id/eprint/138932

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