title: Coronavirus subgenomic minus-strand RNAs and the potential for mRNA replicons.
abstract: The genome of the porcine transmissible gastroenteritis coronavirus is a plus-strand, polyadenylylated, infectious RNA molecule of approximately 20 kilobases. During virus replication, seven subgenomic mRNAs are generated by what is thought to be a leader-priming mechanism to form a 3'-coterminal nested set. By using radiolabeled, strand-specific, synthetic oligodeoxynucleotide probes in RNA blot hybridization analyses, we have found a minus-strand counterpart for the genome and for each subgenomic mRNA species in the cytoplasm of infected cells. Subgenomic minus strands were found to be components of double-stranded replicative forms and in numbers that surpass full-length antigenome. We propose that subgenomic mRNA replication, in addition to leader-primed transcription, is a significant mechanism of mRNA synthesis and that it functions to amplify mRNAs. It is a mechanism of amplification that has not been described for any other group of RNA viruses. Subgenomic replicons may also function in a manner similar to genomes of defective interfering viruses to lead to the establishment of persistent infections, a universal property of coronaviruses.
authors.affiliation: Department of Microbiology, Univeristy of Tennessee, Knoxville 37996-0845.
authors.forename: P B
authors.initials: PB
authors.lastname: Sethna
authors.forename: S L
authors.initials: SL
authors.lastname: Hung
authors.forename: D A
authors.initials: DA
authors.lastname: Brian
mesh_terms: D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D003332:Coronaviridae / Q000235:genetics*; D005814:Genes, Viral; D007700:Kinetics; D008297:Male; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics*; D012367:RNA, Viral / Q000096:biosynthesis / Q000235:genetics*; D012093:Replicon; D013552:Swine; D013737:Testis / Q000166:cytology; D005760:Transmissible gastroenteritis virus / Q000235:genetics*
chemical_list: D015345:Oligonucleotide Probes; D012333:RNA, Messenger; D012367:RNA, Viral