title: Transmissible gastroenteritis coronavirus gene 7 is not essential but influences in vivo virus replication and virulence.
abstract: Transmissible gastroenteritis coronavirus (TGEV) contains eight overlapping genes that are expressed from a 3'-coterminal nested set of leader-containing mRNAs. To facilitate the genetic manipulation of the viral genome, genes were separated by duplication of transcription regulating sequences (TRSs) and introduction of unique restriction endonuclease sites at the 5' end of each gene using an infectious cDNA clone. The recombinant TGEV (rTGEV) replicated in cell culture with similar efficiency to the wild-type virus and stably maintained the modifications introduced into the genome. In contrast, the rTGEV replication level in the lungs and gut of infected piglets and virulence were significantly reduced. rTGEV in which gene 7 expression was abrogated (rTGEV-delta7) were recovered from cDNA constructs, indicating that TGEV gene 7 was a nonessential gene for virus replication. Interestingly, in vivo infections with rTGEV-delta7 showed an additional reduction in virus replication in the lung and gut, and in virulence, indicating that TGEV gene 7 influences virus pathogenesis.
authors.affiliation: Centro Nacional de Biotecnología, CSIC, Department of Molecular and Cell Biology, Campus Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Ortego
authors.forename: Isabel
authors.initials: I
authors.lastname: Sola
authors.forename: Fernando
authors.initials: F
authors.lastname: Almazán
authors.forename: Juan E
authors.initials: JE
authors.lastname: Ceriani
authors.forename: Cristina
authors.initials: C
authors.lastname: Riquelme
authors.forename: Monica
authors.initials: M
authors.lastname: Balasch
authors.forename: Juan
authors.initials: J
authors.lastname: Plana
authors.forename: Luis
authors.initials: L
authors.lastname: Enjuanes
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002460:Cell Line; D006224:Cricetinae; D005761:Gastroenteritis, Transmissible, of Swine / Q000821:virology*; D005814:Genes, Viral / Q000502:physiology*; D007422:Intestines / Q000821:virology; D008168:Lung / Q000821:virology; D016254:Mutagenesis, Insertional; D011995:Recombination, Genetic; D013552:Swine; D005760:Transmissible gastroenteritis virus / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D014774:Virulence / Q000235:genetics; D014779:Virus Replication