title: Mouse hepatitis virus S RNA sequence reveals that nonstructural proteins ns4 and ns5a are not essential for murine coronavirus replication.
abstract: Genes 4 and 5 of mouse hepatitis virus (MHV) are known to encode nonstructural proteins ns4, ns5a, and ns5b, whose function is unknown. In this study, we demonstrated that one of the MHV strains, MHV-S, did not synthesize mRNA 4 and made a smaller mRNA 5. Sequence analysis showed that the transcription initiation site for gene 4 of MHV-S was mutated from the consensus UCUAAAC to UUUAAAC, consistent with the idea that mutations in this region abolish mRNA synthesis. Furthermore, within gene 5 there were deletions totaling 307 nucleotides which deleted almost all of open reading frame 5a, but preserved open reading frame 5b of gene 5. Comparison of the growth of MHV-S with other MHV strains in DBT cells revealed no significant growth defect in MHV-S. These results suggest that ns4 and ns5a are not essential for viral replication in tissue culture cells, and thus join gene 2 and the hemagglutinin-esterase (HE) gene as nonessential viral genes in MHV.
authors.affiliation: Howard Hughes Medical Institute, University of Southern California School of Medicine, Los Angeles 90033-1054.
authors.forename: K
authors.initials: K
authors.lastname: Yokomori
authors.forename: M M
authors.initials: MM
authors.lastname: Lai
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002213:Capsid / Q000235:genetics* / Q000502:physiology; D002460:Cell Line; D002872:Chromosome Deletion; D003332:Coronaviridae / Q000235:genetics* / Q000502:physiology; D051379:Mice; D008969:Molecular Sequence Data; D006517:Murine hepatitis virus / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*; D012367:RNA, Viral / Q000235:genetics*; D014758:Viral Core Proteins / Q000235:genetics* / Q000502:physiology; D017361:Viral Nonstructural Proteins; D014779:Virus Replication / Q000235:genetics*
chemical_list: D012333:RNA, Messenger; D012367:RNA, Viral; D014758:Viral Core Proteins; D017361:Viral Nonstructural Proteins