Rubella virus RNA replication is cis-preferential and synthesis of negative- and positive-strand RNAs is regulated by the processing of nonstructural protein.
Rubella virus (RV) genome encodes nonstructural protein (NSP) in a large open reading frame at its 5' end. It is translated into p200 and further processed into p150 and p90. The NSPs are responsible for viral RNA replication, during which a full-length negative-strand RNA serves as the intermediate for the replication of positive-strand genomic RNA and the transcription of subgenomic RNA. Using complementation experiments, we demonstrated that RV negative-strand RNA is synthesized preferentially in cis while positive-strand RNAs can be synthesized both in cis and in trans but with higher efficiency in cis. During virus infection, negative-strand RNA accumulates until 10 hours postinfection (hpi) and remains nearly constant thereafter. In contrast, positive-strand RNAs (both genomic and subgenomic RNA) do not increase much before 10 hpi and accumulate rapidly thereafter. Previously we demonstrated that p200 synthesizes negative- but not positive-strand RNA, whereas cleavage products p150/p90 are required for efficient production of positive-strand RNAs. In this study, we present evidence demonstrating that a higher concentration of p150/p90 is associated with lower production of negative-strand RNA. Our data support the hypothesis that p200 is the principal replicase for negative-strand RNA, as is p150/p90 for positive-strand RNA. The switch from the synthesis of negative- to positive-strand RNA is thus regulated by NSP processing, which not only activates the efficient production of positive-strand RNA, but also disables negative-strand RNA synthesis. A mechanism for NSP translation, processing, and regulation of RV RNA synthesis is proposed.
Liang
Y
Y
Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, V5Z 4H4, Canada.
Gillam
S
S
D000818:Animals; D002460:Cell Line; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003673:Defective Viruses / Q000235:genetics / Q000502:physiology; D016679:Genome, Viral; D006378:Helper Viruses / Q000235:genetics / Q000502:physiology; D008954:Models, Biological; D008970:Molecular Weight; D009154:Mutation / Q000235:genetics; D023282:Nuclease Protection Assays; D016366:Open Reading Frames / Q000235:genetics; D014176:Protein Biosynthesis; D011499:Protein Processing, Post-Translational; D012367:RNA, Viral / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D012412:Rubella virus / Q000235:genetics / Q000502:physiology*; D013997:Time Factors; D014709:Vero Cells; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000378:metabolism*; D014779:Virus Replication
D012367:RNA, Viral; D017361:Viral Nonstructural Proteins