Nonreplicative RNA Recombination of an Animal Plus-Strand RNA Virus in the Absence of Efficient Translation of Viral Proteins.
RNA recombination is a major driving force for the evolution of RNA viruses and is significantly implicated in the adaptation of viruses to new hosts, changes of virulence, as well as in the emergence of new viruses including drug-resistant and escape mutants. However, the molecular details of recombination in animal RNA viruses are only poorly understood. In order to determine whether viral RNA recombination depends on translation of viral proteins, a nonreplicative recombination system was established which is based on cotransfection of cells with synthetic bovine viral diarrhea virus (family Flaviviridae) RNA genome fragments either lacking the internal ribosome entry site required for cap-independent translation or lacking almost the complete polyprotein coding region. The emergence of a number of recombinant viruses demonstrated that IRES-mediated translation of viral proteins is dispensable for efficient recombination and suggests that RNA recombination can occur in the absence of viral proteins. Analyses of 58 independently emerged viruses led to the detection of recombinant genomes with duplications, deletions and insertions in the 5' terminal region of the open reading frame, leading to enlarged core fusion proteins detectable by Western blot analysis. This demonstrates a remarkable flexibility of the pestivirus core protein. Further experiments with capped and uncapped genome fragments containing a luciferase gene for monitoring the level of protein translation revealed that even a ∼1,000-fold enhancement of translation of viral proteins did not increase the frequency of RNA recombination. Taken together, this study highlights that nonreplicative RNA recombination does not require translation of viral proteins.
Department of Infectious Diseases, Institute of Virology, University of Veterinary Medicine Hannover, Germany.
Maximiliane
M
Kleine Büning
Department of Infectious Diseases, Institute of Virology, University of Veterinary Medicine Hannover, Germany.
Denise
D
Meyer
Department of Infectious Diseases, Institute of Virology, University of Veterinary Medicine Hannover, Germany.
Sophia
S
Austermann-Busch
Institut Pasteur, Unit of Structural Virology, Paris, France.
Gleyder
G
Roman-Sosa
Department of Pathobiology, Institute of Virology, University of Veterinary Medicine Vienna, Austria.
Tillmann
T
Rümenapf
Department of Infectious Diseases, Institute of Virology, University of Veterinary Medicine Hannover, Germany.
Paul
P
Becher
D000818:Animals; D002417:Cattle; D001908:Diarrhea Viruses, Bovine Viral / Q000235:genetics* / Q000472:pathogenicity; D016679:Genome, Viral; D016366:Open Reading Frames; D014176:Protein Biosynthesis; D012328:RNA Viruses / Q000235:genetics*; D012367:RNA, Viral / Q000235:genetics; D011995:Recombination, Genetic; D012270:Ribosomes / Q000235:genetics; D014764:Viral Proteins / Q000096:biosynthesis / Q000235:genetics*; D014779:Virus Replication / Q000235:genetics
D012367:RNA, Viral; D014764:Viral Proteins
Bovine Viral Diarrhea Virus; Flaviviridae; nonhomologous; nonreplicative RNA recombination; virus evolution