Activity of polymerase proteins of vaccine and wild-type measles virus strains in a minigenome replication assay.
The relative activities of five measles virus (MV) polymerase (L) proteins were compared in an intracellular, plasmid-based replication assay. When coexpressed with N and P proteins from an attenuated strain, L proteins from two attenuated viruses directed the production of up to eight times more reporter protein from an MV minigenome than the three wild-type L proteins. Northern blot analysis demonstrated that the differences in reporter protein production correlated with mRNA transcription levels. Increased activity of polymerases from attenuated viruses equally affected mRNA transcription and minigenome replication. The higher level of transcription may be a consequence of increased template availability or may be an independent effect of the elevated activity of the attenuated polymerases. Coexpression of wild-type L proteins with homologous N and P proteins did not affect the activity of the wild-type polymerases, indicating that the differential activity was a function of the L proteins alone. Use of a minigenome that incorporated two nucleotide changes found in the genomic leader of the three wild-type viruses did not raise the activity of the wild-type L proteins. These data demonstrate that increased polymerase activity differentiates attenuated from wild-type viruses and suggest that functions involved in RNA synthesis contribute to the attenuated phenotype of MV vaccine strains.
Bankamp
Bettina
B
Respiratory and Enteric Viruses Branch, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
Kearney
Sean P
SP
Liu
Xin
X
Bellini
William J
WJ
Rota
Paul A
PA
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002642:Chick Embryo; D002522:Chlorocebus aethiops; D016679:Genome, Viral; D008458:Measles Vaccine; D008459:Measles virus / Q000201:enzymology* / Q000472:pathogenicity; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism; D012324:RNA-Dependent RNA Polymerase / Q000378:metabolism*; D014158:Transcription, Genetic; D014709:Vero Cells; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
D008458:Measles Vaccine; C055859:P protein, Sendai virus; D010750:Phosphoproteins; D012367:RNA, Viral; D014764:Viral Proteins; D012324:RNA-Dependent RNA Polymerase