title: Determination of spontaneous mutation frequencies in measles virus under nonselective conditions.
abstract: There is a paradox between the remarkable genetic stability of measles virus (MV) in the field and the high mutation rates implied by the frequency of the appearance of monoclonal antibody escape mutants generated when the virus is pressured to revert in vitro (S. J. Schrag, P. A. Rota, and W. J. Bellini, J. Virol. 73:51-54, 1999). We established a highly sensitive assay to determine frequencies of various categories of mutations in large populations of wild-type and laboratory-adapted MVs using recombinant viruses containing an additional transcription unit (ATU) encoding enhanced green fluorescent protein (EGFP). Single and double mutations were made in the fluorophore of EGFP to ablate fluorescence. The frequencies of reversion mutants in the population were determined by measuring the appearance of fluorescence indicating a revertant virus. This allows mutation rates to be measured under nonselective conditions, as phenotypic reversion to fluorescence requires only either a single- or a double-nucleotide change and amino acid substitution, which does not affect the length of the nonessential reporter protein expressed from the ATU. Mutation rates in MV are the same for wild-type and laboratory-adapted viruses, and they are an order of magnitude lower than the previous measurement assessed under selective conditions. The actual mutation rate for MV is approximately 1.8 × 10(-6) per base per replication event.
authors.affiliation: Centre for Infection and Immunity, School of Medicine, Dentistry and Biomedical Sciences, Queen's University of Belfast, Belfast, United Kingdom.
authors.forename: Xiaomeng
authors.initials: X
authors.lastname: Zhang
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Rennick
authors.forename: W Paul
authors.initials: WP
authors.lastname: Duprex
authors.forename: Bert K
authors.initials: BK
authors.lastname: Rima
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D002522:Chlorocebus aethiops; D014644:Genetic Variation; D049452:Green Fluorescent Proteins / Q000235:genetics; D008459:Measles virus / Q000235:genetics*; D009154:Mutation; D059645:Mutation Rate; D011956:Receptors, Cell Surface / Q000378:metabolism; D000071177:Signaling Lymphocytic Activation Molecule Family Member 1; D014709:Vero Cells; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics; D014779:Virus Replication
chemical_list: D015703:Antigens, CD; D011956:Receptors, Cell Surface; D014764:Viral Proteins; D049452:Green Fluorescent Proteins; D000071177:Signaling Lymphocytic Activation Molecule Family Member 1