title: Species-independent bioassay for sensitive quantification of antiviral type I interferons.
abstract: BACKGROUND
  Studies of the host response to infection often require quantitative measurement of the antiviral type I interferons (IFN-alpha/beta) in biological samples. The amount of IFN is either determined via its ability to suppress a sensitive indicator virus, by an IFN-responding reporter cell line, or by ELISA. These assays however are either time-consuming and lack convenient readouts, or they are rather insensitive and restricted to IFN from a particular host species.
  
  
  RESULTS
  An IFN-sensitive, Renilla luciferase-expressing Rift Valley fever virus (RVFV-Ren) was generated using reverse genetics. Human, murine and avian cells were tested for their susceptibility to RVFV-Ren after treatment with species-specific IFNs. RVFV-Ren was able to infect cells of all three species, and IFN-mediated inhibition of viral reporter activity occurred in a dose-dependent manner. The sensitivity limit was found to be 1 U/ml IFN, and comparison with a standard curve allowed to determine the activity of an unknown sample.
  
  
  CONCLUSIONS
  RVFV-Ren replicates in cells of several species and is highly sensitive to pre-treatment with IFN. These properties allowed the development of a rapid, sensitive, and species-independent antiviral assay with a convenient luciferase-based readout.
authors.affiliation: Department of Virology, University of Freiburg, D-79008 Freiburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kuri
authors.forename: Matthias
authors.initials: M
authors.lastname: Habjan
authors.forename: Nicola
authors.initials: N
authors.lastname: Penski
authors.forename: Friedemann
authors.initials: F
authors.lastname: Weber
mesh_terms: D000818:Animals; D001681:Biological Assay / Q000379:methods*; D001717:Birds; D002460:Cell Line; D017930:Genes, Reporter; D006801:Humans; D007370:Interferon Type I / Q000276:immunology*; D049410:Luciferases, Renilla / Q000235:genetics / Q000378:metabolism; D051379:Mice; D012680:Sensitivity and Specificity; D014777:Virus Diseases / Q000276:immunology*; D014780:Viruses / Q000276:immunology*
chemical_list: D007370:Interferon Type I; D049410:Luciferases, Renilla