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Using Reverse Genetics to Manipulate the NSs Gene of the Rift Valley Fever Virus MP-12 Strain to Improve Vaccine Safety and Efficacy
Published on: November 1, 2011
Modulation of type I IFN induction by a virulence determinant within the alphavirus nsP1 protein
Catherine C Cruz1, Mehul S Suthar2, Stephanie A Montgomery1
1Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Carolina Vaccine Institute, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
Abstract:
Alphaviruses are mosquito-borne viruses that cause serious human and animal diseases. Previous studies demonstrated that a determinant within the nsP1/nsP2 cleavage domain of the virulent Sindbis AR86 virus played a key role in regulating adult mouse virulence without adversely affecting viral replication. Additional characterization of this determinant demonstrated that a virus with the attenuating mutation induced more type I IFN production both in vivo and in vitro. Interestingly, this phenotype was not specific to the Sindbis AR86 virus, as a similar mutation in a distantly related alphavirus, Ross River Virus (RRV), also led to enhanced IFN induction. This effect was independent of virus-induced host shutoff, since IRF-3 phosphorylation, which occurs independently of de novo host transcription/translation, was induced more robustly in cells infected with the mutant viruses. Altogether, these results demonstrate that critical determinants within the nsP1/nsP2 cleavage domain play an important role in regulating alphavirus-induced IFN responses.
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