Attenuation of the type I interferon response in cells infected with human rhinovirus

The type I interferon (IFN) response requires the coordinated activation of the latent transcription factors NF-κB, IRF-3 and ATF-2 which in turn activate transcription from the IFN-β promoter. Here we have examined the type I interferon response in rhinovirus type 14-infected A549 cells, with particular emphasis on the status of the transcription factor IRF-3. Our results indicate that although rhinovirus type 14 (RV14) infection induces the activation of NF-κB and ATF-2, only very low levels of IFN-β mRNA are detected. Analysis of ISG54 mRNA levels revealed very little induction of this IRF-3 responsive transcript and suggested that IRF-3 activation might be impaired. Examination of IRF-3 in RV14-infected cells demonstrated only low levels of phosphorylation, a lack of homodimer formation and an absence of nuclear accumulation indicating that this transcription factor is not activated. Inhibition of viral protein synthesis following infection resulted in an increase in IFN-β mRNA levels indicating that viral gene products prevent induction of this pathway. Collectively, these results indicate that RV14 infection inhibits the host type I interferon response by interfering with IRF-3 activation.