Chicken and duck myotubes are highly susceptible and permissive to influenza virus infection.
Bottom Line: Besides its primary function in movement and posture, skeletal muscle is a significant innate immune organ with the capacity to produce cytokines and chemokines and respond to proinflammatory cytokines.Infected chicken myotubes produced significantly higher levels of proinflammatory cytokines than did the corresponding duck cells.Our results indicate that avian skeletal muscle fibers of chicken and duck could be significant contributors to progeny production of highly pathogenic H5N1 viruses.
Affiliation: School of Veterinary Medicine and Science, University of Nottingham, Loughborough, Leicestershire, United Kingdom.Show MeSH
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Mentions: We next focused on the expression of the chicken IFN-β gene and three interferon-inducible genes, Mx1, 2′,5′-OAS, and PKR, which are all known to have antiviral activity against influenza A virus. We also quantified the expression level of MDA-5, a previously identified PRR of influenza virus in chicken cells (43). Chicken myotubes at 6 h p.i. with LPAI H2N3 (MOI of 1.0) showed a 75-fold induction of IFN-β transcription (Fig. 6A). The level of production of IFN-β peaked at 12 h p.i. (≈685-fold increase) and remained high at 24 h p.i. (≈555-fold). IFN-β induction correlated with the upregulation of the MDA-5, Mx1, 2′,5-OAS, and PKR genes. Notably, the Mx1 gene was highly upregulated during early infection. Mx1 gene expression showed ≈530-fold, ≈930-fold, and ≈5,000-fold increases at 6 h, 12 h, and 24 h p.i., respectively. The 2′,5′-OAS gene was also strongly upregulated, reaching an ≈400-fold increase at 24 h of infection. In contrast, chicken cells infected with HPAI H5N1 50-92 (Fig. 6B) and HPAI H5N1 tyTy05 (Fig. 6C) viruses (both at a MOI of 1.0), showed relatively modest IFN-β induction, with a <20-fold increase. Lower-level IFN-β induction was accompanied by the downregulation of the MDA-5 and PKR genes and much weaker Mx1 and 2′,5′-OAS gene responses at 24 h p.i. than with the corresponding LPAI H2N3 virus infection. Collectively, chicken myotubes appeared to mount a more robust antiviral response to LPAI H2N3 virus than to HPAI H5N1 viruses.
Affiliation: School of Veterinary Medicine and Science, University of Nottingham, Loughborough, Leicestershire, United Kingdom.