Immune response in the duck intestine following infection with low-pathogenic avian influenza viruses or stimulation with a Toll-like receptor 7 agonist administered orally.
This study analysed the immune response in the intestinal tract of ducks infected with low-pathogenic avian influenza viruses compared with ducks treated orally with R848, a synthetic Toll-like receptor 7 (TLR7) agonist. Influenza virus infection induced a type I interferon (IFN)-dependent immune response characterized by the expression of Mx transcripts in the ileum at levels that were proportional to viral load. Mx transcripts were detected in differentiated enterocytes from influenza virus-infected ducks. By contrast, in R848-treated ducks, Mx transcripts were detected solely in intraepithelial round cells of haematopoietic origin. An increase was detected in the number of intraepithelial TLR7-positive cells and intraepithelial IFN-α-producing cells in influenza virus-infected ducks, albeit to a lower level than in R848-treated ducks. IFN-γ expression was also upregulated in the intestine of influenza virus-infected and R848-treated ducks. Finally, interleukin (IL)-1β and IL-8 transcripts were expressed at high levels in R848-treated ducks but were not increased in influenza virus-infected ducks. These findings suggest that a type I IFN-mediated immune response in enterocytes and the activation of IFN-γ-secreting cells contribute to the control of influenza virus replication in the duck intestine.
INRA, UMR 1225, Ecole nationale vétérinaire de Toulouse, F-31076 Toulouse, France.
Christelle
C
Volmer
Sébastien M
SM
Soubies
Bertrand
B
Grenier
Jean-Luc
JL
Guérin
Romain
R
Volmer
D000818:Animals; D004372:Ducks; D020895:Enterocytes / Q000276:immunology; D007082:Ileum / Q000276:immunology*; D007093:Imidazoles / Q000008:administration & dosage* / Q000276:immunology; D007150:Immunohistochemistry; D057916:Influenza A Virus, H7N1 Subtype / Q000276:immunology*; D005585:Influenza in Birds / Q000276:immunology*; D016898:Interferon-alpha / Q000096:biosynthesis / Q000276:immunology; D007371:Interferon-gamma / Q000096:biosynthesis / Q000276:immunology; D053583:Interleukin-1beta / Q000096:biosynthesis / Q000276:immunology; D016209:Interleukin-8 / Q000096:biosynthesis / Q000276:immunology; D008853:Microscopy; D051199:Toll-Like Receptor 7 / Q000819:agonists* / Q000276:immunology*
D007093:Imidazoles; D016898:Interferon-alpha; D053583:Interleukin-1beta; D016209:Interleukin-8; D051199:Toll-Like Receptor 7; D007371:Interferon-gamma; C402365:resiquimod