A rapid and transient innate immune response to avian influenza infection in mallards. (March 2018)

• Record Type: Journal Article
• Authors: Helin, Anu S.; Wille, Michelle; Atterby, Clara; Järhult, Josef D.; Waldenström, Jonas; Chapman, Joanne R.
• Is Part Of: Molecular immunology. Volume 95(2018:Mar.)
• Page Start: 64
• Page End: 72
• Publication Date: 2018-03
• Subjects: Anas platyrhynchos -- Zoonotic disease -- Avian disease -- Gene expression -- Retinoic acid inducible gene 1 RIG-I -- Myxovirus resistance gene Mx -- Influenza A virus -- LPAI -- HPAI -- Ecoimmunology -- Tolerance; Immunochemistry -- Periodicals; Molecular biology -- Periodicals; Immunochemistry -- Periodicals; Allergy and Immunology -- Periodicals; Molecular Biology -- Periodicals; Immunochimie -- Périodiques; Biologie moléculaire -- Périodiques; Immunochemistry; Molecular biology; Periodicals; Electronic journals; 571.96
• DOI: 10.1016/j.molimm.2018.01.012
• Languages: English
• ISSNs: 0161-5890

Abstract

Highlights: Mallard ducks ( Anas platyrhynchos ) are important reservoirs for avian influenza virus (AIV) in nature. Expression of two innate immune genes in influenza-infected mallards is investigated. RIG-I and Mx show rapid yet transient upregulation. The bulk of the immune response is focussed on the first 24 hours of infection. The spleen plays a key role in the mallard immune response to AIV. Abstract: The vertebrate innate immune system provides hosts with a rapid, non-specific response to a wide range of invading pathogens. However, the speed and duration of innate responses will be influenced by the co-evolutionary dynamics of specific host-pathogen combinations. Here, we show that low pathogenic avian influenza virus (LPAI) subtype H1N1 elicits a strong but extremely transient innate immune response in its main wildlife reservoir, the mallard ( Anas platyrhynchos ). Using a series of experimental and methodological improvements over previous studies, we followed the expression of retinoic acid inducible gene 1 ( RIG-I ) and myxovirus resistance gene ( Mx ) in mallards semi-naturally infected with low pathogenic H1N1. One day post infection, both RIG-I and Mx were significantly upregulated in all investigated tissues. By two days post infection, the expression of both genes had generally returned to basal levels, and remained so for the remainder of the experiment. This is despite the fact that birds continued to actively shed viral particles throughout the study period. We additionally show that the spleen plays a particularly active role in the innate immune response to LPAI. Waterfowl and avian influenza viruses have a long co-evolutionary history, suggesting that the mallard innate immune response has evolved to provide a minimum effective response to LPAIs such that the viral infection is brought under control while minimising the damaging effects of a sustained immune response.