Abstract Title
Pathobiology and variable genetic determinants for virulence, transmission and tissue tropism of H7N7 avian influenza virus in chickens, turkeys and ducks
Abstract
High pathogenicity (HP) avian influenza viruses (AIV) cause severe mortality in chickens (Gallus gallus domesticus) and turkeys (Meleagris gallopavo), although turkeys are more sensitive than chickens. Little is known about the virulence determinants in both bird species, beyond the polybasic cleavage site (CS) in the hemagglutinin (HA). In 2015, HPAIV H7N7 and a low pathogenicity (LP) ancestor were isolated from the same chicken farm. The aim of this study was to investigate the pathobiology and the genetic determinants for virulence and transmission of these viruses in chickens, turkeys and ducks. Using reverse genetics different virus reassortants with an LP backbone carrying the polybasic CS (designated Lp_poly) and single or multiple HP segments were generated. In contrast to chickens and turkeys, LP and HP viruses were avirulent in ducks and infection was restricted to the respiratory and digestive tracts, while oral and cloacal swabs showed excretion at considerable levels. Interestingly, in turkeys and chickens, Lp_poly viruses carrying the HP NS or M gene segments were as virulent and transmissible as the parental HPAIV, respectively. All Lp_poly viruses were detected in the brain of chickens and turkeys, although endothelial infection was exclusively found in chickens. Together, ducks are clinically resistant to this H7N7 virus but excreted high amounts of viruses. This study showed two major differences between chickens and turkeys: more genetic constellations to confer high virulence and transmission in turkeys than in chickens and neurotropism in turkeys vs. neuronal and endothelial tropism in chickens.
Co-Author(s)
David Scheibner1,5, Reiner Ulrich2, Juliane Lang1, Diana Palme1, Maryna Kuryshko1, Christine Luttermann3, Thomas C. Mettenleiter4 and Elsayed M. Abdelwhab1*
1Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493 Greifswald-Insel Riems, Germany
2Institute of Veterinary Pathology, Leipzig University, Leipzig, Germany
3 Institute of Immunology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493 Greifswald-Insel Riems, Germany
4Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493 Greifswald-Insel Riems, Germany
5Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493 Greifswald-Insel Riems, Germany
Abstract Category
Transmission pathways, pathobiology, immune responses