Genomic and Virulence Profiling of Erysipelothrix rhusiopathiae Isolated from Widespread Muskox Mortalities in Arctic Archipelago
Date
2023-04-21
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Abstract
Muskoxen are an important food and economic resource for the indigenous people in the Canadian Arctic; however, in recent years this species has experienced substantial disease-related population declines. A single strain (‘Arctic clone’) of Erysipelothrix rhusiopathiae was associated with mass mortalities of muskoxen on Banks and Victoria Islands in 2010-2013, and various wild species on Prince Patrick Island in 2017. In 2021, an outbreak of E. rhusiopathiae was reported for the first time in muskoxen on Ellesmere Island. The predominance of the Arctic clone in the Arctic raises the question of virulence of this lineage. Objectives of this study were to characterize E. rhusiopathiae isolates from Ellesmere Island and identify amino acid sequence variations among 17 virulence genes, pathogenicity islands and prophages among 28 Arctic clone and 31 other closely related E. rhusiopathiae genomes. In addition, unique genetic contents of the Arctic clone that may encode virulence traits were determined via pan-genome wide association studies. Comparison of virulence gene sequences among 59 E. rhusiopathiae genomes offered insights into amino acid variations unique to the Arctic clone. I found that 16 of 17 virulence genes investigated were present and 4 of 17 were highly conserved among all the genomes. Putative virulence gene sequences of adhesin, rhusiopathiae surface protein-A, choline binding protein-B and leucine rich repeat protein had amino acid sequence variants unique to the Arctic clone. These genes encoded proteins that help E. rhusiopathiae to attach to the host endothelial cells and form biofilms. Characterizing pathogenicity islands revealed a novel finding of 12/28 Arctic clone isolates harbouring toxin-B. Toxin-B is an exotoxin produced by Clostridiodes difficile and causes pathogenesis via cytolysis. None of the prophages harboured virulence genes. The core genome alignment of 59 E. rhusiopathiae whole genomes provided evidence that the Arctic clone might be associated with the mortality on Ellesmere Island. The newly isolated E. rhusiopathiae belong to the Arctic clone, which was found to contain unique
amino acid sequences for known virulence genes. The Arctic clone may have gained new virulence traits via mobile genetic elements mediated.
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Keywords
Arctic, muskoxen, mortality, Erysipelothrix rhusiopathiae, virulence genes, pathogenicity islands, prophages, pan-genome wide association studies
Citation
Seru, L. V. (2023). Genomic and virulence profiling of Erysipelothrix rhusiopathiae isolated from widespread muskox mortalities in Arctic Archipelago (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.