Phylogenomic Characterization of a Novel Corynebacterium Species Associated with Fatal Diphtheritic Stomatitis in Endangered Yellow-Eyed Penguins

Saunderson, Sarah C., Nouioui, Imen, Midwinter, Anne C., Wilkinson, David A., Young, Melanie J., McInnes, Kate M., Watts, Jim and Sangal, Vartul (2021) Phylogenomic Characterization of a Novel Corynebacterium Species Associated with Fatal Diphtheritic Stomatitis in Endangered Yellow-Eyed Penguins. mSystems, 6 (3). e00320-21. ISSN 2379-5077

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Official URL: https://doi.org/10.1128/mSystems.00320-21

Abstract

Yellow-eyed penguins, Megadyptes antipodes, are an endangered species that are endemic to New Zealand. Outbreaks of diphtheritic stomatitis have caused significant mortality for this species, especially among young chicks. In this study, we isolated 16 Corynebacterium sp. isolates from the oral cavities of 2- to 14-day-old chicks at a range of infection stages and sequenced the genomes to understand their virulence mechanisms. Phylogenomic and matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) characterization indicate that these strains belong to a novel Corynebacterium species. A simple multiplex PCR-based diagnostic assay has been developed to identify these strains rapidly and reliably. Similar to other corynebacteria, genomic islands and prophages introduced significant diversity among these strains that has potentially led to minor functional variations between the two lineages. Despite the presence of multiple corynebacterial virulence genes and a spaDEF-type pilus gene cluster among these strains, the survival rate was much higher in Galleria mellonella larvae than in those inoculated with Corynebacterium ulcerans NZRM 818 and Corynebacterium pseudotuberculosis NZRM 3004. Therefore, these strains are opportunistic pathogens causing high mortality among young penguin chicks due to a less-developed immune system.
IMPORTANCE Yellow-eyed penguins, Megadyptes antipodes, are endangered species with a sharp decline in the numbers of breeding pairs over the last 2 decades. Diphtheritic stomatitis, characterized by a thick fibrinopurulent exudate in the oral cavities and symptoms, including inanition and significant weight loss, is responsible for significant mortality among the young chicks. These chicks are treated with antibiotics, amoxicillin-clavulanic acid or enrofloxacin, but do not always recover from the infection. The pathogen causing these infections and the mechanism of pathogenesis are unclear. This study has identified a novel Corynebacterium species to be associated with diphtheritic stomatitis in yellow-eyed penguins with potential virulence genes that are likely involved in pathogenesis. Importantly, a gene encoding an exotoxin, phospholipase D, is present among these strains. The inactivated form of this enzyme could potentially be used as an effective vaccine to protect these penguins from infection.

Item Type: Article
Additional Information: Funding information: This research was undertaken as part of a management project facilitated by the New Zealand Department of Conservation (DOC). In undertaking this research on hoiho, we acknowledge DOC’s treaty partner, Te Rūnanga o Ngāi Tahu, and their kaitiakitanga. We thank DOC for funding. We thank the MicrobesNG facility for assistance in genome sequencing and Gabriele Pötter (Leibniz-Institut DSMZ–Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Braunschweig, Germany) for her help with mycolic acid analysis. We also thank the Avian Health Research Fund, Massey University, New Zealand, for funding the Galleria challenge work. Data availability: The whole-genome shotgun project has been deposited at DDBJ/ENA/GenBank under the accession numbers PQMG00000000 to PQMV00000000 (BioProject PRJNA393261).
Uncontrolled Keywords: Corynebacterium, virulence genes, yellow-eyed penguin, diphtheritic stomatitis, Megadyptes antipodes, core genome, novel species
Subjects: C500 Microbiology
Department: Faculties > Health and Life Sciences > Applied Sciences
Depositing User: Elena Carlaw
Date Deposited: 09 Jun 2021 11:10
Last Modified: 09 Jun 2021 11:15
URI: http://nrl.northumbria.ac.uk/id/eprint/46394

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