Phylogenomic characterisation of a novel corynebacterial species pathogenic to animals

Jens Möller,Vyacheslav Melnikov,Vartul Sangal,Luca Musella,Andreas Burkovski,Walter Geißdörfer

doi:10.1007/s10482-020-01430-5

Abstract

The genus Corynebacterium includes species of biotechnological, medical and veterinary importance. An atypical C. ulcerans strain, W25, was recently isolated from a case of necrotizing lymphadenitis in a wild boar. In this study, we have analysed the genome sequence of this strain and compared the phenotypic and virulence properties with other corynebacterial pathogens. Phylogenomic analyses revealed that strain W25 belongs to a novel species along with PO100/5 and KL1196. The latter strains were isolated from a pig and a roe deer, respectively; hence, this species appears to be associated to animals. The isolate W25 is likely a non-toxigenic tox gene bearing strain and may have compromised abilities to adhere to pharyngeal and laryngeal epithelial cells due to potential loss of the gene functions in spaBC and spaDEF pilus gene clusters. A number of corynebacterial virulence genes are present including pld encoding phospholipase D. Therefore, this strain may be able to cause severe invasive infections in animals and zoonotic infections in humans.

Highlights

Corynebacterium is a diverse genus that includes species of biotechnological, medical and veterinary importance (Bernard and Funke 2015)
strain and Type (Strain) W25 was initially identified by MALDI-TOF mass spectrometry as C. ulcerans with a score of 2.065
Multiplex PCR amplified fragments of 16S rRNA, rpoB and tox genes with a faint DNA band for pld gene for strain W25 (Fig. 1), a profile consistent with other C. ulcerans isolates as the primers were designed to amplify the fragments of rpoB and tox genes for C. diphtheriae, C. pseudotuberculosis and C. ulcerans, 16S rRNA for C. ulcerans and C. pseudotuberculosis, pld for C. pseudotuberculosis and dtxR for C. diphtheriae strains

Summary

Introduction

Corynebacterium is a diverse genus that includes species of biotechnological, medical and veterinary importance (Bernard and Funke 2015). One of the corynebacterial species, Corynebacterium ulcerans, is an important zoonotic pathogen often acquired from canine pets and causes diphtheria-like infections in humans (Hacker et al 2016; Mattos-Guaraldi et al 2014). The key virulence factor among C. ulcerans strains is the tox gene (Sangal and Hoskisson 2014; Sangal et al 2014; Subedi et al 2018); which is borne by a corynephage (Sekizuka et al 2012) or pathogenicity island (Meinel et al 2014). Other known virulence-associated genes in C. ulcerans include pld (phospholipase D), nanH (neuraminidase H), cp (corynebacterial protease), vsp and vsp (venom serine protease) and rbp (Sangal et al 2014; Sekizuka et al 2012; Subedi et al 2018; Trost et al 2011). The rbp gene encodes a ribosomal-binding protein that is similar to Shiga-like toxin and is only reported in C. ulcerans strain 809 (Subedi et al 2018; Trost et al 2011). An Rbp homolog was found in C. diphtheriae HC04 (Weerasekera et al 2019)

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Discussion

Conclusion