AUTHOR=Rychener Lorenz , In-Albon Saria , Djordjevic Steven P. , Chowdhury Piklu Roy , Nicholson Pamela , Ziech Rosangela E. , de Vargas Agueda C. , Frey Joachim , Falquet Laurent 

TITLE=Clostridium chauvoei, an Evolutionary Dead-End Pathogen

JOURNAL=Frontiers in Microbiology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2017.01054

DOI=10.3389/fmicb.2017.01054

ISSN=1664-302X

ABSTRACT=<p>Full genome sequences of 20 strains of <italic>Clostridium chauvoei</italic>, the etiological agent of blackleg of cattle and sheep, isolated from four different continents over a period of 64 years (1951–2015) were determined and analyzed. The study reveals that the genome of the species <italic>C. chauvoei</italic> is highly homogeneous compared to the closely related species <italic>C. perfringens</italic>, a widespread pathogen that affects human and many animal species. Analysis of the CRISPR locus is sufficient to differentiate most <italic>C. chauvoei</italic> strains and is the most heterogenous region in the genome, containing in total 187 different spacer elements that are distributed as 30 – 77 copies in the various strains. Some genetic differences are found in the 3 allelic variants of <italic>fliC1</italic>, <italic>fliC2</italic> and <italic>fliC3</italic> genes that encode structural flagellin proteins, and certain strains do only contain one or two alleles. However, the major virulence genes including the highly toxic <italic><underline>C.</underline><underline>c</underline>hauvoei <underline>t</underline>oxin <underline>A</underline></italic>, the sialidase and the two hyaluronidases are fully conserved as are the metabolic and structural genes of <italic>C. chauvoei</italic>. These data indicate that <italic>C. chauvoei</italic> is a strict ruminant-associated pathogen that has reached a dead end in its evolution.</p>