Genome Sequencing and Analysis of a Type A Clostridium perfringens Isolate from a Case of Bovine Clostridial Abomasitis

Victoria J Nowell,Andrew M Kropinski,Janet I Macinnes,John F Prescott,Valeria R Parreira,J Glenn Songer,J Ross Fitzgerald

doi:10.1371/journal.pone.0032271

Victoria J Nowell, Andrew M Kropinski + Show 5 more

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https://doi.org/10.1371/journal.pone.0032271

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Abstract

Clostridium perfringens is a common inhabitant of the avian and mammalian gastrointestinal tracts and can behave commensally or pathogenically. Some enteric diseases caused by type A C. perfringens, including bovine clostridial abomasitis, remain poorly understood. To investigate the potential basis of virulence in strains causing this disease, we sequenced the genome of a type A C. perfringens isolate (strain F262) from a case of bovine clostridial abomasitis. The ∼3.34 Mbp chromosome of C. perfringens F262 is predicted to contain 3163 protein-coding genes, 76 tRNA genes, and an integrated plasmid sequence, Cfrag (∼18 kb). In addition, sequences of two complete circular plasmids, pF262C (4.8 kb) and pF262D (9.1 kb), and two incomplete plasmid fragments, pF262A (48.5 kb) and pF262B (50.0 kb), were identified. Comparison of the chromosome sequence of C. perfringens F262 to complete C. perfringens chromosomes, plasmids and phages revealed 261 unique genes. No novel toxin genes related to previously described clostridial toxins were identified: 60% of the 261 unique genes were hypothetical proteins. There was a two base pair deletion in virS, a gene reported to encode the main sensor kinase involved in virulence gene activation. Despite this frameshift mutation, C. perfringens F262 expressed perfringolysin O, alpha-toxin and the beta2-toxin, suggesting that another regulation system might contribute to the pathogenicity of this strain. Two complete plasmids, pF262C (4.8 kb) and pF262D (9.1 kb), unique to this strain of C. perfringens were identified.

Highlights

Clostridium perfringens is a Gram-positive bacterium that flourishes in the nutrient-rich environment of the mammalian and avian gastrointestinal tract and causes disease when relevant toxins are expressed [1]
Bacterial isolates Isolate F262 was recovered in large numbers from the abomasal content of a calf that died of clostridial abomasitis, diagnosed on the basis of typical gross and histopathological lesions of acute necrotizing inflammation, with emphysema
Pulsed-field gel electrophoresis showed that a C. perfringens isolate from another calf in the clostridial abomasitis outbreak shared the same pulsed-field gel electrophoresis restriction pattern as C. perfringens F262

Summary

Introduction

Clostridium perfringens is a Gram-positive bacterium that flourishes in the nutrient-rich environment of the mammalian and avian gastrointestinal tract and causes disease when relevant toxins are expressed [1]. Clostridial abomasitis is a severe enteric disease of calves that often presents as fatal hemorrhagic enteritis involving the abomasum and upper small intestine [2]. The disease is thought to be caused by type A C. perfringens, though the mechanisms of pathogenesis are not understood. Calves display acute necrotizing hemorrhagic inflammation, with emphysema in the abomasum and often in the upper small intestine [2,3], and present clinically with abomasal tympany, abdominal bloating and distension [4]. The discovery of toxins has aided in the understanding of some other type A-mediated enteric diseases, such as the recent recognition of the critically important pore-forming toxin NetB in isolates causing necrotic enteritis in chickens [6], no known toxins have been convincingly or reproducibly linked to clostridial abomasitis. The suggestion has been made that the beta2-toxin may be involved, but experimental findings are sparse and often contradictory [7,8,9,10,11]

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