The pathogenic biomarker alcohol dehydrogenase protein is involved in Bacillus cereus virulence and survival against host innate defence.

Devon W Kavanaugh,Nalini Ramarao,Rozenn Dervyn,Constance Porrini

doi:10.1371/journal.pone.0259386

Abstract

Bacillus cereus is a spore forming bacteria recognized among the leading agents responsible for foodborne outbreaks in Europe. B. cereus is also gaining notoriety as an opportunistic human pathogen inducing local and systemic infections. The real incidence of such infection is likely underestimated and information on genetic and phenotypic characteristics of the incriminated strains is generally scarce. We have recently analyzed a large strain collection of varying pathogenic potential. Screening for biomarkers to differentiate among clinical and non-clinical strains, a gene encoding an alcohol dehydrogenase-like protein was identified among the leading candidates. This family of proteins has been demonstrated to be involved in the virulence of several bacterial species. The relevant gene was knocked out to elucidate its function with regards to resistance to host innate immune response, both in vitro and in vivo. Our results demonstrate that the adhB gene plays a significant role in resistance to nitric oxide and oxidative stress in vitro, as well as its pathogenic ability with regards to in vivo toxicity. These properties may explain the pathogenic potential of strains carrying this newly identified virulence factor.

Highlights

Bacillus cereus is an ubiquitous spore forming human pathogen
Our results demonstrate that adhB plays a significant role in resistance to nitric oxide (NO) and oxidative stress in vitro, as well as its pathogenic ability with regards to in vivo infection and toxicity
The presence/absence of the adhB gene was assessed by PCR on a collection of strains of varying pathogenic potential: 21 non-pathogenic strains and 35 clinical strains (Table 1). adhB was present in 34/35 (97%) clinical isolates, whereas it was present in 5 of 21 (24%) non-pathogenic isolates

Summary

Introduction

Bacillus cereus is an ubiquitous spore forming human pathogen. It is present in soil, foods, almost all surfaces in hospital settings, and human skin. It is the second leading cause of collective foodborne outbreaks in France after Staphylococcus aureus and the third in Europe [1,2,3]. B. cereus can cause severe systemic infections, especially in immunocompromised patients leading to patient death in approximately 10% of cases [4,5,6,7,8,9]. Some B. cereus strains can cause severe and even fatal infections in healthy people [10]. The pathogenic potential of B. cereus is extremely variable, with some strains being harmless and others lethal [11]

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Conclusion