Novel Giant Siphovirus from Bacillus anthracis Features Unusual Genome Characteristics

Holly H Ganz,Wolfgang Beyer,Martina Schmuki,Richard Calendar,Martin J Loessner,Christina Law,Jonas Korlach,Jochen Klumpp,Fritz Eichenseher,Wayne M Getz

doi:10.1371/journal.pone.0085972

Abstract

Here we present vB_BanS-Tsamsa, a novel temperate phage isolated from Bacillus anthracis, the agent responsible for anthrax infections in wildlife, livestock and humans. Tsamsa phage is a giant siphovirus (order Caudovirales), featuring a long, flexible and non-contractile tail of 440 nm (not including baseplate structure) and an isometric head of 82 nm in diameter. We induced Tsamsa phage in samples from two different carcass sites in Etosha National Park, Namibia. The Tsamsa phage genome is the largest sequenced Bacillus siphovirus, containing 168,876 bp and 272 ORFs. The genome features an integrase/recombinase enzyme, indicative of a temperate lifestyle. Among bacterial strains tested, the phage infected only certain members of the Bacillus cereus sensu lato group (B. anthracis, B. cereus and B. thuringiensis) and exhibited moderate specificity for B. anthracis. Tsamsa lysed seven out of 25 B. cereus strains, two out of five B. thuringiensis strains and six out of seven B. anthracis strains tested. It did not lyse B. anthracis PAK-1, an atypical strain that is also resistant to both gamma phage and cherry phage. The Tsamsa endolysin features a broader lytic spectrum than the phage host range, indicating possible use of the enzyme in Bacillus biocontrol.

Highlights

We present a novel temperate phage isolated from Bacillus anthracis, the causative agent of anthrax infections in wildlife, livestock and humans [1]
Bacillus anthracis is a member of the Bacillus cereus sensu lato group of six closely related species: B. cereus, B. anthracis, B. thuringiensis, B. mycoides, B. pseudomycoides and B. weihenstephanensis [2]
Tsamsa phage is unable to infect B. subtilis 168 and DSM675, B. megaterium DSM90, B. sphaericus DSM395, B. weihenstephanensis WSBC10550 as well as all tested strains from other bacterial genera (Listeria ivanovii and L. monocytogenes, Staphylococcus aureus and S. epidermidis, Salmonella Typhimurium, Escherichia coli, Streptococcus salivarius, Lactococcus lactis or Enterococcus faecalis) (Table 1). It is a narrow host-range virus that infects some members of the Bacillus cereus sensu lato group and exhibits moderate specificity for B. anthracis

Summary

Introduction

We present a novel temperate phage isolated from Bacillus anthracis, the causative agent of anthrax infections in wildlife, livestock and humans [1]. Bacillus anthracis is a member of the Bacillus cereus sensu lato group of six closely related species: B. cereus, B. anthracis, B. thuringiensis, B. mycoides, B. pseudomycoides and B. weihenstephanensis [2]. This group contains both obligate and opportunistic animal pathogens, including B. anthracis, B. cereus, strains of which cause food poisoning and opportunistic infections in humans [3], and B. thuringiensis, an insect pathogen commonly used as a pesticide in agriculture [4]. The lytic activity and high specificity of bacteriophages provide a promising resource for the development of innovative treatments for human pathogens, including B. anthracis

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