Oral manifestations of E. faecalis infections include persistent periapical periodontitis in endodontically treated teeth (Stuart et al., 2006), and the presence of this organism in the subgingival plaque of 5% of teeth with severe periodontitis (Rams et al., 1992). This pathogenic potential has led to concern over the fact that increasingly,

strains of E. faecalis have been found to be resistant to currently available antibiotics. In this regard, strains of E. faecalis have recently been found to be resistant to vancomycin, one of the last antibiotics previously thought to be reliably effective against this organism (Bonten et al., 2001). The genome of one such vancomycin-resistant E. faecalis strain check details (strain V583) has been sequenced, JQ1 and within this genome, seven integrated prophage regions were detected (Paulsen et al., 2003). Along with numerous insertion elements, transposons, and integrated plasmid genes, these seven integrated prophage regions comprise over 25% of the total E. faecalis chromosome (Paulsen et al., 2003). Although the degree to which the E. faecalis chromosome is inhabited by exogenous/mobile genetic elements such as prophages is quite remarkable (and unique among sequenced bacterial genomes), the existence of these E. faecalis bacteriophage genomes is not surprising. Enterococcus faecalis bacteriophages

have been known for >70 years (Evans, 1934; Bleiweis & Zimmerman, 1961), and their inducibility from lysogenic E. faecalis strains has similarly been well established (Kjems, 1955). Enterococcus faecalis phages have been isolated directly, or induced from E. faecalis lysogens, from a variety of sources such as fresh water streams (Paisano et al., 2004), sewage (Evans, 1934; Bleiweis & Zimmerman, 1961; Uchiyama et al., 2008), rat intestinal contents (Rogers & Sarles, 1963), human urogential secretions (Ackermann et al., 1975), human saliva

(Bachrach et al., Dipeptidyl peptidase 2003), and human oral mucosae (Natkin, 1967). Recently, we isolated temperate bacteriophages that were induced from E. faecalis strains recovered from the infected root canals of teeth that had previously undergone endodontic treatment (Stevens et al., 2009). One of the isolates, designated phage φEf11, was characterized as a Siphoviridae morphotype, with a spherical head and a long noncontactile tail. Analysis of NdeI and NsiI restriction fragments indicated a DNA length of approximately 41 kb. To further our understanding of this virus, and explore its potential for either contributing to or mitigating against the pathogenicity of its host cell, we undertook the sequencing and functional analysis of its complete genome. TUSoD11 is a lysogenic strain of E. faecalis that was originally isolated from an infected human root canal (Stevens et al., 2009). Enterococcus faecalis JH2-2 (originally generously provided by Dr Nathan Shankar, University of Oklahoma Health Science Center) served as an indicator strain in plaque assays.