In Silico and In Vivo Evaluation of Bacteriophage EF24C, a Candidate for Treatment of Enterococcus faecalis Infections

Departments of Pediatrics, Microbiology and Infection, Kochi Medical School, Oko-cho Nankoku City, Kochi 783-8505, Japan

^* To whom correspondence should be addressed. Email: matuzaki{at}kochi-u.ac.jp.

	Abstract

Along with the increasing threat of nosocomial infections by vancomycin-resistant Enterococcus faecalis, bacteriophage (phage) therapy has been expected as an alternative therapy against infectious disease. Although genome information and proof of applicability are prerequisites in modern therapeutic phage, E. faecalis phage has not been analyzed from such aspects. Previously, we reported a novel virulent phage EF24C, and its biology inferred its therapeutic potential against E. faecalis infection. In this study, the EF24C genome was analyzed and the in vivo therapeutic applicability of EF24C was also briefly assessed. Its complete genome (142,072 bp) was predicted to have 221 open reading frames (ORFs) and five tRNA genes. In our functional analysis of the ORFs using a public database, no proteins undesirable in phage therapy, such as pathogenic and integration-related proteins, were predicted. The non-competitive directions of replication and transcription, and the host-adapted translation of the phage were deduced bioinformatically. Its genomic features indicated that EF24C is a member of the genus SPO1-like phage, and especially has close relationship to the Listeria monocytogenes phage P100, which is authorized for prophylactic use. Thus, these bioinformatics analyses rationalized therapeutic eligibility of EF24C. Moreover, EF24C in vivo therapeutic potential, which was effective at low concentration and was not affected by host sensitivity to the phage, was proven in sepsis BALB/c mouse models. Furthermore, no change in mouse lethality was observed under both single and repeated phage exposures. Although further study is required, EF24C can be a promising therapeutic phage against E. faecalis infections.