Improved adsorption of an Enterococcus faecalis bacteriophage ?EF24C with a spontaneous point mutation.

ABSTRACT: Some bacterial strains of the multidrug-resistant Gram-positive bacteria Enterococcus faecalis can significantly reduce the efficacy of conventional antimicrobial chemotherapy. Thus, the introduction of bacteriophage (phage) therapy is expected, where a phage is used as a bioagent to destroy bacteria. E. faecalis phage ?EF24C is known to be a good candidate for a therapeutic phage against E. faecalis. However, this therapeutic phage still produces nonuniform antimicrobial effects with different bacterial strains of the same species and this might prove detrimental to its therapeutic effects. One solution to this problem is the preparation of mutant phages with higher activity, based on a scientific rationale. This study isolated and analyzed a spontaneous mutant phage, ?EF24C-P2, which exhibited higher infectivity against various bacterial strains when compared with phage ?EF24C. First, the improved bactericidal effects of phage ?EF24C-P2 were attributable to its increased adsorption rate. Moreover, genomic sequence scanning revealed that phage ?EF24C-P2 had a point mutation in orf31. Proteomic analysis showed that ORF31 (mw, 203 kDa) was present in structural components, and immunological analysis using rabbit-derived antibodies showed that it was a component of a long, flexible fine tail fiber extending from the tail end. Finally, phage ?EF24C-P2 also showed higher bactericidal activity in human blood compared with phage ?EF24C using the in vitro assay system. In conclusion, the therapeutic effects of phage ?EF24C-P2 were improved by a point mutation in gene orf31, which encoded a tail fiber component.

SUBMITTER: Uchiyama J 

PROVIDER: S-EPMC3201976 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature