Collection of staphylococcal polyvalent bacteriophages suitable for phage therapy exhibiting broad lytic host-range on methicillin resistant Staphylococcus aureus strains
| Authors | |
|---|---|
| Year of publication | 2017 |
| Type | Article in Proceedings |
| Conference | IUMS 2017 Singapore - 15th International Congress of Bacteriology and Applied Microbiology |
| MU Faculty or unit | |
| Citation | |
| Field | Genetics and molecular biology |
| Keywords | Bacteriophage; Biological control; Specialized collections; Staphylococcus aureus; MRSA |
| Description | Objectives: Phages represent a promising alternative to antibiotics for the treatment of seriuos staphylococcal infections. Due to a high lytic activity and a broad host range towards Staphylococcus aureus strains, the most suitable are polyvalent Twort-like bacteriophages of genus Kayvirus, family Myoviridae represented by phage 812. This phage is used for phage therapy in the Czech Republic and is well characterized on genomic, proteomic and structural level. Methods: Spontaneous mutants from phage 812 were isolated as rare plaques on resistant staphylococcal strains. Their lytic effect was determined on a set of 200 well characterized human and livestock-associated MRSA isolates by a phage plaque assay. Phage genome sequences were obtained using 454 sequencing with a GS Junior System (Roche 454 Life Science, USA) and assembled using the GS De Novo Assembler v.2.6. For ORF prediction, GeneMark.hmm along with GeneMark S, optimized for phage sequences, were employed. Results: Phage 812 or its mutants were able to lyse 97 % of the MRSA livestock strains and 86 % of human MRSA strains. The lytic effect is preserved also in phage coctails, therefore the novel mutants could be used for innovation of recent phage preparations in order to increase their effect on currently circulating strains.To assess the safety of phage 812 mutants, the complete genome sequences were determined and compared to the wild-type phage 812. We have found that the mutants differ from the original genome mostly by short indels. Mutations seem to affect the host range in two ways: either interfere with adsorption genes (tail-fibre) and lysis (endolysin), or affect sequences that are the target of bacterial defence mechanisms such as RM-systems or CRISCP-Cas. Conlusion: Recently the collection includes 15 well characterized phage mutants. Mutations do not lead to the ability of lysogenic conversion and transduction nor virulence factors production. Therefore, the mutants thus obtained can be considered safe for phage therapy. Acknowledgement: Research was supported by a grant of Ministry of Agriculture of the Czech Republic No. QJ1510216. |
| Related projects: |