Characterisation of bacteriophage JD419, a Staphylococcal phage with an unusual morphology and broad host range

As an antimicrobial therapy, therapeutic phages, also known as "Phage therapy" are able to inactivate multi-drug resistant bacteria such as methicillin and vancomycin resistant S. aureus and thus present a possible treatment for infections that are otherwise incurable. In this paper, we present a novel phage called JD419, which has a remarkably wide host-range. The virulent phage JD419 exhibits an elongated capsid and was able to infect and lyse 83 of all 129 tested clinical strains (64.3%) of multi-drug resistant S. aureus including MRSA. To evaluate the potential as a therapeutic phage, we tested the ability of phage JD419 to remain infectious after treatment exceeding physiological pH or temperature. The lytic activity of the phage was retained at pH values of 6.0-8.0 and at temperatures below 50{degrees}C. As phages sometimes contain virulence genes, we sequenced the complete genome of JD419. The 45509 bp genome contains a predicted 65 ORFs, none of which show homology to any known virulence or antibiotic resistance genes. Our study illustrates that Staphylococcus phage JD419 has the potential to be used for diagnostic, prophylaxic and therapeutic purposes.