Global Transcriptomic Analysis of Bacteriophage-Host Interactions between a Kayvirus Therapeutic Phage and Staphylococcus aureus.

Kayviruses are polyvalent broad host range staphylococcal phages with a potential to combat staphylococcal infections. However, the implementation of rational phage therapy in medicine requires a thorough understanding of the interactions between bacteriophages and pathogens at omics level. To evaluate the effect of a phage used in therapy on its host bacterium, we performed differential transcriptomic analysis by RNA-Seq from bacteriophage K of genus Kayvirus infecting two Staphylococcus aureus strains, prophage-less strain SH1000 and quadruple lysogenic strain Newman. The temporal transcriptional profile of phage K was comparable in both strains except for a few loci encoding hypothetical proteins. Stranded sequencing revealed transcription of phage noncoding RNAs that may play a role in the regulation of phage and host gene expression. The transcriptional response of S. aureus to phage K infection resembles a general stress response with differential expression of genes involved in a DNA damage response. The host transcriptional changes involved upregulation of nucleotide, amino acid and energy synthesis and transporter genes and downregulation of host transcription factors. The interaction of phage K with variable genetic elements of the host showed slight upregulation of gene expression of prophage integrases and antirepressors. The virulence genes involved in adhesion and immune evasion were only marginally affected, making phage K suitable for therapy. IMPORTANCE Bacterium Staphylococcus aureus is a common human and veterinary pathogen that causes mild to life-threatening infections. As strains of S. aureus are becoming increasingly resistant to multiple antibiotics, the need to search for new therapeutics is urgent. A promising alternative to antibiotic treatment of staphylococcal infections is a phage therapy using lytic phages from the genus Kayvirus. Here, we present a comprehensive view on the phage-bacterium interactions on transcriptomic level that improves the knowledge of molecular mechanisms underlying the Kayvirus lytic action. The results will ensure safer usage of the phage therapeutics and may also serve as a basis for the development of new antibacterial strategies.

The induction, purification, whole genome sequencing and comparative genome analysis of a novel staphylococcus haemolyticus bacteriophage IME-SA4 / 中国医师杂志

Objective To induce a novel temperate bacteriophage from staphylococcus haemolyticus strain SA98,observe the morphology and size,complete the whole genome sequencing,analyse the structure of genome and evolutionary relationship.Methods The mitomycin C was used to induce the temperate phage from staphylococcushaemolyticus strain SA98,the induced phage was observed by transmission electron microscopy after be concentrated and purified.The genome DNA was extracted and high through sequenced.The feature of whole genome and evolutionary relationship was analyzed.Results A temperate phage IME-SA4 was successfully induced from staphylococcus haemolyticus strain SA98.Transmission electron microscopy analysis indicated that IME-SA4 had an isometric head and a non-contractile long tail.The whole genome of IME-SA4 was long as 41 843 bp,and the whole genome blast result indicated IME-SA4 shared only 13％ homology with most related strain phiRS7.Conclusions A novel staphylococcus haemolyticus temperate phage with low homology with other staphylococcusphages was successfully induced from staphylococcus haemolyticus strain SA98.The research of its morphology,whole genome sequencing and comparative genome analysis make the foundation for further study of staphylococcus phages' properties and practical application.