Lytic bacteriophages are valuable therapeutic agents against bacterial infections. There is continual effort to obtain new phages to increase the effectivity of phage preparations against emerging phage-resistant strains. Here we described the genomic diversity of spontaneous host-range mutants of kayvirus 812. Five mutant phages were isolated as rare plaques on phage-resistant Staphylococcus aureus strains. The host range of phage 812-derived mutants was 42% higher than the wild type, determined on a set of 186 methicillin-resistant S. aureus strains representing the globally circulating human and livestock-associated clones. Comparative genomics revealed that single-nucleotide polymorphisms from the parental phage 812 population were fixed in next-step mutants, mostly in genes for tail and baseplate components, and the acquired point mutations led to diverse receptor binding proteins in the phage mutants. Numerous genome changes associated with rearrangements between direct repeat motifs or intron loss were found. Alterations occurred in host-takeover and terminal genomic regions or the endolysin gene of mutants that exhibited the highest lytic activity, which implied various mechanisms of overcoming bacterial resistance. The genomic data revealed that Kayvirus spontaneous mutants are free from undesirable genes and their lytic properties proved their suitability for rapidly updating phage therapeutics.
- MeSH
- bakteriální léková rezistence MeSH
- bakteriofágy genetika MeSH
- délka genomu MeSH
- genom virový MeSH
- genomika MeSH
- jednonukleotidový polymorfismus MeSH
- methicilin farmakologie MeSH
- mutace * MeSH
- Staphylococcus aureus růst a vývoj virologie MeSH
- zastoupení bazí MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Staphylococcus aureus je významný oportunní patogen a častý původce bakteriálních nozokomiálních nákaz.Patogenní vlastnosti této bakterie jsou často kódovány mobilními genetickými elementy, jako jsou např. plazmi-dy. Na plazmidu se nachází i gen etb pro exfoliativní toxin B (ETB), který je příčinou puchýřnatého onemocnění(bulózní impetigo), jehož generalizovaná a život ohrožující forma se označuje jako stafylokokový syndrom opařené kůže. U pěti etb-pozitivních plazmidů, izolovaných během let 1999–2015 z kmenů S. aureus pocházejícíchz českých nemocnic, byla provedena srovnávací sekvenční analýza. Bylo zjištěno, že velká většina z nich sdílírozsáhlou oblast sekvence DNA, která zahrnuje typické geny virulence, avšak obsahují i variabilní úseky umož-ňující jejich diferenciaci. Přestože se dosud předpokládalo, že jsou ETB plazmidy relativně uniformní, byl izolo-ván a popsán nový typ, který s ostatními ETB plazmidy vykazuje jen minimální sekvenční shodu. Nese navíc geny pro horizontální přenos konjugací a nové varianty genů pro faktory virulence včetně etb, čímž reprezentuje zcela novou linii plazmidů kódujících exfoliatin B.
Staphylococcus aureus is an important opportunistic pathogen and a common cause of bacterial nosocomialinfections. Pathogenic properties of this bacterium are often encoded by mobile genetic elements, such as plas-mids. Plasmids also carry the etb gene encoding exfoliative toxin B(ETB), which is the cause of ablistering disease(bullous impetigo)whose generalized and life-threatening form is known as staphylococcal scalded skin syn-drome. Comparative sequence analysis was conducted to study five etb-positive plasmids, isolated from S. aureusstrains from Czech hospitals between 1999 and 2015. They were found to share a large part of the DNA sequencecomprising typical virulence genes. However, they also contain variable fragments, which help us to differentiatebetween them. Although ETB plasmids were previously assumed to be relatively uniform, a new type showingminimal sequence similarity to other ETB plasmids was isolated and described. Moreover, it carries genes forhorizontal transfer by conjugation as well as new variants of genes for virulence factors, including etb, and assuch it represents a completely new lineage of exfoliative toxin B-encoding plasmids.
Exfoliative toxin B (ETB) encoded by some large plasmids plays a crucial role in epidermolytic diseases caused by Staphylococcus aureus. We have found as yet unknown types of etb gene-positive plasmids isolated from a set of impetigo strains implicated in outbreaks of pemphigus neonatorum in Czech maternity hospitals. Plasmids from the strains of clonal complex CC121 were related to archetypal plasmid pETBTY4. Sharing a 33-kb core sequence including virulence genes for ETB, EDIN C, and lantibiotics, they were assigned to a stand-alone lineage, named pETBTY4-based plasmids. Differing from each other in the content of variable DNA regions, they formed four sequence types. In addition to them, a novel unique plasmid pETB608 isolated from a strain of ST130 was described. Carrying conjugative cluster genes, as well as new variants of etb and edinA genes, pETB608 could be regarded as a source of a new lineage of ETB plasmids. We have designed a helpful detection assay, which facilitates the precise identification of the all described types of ETB plasmids.
- MeSH
- bakteriální proteiny genetika MeSH
- bakteriociny genetika MeSH
- dermatotoxiny genetika MeSH
- DNA bakterií genetika MeSH
- exfoliatiny genetika MeSH
- fylogeneze MeSH
- impetigo epidemiologie mikrobiologie MeSH
- lidé MeSH
- pemfigus epidemiologie mikrobiologie MeSH
- plazmidy genetika izolace a purifikace MeSH
- sekvenování celého genomu MeSH
- Staphylococcus aureus klasifikace genetika MeSH
- virulence genetika MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika epidemiologie MeSH
Exfoliative toxin A (ETA)-coding temperate bacteriophages are leading contributors to the toxic phenotype of impetigo strains of Staphylococcus aureus. Two distinct eta gene-positive bacteriophages isolated from S. aureus strains which recently caused massive outbreaks of pemphigus neonatorum in Czech maternity hospitals were characterized. The phages, designated φB166 and φB236, were able to transfer the eta gene into a prophageless S. aureus strain which afterwards converted into an ETA producer. Complete phage genome sequences were determined, and a comparative analysis of five designed genomic regions revealed major variances between them. They differed in the genome size, number of open reading frames, genome architecture, and virion protein patterns. Their high mutual sequence similarity was detected only in the terminal regions of the genome. When compared with the so far described eta phage genomes, noticeable differences were found. Thus, both phages represent two new lineages of as yet not characterized bacteriophages of the Siphoviridae family having impact on pathogenicity of impetigo strains of S. aureus.
- MeSH
- DNA virů chemie genetika MeSH
- DNA viry genetika izolace a purifikace MeSH
- epidemický výskyt choroby MeSH
- exfoliatiny genetika MeSH
- fylogeneze MeSH
- genom virový * MeSH
- impetigo epidemiologie mikrobiologie MeSH
- infekce spojené se zdravotní péčí epidemiologie MeSH
- lidé MeSH
- molekulární sekvence - údaje MeSH
- novorozenec MeSH
- otevřené čtecí rámce MeSH
- polymorfismus délky restrikčních fragmentů MeSH
- pořadí genů MeSH
- porodnice MeSH
- přenos genů horizontální MeSH
- profágy klasifikace genetika izolace a purifikace MeSH
- sekvenční analýza DNA MeSH
- sekvenční homologie MeSH
- shluková analýza MeSH
- stafylokokové bakteriofágy klasifikace genetika izolace a purifikace MeSH
- stafylokokové infekce epidemiologie mikrobiologie MeSH
- Staphylococcus aureus izolace a purifikace virologie MeSH
- syntenie MeSH
- transdukce genetická MeSH
- Check Tag
- lidé MeSH
- novorozenec MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
