In this case, CRISPR-Cas programmed to target AMR genes was delivered by a temperate phage. In an attempt to increase the selective advantage of re-sensitised bacteria, a technology using temperate and lytic phage to re-sensitise bacteria to β-lactam antibiotics was developed. While these studies showed that bacteria can be re-sensitised to antibiotic treatment using CRISPR-Cas, a clear problem was that these bacteria have no selective benefit over resistant ones, allowing residual resistant bacteria to be maintained in the population.
AUBURN JOURNAL JUNE 14 2018 SKIN
coli or on the skin of mice colonised with S. Both studies also showed that the CRISPR-Cas9 phagemids are able to kill specific bacteria in vivo, either in Galleria mellonella larvae exposed to enterohaemorrhagic E. The other study demonstrated sequence-specific killing of bacteria harbouring virulence genes using phagemid-mediated delivery of CRISPR-Cas9 and also showed that this approach was able to remove plasmids carrying AMR genes, thus effectively re-sensitising bacteria to antibiotics. In addition, delivery of CRISPR-Cas9 by conjugative plasmids was used to kill bacteria carrying AMR genes in the chromosome. One of these studies used phagemid transduction to deliver CRISPR-Cas9 constructs programmed to target AMR genes harboured on plasmids, which effectively removed these plasmids from bacteria. Two studies demonstrated that CRISPR-Cas9 can be delivered using phagemids (plasmids packaged in phage capsids) to selectively kill the clinically relevant bacterial pathogens E. Highlighting the specificity of CRISPR-Cas antimicrobials, individual bacterial strains were selectively removed from a mixed population of Escherichia coli genotypes by transforming the population with a plasmid encoding CRISPR-Cas programmed to target a sequence unique to each genotype. More recent studies have confirmed the potential for CRISPR-Cas to precisely remove bacterial strains that carry genes, including those determining drug resistance, from populations and to re-sensitise bacteria to antibiotics by selectively removing AMR-encoding plasmids. It was initially postulated several years ago that a synthetic CRISPR-Cas system could be utilised as an antimicrobial to kill specific bacterial genotypes. While most of these applications have been thoroughly reviewed, one that has received comparatively little attention is using CRISPR-Cas to eradicate AMR genes from bacterial populations and communities. The latter class encompasses the type II CRISPR-Cas9 system, whose targeting specificity, versatility, and simplicity has led to many revolutionary applications in genome editing and ecological engineering. CRISPR-Cas systems are classified into two classes and six types, in which class 1 (types I, III, and IV) have a more complex architecture, with multiple Cas proteins participating in foreign DNA recognition and cleavage processes, whereas class 2 systems (types II, V, and VI) have simpler architecture, with recognition and cleavage carried out by a single multidomain enzyme. Short sequences (‘spacers’) derived from foreign DNA or RNA elements, such as bacteriophages and plasmids, are inserted in CRISPR loci on the bacterial genome and later used by the Cas protein machinery to recognise and destroy invading nucleic acids carrying the same sequence. Using CRISPR-Cas to target AMR in bacteriaĬRISPR-Cas is an immune system that protects bacteria and archaea against invading nucleic acids. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Ĭompeting interests: The authors have declared that no competing interests exist. SVH acknowledges funding from the People Programme (Marie Curie Actions ) of the European Union’s Horizon 2020 (REA grant agreement n° 660039) and from the BBSRC (BB/R010781/1). ERW acknowledges the Natural Environment Research Council ( ) (NE/M018350/1), the BBSRC (BB/N017412/1), the Wellcome Trust ( ) (109776/Z/15/Z) and the European Research Council ( ) (ERC-STG-2016-714478 - EVOIMMECH) for funding. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.įunding: WHG acknowledges funding from the Medical Research Council ( ) and the Biotechnology and Biological Sciences Research Council (BBSRC ) (MR/N007174/1). Hogan, Geisel School of Medicine at Dartmouth, UNITED STATESĬopyright: © 2018 Pursey et al. Citation: Pursey E, Sünderhauf D, Gaze WH, Westra ER, van Houte S (2018) CRISPR-Cas antimicrobials: Challenges and future prospects.
0 kommentar(er)
