Model-based evaluation of Targeted-Antibacterial-Plasmids (TAPs) transfer kinetics and resensitization of pOXA-48 carbapenem-resistant Escherichia coli
Background Targeted-Antibacterial Plasmids (TAPs) are engineered mobile genetic elements that use bacterial conjugation to deliver selective CRISPR/Cas9 antibacterial activity against a specific target strain. Yet, the efficiency of TAPs is typically evaluated at a single time point, whereas the success of TAP-mediated resensitization critically depends on the dynamics of plasmid transfer and the…
The study examines the transfer kinetics and resensitization of pOXA-48 carbapenem-resistant Escherichia coli using Targeted-Antibacterial Plasmids (TAPs). Unlike traditional evaluations, this research assesses the efficiency at multiple time points, as the success of TAP-mediated resensitization relies on the dynamics of plasmid transfer and interactions between bacterial subpopulations.
The study introduces a model analogous to conventional antibiotics to analyze the role of each process in resensitization: plasmid delivery, dCas9 activity, and the emergence of refractory and escape populations. By fitting the model to 44 longitudinal conjugation experiments over 24 hours, researchers discovered that up to 24% of recipients become refractory to further conjugation within the same timeframe, while transconjugant emergence remains below 0.01%.
Overall, resensitization efficiency reaches up to 80%. The results indicate that plasmid transfer, rather than dCas9 repression, is the primary bottleneck limiting the efficiency of TAPF-dCas9-OXA48. This finding highlights plasmid delivery as a critical engineering target for enhancing the performance of future TAPs.
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