Evolution of the CRISPR-Cas adaptive immunity systems in prokaryotes: models and observations on virus–host coevolution

摘要: CRISPR-Cas is an adaptive immunity system in prokaryotes that functions via a unique mechanism which involves incorporation of foreign DNA fragments into CRISPR arrays and subsequent utilization transcripts these inserts (known as spacers) guide RNAs to cleave the cognate selfish element genome. Multiple attempts have been undertaken explore coevolution viruses microbial hosts carrying using mathematical models employ either systems differential equations or agent-based approach, combinations thereof. Analysis reveals highly complex co-evolutionary dynamics ensues from combination heritability CRISPR-mediated with existence different degrees depending on number spacers cost locus. Depending details models, variety testable, sometimes conflicting predictions made dependence degree benefit maintaining abundance diversity viruses. Some already directly validated experimentally. In particular, both reality virus–host arms race, escaping resistance reacquiring it through capture new spacers, fitness due curtailment beneficial HGT reproduced laboratory. However, test more specifically, detailed studies coevolving populations microbes nature laboratory are essential. Such analyses expected yield disagreements current, oversimplified trigger round theoretical developments.