Immigration of susceptible hosts triggers the evolution of alternative parasite defence strategies

Chabas, Hélène; Houte, Stineke van; Høyland‐Kroghsbo, Nina Molin; Buckling, Angus; Westra, Edze R.

doi:10.1098/rspb.2016.0721

Cited by 38 publications

(48 citation statements)

References 42 publications

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“…In this context, the key question is when CRISPR-Cas is favoured over alternative defence strategies [32]. Experimental, theoretical and correlational studies have suggested a role for viral abundance and diversity [27,28,33,34], direct and indirect fitness costs of CRISPR-Cas immune systems (e.g. autoimmunity, reduced horizontal gene transfer, induced fitness costs, see §1c below) [35 -38] and epistasis with other host genes [39,40].…”

Section: (B) Ecology and Diversity Of Crispr-cas Immunitymentioning

confidence: 99%

The ecology and evolution of microbial CRISPR-Cas adaptive immune systems

Westra

Houte

Gandon

et al. 2019

Phil. Trans. R. Soc. B

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Section: (B) Ecology and Diversity Of Crispr-cas Immunitymentioning

confidence: 99%

The ecology and evolution of microbial CRISPR-Cas adaptive immune systems

Westra

Houte

Gandon

et al. 2019

Phil. Trans. R. Soc. B

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“…How phage can persist in the face of this extremely adaptable immune system remains unclear. Previous theoretical and limited experimental work has explained persistence by invoking spatial hetereogeneity [34,69], negative frequency-dependent selection [61], and host switching to a constitutive defense strategy such as surface receptor modification [70,71].…”

Section: A Case Study: Crispr-phage Coevolutionmentioning

confidence: 99%

Immune Loss as a Driver of Coexistence During Host-Phage Coevolution

Weissman

Holmes

Barrangou

et al. 2017

Preprint

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phenomenon by invoking fitness tradeoffs, which can diminish an arms race dynamic. 7Here we propose that the regular loss of immunity by the bacterial host can also 8 produce host-phage coexistence. We pair a general model of immunity with an 9 experimental and theoretical case study of the CRISPR-Cas immune system to contrast 10 the behavior of tradeoff and loss mechanisms in well-mixed systems. We find that, while 11 both mechanisms can produce stable coexistence, only immune loss does so robustly 12 within realistic parameter ranges.

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“…Processed CRISPR transcripts guide Cas proteins to detect and destroy reinfecting phage that carry the cognate target sequence [12,13]. Phage can in turn overcome CRISPR-based immunity by acquiring a point mutation in the target sequence on their genome [14], although the emergence and spread of such phage "escape" mutants is constrained by both the diversity of CRISPR immunity alleles in the bacterial population and the fitness costs associated with the phage mutations [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

The effect of phage genetic diversity on bacterial resistance evolution

et al. 2020

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CRISPR-Cas adaptive immune systems are found in bacteria and archaea and provide defence against phage by inserting phage-derived sequences into CRISPR loci on the host genome to provide sequence specific immunological memory against re-infection. Under laboratory conditions the bacterium Pseudomonas aeruginosa readily evolves the high levels of CRISPR-based immunity against clonal populations of its phage DMS3vir, which in turn causes rapid extinction of the phage. However, in nature phage populations are likely to be more genetically diverse, which could theoretically impact the frequency at which CRISPR-based immunity evolves which in turn can alter phage persistence over time. Here we experimentally test these ideas and found that a smaller proportion of infected bacterial populations evolved CRISPR-based immunity against more genetically diverse phage populations, with the majority of the population evolving a sm preventing phage adsorption and providing generalised defence against a broader range of phage genotypes. However, those cells that do evolve CRISPR-based immunity in response to infection with more genetically diverse phage acquire greater numbers of CRISPR memory sequences in order to resist a wider range of phage genotypes. Despite differences in bacterial resistance evolution, the rates of phage extinction were similar in the context of clonal and diverse phage infections suggesting selection for CRISPR-based immunity or sm-based resistance plays a relatively minor role in the ecological dynamics in this study. Collectively, these data help to understand the drivers of CRISPR-based immunity and their consequences for bacteria-phage coexistence, and, more broadly, when generalised defences will be favoured over more specific defences.

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Immigration of susceptible hosts triggers the evolution of alternative parasite defence strategies

Cited by 38 publications

References 42 publications

The ecology and evolution of microbial CRISPR-Cas adaptive immune systems

The ecology and evolution of microbial CRISPR-Cas adaptive immune systems

Immune Loss as a Driver of Coexistence During Host-Phage Coevolution

The effect of phage genetic diversity on bacterial resistance evolution

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