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Characterization of CRISPR Spacer and Protospacer Sequences in Paenibacillus larvae and Its Bacteriophages
Casey Stamereilers1, Simon Wong1, Philippos K Tsourkas1
1School of Life Sciences, University of Nevada, Las Vegas, NV 89154, USA.
Abstract:
The bacterium Paenibacillus larvae is the causative agent of American foulbrood, the most devastating bacterial disease of honeybees. Because P. larvae is antibiotic resistant, phages that infect it are currently used as alternative treatments. However, the acquisition by P. larvae of CRISPR spacer sequences from the phages could be an obstacle to treatment efforts. We searched nine complete genomes of P. larvae strains and identified 714 CRISPR spacer sequences, of which 384 are unique. Of the four epidemiologically important P. larvae strains, three of these have fewer than 20 spacers, while one strain has over 150 spacers. Of the 384 unique spacers, 18 are found as protospacers in the genomes of 49 currently sequenced P. larvae phages. One P. larvae strain does not have any protospacers found in phages, while another has eight. Protospacer distribution in the phages is uneven, with two phages having up to four protospacers, while a third of phages have none. Some phages lack protospacers found in closely related phages due to point mutations, indicating a possible escape mechanism. This study serve a point of reference for future studies on the CRISPR-Cas system in P. larvae as well as for comparative studies of other phage-host systems.
Insights
Honeybee pathogen Paenibacillus larvae acquires CRISPR spacers from phages, potentially hindering phage therapy. Analysis revealed unique spacers and protospacer distribution, offering insights into phage-host interactions.
Area of Science:
- Microbiology
- Genomics
- Immunology
Background:
- * Paenibacillus larvae causes American foulbrood, a severe honeybee bacterial disease.
- * Antibiotic resistance in P. larvae necessitates alternative treatments like phage therapy.
- * CRISPR spacer acquisition by P. larvae from phages may impede treatment efficacy.
Purpose of the Study:
- * To investigate CRISPR spacer sequences in P. larvae genomes.
- * To identify protospacers within P. larvae phages.
- * To assess the potential for CRISPR-Cas systems to interfere with phage therapy.
Main Methods:
- * Bioinformatic analysis of nine complete P. larvae genomes.
- * Identification and characterization of CRISPR spacer sequences.
- * Comparative genomics of P. larvae strains and their associated phages.
Main Results:
- * 714 CRISPR spacer sequences identified in P. larvae, with 384 unique.
- * 18 unique spacers found as protospacers in 49 P. larvae phage genomes.
- * Uneven distribution of protospacers in phages, with some lacking them due to mutations.
Conclusions:
- * CRISPR-Cas systems in P. larvae can target phage DNA, potentially limiting phage therapy success.
- * Phage genome evolution, including point mutations, may facilitate evasion of CRISPR-mediated immunity.
- * This study provides a foundation for understanding P. larvae CRISPR-Cas systems and phage-host dynamics.
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