Biased acquisition of spacers by the CRISPR System of the V. cholerae

Abstract

Cholera is a deadly waterborne disease that is caused by the serogroup of O1 or O139 of Vibrio cholerae. Also, there are many non-pathogenic Vibrio cholerae strains known as non-O1 and non-O139. Bacteriophages are bacteria eating viruses and are highly specific towards the host cell. They require host cellular machinery to perform their metabolic activities. Many of the Vibrio cholerae strains contain CRISPR which is an immune defense system that targets foreign DNA like plasmids, phage DNA and even other bacterial DNA that are inserted into CRISPR arrays. When a phage or any invader attacks bacteria, the CRISPR system inserts the fragments of phage or the invader’s DNA into the CRISPR array. It is known as spacers which later work as an immune memory. This study includes analysis of V. cholerae strains that contain CRISPR, specifically the in depth analysis of spacers using different bioinformatics tools and softwares. One of the major findings of this study was that the spacers come from some specific regions of the phage whole genome.