Pan-genomic analysis of Campylobacter jejuni confers hypervariable sequences and functional genes involved in pathogenicity

Abstract

The bacterial Pan-genomic analysis gives a comprehensive view of genes present in strains. It offers detailed views of genetic diversity and adaptation among closely related strains such as duplication, loss of genes, and horizontal genes transfer mechanism. Campylobacter jejuni is associated with various food-borne illnesses worldwide. In this study, the Pan-genomic Analysis Pipeline tool (PGAP) was used to perform genomic analysis of Campylobacter jejuni to find functional gene distribution that might be responsible for normal gene functioning and virulence. A total of 56,455 whole proteins (Wp_Count) were present in the strains of Campylobacter jejuni and the subdivision of these Wp_Count in the core, shared and unique genome were 44,845, 10,981, and 629. In the core genome, 211 genes were found to be involved in pathogenicity. Flagellar assembly protein (FliW) and two-compartment system (TCS) flagellar assembly protein response regulator was found in all 35 strains which play an important role in host colonization. The other important functional genes were also present, which are reportedly involved in host immune invasion and pathogenicity. In the shared genome, 11 genes were found against selected query proteins and cluster analysis revealed hypervariable sequences were present in gene coding flagellum. Phylogenetic analyses revealed the evolution in Campylobacter jejuni flaA and flaB genes occurred at the same time. Phylogenetic analysis also discloses that the evolution of the Campylobacter jejuni strains was acquired by the high rate of recombination possibly due to horizontal gene transfer (HGT) showed variability and diversity in allelic genes. There was no unique gene found with reference to the query protein. This study provides baseline data to find a possible solution for improved treatment and overcome the resistance pattern within the specie. Apart from limited time and resources in the future, our focus is to advance the current study to do protein modeling and targeted drug development.