Comparative genomics of Helicobacter pullorum from different countries

Area of Science:

• Microbiology and Genomics
• Bacterial Pathogenesis
• Antimicrobial Resistance

Background:

• Helicobacter pullorum is a poultry bacterium causing gastroenteritis, with potential zoonotic transmission leading to human colitis and hepatitis.
• Limited understanding of H. pullorum's genetic makeup hinders effective control and treatment strategies.
• This research addresses the knowledge gap by performing a comparative genomic analysis of diverse H. pullorum strains.

Purpose of the Study:

• To comprehensively characterize the genomes of 23 H. pullorum strains from various global locations.
• To identify key genetic factors contributing to H. pullorum's virulence and antibiotic resistance.
• To explore the genetic diversity and phylogenetic relationships within H. pullorum populations.

Main Methods:

• Comparative genomic analysis of 23 H. pullorum strains using whole-genome sequencing.
• Core-pan genome analysis with Roary pipeline and core genome single nucleotide polymorphism (cg-SNP) analysis with Snippy4 software.
• Phylogenetic analysis based on cg-SNPs and antimicrobial susceptibility testing (MIC determination) for specific strains.

Main Results:

• Genome sizes ranged from 1.55 to 2.03 Mb with ~34% GC content, revealing 4064 pan genes and 1267 core genes.
• Phylogenetic analysis identified two distinct H. pullorum groups. Virulence factors (adhesion, immune regulation, motility, antiphagocytosis, toxin, quorum sensing) and antibiotic resistance genes (APH(3')-IIIa, APH(2'')-If, AAC(6')-Ie-APH(2'')-Ia) were identified.
• The strain 2013BJHL exhibited multidrug resistance to ciprofloxacin, nalidixic acid, tetracycline, gentamicin, streptomycin, and erythromycin, correlating with identified resistance genes. Two types of Type VI secretion systems (T6SS) were found in 52.2% of strains.

Conclusions:

• This study provides the first comprehensive description of H. pullorum's genetic characteristics, highlighting significant genetic diversity.
• Novel virulence factors and antibiotic resistance determinants were identified, offering targets for future research and intervention.
• The discovery of two T6SS subtypes in H. pullorum represents a significant finding, potentially impacting bacterial interactions and pathogenicity.