Phylogeny and putative virulence gene analysis of Bartonellabovis

[摘要] Bartonella bovis is a small Gram-negative bacterium recognized as anetiological agent for bacteremia and endocarditis in cattle. As few reports are availableon the taxonomic position of B. bovis and its mechanism of virulence,this study aims to resolve the phylogeny of B. bovis and investigateputative virulence genes based on whole genome sequence analysis. Genome-wide comparisonsbased on single nucleotide polymorphisms (SNP) and orthologous genes were performed inthis study for phylogenetic inference of 27 Bartonella species. RapidAnnotation using Subsystem Technology (RAST) analysis was used for annotation of putativevirulence genes. The phylogenetic tree generated from the genome-wide comparison oforthologous genes exhibited a topology almost similar to that of the tree generated fromSNP-based comparison, indicating a high concordance in the nucleotide and amino acidsequences of Bartonella spp. The analyses show consistent grouping ofB. bovis in a cluster related to ruminant-associated species, includingBartonella australis, Bartonella melophagi andBartonella schoenbuchensis. RAST analysis revealed genes encodingflagellar components, in corroboration with the observation of flagella-like structure ofBbUM strain under negative straining. Genes associated with virulence, disease anddefence, prophages, membrane transport, iron acquisition, motility and chemotaxis areannotated in B. bovis genome. The flagellin (flaA) geneof B. bovis is closely related to Bartonellabacilliformis and Bartonella clarridgeiae but distinct fromother Gram-negative bacteria. The absence of type IV secretion systems, the bonafide pathogenicity factors of bartonellae, in B. bovissuggests that it may have a different mechanism of pathogenicity.

[学科分类] 兽医学

[关键词] Bartonella bovis;genome-based phylogeny;putativevirulence genes