Comparative genome analysis of an avirulent and two virulent strains of avian Pasteurella multocida reveals candidate genes involved in fitness and pathogenicity

Timothy J Johnson,Fred M Tatum,Samuel S Hunter,Robert E Briggs,Samuel K Maheswaran,Melissa Hauglund,Juan E Abrahante

doi:10.1186/1471-2180-13-106

Abstract

BackgroundPasteurella multocida is the etiologic agent of fowl cholera, a highly contagious and severe disease of poultry causing significant mortality and morbidity throughout the world. All types of poultry are susceptible to fowl cholera. Turkeys are most susceptible to the peracute/acute forms of the disease while chickens are most susceptible to the acute and chronic forms of the disease. The whole genome of the Pm70 strain of P. multocida was sequenced and annotated in 2001. The Pm70 strain is not virulent to chickens and turkeys. In contrast, strains X73 and P1059 are highly virulent to turkeys, chickens, and other poultry species. In this study, we sequenced the genomes of P. multocida strains X73 and P1059 and undertook a detailed comparative genome analysis with the avirulent Pm70 strain. The goal of this study was to identify candidate genes in the virulent strains that may be involved in pathogenicity of fowl cholera disease.ResultsComparison of virulent versus avirulent avian P. multocida genomes revealed 336 unique genes among the P1059 and/or X73 genomes compared to strain Pm70. Genes of interest within this subset included those encoding an L-fucose transport and utilization system, several novel sugar transport systems, and several novel hemagglutinins including one designated PfhB4. Additionally, substantial amino acid variation was observed in many core outer membrane proteins and single nucleotide polymorphism analysis confirmed a higher dN/dS ratio within proteins localized to the outer membrane.ConclusionsComparative analyses of highly virulent versus avirulent avian P. multocida identified a number of genomic differences that may shed light on the ability of highly virulent strains to cause disease in the avian host, including those that could be associated with enhanced virulence or fitness.

Highlights

Pasteurella multocida is the etiologic agent of fowl cholera, a highly contagious and severe disease of poultry causing significant mortality and morbidity throughout the world
While the Pm70 genome sequence has been a great asset in our studies, progress has been modest in the identification and understanding of P. multocida virulence [27]
The goal of this study is to enable narrowed identification of a repertoire of unique genes present in the highly pathogenic avian strains that may play a role in virulence

Summary

Introduction

Pasteurella multocida is the etiologic agent of fowl cholera, a highly contagious and severe disease of poultry causing significant mortality and morbidity throughout the world. All types of poultry are susceptible to the disease, among them turkeys, pheasants and partridges are highly susceptible to peracute/acute forms of disease whereas chickens are relatively more resistant [11]. This strain belongs to serotype F:3 [28] and not A:3 as reported earlier [15], is avirulent and does not cause experimental fowl cholera disease in chickens [28]. Other strains of P. multocida have been isolated, such as strains X73 and the P1059, that are highly virulent to chickens, turkeys, and other poultry species [29,30]

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