Effect Of Genomic Island On Population Genetics And Virulence Of Pasteurella Multocida Based On Comparative Genomics

Pasteurella multocida(PM)is a causative agent of economically crucial diseases spanning the entire world and anopportunistic pathogeninfects human and various animals.It has been reported that PM contains virulence genes such as capsules,lipopolysaccharides,toxins and iron uptake-related proteins.However,the dynamic genomes of opportunistic pathogens are mainly generated by mobile elements and phage-derived Genomic Island(GI)to help bacteria quickly acquire foreign gene fragments.At present,there is little research on the virulence of GI in PM,and the influence of GI on PM population genetics during the evolution of bacteria is even more unknown.In this study,10 avian-sourced PM through high-throughput sequencing together with 104 publicly available PM genomes from NCBI databases were raw materials.The pan-genome data of the strains were obtained by bioinformatics analysis software such as BioNumerics 7.6 and based on pan-genome the population genome was analyzed.Then,the IslandViewer4 online analysis website was used to obtain possible GIs' regions,and the GIs of 114 strains were determined according to the GI containing integrase,direct repeat sequence,special GC content and only a small amount of presence in the genome of the same genus.The identified GI was compared with the core,accessory and unique gene sets of the pan-genome,the proportion of the genes that GI brought to the pan-genome was acquired,and the effects of GI on the genetic evolution of the PM population were analyzed using a database such as COG and WEGO.Meanwhile,the experiment was to separate the natural attenuated strains of avian PM,compare the difference between virulent and attenuated strain and studyon the relationship between GI andthe difference virulence of avian-sourced PMfrom the molecular level.By comparative genomics,the pan-genome of 114 PM showed an open evolutionary pattern.The phylogeny was closely related to host source and geographical location.The genome of PM haboured280 GIs.Thesegenes of GIs accounted for 5.8% of the core genes in the pan-genome,mainly related to functional metabolic activities;the accessory genes accounted for 42.3%,mainly for the enrichment of adaptive genes;and the unique genes accounted for 35.4%,containing some defence mechanism-related genes.In the context of PM population genetics,it has been determined that GI is very important for gene amplification of population genomes through the large propolation and specific functions of GI in the accseccory,unique gene set of this species,and integrated GI data also contributes to the studies of environmental adaptation and genetic diversity.And the isolation of new natural attenuated strains of PM and the analysis of virulent and attenuated strains found that the cause of the difference in virulence between the virulent strain DY120818 and 4 attenuated strains was probably the integrative and conjugative element ICEPmu2,which provided a theoretical basis for further exploration of the pathogenic mechanism of avain-sourced PM and the effect of GI on virulent of strains.