Multi-omics Analysis To The Interaction Between Bacillus Nematocida B16 And Its Host Caenorhabditis Elegans

The infection of pathogenic microorganisms and immune response of host are one of the most common interactions in biosphere,and both of them are driven by coevolution and produced a variety of infection strategies in the nature.Bacillus nematocida B16(hereinafter referred to as B16)traps nematodes by emitting attractive odor molecules,which causes the worms to be disintegrated from inside.The recurrence of the ancient Greek mythology "Trojan horse" has been reported in our previous research.However,the knowledge of this pathogen-host interaction is mainly from the independent experiment and sporadic acquisition.Many questions are needed to be further clarified: how does the pathogenic bacterium synthesize signal molecules?Besides the above two main virulence factors,are there any other toxic genes acting together? Are there any new virulence factors involved in the infection? What mechanisms can the worms respond to the pathogen?Combined with the methods of comprehensive genomics,comparative genomics,interwork transcriptome of pathogen and host,as well as the functional experiments,we are to determine those critical virulence factors during different infectious stages,such as attracting,colonizing and propagating within the host worms.At the same time,the immunity genes or defense strategies were also been investigated during the worms resist to the pathogen of B16.Main results are as follows:1.From the genomic data,we identify the genes related to those characters such as cell growth,active metabolites,antibiotic resistance,and pathogenesis.Within the genome of B16,it was shown that 248 genes and 170 genes are associated with encoding carbohydrate and amino acid metabolisms,and 119 genes involved in replication and repair.This characters of genome is consistent with the rapidly growth on a variety of carbon and nitrogen sources,and conditional pathogenicity.To the genes responsible for infecting hosts,452 genes in B16 are homologous to the virulence genes from Virulence factors database(VFDB),accounting for 11.5% of the whole genome.These genes may be involved in many different processes,such as immune escape,cell hemolysis and insect degradation etc.In addition,there are also 199 genes encoding secondary metabolites,35 genes encoding bacteriocin,bacilli and multidrug resistance.2.Bacterial transcriptomic analysis reveal that 1692 genes are differentially expressed and 126 genes are up-regulate.In terms of functional classification,the genesresponsible for bacterial infection at least include cytochrome C redox gene,ABC transport system,polyketide gene encoding secondary metabolites,ferredoxin gene and stress resistance protein,which are closely related to the ability of B16 to colonize and invade the intestine and resist the immunity of nematode.3.When nematodes exposed to pathogenic bacteria B16,the transcriptome sequence reveal up-regulated 1090 genes and 2147 down-regulatec genes.Cluster analysis suggested that differential types of immunity genes can be enriched in resistance to pathogenic bacteria.Among the most diverse gene types include: the C-lectin gene account for 55% of 118 total immune genes,follow by neuropeptide receptor protein and Prion-like-(Q/N-rich)-domain family which account for 9%,follow by 8% lysosome gene.The results showed that not a single type,but multiple gene families of immunity genes would be employed in the resistant to pathogens.Additionally,comparing the transcriptome of B16 with the other pathogenic bacteria infecting nematodes,it showed that the immune response also has the specificity depending on the different types of pathogenic bacteria.Altogether,the innovations of our research include:1.A comprehensive multi-omics analysis method is firstly used to describe the virulence factors used by B16 in different stages of bacterial pathogenesis,as well as the defense genes of the host C.elegans.2.Our work confirmed that the different types and the different numbers of immune genes are activated during the host C.elegans resistance to pathogenic bacteria B16,and an interaction existed among those immune genes.