The structure and potential antigenic epitopes of FliCEcN were analysed using bioinformat-ics technology.With the help of ClonExpress? homologous recombination technology,primers were designed to deletion of different structural domains in the highly variable region of FliCEcN and cloned into pET-28a(+)expression vector for expression.The expressed flagellin variants were identified by SDS-PAGE and Western blot.Endotoxin residues in the flagellin variants were detected by horseshoe crab reagent chromatography,and Caco-2 cells were stimulated with differ-ent concentrations of flagellin variants.The biological activity of each flagellin variant was assessed by detecting the secretion level of IL-8.Bioinformatic analysis showed that most of the structural domains in the highly variable region of FliCEcN were predicted to contain potential antigenic epitopes.PC R results showed that fliC△820-1 518,fliC△736-963,fliC△985-1 200,fliC △748-828,fliC△1 114-1 191,andfliC△1 225-1311 were approximately 1 095,1 566,1 578,1 713,1 716 and 1 707 bp,respectively.SDS-PAGE results showed that the sizes of the flagellin variants treated with nickel column purifi-cation and dialysis replication were about 41.36,57.06,57.50,61.97,61.95 and 61.56 kDa,respec-tively.Western blot results showed that all six flagellin variants reacted specifically with anti-His monoclonal antibody and E.coli H7 antigen diagnostic serum.The results of TLR5 activity assay showed that the flagellin variants missing different structural domains retained their TLR5 agonist function.In this study,six flagellin variants with different structural domains of FliCEcN deletion hypervariable region were successfully constructed,and all of them retained their TLR5 agonist function and showed good biological properties.This provides a reference for further research on the adjuvant effect of flagellin after deletion of different structural domains and the effect of flagel-lin antibody titer on its adjuvant effect.

The 16S rRNA sequencing,whole genome sequencing and drug sensitivity tests were used to identify the isolates molecularly and to detect and analyse their virulence genes,resistance genes and drug resistance.The results showed that the isolate was highly homologous to Klebsiella pneumoniae X4 and located on the same branch by 16S rRNA sequence analysis,and it was named as KLKp10.Whole genome sequencing results showed that the KLKp10 genome was 5 342 841 bp in length,containing 5 138 genes,346 repetitive segments,6 rRNAs and 81 tRNAs,with a GC con-tent of 57.30％.MLST analysis showed that KLKp10 belongs to the ST-4263 type.The functions of 4 097 of the genes encoding proteins were classified and annotated by COG,and there were also 382 genes with unknown functions.A total of 50 functional classifications were involved in the an-notation results based on the GO database;33 kinds of signaling pathways were covered based on the signaling pathway annotations in the KEGG database.A total of 443 virulence genes were screened in the VFDB database,of which 339 belonged to the Set A database and could encode 124 virulence factors.The 101 resistance genes were predicted by comparing with the CARD database,among which there were more resistance genes against β-lactam antibiotics.The results of drug sensitivity test showed that KLKp10 was highly sensitive to ceftazidime,gentamicin,azithro-mycin,chloramphenicol,norfloxacin,ofloxacin,and enrofloxacin;moderately sensitive to ceftriax-one,neomycin,kanamycin,and streptomycin;and resistant to ciprofloxacin,tetracycline,amoxicil-lin,and penicillin.In this study,we systematically revealed the gene-wide characterization,virulence factors and drug resistance of Klebsiella pneumoniae KLKp10 of Kole pig origin,which provides important data support for the study of Klebsiella pneumoniae at the overall level of its genome.

The 16S rRNA sequencing,whole genome sequencing and drug sensitivity tests were used to identify the isolates molecularly and to detect and analyse their virulence genes,resistance genes and drug resistance.The results showed that the isolate was highly homologous to Klebsiella pneumoniae X4 and located on the same branch by 16S rRNA sequence analysis,and it was named as KLKp10.Whole genome sequencing results showed that the KLKp10 genome was 5 342 841 bp in length,containing 5 138 genes,346 repetitive segments,6 rRNAs and 81 tRNAs,with a GC con-tent of 57.30％.MLST analysis showed that KLKp10 belongs to the ST-4263 type.The functions of 4 097 of the genes encoding proteins were classified and annotated by COG,and there were also 382 genes with unknown functions.A total of 50 functional classifications were involved in the an-notation results based on the GO database;33 kinds of signaling pathways were covered based on the signaling pathway annotations in the KEGG database.A total of 443 virulence genes were screened in the VFDB database,of which 339 belonged to the Set A database and could encode 124 virulence factors.The 101 resistance genes were predicted by comparing with the CARD database,among which there were more resistance genes against β-lactam antibiotics.The results of drug sensitivity test showed that KLKp10 was highly sensitive to ceftazidime,gentamicin,azithro-mycin,chloramphenicol,norfloxacin,ofloxacin,and enrofloxacin;moderately sensitive to ceftriax-one,neomycin,kanamycin,and streptomycin;and resistant to ciprofloxacin,tetracycline,amoxicil-lin,and penicillin.In this study,we systematically revealed the gene-wide characterization,virulence factors and drug resistance of Klebsiella pneumoniae KLKp10 of Kole pig origin,which provides important data support for the study of Klebsiella pneumoniae at the overall level of its genome.

The structure and potential antigenic epitopes of FliCEcN were analysed using bioinformat-ics technology.With the help of ClonExpress? homologous recombination technology,primers were designed to deletion of different structural domains in the highly variable region of FliCEcN and cloned into pET-28a(+)expression vector for expression.The expressed flagellin variants were identified by SDS-PAGE and Western blot.Endotoxin residues in the flagellin variants were detected by horseshoe crab reagent chromatography,and Caco-2 cells were stimulated with differ-ent concentrations of flagellin variants.The biological activity of each flagellin variant was assessed by detecting the secretion level of IL-8.Bioinformatic analysis showed that most of the structural domains in the highly variable region of FliCEcN were predicted to contain potential antigenic epitopes.PC R results showed that fliC△820-1 518,fliC△736-963,fliC△985-1 200,fliC △748-828,fliC△1 114-1 191,andfliC△1 225-1311 were approximately 1 095,1 566,1 578,1 713,1 716 and 1 707 bp,respectively.SDS-PAGE results showed that the sizes of the flagellin variants treated with nickel column purifi-cation and dialysis replication were about 41.36,57.06,57.50,61.97,61.95 and 61.56 kDa,respec-tively.Western blot results showed that all six flagellin variants reacted specifically with anti-His monoclonal antibody and E.coli H7 antigen diagnostic serum.The results of TLR5 activity assay showed that the flagellin variants missing different structural domains retained their TLR5 agonist function.In this study,six flagellin variants with different structural domains of FliCEcN deletion hypervariable region were successfully constructed,and all of them retained their TLR5 agonist function and showed good biological properties.This provides a reference for further research on the adjuvant effect of flagellin after deletion of different structural domains and the effect of flagel-lin antibody titer on its adjuvant effect.