To elucidate the genomic characteristics of Salmonella strains derived from sheep,this study employed various methods,including bacterial isolation and identification,biochemical identi-fication,pathogenicity test,whole-genome sequencing,and BLAST comparison,along with the screening of integrative conjugative elements(ICE)using ICEfinder and EasyFig for comparative analysis,as well as plasmid comparisons utilizing PlasmidBrig.The results revealed the isolation of a Gram-negative,non-spore-forming bacillus from nasal swabs of diseased sheep,which formed gray-white,smooth-surfaced,and neatly edged circular colonies on TSA sheep blood agar.On XLT-4 agar medium,it produced smooth-surfaced,white,circular colonies.The bacterium was identified as Salmonella enterica through 16S rRNA sequencing and biochemical identification.This bacteri-um induces hemorrhaging in the intestines of guinea pigs,resulting in their demise within a 48-hour period.The pathogen exhibits high virulence.Whole-genome alignment demonstrated a high degree of homology with Salmonella enterica subsp.diarizonae serotype 61:k:1,5,(7).ICE screen-ing and comparative analysis indicated the presence of a novel ICE in this strain,characterized by a core structural framework that includes an integrative shear module,a mobilizable processing mod-ule,a conjugative pair formation module,and a regulatory module.Notably,ICE from different spe-cies containing the same integrase exhibited identical inverted repeat sequences and insertion sites at tRNAPhe.Plasmid homology comparisons revealed that plasmid sequences from different strains of Salmonella enterica subsp.diarizonae serotype 61:k:1,5,(7)also showed high homology;however,the homology with plasmid sequences from other Salmonella and Escherichia coli strains was only 50％.These findings indicate that the isolated strain is Salmonella enterica subsp.diarizonae serotype 61:k:1,5,(7)and contains a novel ICE as well as a plasmid.This study fur-ther enriches the molecular epidemiology of Salmonella and provides a theoretical basis for the prevention and control of infections caused by this pathogen.

pAPN is a zinc-dependent metalloprotease,mediating the fusion between virus and host cell,and playing a role as the receptor of coronavirus.To explore the effect of pAPN on PEDV rep-lication,the full-length pAPN gene was amplified from the porcine small intestinal by PCR,and was cloned into the lentiviral vector via the homologous site digested with BamH Ⅰ and Not Ⅰ to obtain the recombinant lentiviral vector PLVX-pAPN-mCMV-ZsGreen1-puro.The recombinant lentiviral vector and helper plasmids pLP1,pLP2,pLP-VSVG were co-transfected into 293T cells for lentiviral packaging.Vero cells were infected with the packaged lentivirus and the pAPN gene overexpressing cells were screened by puromycin.The stable expression of Vero-pAPN monoclonal cell line was screened by a limited dilution method,and the effect of the cell line on the replication of PEDV was determined by qPCR for N mRNA transcription level,Western blot for N protein level,and TCID50.The results showed that the packaged lentivirus could infect Vero cells,and the monoclonal cell line Vero-pAPN(2C5)could stably expressed pAPN.The Vero-pAPN cell line can promote the replication of PEDV,the N gene mRNA transcription level was significantly different at 12-48 h(P＜0.05),the N protein expression level increased,and the TCID50 was significantly different at 24 and 48 h(P＜0.05).In conclusion,the Vero-pAPN cell line was constructed in this study and it can significantly promote the replication of PEDV,which provides a candidate cell line for PEDV vaccine production and isolation.

To elucidate the genomic characteristics of Salmonella strains derived from sheep,this study employed various methods,including bacterial isolation and identification,biochemical identi-fication,pathogenicity test,whole-genome sequencing,and BLAST comparison,along with the screening of integrative conjugative elements(ICE)using ICEfinder and EasyFig for comparative analysis,as well as plasmid comparisons utilizing PlasmidBrig.The results revealed the isolation of a Gram-negative,non-spore-forming bacillus from nasal swabs of diseased sheep,which formed gray-white,smooth-surfaced,and neatly edged circular colonies on TSA sheep blood agar.On XLT-4 agar medium,it produced smooth-surfaced,white,circular colonies.The bacterium was identified as Salmonella enterica through 16S rRNA sequencing and biochemical identification.This bacteri-um induces hemorrhaging in the intestines of guinea pigs,resulting in their demise within a 48-hour period.The pathogen exhibits high virulence.Whole-genome alignment demonstrated a high degree of homology with Salmonella enterica subsp.diarizonae serotype 61:k:1,5,(7).ICE screen-ing and comparative analysis indicated the presence of a novel ICE in this strain,characterized by a core structural framework that includes an integrative shear module,a mobilizable processing mod-ule,a conjugative pair formation module,and a regulatory module.Notably,ICE from different spe-cies containing the same integrase exhibited identical inverted repeat sequences and insertion sites at tRNAPhe.Plasmid homology comparisons revealed that plasmid sequences from different strains of Salmonella enterica subsp.diarizonae serotype 61:k:1,5,(7)also showed high homology;however,the homology with plasmid sequences from other Salmonella and Escherichia coli strains was only 50％.These findings indicate that the isolated strain is Salmonella enterica subsp.diarizonae serotype 61:k:1,5,(7)and contains a novel ICE as well as a plasmid.This study fur-ther enriches the molecular epidemiology of Salmonella and provides a theoretical basis for the prevention and control of infections caused by this pathogen.

pAPN is a zinc-dependent metalloprotease,mediating the fusion between virus and host cell,and playing a role as the receptor of coronavirus.To explore the effect of pAPN on PEDV rep-lication,the full-length pAPN gene was amplified from the porcine small intestinal by PCR,and was cloned into the lentiviral vector via the homologous site digested with BamH Ⅰ and Not Ⅰ to obtain the recombinant lentiviral vector PLVX-pAPN-mCMV-ZsGreen1-puro.The recombinant lentiviral vector and helper plasmids pLP1,pLP2,pLP-VSVG were co-transfected into 293T cells for lentiviral packaging.Vero cells were infected with the packaged lentivirus and the pAPN gene overexpressing cells were screened by puromycin.The stable expression of Vero-pAPN monoclonal cell line was screened by a limited dilution method,and the effect of the cell line on the replication of PEDV was determined by qPCR for N mRNA transcription level,Western blot for N protein level,and TCID50.The results showed that the packaged lentivirus could infect Vero cells,and the monoclonal cell line Vero-pAPN(2C5)could stably expressed pAPN.The Vero-pAPN cell line can promote the replication of PEDV,the N gene mRNA transcription level was significantly different at 12-48 h(P＜0.05),the N protein expression level increased,and the TCID50 was significantly different at 24 and 48 h(P＜0.05).In conclusion,the Vero-pAPN cell line was constructed in this study and it can significantly promote the replication of PEDV,which provides a candidate cell line for PEDV vaccine production and isolation.