Salmonella has demonstrated considerable potential as a vaccine vector,exhibiting robust immunogenicity,ease of oral administration,and cost-effective production.Live attenuated Salmo-nella carrying heterologous antigens can induce both localized mucosal immunity and systemic a-daptive immune responses in hosts after successfully reaching the intestinal tract via oral delivery.Recent advances such as permanent deletion of virulence genes,regulated-delayed attenuation and lysis systems,have initially achieved a balance between the safety and immunogenicity of these vaccine platforms.Nevertheless,practical applications of such vaccine vectors remain constrained by challenges related to gastrointestinal barrier obstruction,inefficient antigen delivery,and im-mune tolerance.With the rapid advancement of multidisciplinary technologies,these limitations are anticipated to be progressively addressed.This review presented a comprehensive summary and dis-cussion of the immune mechanisms,development strategies,current applications,advantages,and challenges associated with oral live attenuated Salmonella vaccine vectors.It also delineated the fu-ture direction of research and development,with a view to providing theoretical references for re-lated research.

To construct a safe and effective multi-epitope vaccine against the S1 protein of chicken infectious bronchitis virus(IBV).In this study,homologous and non-homologous dominant epitopes of IBV M41,T,QX and H120 virulent strain S1 proteins were screened by various online bioprediction software,respectively,and a new peptide W with high immunogenicity was construc-ted by connecting the screened B-cell and T-cell epitopes with a linker peptide.W was ligated to the truncated sequence of the four viral strains by T2A yietding to the eukaryotic expression vector pEGFP-N1,and it was identified by PCR and double digestion,the obtained recombinant plasmid was transfected into HEK293A cells and target protein expression was measured by Western blot.The constructed plasmid was injected intramuscularly twice to detect the antibody level,cytokine level,and peripheral blood T cell subsets were detected after two immunizations.The epitope pro-tein W was successfully constructed,which was structurally stable,antigenic,and soluble;the re-combinant plasmid pEGFP-WMQtH,pEGFP-W,and pEGFP-MQtH matched the expected size;anti-IBV IgG antibody levels in pEGFP-N1 was increased greatly compared to the PBS group.cyto-kines IL-2,and γ interferon(IFN-γ)were increased greatly(P＜0.05);peripheral blood CD4+/CD8a value(P＜0.05)was increased greatly.The W epitope protein was successfully constructed,which can effectively activate the humoral immunity and cellular immunity against four infectious bronchitis viruses(IBV),laying a foundation for the development of an effective vaccine against IB.

In order to the phage therapy for Clostridium perfringens(Cp),Cp was used as the host bacterium to screen specific phages from sewage collected from a large-scale beef cattle farm in a region of Shandong Province.Transmission electron microscopy was utilized to observe the mor-phological structure of the phages.Their characteristics were analyzed through the optimal multi-plicity of infection(MOI),host range,one-step growth curve,and antibacterial experiments.The re-sults showed that one phage was successfully isolated from 18 sewage samples.The plaque was transparent without a halo,exhibiting a broad host range and no lytic reaction with other tested bacteria.The optimal MOI was 0.1,and the phage entered the burst phase in 30 min.The phage maintained high titers at pH3-13 and remained active after treatment at 60℃ for 60 min,demon-strating good stability.Mice were infected with CP and treated with bacteriophage.Animal experi-ments showed that the isolated bacteriophage had a significant inhibitory effect on CP.The results indicated that the isolated phage,designated vB-CpP-Bp7,was a virulent phage with excellent lytic capability,acid-base stability,and thermal stability,laying a foundation for further application of this phage in phage therapy.

Goose astrovirus(GAstV)has become one of the most important pathogens endangering the goose farming industry in China.To discover the genomic information of prevalent strains in China in 2022 and reveal their biological characteristics,the whole genomes of 9 strains of GAstV-1 and 12 strains of GAstV-2 isolated from parts of China in 2022 were sequenced by the Chromo-some Walking and analyzed by bioinformatics software and websites.The analysis results of gene structure showed that the sizes of the coding genes ranged from 6 977 to 7 215 bp.The open read-ing frame 1(ORF1)of all strains contained the characteristic motifs of serine protease,nuclear lo-calization signal(NLS)and RNA-dependent RNA polymerase(RdRp).The ribosomal frameshift signals(RFS)were all in the form of stem-loop structures.However,the numbers of stem and loop nucleotides in GAstV-1 were"14+11"configuration,while those in GAstV-2 were"12+14"configuration,and the loop of GAstV-2 was in the"8+6"double-loop configuration.The results of homological analysis for ORF1b showed that the homology of the GAstV-1 isolats compared with the representative strains of avian astrovirus types 1,2,and 3(AAstV-1,AAstV-2,AAstV-3)ranged from 7％to 64％,and the homology of the GAstV-2 isolates ranged from 8％to 68％.The average genetic distances of ORF2 were 0.9,1.2,and 0.9 respectively compared with the represent-ative strains of AAstV-1,AAstV-2 and AAstV-3.While for the GAstV-2 isolates,the highest ho-mologies were 68％and 56％,the lowest homologies were 8％and 36％respectively.And the aver-age genetic distances of ORF2 were 1.0,1.2,and 0.5 respectively.B-cell-conformational epitopes screening results of ORF2 showed that,there were four common epitopes in the GAstV Group 1 i-solates,namely PRE,LALQSQSVNTFA,AAG and YQQVTSDQSI except for N-145,N-287 and N-314 in the two strains G1FJ267 and G1JS277.And there were seven common conformational epitopes in the GAstV-2 isolates,namely NQE,RAN,GPE,PRQ,TRAQ,SNS,and AVPPNTPL except for N-83,N-136,N-331 and N-351 in the strain G2FJ283-3B.The above results indicated that GAstV maybe belong to a new type of AAstV because of the difference between the clinical i-solates and the known strains of AAstV.And there was pathogenic diversity among the isolates.All the isolates of GAstV-1 and GAstV-2 belong to two different serotypes,and the possible serologi-cal subtypes among the isolates of GAstV-1 or GAstV-2 are remained to be further identified by serological tests.

Silver nanoparticles(AgNPs)are employed as disinfectants due to their extensive antimi-crobial properties,but their biosafety in the livestock industry has not been comprehensively as-sessed.In this study,16 Black-skin Red-crowned chickens aged 32 weeks were randomly divided in-to four groups and sprayed with AgNP solution at the concentration of 0,0.064,0.128 or 0.256 g/L,respectively,every 72 h in their coops for 30 d.The effects of AgNPs as the disinfectant on lung tissue in chicken were investigated through calculation of organ coefficients,observation of lung tissue sections,analysis of bronchoalveolar lavage fluid,measurement of inflammatory factors,de-tection of silver residue in lung tissue,and exploration of signaling pathways in pulmonary fibrosis.The results indicated that chickens in the 0.128 and 0.256 g/L AgNPs treatment groups showed the blurred pulmonary lobule boundaries,the destroyed alveolar structure,and the significant in-crease in pulmonary fibrosis.These pathological changes were accompanied by the decrease in lung organ coefficient,the reduced SP-C content,the increased total protein concentration in lavage flu-id,and the elevated LDH and silver content in lung tissue.The levels of IL-6 and TNF-α in the 0.128 and 0.256 g/L AgNPs treatment groups were significantly higher than the control group,which suggested that AgNPs exposure could induce the pulmonary inflammatory responses.High concentrations of AgNPs can trigger pulmonary tissue fibrosis,damaging the structure and func-tions of lungs.The relative mRNA expression levels of NF-κB in all AgNPs treatment groups,TGF-β in the 0.128 g/L AgNPs treatment group,and Smad3 in the 0.128 and 0.256 g/L AgNPs treatment groups were significantly higher than these in the control group,respectively.Spraying chickens with 0.128 or 0.256 g/L AgNPs for disinfection led to pulmonary deposition of AgNPs,causing direct structural and functional damages to the lungs.It could also induce the chronic pul-monary inflammation through the NF-κB pathway and promote the TGF-β/Smad3 pathway to in-crease collagen synthesis,leading to pulmonary fibrosis.Therefore,the application of high concen-trations of AgNPs in livestock farming requires careful consideration of their potential biological safety issues.

The objective of this study was to investigate whether Stenotrophomonas maltophilia(S.maltophilia)induces ferroptosis,a form of iron-dependent cell death,leading to an inflamma-tory response in RAW 264.7 macrophages by elevating oxidative stress levels.RAW 264.7 cells were stimulated with varying concentrations of S.maltophilia.The concentrations of TNF-αand IL-1β were quantified using ELISA kits to assess the impact of S.maltophilia on the inflammatory response in RAW 264.7 cells.The activities of glutathione(GSH)and malondialdehyde(MDA)levels were measured using GSH and MDA assay kits to evaluate changes in oxidative stress.West-ern blot analysis was employed to detect the expression levels of COX-2,xCT,GPX4,and other proteins involved in ferroptosis signaling pathways,thereby investigating the effect of S.malto-philia on ferroptosis in RAW 264.7 cells.The results demonstrated that S.maltophilia induced concentration-dependent increases in inflammation and oxidative stress in RAW 264.7 cells,up-regulated the expression of COX-2 protein and down-regulated the expression of xCT and GPX4.Pretreatment with the ROS inhibitor N-acetylcysteine(NAC)significantly mitigated the S.malto-philia-induced oxidative stress and ferroptosis signaling activation,thereby alleviating the inflam-matory response.Furthermore,treatment with the ferroptosis inhibitor Fer-1 directly suppressed the activation of the ferroptosis signaling pathway and reversed the inflammation induced by S.maltophilia.These findings suggest that S.maltophilia triggers inflammation in RAW 264.7 cells by activating the ferroptosis signaling pathway via an increase in oxidative stress levels.

In order to study whether there is a direct interaction between the key variant gene(AP-PV-YN-Mut)protein of atypical porcine pestivirus(APPV)Yunnan strain and the host protein signal sequence receptor subunit 4(SSR4),the physical and chemical properties,spatial structure and subcellular localization of SSR4 protein were analyzed and predicted using online software such as ProtParam,PredictProtein and TMHMM.The recombinant vectors pCMV-Tag4A-SSR4 and pET-GST-Mut were constructed for GST pull-down test in vitro.The recombinant vectors pBiFC-VN173-SSR4 and pBiFC-VC155-Mut were constructed and the bimolecular fluorescence comple-mentary test(BiFC)was performed in cells to verify whether there was direct interaction between APPV-YN-Mut and host protein SSR4 in vitro and in cells.The results showed that SSR4 protein was a hydrophobic stable protein with no transmembrane structure and signal peptide.The second-ary structure was mainly irregular curl,and the tertiary structure was stable,mainly located in the endoplasmic reticulum.GST pull-down and BiFC experiments showed that APPV-YN-Mut interac-ted directly with host protein SSR4 in vitro and in cells.

The synthetic PDCoV N protein gene was optimized and cloned into the pET-30a vector to obtain the pET-30a-N plasmid.Thenthe recombinant plasmid was transformed into three strains of BL21 E.coli using heat-shock to explore protein expression conditions.The expressed proteins was purified using Ni Focurose 6FF(IMAC)and used as antigen to immunize the New Zealand White rabbit to prepare the polyclonal antibody against the PDCoV N protein.The antibody titer was measured by indirect ELISA method.The specificity for the antibody was identified by West-ern blot and indirect immunofluorescence(IFA).The results showed that the pET-30a-N plasmid showed high expression level in BL21 StarTM(DE 3).The optimal expression condition was 37 ℃ 4 h.The purity of the target protein could reach 90.3％after purification.Indirect ELISA showed that the antibody titers was up to 1∶204 800.Western blot and IFA showed that the produced rabbit polyclonal antibody exhibited good specificity.In conclusion,the polyclonal antibody was prepared which specifically recognized the PDCoV N proteins.The results provided some references for the subsequent exploration of PDCoV N protein function and laid a foundation for establishing a diag-nostic method for PDCoV.

Cell is the most basic unit of life,and normal metabolism is the key to cell growth and development.Reactive oxygen species(ROS)are important regulators of cell function,and hypoxi-a-inducible factor-1 alpha(HIF-1α)is a ROS receptor,which can activate transient receptor poten-tial vanilloid(TRPV)channel.TRPV is a sensor for temperature,pain,and osmotic pressure.Changes in the environment can induce changes in the activity of TRPV channel,which regulates various physiological and pathological processes of cells through its downstream signaling path-ways.Low temperature plasma can regulate cellular TRPV channel activity through HIF-1α.This article mainly reviews the effect of HIF-1α on cell function through TRPV channel,which has ref-erence significance for future research on various diseases related to TRPV channel and their pre-vention and treatment,as well as provides a new idea for using low temperature plasma technology to treat diseases through regulating TRPV channel.

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.