The purpose of this study is to develop a shark single domain antibody(SdAb)targeting a unique B cell epitope in the SARS-CoV-2 spike protein,and explore its role in the immunological detection targeting SARS-CoV-2 spike protein S.A u-nique peptide S9 was artificially synthesized based on the sequence of a unique B cell epitope of SARS-CoV-2 spike protein,then it was conjugated to the carrier protein KLH.It was used as an immunogen for subcutaneous injection into shark back and boosted according to the standard immunization protocol.Blood collected from shark tail vein and peripheral blood lymphocytes(PBL)were isolated.Total RNA was purified from PBL and transcribed to cDNA by reverse transcription.Shark vNAR frag-ments were amplified from cDNA templates and cloned into pComb3XSS vector to obtain phage library.A positive clone named T01 was obtained through screening the phage library by indirect ELISA.Then its gene was cloned into the expression vector pET-28a.The SdAb T01 was then prokaryotically expressed and purified,and its specific recognition of the SARS-CoV-2 spike protein S was indentified by Western-blot(WB),indirect ELISA and IF A.T01 binds well with peptide S9 at EC50 value of 2.050±0.064 nmol/L.The purified SdAb T01 was proven by WB to be able to selectively detect recombinant spike protein sub-unit 1(S1)of SARS-CoV-2,with no cross-reactive to recombinant spike protein subunit 1 of other six human coronavirus.It was showed by ELISA that SdAb T01 can sensitively detect the recombinant N terminal domain(NTD)of SARS-CoV-2 pro-tein.Moreover,it also specifically recognizes the spike protein of SARS-CoV-2 that was transiently expressed in transfected HEK293 cells by IFA.Therefore,a shark single domain antibody targeting a unique B cell epitope in the spike protein of SARS-CoV-2 was successfully developed,and has shown potential immunodiagnostic value by WB,ELISA and IFA.Thus,it provides an effective tool for unique antigen detection of SARS-CoV-2.

This study was aimed at developing an in vitro fluorescent substrate assay for the activity of leucyl aminopeptid-ase(LAP)from Echinococcus multilocularis and comparing it with the chemical chromogenic substrate enzyme activity assay.Through the establishment of reaction conditions for the fluorescent substrate-based in vitro enzyme activity assay,we com-pared the differences between the fluorescent substrate L-Leucine-7-amido-4-methylocoumarin(Leu-AMC)and the chemical chromogenic substrate L-Leucine-4-nitroanilide(Leu-pNA)through molecular docking,inhibition rates,and precision measures.Molecular docking revealed that the fluorescent substrate Leu-AMC had higher affinity for the protein than the chemical chromogenic substrate Leu-pNA.Through analysis of the effects of varying reaction conditions on fluorescence intensi-ty,we optimized the fluorescent substrate enzyme activity assay to demonstrate favorable performance at a reaction temperature of 37℃,a pH of 9.0,a protein concentration of 800 nmol/L,and a reaction duration of 60 minutes.Leu-AMC exhibited significant and distinct responses at a 5 μmol/L substrate concentration,under varying substrate conditions.The fluo-rescent substrate assay demonstrated more significant intergroup differences than the chemical chromogenic substrate assay when various inhibitors were added.This study established a fluorescence-based enzyme activity assay for leucyl aminopeptidase from Echinococcus multilocularis by using Leu-AMC as the substrate;this method demonstrated a more significant intergroup difference and sensitivity than the chemical chromogenic substrate assay.

As the world's second largest vector of pathogens,ticks can spread a variety of pathogens by sucking the host's blood.Ticks not only threaten human life and health,but also cause great economic losses in animal husbandry.Artificial breeding of ticks can provide a stable environment for the growth and reproduction of ticks,thereby generating sufficient exper-imental materials for understanding ticks'biological characteristics,studying tick-borne pathogens,and developing anti-tick drugs and vaccines.Current methods of breeding ticks in the laboratory can be roughly divided into two categories:breeding methods using host animals or artificial membranes.The selection of breeding method must be comprehensively considered,ac-cording to tick types,blood-sucking habits,living environments,and other aspects.The development processes of the two methods,and their respective advantages and disadvantages,are described and discussed,to assist laboratories in artificial breeding of ticks.

Malaria,an ancient disease caused by Plasmodium pathogens,poses a serious threat to human health.The body resists and suppresses Plasmodium invasion through two types of immune response:innate immunity and adaptive immunity.Innate immune cells and the cytokines that they produce constitute the first line of defense against foreign pathogens,whereas adaptive immunity has antimalarial effects primarily through humoral and cellular immunity.Rodent models of Plasmodium in-fection are suitable for studying the mechanism of malaria pathogenesis;therefore,exploring the effects of various rodent para-site types on the immune response in mice can advance understanding of malaria and provide research directions for the develop-ment of new treatment targets.This review summarizes various types of rodent Plasmodium parasites;immune cells and their cytokines acting during the immune response;and new targets for malaria treatment,in hopes of enhancing understanding of the immune response to malaria and exploring new directions in malaria treatment.

Albendazole-glucan particles(ABZ-GPS)and abendazole(ABZ)were used to treat secondary alveolar echinococ-cosis in mice.The therapeutic effects of ABZ-GPS on alveolar echinococcosis in vivo were evaluated,and the feasibility of using glucan particles as anti-hydatid drug carriers was further verified.Mice with echinococcosis were randomly divided into an ABZ group,glucan nanoparticle(GP)group,ABZ-GPS group,and control group.After four courses of administration with a final concentration of 50 mg/mL,the therapeutic effects of ABZ-GPS were evaluated on the basis of imaging,histopathological changes,ultrastructure,and immunology.After ABZ-GPS and ABZ administration,clear liver lesion tissue necrosis and large numbers of infiltrating lymphocytes were observed.Significant differences in the average cyst wet weight(t=7.83,P＜0.05),were observed between the ABZ-GPS group and ABZ group.Imaging revealed that ABZ-GPs were targeted to liver tissue.Pa-thology and ultrastructure analyses demonstrated that the alveolar hydatid cells in the liver in the control group and GP group grew well,and the vesicles were large,filled with cystic fluid,and translucent or transparent;the cyst wall tension was high;no calcification was observed;the stratum corneum and germinal layer were clear;and more fertile capsules and different num-bers of protocephalospora were present in the liver.In the ABZ group,the capsular cavity collapsed,and showed partial necro-sis and lymphocyte infiltration.In the ABZ-GP group,the corneum and germinal layer of echinococcus vesicles were difficult to identify,and we observed bulbous necrosis,central calcification,fibrous tissue hyperplasia,inflammatory cell infiltration,coarser,shorter or absent microvilli of the germinal layer,nuclear shrinkage,dissolution or disappearance,clear expansion of cytoplasmic microtubules,and myelin-like or vacuole-like changes.Therefore,ABZ-GPs showed good targeting and killing ac-tivity in vivo in mice with secondary alveolar coccosis.

To investigate the phenotype and genomic characterization of a mucoid-type Salmonella Saintpaul ST50 isolate from a urinary tract infection patient,promoting clinical diagnosis and treatment for urinary tract infections caused by Salmo-nella spp.Culture-based quantitative counts of midstream urine sample from the patient were conducted,and further biochemi-cal identification,mass spectrometry detection,serum agglutination test and antimicrobial susceptibility test(AST)were con-ducted on Salmonella isolate(2024JD5).Whole-genome sequencing(WGS)was performed on isolate 2024JD5 to predict sero-type,multilocus sequence type(MLST),resistance genes,and virulence genes.Two smooth-type of Salmonella Saintpaul ST50 were selected as comparative genomic reference strains from the Chinese local Salmonella genome database.The literature reviews of global Salmonella serotype of urinary tract infection were summarized.Specific serum agglutination confir-mation of isolate 2024JD5 failed due to characterization of the mucus type.The strain 2024JD5 was predicted as Salmonella Saintpaul(4,5,12:e,h:1,2)ST50 using WGS,and was resistant to ciprofloxacin,nalidixic acid,chloramphenicol and tetracy-cline with carrying aminoglycoside resistance genes aac(6')-Ⅰaa and aph(3)-Ⅱa,chloramphenicol resistance gene floR,tetra-cycline resistance gene tet,quinolone resistance gene qnrS1,and S83Y substitution in the gyrA gene was found in the quinolo-ne resistance determination region(QRDR).In addition,the strain 2024JD4 carried six types of non-plasmid-based mobile ge-netic elements and 144 virulence genes,including 71 secretion transporter genes and 58 fimbriae adhesion genes,respectively.Four types of fimbriae regulatory genes(csgB,csgC,fimW,fimY)were absent in comparison with smooth-type Salmonella Saintpaul.The literature reviews showed Salmonella Saintpaul was currently a rare Salmonella serotype in cases of urinary tract infections worldwide.Salmonella Saintpaul ST50 with mucoid-type is the pathogen of urinary tract infection with multi-drug resistant phenotypic and genotypic characteristics,and the high mucoid expression may be related to the compensatory mechanism of fimbriae regulatory genes absence in urinary tract colonization and adaptation.WGS combined with the Chinese local Salmonella genome database can effectively solve the diagnosis and biosafety assessments of rare Salmonella phenotypes.

Bovine rotavirus(BRV)is an important pathogen causing diarrhea in calves.To understand the genomic charac-teristics and genetic variations in bovine rotavirus,and to further enrich data on the biological characteristics of rotavirus,we aimed to amplify 11 gene segments of the isolated and cultured G6P[1]bovine rotavirus BLL strain,perform whole genome se-quencing,and analyze the molecular characteristics.MEGA7.0 and DNAMAN software were used for homology and typing a-nalysis,and the whole genome phylogenetic tree was constructed to analyze genetic evolution relationships.The complete geno-type of the BLL strain was G6-P[1]-I2-R2-C2-M2-A3-N2-T6-E2-H3.Phylogenetic analysis of the VP7 and VP4 genes of the BLL strain showed that the VP7 gene had the highest homology with RVA/Cow-wt/HB01/China/2021,and the VP4 gene of the BLL strain was in the same branch as RVA/Human-tc/ISR/Ro8059/1995.From the sequence alignment of VP8*amino acids,the sialic acid domain of the BLL strain was found to be similar to that in other P[1]strains,but different from those in other types of strains,except for residue 189,which was the same as that in Ro8059 but different from that in other strains.The results suggested that the BLL strain might potentially infect humans.Therefore,continued monitoring and study of the biological characteristics of this strain are necessary to provide more information and evidence supporting further research on the cross-species transmission of group A rotavirus in China.

This study was aimed at understanding the relationships among the drug resistance and genome characteristics of group A Streptococcus in Jiangsu Province.A total of 149 group A Streptococcus strains were collected from hospitals between 2016 and 2023.Thirteen antimicrobial minimal inhibitory concentrations were detected with the micro-dilution broth method.The GAS strains were typed with emm genotyping analysis and whole genome sequencing,to determine the carriage rates of drug resistance genes and the evolutionary relationships among strains.The resistance rates of 149 GAS strains to erythromy-cin,tetracycline,and clindamycin exceeded 90％,whereas the strains showed sensitivity to 8 different antibiotics,including penicillin.Notably,the resistance rates to erythromycin,tetracycline,and clindamycin consistently increased over time.All strains were classified into 9 emm types,among which emm12 accounted for the highest proportion(77/149;51.68％).Signifi-cant statistical differences were observed among emm types,in terms of the drug resistance rate,number of resistant species,and prevalence of drug resistance genes.Furthermore,SNP evolutionary tree analysis revealed 3 distinct clusters within the GAS strains:emm12,emm1,and other emm types.emm 12 and emm1 were the dominant GAS strains in Jiangsu Province.Most isolates were resistant to erythromycin,tetracycline,and clindamycin.Differences in phenotypes and genomic characteris-tics were observed among emm types.

Blood from a case of group B epidemic cerebrospinal meningitis identified in February 2024 in Ganzhou City,Jiangxi Province,and throat swabs from close contacts were collected for isolation and culture.The isolates were subjected to serogrouping,drug sensitivity testing,and whole genome sequencing and analysis,to provide a basis for epidemiological inves-tigation and clinical drug use.One strain of Neisseria meningitidis was isolated from the blood of the case and denoted group B.The MLST type was ST-7962,with no clonal group attribution.The phylogenetic tree showed that it was genetically close to the 1977 Shanghai carrier isolate(id-52231).Drug sensitivity results indicated that the strain was sensitive to 8 drugs:azithro-mycin,cefotaxime,minocycline,ceftriaxone,chloramphenicol,meropenem,rifampicin,and benzylpenicillin;resistant to cot-rimoxazole,levofloxacin,and ciprofloxacin;and showed an intermediate response to penicillin.This report describes the first case of ST-7962 group B meningoencephalitis found in Jiangxi Province.Monitoring of Neisseria meningitidis carriage,drug re-sistance,and molecular characteristics of strains in the healthy population in this region should be strengthened,to provide la-boratory support for the clinical use of medications,traceability,and control of the pathogen underlying meningoencephalitis infection.

This study was aimed at tracing the molecular typing and drug resistance characteristics of a suspected food poi-soning event caused by Clostridium perfringens in a district of Wuhan City.The FilmArray detection system and multiple fluo-rescence quantitative PCR methods were used to rapidly screen for pathogens in samples from the poisoning event.According to the initial screening results,bacteria were isolated,cultured,and identified by mass spectrometry.Fluorescence PCR was used to detect six virulence genes of the isolated Clostridium perfringens strains.On the basis of whole genome sequencing results,we conducted virulence genes,resistance genes,and whole genome single nucleotide polymorphism genetic evolution(wgSNPs)analyses.Antibiotic sensitivity testing was conducted with the agar dilution method.A total of ten strains of Clos-tridium perfringens were isolated,including eight strains from seven anal swab samples,one strain from fecal samples,and one strain from food samples.Food with suspected contamination had a Clostridium perfringens count of 7.8×106 CFU/g.The PLC(a)toxin gene was detected in all ten gas producing capsule isolation strains,but no other 5 tox-in genes such as CPE were detected,thus confirming that all were type A bacteria producing capsule Clostridium.All strains were 100％resistant to clindamycin and almost completely sensitive to antibiotics such as vancomycin,cefoxitin,and meropenem.Ten strains of Clos-tridium perfringens carried resistance genes such as tetB(P),tetA(P),and mprF,followed by ermQ(70％),ant(6)-Ⅰb(10％),and LnuP(10％).Genetic evolution analysis of wgSNPs indicated that the four outbreak strains clustered together and belonged to an independent subbranch with the suspected food sourcestrains,thus indicating close genetic relationships.In con-clusion,this food poisoning incident might have been be caused by hand torn chickens contaminated with Clostridium perfrin-gens,and the molecular types of the strains revealed high genetic diversity.No multiple drug resistance was observed,but all strains were resistant to clindamycin,an aspect requiring further clinical attention.