African swine fever(ASF)caused by African swine fever virus(ASFV)is a febrile,hem-orrhage and highly fatal infectious disease in pigs,which poses a serious threat to the global pig in-dustry.Currently,no vaccine is available for the prevention and control of ASF,and several ASF vaccines,including gene deletion attenuated live vaccines,live vector vaccines,and subunit vaccines are under the development stage in the laboratory research.As one of the most promising vaccines,live vector vaccine has the characteristic of safety and simulation of the pathogen natural infection to effectively stimulate the innate and adaptive immune responses,which becomes one of the hotspots in the research and development of novel ASF vaccines.This review focuses on the pro-gress in using modified viruses as vectors for ASF live vector vaccines,and aims to provide valua-ble information for future development of safe and effective ASF vector vaccines.

African swine fever(ASF)is an acute,febrile,and highly fatal disease caused by African swine fever virus(ASFV)in pigs.Given the current lack of commercial vaccines and the continu-ous evolution of ASFV in recent years,the emergence of moderately virulent genotype Ⅱ strains and the introduction of genotype Ⅰ attenuated strains have led to persistent and chronic infections in pigs.Therefore,the detection of specific antibodies against ASFV has become imperative.In this study,we established a competitive chemiluminescence immunoassay(p30-cCLIA)for detecting ASFV p30 antibodies using p30 monoclonal antibodies.By detecting sera with clear negative and positive backgrounds,we determined that the Cut-off value of this method was 50％,with both di-agnostic sensitivity(Dsn)and diagnostic specificity(Dsp)reaching 100％.Under optimal reaction conditions,we screened out an enzyme-labeled stabilizer suitable for p30 monoclonal antibody 16-5E7E8-HRP.Furthermore,the sensitivity of the established p30-cCLIA method was higher than that of the commercial blocking ELISA kit(1∶2 048 vs 1∶512)and exhibited good repeatability.Detection of sera positive for other porcine virus infections showed no cross-reactivity.The estab-lishment of this method provides a powerful tool for early diagnosis of ASF.

Although no cross protection was observed between different serotypes of foot-and-mouth disease virus(FMDV),there were cross-reactivity between different serotypes of antibodies produced after vaccination,the aim of this paper was to prepare the neutralizing monoclonal anti-body against Foot-and-mouth disease virus(FMDV)serotype O,and to develop the method to dis-tinguish antibody against FMDV serotype O and A based on mAb.The inactivated FMDV serotype O was used as antigen in mAb production,a series of GST fusion overlapping peptides and trun-cated peptides expressed in Escherichia coli were used to identify antigenic epitope recognized by monoclonal antibodies.In order to verify feasibility of the screened monoclonal antibodies in diag-nosis,20 positive serum of FMDV serotype O and A,20 negative serum with known background were detected by blocking ELISA.Results were as follows:five monoclonal antibodies were suc-cessfully screened.The five monoclonal antibodies showed good reactivity with FMDV serotype O,but did not react with FMDV serotype A by Western blot and IFA,these mAbs showed neutrali-zing ability to FMDV/O/MY98/GZBY/2013 by VNT.The same epitope was identified by five monoclonal antibodies,the minimum epitope was145 RGDLQVLA152,Arg145 and Gln149 were key a-mino acids of the epitope.Sequence alignment analysis revealed that the identified epitopes were conserved among most of O type FMDV strains,but Gln149 was mutated among all A,Asia 1 and SAT1-3 type FMDV strains.The mAb-8C5D3 distinguished between antibody of FMDV serotype O and FMDV serotype A by blocking ELISA.The results provided materials for development of O type FMDV antibody detection kit and evaluation of vaccine immune effect.

Although no cross protection was observed between different serotypes of foot-and-mouth disease virus(FMDV),there were cross-reactivity between different serotypes of antibodies produced after vaccination,the aim of this paper was to prepare the neutralizing monoclonal anti-body against Foot-and-mouth disease virus(FMDV)serotype O,and to develop the method to dis-tinguish antibody against FMDV serotype O and A based on mAb.The inactivated FMDV serotype O was used as antigen in mAb production,a series of GST fusion overlapping peptides and trun-cated peptides expressed in Escherichia coli were used to identify antigenic epitope recognized by monoclonal antibodies.In order to verify feasibility of the screened monoclonal antibodies in diag-nosis,20 positive serum of FMDV serotype O and A,20 negative serum with known background were detected by blocking ELISA.Results were as follows:five monoclonal antibodies were suc-cessfully screened.The five monoclonal antibodies showed good reactivity with FMDV serotype O,but did not react with FMDV serotype A by Western blot and IFA,these mAbs showed neutrali-zing ability to FMDV/O/MY98/GZBY/2013 by VNT.The same epitope was identified by five monoclonal antibodies,the minimum epitope was145 RGDLQVLA152,Arg145 and Gln149 were key a-mino acids of the epitope.Sequence alignment analysis revealed that the identified epitopes were conserved among most of O type FMDV strains,but Gln149 was mutated among all A,Asia 1 and SAT1-3 type FMDV strains.The mAb-8C5D3 distinguished between antibody of FMDV serotype O and FMDV serotype A by blocking ELISA.The results provided materials for development of O type FMDV antibody detection kit and evaluation of vaccine immune effect.

African swine fever(ASF)caused by African swine fever virus(ASFV)is a febrile,hem-orrhage and highly fatal infectious disease in pigs,which poses a serious threat to the global pig in-dustry.Currently,no vaccine is available for the prevention and control of ASF,and several ASF vaccines,including gene deletion attenuated live vaccines,live vector vaccines,and subunit vaccines are under the development stage in the laboratory research.As one of the most promising vaccines,live vector vaccine has the characteristic of safety and simulation of the pathogen natural infection to effectively stimulate the innate and adaptive immune responses,which becomes one of the hotspots in the research and development of novel ASF vaccines.This review focuses on the pro-gress in using modified viruses as vectors for ASF live vector vaccines,and aims to provide valua-ble information for future development of safe and effective ASF vector vaccines.

African swine fever(ASF)is an acute,febrile,and highly fatal disease caused by African swine fever virus(ASFV)in pigs.Given the current lack of commercial vaccines and the continu-ous evolution of ASFV in recent years,the emergence of moderately virulent genotype Ⅱ strains and the introduction of genotype Ⅰ attenuated strains have led to persistent and chronic infections in pigs.Therefore,the detection of specific antibodies against ASFV has become imperative.In this study,we established a competitive chemiluminescence immunoassay(p30-cCLIA)for detecting ASFV p30 antibodies using p30 monoclonal antibodies.By detecting sera with clear negative and positive backgrounds,we determined that the Cut-off value of this method was 50％,with both di-agnostic sensitivity(Dsn)and diagnostic specificity(Dsp)reaching 100％.Under optimal reaction conditions,we screened out an enzyme-labeled stabilizer suitable for p30 monoclonal antibody 16-5E7E8-HRP.Furthermore,the sensitivity of the established p30-cCLIA method was higher than that of the commercial blocking ELISA kit(1∶2 048 vs 1∶512)and exhibited good repeatability.Detection of sera positive for other porcine virus infections showed no cross-reactivity.The estab-lishment of this method provides a powerful tool for early diagnosis of ASF.

In order to evaluate the immune effect of the genotype Ⅰ Japanese encephalitis virus prM-E DNA vaccine and the prM-EⅢ fusion protein subunit vaccine on mice using DNA prime-protein boost strategy, the prM-E gene was inserted into the pVAX1 eukaryotic expression vector. The recombinant expression vector prM-E-pVAX1 was constructed as a DNA vaccine for initial immunity, and the recombinant prM-EⅢ fusion protein was obtained using a prokaryotic expression system as a subunit vaccine for enhanced immunity. Thirty two female BALB/c mice aged 4-6 weeks were randomly divided into four groups, and a prM-E-pVAX1 DNA vaccine group, a DNA prime-protein boost immune group, a prM-EⅢ subunit vaccine group, and a pVAX1 vector control group were set up. The specific antibody level in serum was monitored by ELISA, the neutralizing antibody titer was detected by plaque reduction neutralization, and the cellular immune responses induced by different vaccine immune groups were analyzed by cytokine expression abundance and lymphocyte proliferation experiments. The results showed that the neutralizing antibody titers induced by mice immunized with the DNA prime-protein boost strategy were close to that of the group immunized with the single prM-EⅢ subunit vaccine, but significantly higher than that of the group immunized with the single prM-E-pVAX1 DNA vaccine. DNA prime-protein boost strategies induced effective Th1/Th2 immune responses in mouse models, in particular the Th1 cell-mediated immune responses. This study provides a new immune strategy that may facilitate the prevention of Japanese encephalitis.
Animals ; Antibodies, Neutralizing ; Antibodies, Viral ; DNA ; Disease Models, Animal ; Encephalitis Virus, Japanese/genetics* ; Female ; Mice ; Mice, Inbred BALB C ; Vaccines, DNA/genetics* ; Vaccines, Subunit

In order to obtain virus-like particles (VLPs) for prevention of bovine viral diarrhea virus 1 (BVDV-1), the C-E^rns-E1-E2 region was cloned into a pFastBacDaul vector for generating the recombinant Bacmid-BVDV-1 in DH10Bac Escherichia coli. The recombinant baculovirus Baculo-BVDV-1 was produced by transfecting the Sf9 cells with Bacmid-BVDV-1. The expressed protein and the assembled VLPs were determined by immunofluorescence, Western blotting and electron microscopy. Guinea pigs were immunized with inactivated VLPs coupled with the Montanide ISA-201 adjuvant. The immunogenicity of VLPs was evaluated by monitoring the humoral immune response with neutralizing antibody titer determination, as well as by analyzing the cell-mediated immune response with lymphocyte proliferation assay. The protective efficacy of VLPs was evaluated by challenging with 10⁶ TCID₅₀ virulent BVDV-1 strain AV69. The results showed that the recombinant Baculo-BVDV-1 efficiently expressed BVDV structural protein and form VLPs in infected Sf9 cells. The immunization of guinea pigs with VLPs resulted in a high titer (1:144) of neutralizing antibody, indicating an activated cellular immunity. Significantly lower viral RNA in the blood of the post-challenged immunized guinea pigs was observed. The successful preparation of BVDV VLPs with insect cell expression system and the observation of the associated immunogenicity may facilitate further development of a VLPs-based vaccine against BVD.
Animals ; Antibodies, Viral ; Diarrhea ; Diarrhea Virus 1, Bovine Viral ; Guinea Pigs ; Mineral Oil ; Viral Envelope Proteins ; Viral Vaccines

In order to screen African swine fever virus (ASFV) diagnostic antigen with the best enzyme linked immunosorbent assay (ELISA) reactivity. By establishing the ELISA method, the diagnostic antigen of ASFV p30 protein expressed by baculovirus-insect cell expression system as reference, we explored the antigenic properties and diagnostic potential of ASFV p35 protein expressed by prokaryotic expression system as a diagnostic antigen. The results of Western blotting and immunofluorescence show that the molecular weight of the recombinant p35 protein and p30 protein obtained was 40 kDa and 30 kDa, respectively, and these two proteins had good immuno-reactivity with ASFV positive serum. Recombinant p30 and p35 proteins were used as diagnostic antigens to establish ELISA, and the sensitivity and repeatability of these methods were tested. The results show that although the detection sensitivity of the p30-ELISA established in this study was higher than that of the p35-ELISA, the sensitivity of p35-ELISA was 95.8%, and variations in intra- and inter-assay repeatability of the two methods were less than 10%. The coincidence rate between the p35-ELISA and the imported kit was 97.2%. Results show that p35-ELISA was sensitive and stable, and could detect specific antibodies against ASFV.
African Swine Fever/diagnosis* ; African Swine Fever Virus/genetics* ; Animals ; Antibodies, Viral ; Enzyme-Linked Immunosorbent Assay ; Recombinant Proteins/genetics* ; Swine

To screen the best genotypeⅠJapanese encephalitis virus subunit vaccine candidate antigens, the prMEIII gene, the polytope gene and the prMEIII-polytope fusion gene of the GenotypeⅠJapanese encephalitis virus GS strain were cloned into prokaryotic expression vector pET-30a. The recombinant proteins were obtained after the induction and purification. The prepared recombinant proteins were immunized to mice, and the immunogenicity of the subunit vaccine candidate antigens was evaluated through monitoring the humoral immune response by ELISA, detecting the neutralizing antibody titer by plaque reduction neutralization test, and testing the cell-mediated immune response by lymphocyte proliferation assay and cytokine profiling. The recombinant proteins with the molecular weights of 35 (prMEIII), 28 (polytope antigen) and 57 kDa (prMEIII-polytope) induced strong humoral and cellular immune responses in mice. Compared with prMEIII-polytope and polytope proteins, the prMEIII protein induced a significant expression of IL-2 and IFN-γ (P<0.05) and the significant lymphoproliferation of splenocytes (P<0.05). The neutralizing antibody titer induced by the prMEIII protein was close to that induced by the commercial attenuated vaccine SA14-14-2 (P>0.05). The study suggests that the prMEIII protein can be used for the development of the Japanese encephalitis virus subunit vaccine.
Animals ; Antibodies, Viral ; blood ; Antigens, Viral ; immunology ; Encephalitis Virus, Japanese ; immunology ; Encephalitis, Japanese ; immunology ; prevention & control ; Immunogenicity, Vaccine ; Mice ; Mice, Inbred BALB C ; Vaccines, Subunit ; immunology ; Viral Vaccines ; immunology