Bio-mineralization has emerged as a promising strategy to enhance vaccine immunogenicity. This study optimized the calcium phosphate (CaP) mineralization process of foot-and-mouth disease virus-like particles (FMD VLPs) to achieve high mineralization efficiency and scalability. Key parameters, including concentrations of Ca²⁺, HPO₄^2-, NaCl, and VLPs, as well as stirring speed, were systematically optimized. Stability of the scaled-up reaction system and immunogenicity of the mineralized vaccine were evaluated. Optimal conditions [25.50 mmol/L Ca(NO₃)₂, 15 mmol/L Na₂HPO₄, 300 mmol/L NaCl, 0.75 mg/mL VLPs, and 1 500 r/min] yielded CaP-mineralized VLPs (VLPs-CaP) with high mineralization efficiency, uniform morphology, and a favorable particle size. Scaling up the reaction by 25 folds maintained consistent mineralization efficiency and particle characteristics. Immunization in mice demonstrated that VLPs-CaP induced higher titers of specific antibodies and neutralizing antibodies than unmineralized VLPs (P < 0.05). Higher IgG2a/IgG1 ratio and enhanced IFN-γ secretion (P < 0.05) further indicated robust cellular immune responses. We establish a stable and scalable protocol for VLPs-CaP, providing a theoretical and technical foundation for developing high-efficacy VLPs-CaP vaccines.
Vaccines, Virus-Like Particle/immunology* ; Immunogenicity, Vaccine ; Calcium Phosphates/chemistry* ; Foot-and-Mouth Disease Virus ; Biomineralization ; Particle Size ; Animals ; Mice ; Antibodies, Neutralizing/blood* ; Antibodies, Viral/blood* ; Immunity, Cellular

Vaccination is a crucial strategy for the prevention and control of infectious diseases. Virus-like particles (VLPs), composed of structural proteins, have garnered significant attention as a novel type of vaccine due to their excellent safety and immunogenicity. However, similar to most vaccine antigens, VLPs exhibit insufficient thermal stability, which not only restricts the widespread application of vaccines but also increases the risk of vaccine inactivation. This study aims to enhance the stability and shelf life of VLPs derived from type A foot-and-mouth disease virus (FMDV) by employing vacuum freeze-drying technology. The optimal lyoprotectant formulation was determined through single-factor and combinatorial screening. Subsequently, the correlation between the immunogenicity of the freeze-dried vaccine and the content of FMDV VLPs was evaluated via a mouse model. The stability of FMDV VLPs before and after freeze-drying was further assessed by storing them at 4, 25, and 37 ℃ for varying time periods. Results indicated that the lyoprotectant formulation No.1, composed of 7.5% trehalose, 0.1% Tween 80, 50 mmol/L glycine, 1% sodium glutamate, and 3% polyvinylpyrrolidone (PVP), effectively preserved the content of FMDV VLPs during the vacuum freeze-drying process. The immunization trial in mice revealed that the levels of specific antibodies, immunoglobulin G1 (IgG1), interleukin-4 (IL-4), and neutralizing antibodies induced by freeze-dried FMDV VLPs were comparable to those induced by non-freeze-dried FMDV VLPs. The heat treatment results showed that the storage periods of freeze-dried FMDV VLPs at 4, 25, and 37 ℃ were significantly longer than those of non-freeze-dried FMDV VLPs. In conclusion, the selected lyoprotectant formulation effectively improved the stability of FMDV VLPs vaccines. This study provides valuable insights for enhancing the stability of novel subunit vaccines.
Freeze Drying/methods* ; Animals ; Foot-and-Mouth Disease Virus/immunology* ; Mice ; Vaccines, Virus-Like Particle/chemistry* ; Foot-and-Mouth Disease/immunology* ; Vacuum ; Drug Stability ; Mice, Inbred BALB C ; Viral Vaccines/immunology*

Pseudorabies (PR) is an infectious disease caused by the pseudorabies virus (PRV), affecting various domesticated and wild animals. Since pigs are the only natural hosts of PRV, PR poses a serious threat to the pig farming industry. Currently, PR is primarily prevented through vaccination with inactivated vaccines or genetically modified attenuated live vaccines. Developing safe and effective genetically engineered vaccines would facilitate the eradication and control of PR. In this study, the PRV vaccine strain Bartha-K61 was used as the reference strain. The gB protein was expressed via the baculovirus-insect cell expression system. Non-denaturing gel electrophoresis confirmed that the gB protein could form a trimeric structure. The purified gB protein was used to immunize mice, and the immune effect was evaluated by a challenge test. The results showed that the gB antigen induced a strong immune response in mice, with the serum-neutralizing antibody titer above 1:70. The lymphocyte stimulation index reached more than 1.29, and the level of (interferon gamma, IFN-γ) release was higher than 100 pg/mL. After immunization, mice were challenged with the virus at a dose of 10⁴ TCID₅₀/mL, 200 μL per mouse, and the clinical protection rate was 100%. Immunohistochemistry, histopathological section, and tissue viral load results showed that the pathological damage and viral load in the gB-immunized group were significantly lower than those in the PBS group. In summary, the gB protein obtained in this study induced strong humoral and cellular immune responses in mice, laying a foundation for developing a recombinant gB protein subunit vaccine.
Animals ; Mice ; Baculoviridae/metabolism* ; Viral Envelope Proteins/biosynthesis* ; Herpesvirus 1, Suid/genetics* ; Pseudorabies/immunology* ; Swine ; Pseudorabies Vaccines/genetics* ; Antibodies, Viral/blood* ; Insecta/cytology* ; Mice, Inbred BALB C ; Female ; Viral Vaccines/immunology*

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.

To construct a subgenomic replication subsystem of foot-and-mouth disease virus(FM-DV)carrying fluorescent protein(UnaG),the full-length cDNA plasmid of FMDV was employed as the template.A few of structural and non-structural protein genes of FMDV were removed by double-enzyme digestion.By substituting reporter gene sequences expressing the green fluorescent protein UnaG for specific structural protein sequences of FMDV,FMDV-UnaG replicators were successfully created.After PCR and sequencing,linearized FMDV-UnaG replicons were transfected into BSR/T7 cells expressing T7 RNA polymerase,and the fluorescence signal was observed through fluorescence microscopy and laser confocal technique.The results demonstrated that the constructed FMDV-UnaG replicons could effectively express UnaG protein,and the protein colo-calized with FMDV 3A protein.Additionally,Western blot and RT-qPCR also detected that the replicator RNA could express the non-structural proteins of the virus and replicate autonomously in BSR/T7 cells,respectively.In conclusion,the successful construction of FMDV-UnaG sub-genomic replicators offers a favorable tool for further research on the replication and translation mechanism of FMDV and the development of vaccine vectors.

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.

To construct a subgenomic replication subsystem of foot-and-mouth disease virus(FM-DV)carrying fluorescent protein(UnaG),the full-length cDNA plasmid of FMDV was employed as the template.A few of structural and non-structural protein genes of FMDV were removed by double-enzyme digestion.By substituting reporter gene sequences expressing the green fluorescent protein UnaG for specific structural protein sequences of FMDV,FMDV-UnaG replicators were successfully created.After PCR and sequencing,linearized FMDV-UnaG replicons were transfected into BSR/T7 cells expressing T7 RNA polymerase,and the fluorescence signal was observed through fluorescence microscopy and laser confocal technique.The results demonstrated that the constructed FMDV-UnaG replicons could effectively express UnaG protein,and the protein colo-calized with FMDV 3A protein.Additionally,Western blot and RT-qPCR also detected that the replicator RNA could express the non-structural proteins of the virus and replicate autonomously in BSR/T7 cells,respectively.In conclusion,the successful construction of FMDV-UnaG sub-genomic replicators offers a favorable tool for further research on the replication and translation mechanism of FMDV and the development of vaccine vectors.

The variable domain of heavy-chain antibody (VHH) has been developed widely in drug therapy, diagnosis, and research. Escherichia coli is the most popular expression system for VHH production, whereas low bioactivity occurs sometimes. Mammalian cells are one of the most ideal hosts for VHH expression at present. To improve the yield of VHH in Expi293F cells, we optimized the signal peptide (SP) and codons of VHH. Firstly, the fusion protein VHH1-Fc was used to screen SPs. The SP IFN-α2 showed the highest secretion as quantified by enzyme-linked immunosorbent assay (ELISA). Subsequently, codon optimization by improving GC3 and GC content doubled the yield of VHH1 and kept its binding activity to Senecavirus A (SVA). Finally, the mean yields of other 5 VHHs that fused with SP IFN-α2 and codon-optimized were over 191.6 mg/L, and these VHHs had high recovery and high purity in the culture supernatant. This study confirms that SP IFN-α2 and codon optimization could produce VHHs in Expi293F cells efficiently, which provides a reference for the large-scale production of VHHs.
Codon/genetics* ; Protein Sorting Signals/genetics* ; Escherichia coli/metabolism* ; Humans ; Recombinant Fusion Proteins/biosynthesis* ; Interferon-alpha/metabolism* ; Immunoglobulin Heavy Chains/immunology* ; Cell Line ; Immunoglobulin Variable Region/immunology*

ObjectiveTo explore the underlying mechanism of bran-fried Atractylodis Rhizoma （AR） in improving gastrointestinal function by comparing the effects of raw AR and bran-fried AR on the small intestine tissue structure and transport-related protein carriers in rats with spleen deficiency syndrome. MethodSeventy male SD rats were randomly divided into a normal group， a model group， high- and low-dose raw AR groups （10， 2.5 g·kg^-1）， high- and low-dose bran-fried AR groups （10， 2.5 g·kg^-1）， and a compound glutamine group （9 mg·kg^-1）， with 10 rats in each group. Except for the normal group， the other six groups were subjected to the spleen deficiency model induced by the method of bitter and cold breaking stagnated Qi and abnormal hunger and fullness for 21 days. After modeling， each treatment group was given medication orally according to the corresponding doses every day for a total of 14 days， and the normal group and the model group were given an equal volume of normal saline orally. During the treatment period， the general survival status， macroscopic syndrome score， daily increase in body weight and food intake， and rectal temperature of the spleen deficiency rats were evaluated， and after the treatment， the rats were sacrificed. The pathological changes in the small intestine tissues of each group were observed by hematoxylin-eosin （HE） staining. The content of serum 5-hydroxytryptamine （5-HT） was detected by enzyme-linked immunosorbent assay （ELISA）， and the content of serum D-xylose， lactate， and amylase was detected by colorimetry. The levels of free fatty acid receptor 3 （FFA3） and peptide transporter 1 （PepT1） in small intestinal tissues were detected by the Bradford method， and the protein expression of sodium-dependent glucose transporter 1 （SGLT1） and glucose transporter 1 （GLUT1） in small intestinal tissue was detected by immunohistochemistry. Real-time fluorescence-based quantitative PCR was used to detect the mRNA expression of glucose transporter 2 （GLUT2）， sodium/hydrogen exchanger 3 （NHE3）， and 5-hydroxytryptamine receptor 4 （5-HT4R）. ResultCompared with the normal group， the model group exhibited symptoms of spleen deficiency， such as sluggishness， squint， reduced food intake， and lethargy at the end of modelling， damaged basic structure of the small intestinal mucosal epithelium and lamina propria， increased serum lactate and 5-HT content， and decreased serum amylase and D-xylose （P<0.01）. Compared with the model group， all treatment groups showed varying degrees of improvement， with the small intestinal microstructure repaired to different degrees. The daily weight gain， anal temperature， and macroscopic syndrome score of spleen deficiency improved to varying degrees （P<0.05， P<0.01）. The serum lactate and 5-HT content decreased to varying degrees， while the serum amylase and D-xylose content increased to varying degrees （P<0.05， P<0.01）. The PepT1 content in the small intestinal tissues increased， while the FFA3 content decreased to varying degrees. The protein expression of SGLT1 and GLUT1 increased， while the mRNA expression of GLUT2 and NHE3 increased to varying degrees. The mRNA expression of 5-HT4R decreased to varying degrees （P<0.05， P<0.01）. Compared with the high- and low-dose raw AR groups， the high- and low-dose bran-fried AR groups showed significant improvement in general conditions and histopathological improvement of the small intestinal tissues. The daily weight gain， anal temperature， and macroscopic syndrome score of spleen deficiency also improved （P<0.05， P<0.01）. The serum lactate and 5-HT content decreased， while the serum amylase and D-xylose content increased （P<0.05， P<0.01）. The PepT1 content in the small intestinal tissues increased， while the FFA3 content decreased. The protein expression of SGLT1 and GLUT1 increased， while the mRNA expression of GLUT2 and NHE3 increased. The mRNA expression of 5-HT4R decreased significantly （P<0.05， P<0.01）. ConclusionBran-fried AR can improve the spleen deficiency-related symptoms and histopathology of the small intestinal tissues in spleen deficiency model rats. Its mechanism may be related to the regulation of the expression of various transport-related protein carriers and the secretion of various digestive enzymes after stir-frying of AR， thus restoring the absorption and transport function of the small intestine.

To further enhance the immune effect of the foot-and-mouth disease (FMD) virus-like particles (VLPs) vaccine, this study prepared FMDV VLPs-zeolitic imidazolate (framework-8, ZIF-8) complexes with different particle sizes. We used a biomimetic mineralization method with Zn²⁺ and 2-methylimidazole in different concentration ratios to investigate the effect of size on the immunization effect. The results showed that FMDV VLPs-ZIF-8 with three different sizes were successfully prepared, with an approximate size of 70 nm, 100 nm, and 1 000 nm, respectively. Cytotoxicity and animal toxicity tests showed that all three complexes exhibited excellent biological safety. Immunization tests in mice showed that all three complexes enhanced the titers of neutralizing and specific antibodies, and their immune effects improved as the size of the complexes decreased. This study showed that ZIF-8 encapsulation of FMDV VLPs significantly enhanced their immunogenic effect in a size-dependent manner.
Animals ; Mice ; Foot-and-Mouth Disease/prevention & control* ; Foot-and-Mouth Disease Virus ; Antibodies, Neutralizing ; Immunity, Humoral ; Immunization ; Vaccines, Virus-Like Particle ; Antibodies, Viral ; Viral Vaccines