Search

Background & Aims: The spread of foot-and-mouth disease virus (FMDV) through aerosol droplets among cloven-hoofed ungulates in close contact is a major obstacle for successful animal husbandry. Therefore, the development of suitable mucosal vaccines, especially nasal vaccines, to block the virus at the initial site of infection is crucial., Patients and Methods: Here, we constructed eukaryotic expression plasmids containing the T and B-cell epitopes (pTB) of FMDV in tandem with the molecular mucosal adjuvant Fms-like tyrosine kinase receptor 3 ligand (Flt3 ligand, FL) (pTB-FL). Then, the constructed plasmid was electrostatically attached to mannose-modified chitosan-coated poly(lactic-co-glycolic) acid (PLGA) nanospheres (MCS-PLGA-NPs) to obtain an active nasal vaccine targeting the mannose-receptor on the surface of antigen-presenting cells (APCs)., Results: The MCS-PLGA-NPs loaded with pTB-FL not only induced a local mucosal immune response, but also induced a systemic immune response in mice. More importantly, the nasal vaccine afforded an 80% protection rate against a highly virulent FMDV strain (AF72) when it was subcutaneously injected into the soles of the feet of guinea pigs., Conclusions: The nasal vaccine prepared in this study can effectively induce a cross-protective immune response against the challenge with FMDV of same serotype in animals and is promising as a potential FMDV vaccine., Competing Interests: Declaration of competing interest The authors declare no competing interests, and manuscript is approved by all authors for publication. I would like to declare on behalf of my co-authors that the work described was original research that has not been published previously, and not under consideration for publication elsewhere, in whole or in part., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The efficacy of an inactivated foot-and-mouth disease (FMD) vaccine is mainly dependent on the integrity of the foot-and-mouth disease virus (FMDV) particles. At present, the standard method to quantify the active component, the 146S antigen, of FMD vaccines is sucrose density gradient (SDG) analysis. However, this method is highly operator dependent and difficult to automate. In contrast, the enzyme-linked immunosorbent assay (ELISA) is a time-saving technique that provides greater simplicity and sensitivity. To establish a valid method to detect and quantify the 146S antigen of a serotype O FMD vaccine, a double-antibody sandwich (DAS) ELISA was compared with an SDG analysis. The DAS ELISA was highly correlated with the SDG method (R2 = 0.9215, P<0.01). In contrast to the SDG method, the DAS ELISA was rapid, robust, repeatable and highly sensitive, with a minimum quantification limit of 0.06 μg/mL. This method can be used to determine the effective antigen yields in inactivated vaccines and thus represents an alternative for assessing the potency of FMD vaccines in vitro. But it still needs to be prospectively validated by analyzing a new vaccine preparation and determining the proper protective dose followed by an in vivo vaccination-challenge study to confirm the ELISA findings.

Virus-like particles (VLP), which are similar to natural virus particles but do not contain viral genes, have brought about significant breakthroughs in many research fields because of their unique advantages. The ordered repeating epitopes of VLP can induce immunity responses similar to those prompted by natural viral infection; thus, VLP vaccines are regarded as candidate alternatives to whole-virus vaccines. As picornavirus has serious impacts on human and animal health, the development of efficient and safe vaccines is a key endeavor in preventing virus infections. The characteristics of picornavirus capsid proteins allow the development of VLP vaccines. This paper investigates research scenarios and progress on picornavirus VLP vaccines with the aim of providing a reference for researchers focusing on virology and vaccinology.

Canine parvovirus disease is an acute infectious disease caused by canine parvovirus (CPV). Current commercial vaccines are mainly attenuated and inactivated; as such, problems concerning safety may occur. To resolve this problem, researchers developed virus-like particles (VLPs) as biological nanoparticles resembling natural virions and showing high bio-safety. This property allows the use of VLPs for vaccine development and mechanism studies of viral infections. Tissue-specific drug delivery also employs VLPs as biological nanomaterials. Therefore, VLPs derived from CPV have a great potential in medicine and diagnostics. In this study, small ubiquitin-like modifier (SUMO) fusion motif was utilized to express a whole, naturalVP2 protein of CPV in Escherichia coli. After the cleavage of the fusion motif, the CPV VP2 protein has self-assembled into VLPs. The VLPs had a size and shape that resembled the authentic virus capsid. However, the self-assembly efficiency of VLPs can be affected by different pH levels and ionic strengths. The mice vaccinated subcutaneously with CPV VLPs and CPV-specific immune responses were compared with those immunized with the natural virus. This result showed that VLPs can effectively induce anti-CPV specific antibody and lymphocyte proliferation as a whole virus. This result further suggested that the antigen epitope of CPV was correctly present on VLPs, thereby showing the potential application of a VLP-based CPV vaccine.

Foot-and-mouth disease virus (FMDV) causes a highly contagious infection in cloven-hoofed animals. The format of FMD virus-like particles (VLP) as a non-replicating particulate vaccine candidate is a promising alternative to conventional inactivated FMDV vaccines. In this study, we explored a prokaryotic system to express and assemble the FMD VLP and validated the potential of VLP as an FMDV vaccine candidate. VLP composed entirely of FMDV (Asia1/Jiangsu/China/2005) capsid proteins (VP0, VP1 and VP3) were simultaneously produced as SUMO fusion proteins by an improved SUMO fusion protein system in E. coli. Proteolytic removal of the SUMO moiety from the fusion proteins resulted in the assembly of VLP with size and shape resembling the authentic FMDV. Immunization of guinea pigs, swine and cattle with FMD VLP by intramuscular inoculation stimulated the FMDV-specific antibody response, neutralizing antibody response, T-cell proliferation response and secretion of cytokine IFN-γ. In addition, immunization with one dose of the VLP resulted in complete protection of these animals from homologous FMDV challenge. The 50% protection dose (PD50) of FMD VLP in cattle is up to 6.34. These results suggest that FMD VLP expressed in E. coli are an effective vaccine in guinea pigs, swine and cattle and support further development of these VLP as a vaccine candidate for protection against FMDV.

Background: Porcine circovirus type 2 (PCV2) is a primary etiological agent of post-weaning multi-systemic wasting syndrome (PMWS), which is a disease of increasing importance to the pig industry worldwide. Hollow mesoporous silica nanoparticles (HMSNs) have gained increasing interest for use in vaccines., Methods: To study the potential of HMSNs for use as a protein delivery system or vaccine carriers. HMSNs were synthesized by a sol-gel/emulsion(oil-in-water/ethanol) method, purified PCV2 GST-ORF2-E protein was loaded into HMSNs, and the resulting HMSN/protein mixture was injected into mice. The uptake and release profiles of protein by HMSNs in vitro were investigated. PCV2 GST-ORF2-E specific antibodies and secretion of IFN-γ were detected by enzyme-linked immunosorbent assays, spleen lymphocyte proliferation was measured by the MTS method, and the percentage of CD4+ and CD8+ were determined by flow cytometry., Results: HMSNs were found to yield better binding capacities and delivery profiles of proteins; the specific immune response induced by PCV2 GST-ORF2-E was maintained for a relatively long period of time after immunization with the HMSN/protein complex., Conclusion: The findings suggest that HMSNs are good protein carriers and have high potential for use in future applications in therapeutic drug delivery.

A suicidal DNA vaccine based on a Semliki Forest virus (SFV) replicon was evaluated for the development of a vaccine against swine vesicular disease virus (SVDV). The 1BCD gene of SVDV was cloned and inserted into pSCA1, an SFV DNA-based replicon vector. The resultant plasmid, pSCA/1BCD, was transfected into BHK-21 cells and the antigenicity of the expressed protein was confirmed using an indirect immunofluorescence assay. Immunogenicity was studied in guinea pigs and swine. Animals were injected intramuscularly three times with pSCA/1BCD at regular intervals. Anti-SVDV antibodies were detected by ELISA, the lymphocyte proliferation response was tested by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide method and neutralizing antibodies were measured by microneutralization tests. The data showed that SVDV-specific antibodies, neutralizing antibodies and lymphocyte proliferation were induced in both guinea pigs and swine. Furthermore, after three successive vaccinations with pSCA/1BCD, half of the pigs were protected against challenge with SVDV. These results should encourage further work towards the development of a DNA vaccine against SVDV.