Expression, purification, crystallization and preliminary X-ray diffraction analysis of swine leukocyte antigen 2 complexed with a CTL epitope AS64 derived from Asia1 serotype of foot-and-mouth disease virus

Foot-and-mouth disease: genomic and proteomic structure, antigenic sites, serotype relationships, immune evasion, recent vaccine development strategies, and future perspectives

Foot-and-mouth disease (FMD) is a highly contagious and transmissible disease that can have significant economic and trade repercussions during outbreaks. In Egypt, despite efforts to mitigate FMD through mandatory immunization, the disease continues to pose a threat due to the high genetic variability and quasi-species nature of the FMD virus (FMDV). Vaccines have been crucial in preventing and managing FMD, and ongoing research focusses on developing next-generation vaccines that could provide universal protection against all FMDV serotypes. This review thoroughly examines the genetic structure of FMDV, including its polyprotein cleavage process and the roles of its structural and non-structural proteins in immune evasion. Additionally, it explores topics such as antigenic sites, specific mutations, and serotype relationships from Egypt and Ethiopia, as well as the structural changes in FMDV serotypes for vaccine development. The review also addresses the challenges associated with creating effective vaccines for controlling FMD, particularly focusing on the epitope-based vaccine. Overall, this review offers valuable insights for researchers seeking to develop effective strategies and vaccines for controlling FMD.

DEC-205 receptor targeted poly(lactic-co-glycolic acid) nanoparticles containing Eucommia ulmoides polysaccharide enhances the immune response of foot-and-mouth disease vaccine in mice

Nanoparticles targeting the DEC-205 receptor were found to induce antigen-specific protective immune response. When the delivery system carries both antigens and immunomodulators, it can maximize the expected therapeutic effect of the drug and induce effective humoral and cellular immune responses to antigens.In this study, we encapsulated the Eucommia ulmoides Oliv. polysaccharides (EUPS) into PLGA nanoparticles (NPs) and conjugated it with anti-CD205 monoclonal Ab (MAb) to produce a DEC-205 receptor targeted PLGA nanoparticles (anti-DEC-205-EUPS-PLGA NPs). The physicochemical characteristics and adjuvant activity of the above NPs were evaluated in vitro and in vivo. In the in vitro setting, 200 μg·mL-1 anti-DEC-205-EUPS-PLGA could improve the proliferation of DCs and promote their antigen up-take activity. In the in vivo setting, anti-DEC-205-EUPS-PLGA NPs remarkably controlled the release of drug and antigen to induce sustained immune responses and up-regulated the levels of FMDV-specific IgG antibodies, promoted the cytotoxic activity of CTLs and NK cells, and improved the proliferation of splenocytes. Moreover, the anti-DEC-205-EUPS-PLGA NPs facilitated the maturation of DCs. The above data indicated that anti-DEC-205-EUPS-PLGA NPs employed as an targeted adjuvant induced the humoral and cellular immune activity by promoting the maturation of DCs. These findings may provide a new insight onto the development of vaccine adjuvants.

The Parallel Presentation of Two Functional CTL Epitopes Derived from the O and Asia 1 Serotypes of Foot-and-Mouth Disease Virus and Swine SLA-2*HB01: Implications for Universal Vaccine Development

Foot-and-mouth disease virus (FMDV) poses a significant threat to the livestock industry. Through their recognition of the conserved epitopes presented by the swine leukocyte antigen (SLA), T cells play a pivotal role in the antiviral immunity of pigs. Herein, based on the peptide binding motif of SLA-2*HB01, from an original SLA-2 allele, a series of functional T-cell epitopes derived from the dominant antigen VP1 of FMDV with high binding capacity to SLA-2 were identified. Two parallel peptides, Hu64 and As64, from the O and Asia I serotypes, respectively, were both crystallized with SLA-2*HB01. Compared to SLA-1 and SLA-3, the SLA-2 structures showed the flexibility of residues in the P4, P6, and P8 positions and in their potential interface with TCR. Notably, the peptides Hu64 and As64 adopted quite similar overall conformation when bound to SLA-2*HB01. Hu64 has two different conformations, a more stable 'chair' conformation and an unstable 'boat' conformation observed in the two molecules of one asymmetric unit, whereas only a single 'chair' conformation was observed for As64. Both Hu64 and As64 could induce similar dominant T-cell activities. Our interdisciplinary study establishes a basis for the in-depth interpretation of the peptide presentation of SLA-I, which can be used toward the development of universal vaccines.

Peptide-Based Vaccines: Foot-and-Mouth Disease Virus, a Paradigm in Animal Health

Vaccines are considered one of the greatest global health achievements, improving the welfare of society by saving lives and substantially reducing the burden of infectious diseases. However, few vaccines are fully effective, for reasons ranging from intrinsic limitations to more contingent shortcomings related, e.g., to cold chain transport, handling and storage. In this context, subunit vaccines where the essential antigenic traits (but not the entire pathogen) are presented in rationally designed fashion have emerged as an attractive alternative to conventional ones. In particular, this includes the option of fully synthetic peptide vaccines able to mimic well-defined B- and T-cell epitopes from the infectious agent and to induce protection against it. Although, in general, linear peptides have been associated to low immunogenicity and partial protection, there are several strategies to address such issues. In this review, we report the progress towards the development of peptide-based vaccines against foot-and-mouth disease (FMD) a highly transmissible, economically devastating animal disease. Starting from preliminary experiments using single linear B-cell epitopes, recent research has led to more complex and successful second-generation vaccines featuring peptide dendrimers containing multiple copies of B- and T-cell epitopes against FMD virus or classical swine fever virus (CSFV). The usefulness of this strategy to prevent other animal and human diseases is discussed.

Advanced Foot-And-Mouth Disease Vaccine Platform for Stimulation of Simultaneous Cellular and Humoral Immune Responses

Currently available commercial foot-and-mouth disease (FMD) vaccines have various limitations, such as the slow induction and short-term maintenance of antibody titers. Therefore, a novel FMD vaccine that can rapidly induce high neutralizing antibody titers to protect the host in early stages of an FMD virus infection, maintain high antibody titers for long periods after one vaccination dose, and confer full protection against clinical symptoms by simultaneously stimulating cellular and humoral immunity is needed. Here, we developed immunopotent FMD vaccine strains A-3A and A-HSP70, which elicit strong initial cellular immune response and induce humoral immune response, including long-lasting memory response. We purified the antigen (inactivated virus) derived from these immunopotent vaccine strains, and evaluated the immunogenicity and efficacy of the vaccines containing these antigens in mice and pigs. The immunopotent vaccine strains A-3A and A-HSP70 demonstrated superior immunogenicity compared with the A strain (backbone strain) in mice. The oil emulsion-free vaccine containing A-3A and A-HSP70 antigens effectively induced early, mid-term, and long-term immunity in mice and pigs by eliciting robust cellular and humoral immune responses through the activation of co-stimulatory molecules and the secretion of proinflammatory cytokines. We successfully derived an innovative FMD vaccine formulation to create more effective FMD vaccines.

Crystallization of SLA-2*04:02:02 complexed with a CTL epitope derived from FMDV

Presentation of viral epitopes by swine MHC I (termed leukocyte antigen class I, SLA I) to cytotoxic T lymphocytes (CTLs) is crucial for swine immunity. The SLA-2 structure, however, remains largely unknown. To illustrate the structural basis of swine CTL epitope presentation, the crystal structure of SLA-2*04:02:02 complexed with one peptide, derived from foot-and-mouth disease virus (FMDV), was analyzed in this study. SLA-2*04:02:02 and swine β2-microglobulin (sβ2m) were refolded in vitro in the presence of peptides. X-ray diffraction data of SLA-2*04:02:02-peptide-sβ2m (referred to as p/SLA-2*04:02:02) were collected. The diffraction dataset was 2.3 Å in resolution and the space group was P3(2)21. Relevant data included a = 101.8 Å, b = 101.8 Å, c = 73.455 Å,α = 90.00°, β = 90.00°, γ = 120.00°. The structure of p/SLA-2*04:02:02 was analyzed. The results revealed that Glu24, Met68, Gly76, and Gln173 in PBG of SLA-2*04:02:02 are different from other MHC I. Furthermore, Asn63 is different from other SLA I. Gln57, Met174 and Gln180 in PBG of SLA I are different from other species' MHC I. All of these features are different from known mammalian peptide-MHC class I complexes (referred to as p/MHC I). In addition, P4-His, P6-Val, and P8-Pro in the peptide were exposed, and these residues as epitopes can be presented by SLA-2*04:02:02. This study not only provides a structural basis for peptide presentation by SLA-2, but also screens one potential FMDV CTL epitope. The results may be of interest in future vaccine development.