The High Immunity Induced by the Virus-Like Particles of Foot-and-Mouth Disease Virus Serotype O

Mechanistic investigation of calcium phosphate mineralization potentiating the cellular immune response of foot-and-mouth disease virus-like particle vaccines

Virus-like particles (VLPs), composed of structural proteins, have emerged as a promising vaccine platform for preventing infectious diseases due to their outstanding advantages. Enhancing immune responses specific to VLPs, particularly cellular immunity, has emerged as a pivotal area of current immunological research. The nanovaccines for the foot-and-mouth disease virus (FMDV) composed of VLPs mineralized with calcium phosphate (VLPs-CaP), developed based on biomineralization principles, demonstrates superior immunogenicity. In this study, we elucidated the efficacy and mechanism of VLPs-CaP in eliciting cellular immune responses. The results demonstrated that VLPs-CaP were efficiently internalized by dendritic cells (DCs) via energy-dependent endocytosis mediated by actin, microtubules, and clathrin. Upon uptake, VLPs-CaP decomposed within lysosomes, leading to the release of Ca2+ ions and an increase in lysosomal permeability. This facilitates the escape of VLPs into the cytoplasm for cross-presentation. Furthermore, CaP mineralization enhanced the level of activation of DCs by FMDV VLPs, evidenced by elevated expression of CD40 and CD86, and the secretion of IL-2 and IL-12p70. Immunization studies in mice revealed that VLPs-CaP elicited higher levels of specific antibodies compared to unmineralized VLPs; notably, there was an increased IgG2a/IgG1 ratio along with a greater number of cytotoxic T lymphocytes (CTLs). This study elucidated the mechanism by which CaP-mineralized VLPs induce cellular immune responses, offering new insights and strategies aimed at enhancing the cellular immune efficacy of VLP-based vaccines that primarily elicit humoral immunity.

Neutralizing Antibody Screening Using NanoBiT-Based Virus-like Particles of Foot-and-Mouth Disease Type Asia1 Enhances Biosafety and Sensitivity

BACKGROUND/OBJECTIVES

Foot-and-mouth disease (FMD) is a highly contagious class 1 animal disease that affects cloven-hoofed animals, such as cattle, pigs, and goats. Diagnosis and research on live FMD virus (FMDV) typically require biosafety level 3 facilities, which are challenging to maintain due to strict protocols and high costs. The development of NanoBiT-based assays has accelerated in response to the coronavirus disease pandemic, providing safer alternatives for viral research, and is now applicable for general laboratories. This study aimed to develop a NanoBiT-based virus-like particle (VLP) assay for the rapid and safe screening of neutralizing antibodies against FMDV Asia1 Shamir (AS).

METHODS

We developed an AS VLP with an inserted HiBiT tag that enabled the detection of entry into LgBiT cells through luminescence signals.

RESULTS

HiBiT-tagged AS VLPs mixed with anti-serum and introduced into LgBiT-expressing cells led to a reduction in luciferase activity. Therefore, we established a NanoBiT-based viral neutralizing antibody test (VNT) that demonstrated a high correlation (R2 = 0.881) with the traditional gold standard VNT.

CONCLUSIONS

The assay demonstrated high sensitivity and could be performed in BL-2 facilities, offering a safer and more efficient alternative to traditional assays while reducing the need to handle live viruses in high-containment facilities. This method provides a valuable tool for rapid screening of neutralizing antibodies and can be adapted for broader applications in FMDV research.

The Pathogenesis of Foot-and-Mouth Disease Virus Infection: How the Virus Escapes from Immune Recognition and Elimination

Foot-and-mouth disease virus (FMDV) is a highly contagious and economically devastating pathogen that affects cloven-hoofed animals worldwide. FMDV infection causes vesicular lesions in the mouth, feet, and mammary glands, as well as severe systemic symptoms such as fever, salivation, and lameness. The pathogenesis of FMDV infection involves complex interactions between the virus and the host immune system, which determine the outcome of the disease. FMDV has evolved several strategies to evade immune recognition and elimination, such as antigenic variation, receptor switching, immune suppression, and subversion of innate and adaptive responses. This review paper summarizes the current knowledge on the pathogenesis of FMDV infection and the mechanisms of immune evasion employed by the virus. It also discusses the challenges and opportunities for developing effective vaccines and therapeutics against this important animal disease.

Synergetic interaction of capsid proteins for virus-like particles assembly of foot-and-mouth disease virus (serotype O) from the inclusion bodies

Recombinant virus-like particles (VLP) with single capsid protein have been successfully produced through prokaryotic system, but for those with multiple capsid proteins such as the foot-and-mouth disease virus (FMDV), this approach is more challenging. In this study, in vitro assembly of FMDV VLP was investigated with its capsids VP1, VP2 and VP3 separately expressed as inclusion bodies. After extraction and solubilization, three capsids were purified in denatured state through a flow-through model, increasing its purity to 90%. VLP assembly for FMDV was observed after diluting the mixture of denatured capsids in the ration of 1: 1: 1, while no VLP appeared if the separately diluted and refolded capsids were co-incubated. This result suggests certain synergetic interactions exist among the three capsids, which are crucial for FMDV VLP assembly. Sodium chloride and capsid protein concentration both greatly affect the assembling efficiency. After purification through size exclusion chromatography, VLP with similar diameter and morphology as inactivated FMDV were obtained, which elicited high IgG titers and B cell activation when vaccinated in mouse. It could also induce specific humoral and cellular immune responses in splenocytes proliferative experiments. Our study demonstrated the feasibility of in vitro assembling FMDV VLP from inclusion bodies of VP1, VP2 and VP3 for the first time.

Expression of FMD virus-like particles in yeast Hansenula polymorpha and immunogenicity of combine with CpG and aluminum adjuvant

BACKGROUND

Inactivated vaccines are limited in preventing foot-and-mouth disease (FMD) due to safety problems. Recombinant virus-like particles (VLPs) are an excellent candidate for a novel vaccine for preventing FMD, given that VLPs have similar immunogenicity as natural viruses and are replication- and infection-incompetent.

OBJECTIVES

The 3C protease and P1 polyprotein of type O FMD virus (FDMV) was expressed in yeast Hansenula polymorpha to generate self-resembling VLPs, and the potential of recombinant VLPs as an FMD vaccine was evaluated.

METHODS

BALB/c mice were immunized with recombinant purified VLPs using CpG oligodeoxynucleotide and aluminum hydroxide gel as an adjuvant. Cytokines and lymphocytes from serum and spleen were analyzed by enzyme-linked immunosorbent assay, enzyme-linked immunospot assay, and flow cytometry.

RESULTS

The VLPs of FMD were purified successfully from yeast protein with a diameter of approximately 25 nm. The immunization of mice showed that animals produced high levels of FMDV antibodies and a higher level of antibodies for a longer time. In addition, higher levels of interferon-γ and CD4⁺ T cells were observed in mice immunized with VLPs.

CONCLUSIONS

The expression of VLPs of FMD in H. polymorpha provides a novel strategy for the generation of the FMDV vaccine.

Development of Foot-and-Mouth Disease Vaccines in Recent Years

Foot-and-mouth disease (FMD) is a serious disease affecting the global graziery industry. Once an epidemic occurs, it can lead to economic and trade stagnation. In recent decades, FMD has been effectively controlled and even successfully eradicated in some countries or regions through mandatory vaccination with inactivated foot-and-mouth disease vaccines. Nevertheless, FMD still occurs in some parts of Africa and Asia. The transmission efficiency of foot-and-mouth disease is high. Both disease countries and disease-free countries should always be prepared to deal with outbreaks of FMD. The development of vaccines has played a key role in this regard. This paper summarizes the development of several promising vaccines including progress and design ideas. It also provides ways to develop a new generation of vaccines for FMDV and other major diseases.

Development of Novel Recombinant Antigens of Nucleoprotein and Matrix Proteins of Porcine orthorubulavirus: Antigenicity and Structural Prediction

Blue eye disease (BED) is a swine viral infection that affects the pork industry of Mexico. Porcine orthorubulavirus (PRV) is the etiological agent, and the hemagglutinin-neuraminidase protein (HN) is characterized as the best antigen for serological tests, although other structural proteins, including the nucleoprotein (NP) and the matrix (M) protein, have been investigated during the infection of members of the Paramyxoviridae family, generating promising results. Herein, for the first time, we successfully produced and characterized both the NP and M proteins of PRV by using a recombinant strategy in the E. coli heterologous system. The ORF of the NP and M genes were cloned in-frame with the pET-SUMO expression vector. Recombinant proteins proved to be a sensitive target to detect seroconversion at 7 days until 28 days in vaccinated mice (BALB/c) by indirect ELISAs. Immunoreactivity was also tested using porcine serum samples, in which antibodies were recognized from early stages to a persistence of PRV infection, which is indicative that these proteins contain properties similar to native antigens. The predicted tertiary structure showed that both proteins have a conserved structure that resembles those found in others Paramyxovirus. Our results pave the way for developing biotechnological tools based on these proteins for the control and prevention of BED.

mRNA Vaccine Development for Emerging Animal and Zoonotic Diseases

In the prevention and treatment of infectious diseases, mRNA vaccines hold great promise because of their low risk of insertional mutagenesis, high potency, accelerated development cycles, and potential for low-cost manufacture. In past years, several mRNA vaccines have entered clinical trials and have shown promise for offering solutions to combat emerging and re-emerging infectious diseases such as rabies, Zika, and influenza. Recently, the successful application of mRNA vaccines against COVID-19 has further validated the platform and opened the floodgates to mRNA vaccine's potential in infectious disease prevention, especially in the veterinary field. In this review, we describe our current understanding of the mRNA vaccines and the technologies used for mRNA vaccine development. We also provide an overview of mRNA vaccines developed for animal infectious diseases and discuss directions and challenges for the future applications of this promising vaccine platform in the veterinary field.

Recent Development of Ruminant Vaccine Against Viral Diseases

Pathogens of viral origin produce a large variety of infectious diseases in livestock. It is essential to establish the best practices in animal care and an efficient way to stop and prevent infectious diseases that impact animal husbandry. So far, the greatest way to combat the disease is to adopt a vaccine policy. In the fight against infectious diseases, vaccines are very popular. Vaccination's fundamental concept is to utilize particular antigens, either endogenous or exogenous to induce immunity against the antigens or cells. In light of how past emerging and reemerging infectious diseases and pandemics were handled, examining the vaccination methods and technological platforms utilized for the animals may provide some useful insights. New vaccine manufacturing methods have evolved because of developments in technology and medicine and our broad knowledge of immunology, molecular biology, microbiology, and biochemistry, among other basic science disciplines. Genetic engineering, proteomics, and other advanced technologies have aided in implementing novel vaccine theories, resulting in the discovery of new ruminant vaccines and the improvement of existing ones. Subunit vaccines, recombinant vaccines, DNA vaccines, and vectored vaccines are increasingly gaining scientific and public attention as the next generation of vaccines and are being seen as viable replacements to conventional vaccines. The current review looks at the effects and implications of recent ruminant vaccine advances in terms of evolving microbiology, immunology, and molecular biology.