Immunization with a recombinant fusion of porcine reproductive and respiratory syndrome virus modified GP5 and ferritin elicits enhanced protective immunity in pigs

Protection against the H1N1 influenza virus using self-assembled nanoparticles formed by lumazine synthase and bearing the M2e peptide

There is an urgent need for influenza vaccines that offer broad cross-protection. The highly conserved ectodomain of the influenza matrix protein 2 (M2e) is a promising candidate; however, its low immunogenicity can be addressed. In this study, we developed influenza vaccines using the Lumazine synthase (LS) platform. The primary objective of this study was to determine the protective potential of M2e proteins expressed on Lumazine synthase (LS) nanoparticles. M2e-LS proteins, produced through the E. coli system, spontaneously assemble into nanoparticles. The study investigated the efficacy of the M2e-LS nanoparticle vaccine in mice. Mice immunized with M2e-LS nanoparticles exhibited significantly higher levels of intracellular cytokines than those receiving soluble M2e proteins. The M2e-LS protein exhibited robust immunogenicity and provided 100% protection against cross-clade influenza.

Development of a Ferritin Protein Nanoparticle Vaccine with PRRSV GP5 Protein

Porcine reproductive and respiratory syndrome virus (PRRSV) presents a significant threat to the global swine industry. The development of highly effective subunit nanovaccines is a promising strategy for preventing PRRSV variant infections. In this study, two different types of ferritin (Ft) nanovaccines targeting the major glycoprotein GP5, named GP5m-Ft and (Bp-IVp)3-Ft, were constructed and evaluated as vaccine candidates for PRRSV. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) demonstrated that both purified GP5m-Ft and (Bp-IVp)3-Ft proteins could self-assemble into nanospheres. A comparison of the immunogenicity of GP5m-Ft and (Bp-IVp)3-Ft with an inactivated PRRSV vaccine in BALB/c mice revealed that mice immunized with GP5m-Ft exhibited the highest ELISA antibody levels, neutralizing antibody titers, the lymphocyte proliferation index, and IFN-γ levels. Furthermore, vaccination with the GP5m-Ft nanoparticle effectively protected piglets against a highly pathogenic PRRSV challenge. These findings suggest that GP5m-Ft is a promising vaccine candidate for controlling PRRS.

Ferritin Nanoparticle Delivery of the E2 Protein of Classical Swine Fever Virus Completely Protects Pigs from Lethal Challenge

Classical swine fever (CSF), caused by the classical swine fever virus (CSFV), results in significant economic losses to the swine industry in many countries. Vaccination represents the primary strategy to control CSF and the CSFV E2 protein is known as the major protective antigen. However, the E2 protein expressed or presented by different systems elicits distinct immune responses. In this study, we established a stable CHO cell line to express the E2 protein and delivered it using self-assembled ferritin nanoparticles (NPs). Subsequently, we compared the adaptive immune responses induced by the E2-ferritin NPs and the monomeric E2 protein produced by the CHO cells or a baculovirus expression system. The results revealed that the NP-delivered E2 protein elicited higher titers of neutralizing antibodies than did the monomeric E2 protein in pigs. Importantly, only the NP-delivered E2 protein significantly induced CSFV-specific IFN-γ-secreting cells. Furthermore, all the pigs inoculated with the E2-ferritin NPs were completely protected from a lethal CSFV challenge infection. These findings demonstrate the ability of the E2-ferritin NPs to protect pigs against the lethal CSFV challenge by eliciting robust humoral and cellular immune responses.

A ferritin nanoparticle vaccine based on the hemagglutinin extracellular domain of swine influenza A (H1N1) virus elicits protective immune responses in mice and pigs

Introduction

Swine influenza viruses (SIVs) pose significant economic losses to the pig industry and are a burden on global public health systems. The increasing complexity of the distribution and evolution of different serotypes of influenza strains in swine herds escalates the potential for the emergence of novel pandemic viruses, so it is essential to develop new vaccines based on swine influenza.

Methods

Here, we constructed a self-assembling ferritin nanoparticle vaccine based on the hemagglutinin (HA) extracellular domain of swine influenza A (H1N1) virus using insect baculovirus expression vector system (IBEVS), and after two immunizations, the immunogenicities and protective efficacies of the HA-Ferritin nanoparticle vaccine against the swine influenza virus H1N1 strain in mice and piglets were evaluated.

Results

Our results demonstrated that HA-Ferritin nanoparticle vaccine induced more efficient immunity than traditional swine influenza vaccines. Vaccination with the HA-Ferritin nanoparticle vaccine elicited robust hemagglutinin inhibition titers and antigen-specific IgG antibodies and increased cytokine levels in serum. MF59 adjuvant can significantly promote the humoral immunity of HA-Ferritin nanoparticle vaccine. Furthermore, challenge tests showed that HA-Ferritin nanoparticle vaccine conferred full protection against lethal challenge with H1N1 virus and significantly decreased the severity of virus-associated lung lesions after challenge in both BALB/c mice and piglets.

Conclusion

Taken together, these results indicate that the hemagglutinin extracellular-based ferritin nanoparticle vaccine may be a promising vaccine candidate against SIVs infection.

Self-assembled nanoparticle with E protein domain III of DTMUV based on ferritin as carrier can induce a more comprehensive immune response and against DTMUV challenge in duck

Duck Tembusu virus (DTMUV) causes severe reduction in egg production and neurological symptoms in ducklings. Vaccination is the primary measure used to prevent DTMUV infections. In this study, self-assembled nanoparticles with the E protein domain III of DTMUV, using ferritin as a carrier (EDⅢ-RFNp), were prepared using a prokaryotic expression system. Ducks were intramuscularly vaccinated with EDⅢ-RFNp, EDⅢ protein, an inactivated vaccine HB strain (InV-HB), and PBS. At 0, 4, and 6 weeks post-primary vaccination, the EDIII protein-specific antibody titre, IL-4, and IFN-γ concentrations in serum were determined by ELISA, and neutralising antibodies titres in sera were determined by virus neutralising assay. Peripheral blood lymphocytes proliferation was determined by CCK-8 kit. Following challenge with the virulent DTMUV strain, the clinical signals and survival rate of the vaccinated ducks were recorded, and DTMUV RNA levels in the blood and tissues of the surviving ducks were determined by real-time quantitative RT-PCR. The near-spherical EDⅢ-RFNp nanoparticles with 13.29 ± 1.43 nm diameter were observed by transmission electron microscope. At 4 and 6 weeks post-primary vaccination, special and Virus neutralisation (VN) antibodies, lymphocyte proliferation (stimulator index, SI), and concentrations of IL-4 and IFN-γ in the EDⅢ-RFNp group were significantly higher than in the EDⅢ and PBS groups. In the DTMUV virulent strain challenge test, the EDⅢ-RFNp-vaccinated ducks showed milder clinical signs and higher survival rates than EDⅢ- and PBS-vaccinated ducks. The DTMUV RNA levels in the blood and tissues of EDⅢ-RFNp-vaccinated ducks were significantly lower than those in EDⅢ- and PBS-vaccinated ducks. Additionally, the EDⅢ protein-special and VN antibodies, SI value, and concentration of IL-4 and IFN-γ in the InV-HB group was significantly higher than that of the PBS group at 4 and 6 weeks post-primary vaccination. InV-HB provided more efficient protection than PBS based on a higher survival rate, milder signals, and lower levels of the DTMUV virus in the blood and tissues. These results indicated that EDⅢ-RFNp effectively protected ducks against DTMUV challenge and could be a vaccine candidate to prevent DTMUV infection.

Protein-based Nanoparticle Vaccine Approaches Against Infectious Diseases

The field of vaccine development has seen an increase in the number of rationally designed technologies that increase effectiveness against vaccine-resistant pathogens, while not compromising safety. Yet, there is still an urgent need to expand and further understand these platforms against complex pathogens that often evade protective responses. Nanoscale platforms have been at the center of new studies, especially in the wake of the coronavirus disease 2019 (COVID-19), with the aim of deploying safe and effective vaccines in a short time period. The intrinsic properties of protein-based nanoparticles, such as biocompatibility, flexible physicochemical characteristics, and variety have made them an attractive platform against different infectious disease agents. In the past decade, several studies have tested both lumazine synthase-, ferritin-, and albumin-based nanoplatforms against a wide range of complex pathogens in pre-clinical studies. Owed to their success in pre-clinical studies, several studies are undergoing human clinical trials or are near an initial phase. In this review we highlight the different protein-based platforms, mechanisms of synthesis, and effectiveness of these over the past decade. In addition, some challenges, and future directions to increase their effectiveness are also highlighted. Taken together, protein-based nanoscaffolds have proven to be an effective means to design rationally designed vaccines, especially against complex pathogens and emerging infectious diseases.

Evaluation of the Mucosal Immunity Effect of Bovine Viral Diarrhea Virus Subunit Vaccine E2Fc and E2Ft

Classified as a class B infectious disease by the World Organization for Animal Health (OIE), bovine viral diarrhea/mucosal disease is an acute, highly contagious disease caused by the bovine viral diarrhea virus (BVDV). Sporadic endemics of BVDV often lead to huge economic losses to the dairy and beef industries. To shed light on the prevention and control of BVDV, we developed two novel subunit vaccines by expressing bovine viral diarrhea virus E2 fusion recombinant proteins (E2Fc and E2Ft) through suspended HEK293 cells. We also evaluated the immune effects of the vaccines. The results showed that both subunit vaccines induced an intense mucosal immune response in calves. Mechanistically, E2Fc bonded to the Fc γ receptor (FcγRI) on antigen-presenting cells (APCs) and promoted IgA secretion, leading to a stronger T-cell immune response (Th1 type). The neutralizing antibody titer stimulated by the mucosal-immunized E2Fc subunit vaccine reached 1:64, which was higher than that of the E2Ft subunit vaccine and that of the intramuscular inactivated vaccine. The two novel subunit vaccines for mucosal immunity developed in this study, E2Fc and E2Ft, can be further used as new strategies to control BVDV by enhancing cellular and humoral immunity.

Improving cross-protection against influenza virus in mice using a nanoparticle vaccine of mini-HA

This study aimed to investigate the protective effect of mini-hemagglutinin (mini-HA) proteins expressed on lumazine synthase (LS) nanoparticles against influenza. Soluble mini-HA proteins were assembled with LS proteins via SpyTag/SpyCatcher in vitro. The size of mini-HA-LS nanoparticles was characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS), and the effect of mini-HA-LS nano-vaccines was explored in mice. The results indicate that the diameter of mini-HA-LS nanoparticles was approximately 60-80 nm. The nanoparticles could induce stronger humoral and cellular immune responses and produce cross-clade protection against influenza in mice.

Functionalizing Ferritin Nanoparticles for Vaccine Development

In the last decade, the interest in ferritin-based vaccines has been increasing due to their safety and immunogenicity. Candidates against a wide range of pathogens are now on Phase I clinical trials namely for influenza, Epstein-Barr, and SARS-CoV-2 viruses. Manufacturing challenges related to particle heterogeneity, improper folding of fused antigens, and antigen interference with intersubunit interactions still need to be overcome. In addition, protocols need to be standardized so that the production bioprocess becomes reproducible, allowing ferritin-based therapeutics to become readily available. In this review, the building blocks that enable the formulation of ferritin-based vaccines at an experimental stage, including design, production, and purification are presented. Novel bioengineering strategies of functionalizing ferritin nanoparticles based on modular assembly, allowing the challenges associated with genetic fusion to be circumvented, are discussed. Distinct up/down-stream approaches to produce ferritin-based vaccines and their impact on production yield and vaccine efficacy are compared. Finally, ferritin nanoparticles currently used in vaccine development and clinical trials are summarized.