Self-assembling anticaries mucosal vaccine containing ferritin cage nanostructure and glucan-binding region of S. mutans glucosyltransferase effectively prevents caries formation in rodents

Efficient Neutralizing Antibodies Induction by Human Parvovirus B19 Epitope-Presenting Protein Nanoparticles

Human parvovirus B19 (B19V) causes fetal hydrops in pregnant women. Despite the significant impact of this virus, effective vaccines remain unclear. In this study, we successfully engineered B19V protein nanoparticles by fusing the N-terminal receptor-binding domain corresponding to 5-80 amino acids of VP1 with two distinct types of self-assembling protein nanoparticles. Gel filtration and electron microscopic analysis confirmed the spherical assembly of the antigen-fused nanoparticles. The purified nanoparticles are efficiently bound to the surface of UT7/Epo-S1 cells, which are semi-permissive hosts for B19V infection. Immunization of BALB/c mice with VP1u 5-80 nanoparticles elicited a robust production of B19V-specific IgG antibodies compared to single VP1u 5-80 peptides. Moreover, a neutralization assay using B19V derived from a blood donor sample revealed that antibodies from mice immunized with VP1u 5-80 nanoparticles exhibited stronger infection-neutralizing activity. These findings suggest that nanoparticle formation plays a crucial role in enhancing the immunogenicity of the B19V VP1u 5-80 amino acid peptide and that these nanoparticles could serve as promising vaccine candidates, effectively inducing immunity against B19V.

Recombinant ferritin nanoparticles can induce dendritic cell maturation through TLR4/NF-κB pathway

OBJECTIVE

Immune response initiation and regulation require activation of dendritic cells (DCs). However, the mechanism by which ferritin, a carrier for immunogen, induces DCs maturation remains unclear.

RESULTS

Recombinant ferritin nanoparticle (RFNp), were prepared through the baculovirus expression vector system, formed spherical and hollow cage-liked proteins with a diameter of approximately 12.17 ± 0.87 nm. They induced bone marrow-derived DC (BMDC) maturation via surface molecules up-regulation of (MHC II, CD80, CD86 and CD40), increased pro-inflammatory cytokines production (IL-6, IL-12, TNF-α, and IFN-γ), and decreased antigen capturing capacity. They positively regulated IκBα and NF-κB (p65) phosphorylation, and facilitate NF-κB (p65) translocation into mature BMDCs nuclei. Following pre-treatment of RFNp-treated BMDCs with TLR4 and NF-κB (p65) inhibitors, respectively, surface molecule expression, pro-inflammatory cytokines production, and IκBα and NF-κB (p65) activities were suppressed. RFNp-treated BMDCs can also facilitate T-cell proliferation and differentiation into Th1 and Th2.

CONCLUSION

RFNps induced DCs maturation lends the potential application of RFNps as carrier platforms in DC-based vaccine.

The Combinations Chitosan-Pam3CSK4 and Chitosan-Monophosphoryl Lipid A: Promising Immune-Enhancing Adjuvants for Anticaries Vaccine PAc

We previously demonstrated that recombinant protein PAc could be administered as an anticaries vaccine. However, the relatively weak immunogenicity of PAc limits its application. In the present study, we investigated the effect of two adjuvant combinations of chitosan plus Pam₃CSK₄ (chitosan-Pam₃CSK₄) and of chitosan plus monophosphoryl lipid A (chitosan-MPL) in the immune responses to the PAc protein in vivo and in vitro PAc-chitosan-Pam₃CSK₄ or PAc-chitosan-MPL promoted significantly higher PAc-specific antibody titers in serum and saliva, inhibited Streptococcus mutans colonization onto the tooth surfaces, and endowed better protection effect with significantly less caries activities than PAc alone. Chitosan-Pam₃CSK₄ and chitosan-MPL showed no statistically significant differences. In conclusion, our study demonstrated that the chitosan-Pam₃CSK₄ and chitosan-MPL combinations are promising for anticaries vaccine development.

Dental caries vaccine: are we there yet?

Dental caries, caused by Streptococcus mutans, is a common infection. Caries vaccine has been under investigation for the last 40 years. Many in vitro and in vivo studies and some human clinical trials have determined many pertinent aspects regarding vaccine development. The virulence determinants of Strep. mutans, such as Ag I/II, responsible for adherence to surfaces, glucosyltransferase, responsible for the production of glucan, and the glucan-binding protein, responsible for the attachment of glucan to surfaces, have been known to elicit an antigen-specific immune response. It is also known that more than one antigen or a functional part of the genome responsible for these virulence determinants provide a better host response compared with the monogenic vaccine or complete genome of a specific antigen. To enhance the host response, the use of adjuvants has been studied and the routes of antigen administration have been investigated. In recent years, some promising vaccines such as pGJA-P/VAX, LT derivative/Pi_39-512 , KFD2-rPAc and SBR/GBR-CMV-nirB have been developed and tested in animals. New virulence targets need to be explored. Multicentre collaborative studies and human clinical trials are required and some interest from funders and public health experts should be generated to overcome this hurdle. SIGNIFICANCE AND IMPACT OF THE STUDY: Dental caries is an irreversible, multifactorial opportunistic infection. The treatment is costly, making it a public health problem. Despite many years of promising laboratory research, animal studies and clinical trials, there is no commercially available vaccine today. The research objectives have become more refined from lessons learnt over the years. Multigenic DNA/recombinant vaccines, using the best proved adjuvants with a delivery system for the nasal or sublingual route, should be developed and researched with multicentre collaborative efforts. In addition, new vaccine targets can be identified. To overcome the economic hurdle, funders and public health interest should be stimulated.

The Biology of Streptococcus mutans

As a major etiological agent of human dental caries, Streptococcus mutans resides primarily in biofilms that form on the tooth surfaces, also known as dental plaque. In addition to caries, S. mutans is responsible for cases of infective endocarditis with a subset of strains being indirectly implicated with the onset of additional extraoral pathologies. During the past 4 decades, functional studies of S. mutans have focused on understanding the molecular mechanisms the organism employs to form robust biofilms on tooth surfaces, to rapidly metabolize a wide variety of carbohydrates obtained from the host diet, and to survive numerous (and frequent) environmental challenges encountered in oral biofilms. In these areas of research, S. mutans has served as a model organism for ground-breaking new discoveries that have, at times, challenged long-standing dogmas based on bacterial paradigms such as Escherichia coli and Bacillus subtilis. In addition to sections dedicated to carbohydrate metabolism, biofilm formation, and stress responses, this article discusses newer developments in S. mutans biology research, namely, how S. mutans interspecies and cross-kingdom interactions dictate the development and pathogenic potential of oral biofilms and how next-generation sequencing technologies have led to a much better understanding of the physiology and diversity of S. mutans as a species.

Glycan recognition at the saliva - oral microbiome interface

The mouth is a first critical interface where most potentially harmful substances or pathogens contact the host environment. Adaptive and innate immune defense mechanisms are established there to inactivate or eliminate pathogenic microbes that traverse the oral environment on the way to their target organs and tissues. Protein and glycoprotein components of saliva play a particularly important role in modulating the oral microbiota and helping with the clearance of pathogens. It has long been acknowledged that glycobiological and glycoimmunological aspects play a pivotal role in oral host-microbe, microbe-host, and microbe-microbe interactions in the mouth. In this review, we aim to delineate how glycan-mediated host defense mechanisms in the oral cavity support human health. We will describe the role of glycans attached to large molecular size salivary glycoproteins which act as a first line of primordial host defense in the human mouth. We will further discuss how glycan recognition contributes to both colonization and clearance of oral microbes.