Immune response in humans to a nasal boost with Streptococcus mutans antigens

Intranasal immunization with a Middle East respiratory syndrome-coronavirus antigen conjugated to the M-cell targeting ligand Co4B enhances antigen-specific mucosal and systemic immunity and protects against infection

Middle East respiratory syndrome (MERS) is a threat to public health worldwide. A vaccine against the causative agent of MERS, MERS-coronavirus (MERS-CoV), is urgently needed. We previously identified a peptide ligand, Co4B, which can enhance antigen (Ag) delivery to the nasal mucosa and promote Ag-specific mucosal and systemic immune responses following intranasal immunization. MERS-CoV infects via the respiratory route; thus, we conjugated the Co4B ligand to the MERS-CoV spike protein receptor-binding domain (S-RBD), and used this to intranasally immunize C57BL/6 and human dipeptidyl peptidase 4-transgenic (hDPP4-Tg) mice. Ag-specific mucosal immunoglobulin (Ig) A and systemic IgG, together with virus-neutralizing activities, were highly induced in mice immunized with Co4B-conjugated S-RBD (S-RBD-Co4B) compared to those immunized with unconjugated S-RBD. Ag-specific T cell-mediated immunity was also induced in the spleen and lungs of mice intranasally immunized with S-RBD-Co4B. Intranasal immunization of hDPP4-Tg mice with S-RBD-Co4B reduced immune cell infiltration into the tissues of virus-challenged mice. Finally, S-RBD-Co4B-immunized mice exhibited were better protected against infection, more likely to survive, and exhibited less body weight loss. Collectively, our results suggest that S-RBD-Co4B could be used as an intranasal vaccine candidate against MERS-CoV infection.

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.

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.

LT adjuvant modulates epitope specificity and improves the efficacy of murine antibodies elicited by sublingual vaccination with the N-terminal domain of Streptococcus mutans P1

In this study, we evaluated the immunogenicity, protective efficacy and peptide-based immune signatures of antibodies raised in mice after sublingual immunization with a recombinant form of the P1 (aka AgI/II, PAc) adhesin (P1_39-512) of Streptococcus mutans, a major etiological agent of dental caries. Sublingual administration of P1_39-512 in combination with the mucosal adjuvant LTK4R (a derivative of heat-labile LT toxin) induced strong and long-lasting systemic and mucosal immune responses. Incorporation of the adjuvant resulted in an enhancement of the anti-adhesive and anti-colonization activity against S. mutans as evaluated both under in vitro and in vivo conditions. Incorporation of the adjuvant to the vaccine formulation also changed the epitope specificity of the induced antibodies as determined by immunological signatures of sera collected from vaccinated mice. Use of a peptide microarray library led to the identification of peptide targets recognized by antibodies in serum samples with enhanced anti-adhesive effects. Altogether, the results presented herein showed that the sublingual administration of a P1-based subunit vaccine represents a promising approach for the prevention of dental caries caused by S. mutans. In addition, the present study disclosed the role of adjuvants on the epitope specificity and functionality of antibodies raised by subunit vaccines.

Delivery of antigen to nasal-associated lymphoid tissue microfold cells through secretory IgA targeting local dendritic cells confers protective immunity

BACKGROUND

Transmission of mucosal pathogens relies on their ability to bind to the surfaces of epithelial cells, to cross this thin barrier, and to gain access to target cells and tissues, leading to systemic infection. This implies that pathogen-specific immunity at mucosal sites is critical for the control of infectious agents using these routes to enter the body. Although mucosal delivery would ensure the best onset of protective immunity, most of the candidate vaccines are administered through the parenteral route.

OBJECTIVE

The present study evaluates the feasibility of delivering the chemically bound p24gag (referred to as p24 in the text) HIV antigen through secretory IgA (SIgA) in nasal mucosae in mice.

RESULTS

We show that SIgA interacts specifically with mucosal microfold cells present in the nasal-associated lymphoid tissue. p24-SIgA complexes are quickly taken up in the nasal cavity and selectively engulfed by mucosal dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin-positive dendritic cells. Nasal immunization with p24-SIgA elicits both a strong humoral and cellular immune response against p24 at the systemic and mucosal levels. This ensures effective protection against intranasal challenge with recombinant vaccinia virus encoding p24.

CONCLUSION

This study represents the first example that underscores the remarkable potential of SIgA to serve as a carrier for a protein antigen in a mucosal vaccine approach targeting the nasal environment.

New insights in mucosal vaccine development

Mucosal surfaces are the major entrance for infectious pathogens and therefore mucosal immune responses serve as a first line of defence. Most current immunization procedures are obtained by parenteral injection and only few vaccines are administered by mucosal route, because of its low efficiency. However, targeting of mucosal compartments to induce protective immunity at both mucosal sites and systemic level represents a great challenge. Major efforts are made to develop new mucosal candidate vaccines by selecting appropriate antigens with high immunogenicity, designing new mucosal routes of administration and selecting immune-stimulatory adjuvant molecules. The aim of mucosal vaccines is to induce broad potent protective immunity by specific neutralizing antibodies at mucosal surfaces and by induction of cellular immunity. Moreover, an efficient mucosal vaccine would make immunization procedures easier and be better suited for mass administration. This review focuses on contemporary developments of mucosal vaccination approaches using different routes of administration.

An examination of the advances in science and technology of prevention of tooth decay in young children since the Surgeon General's Report on Oral Health

This paper addresses a number of areas related to how effectively science and technology have met Healthy People 2010 goals for tooth decay prevention. In every area mentioned, it appears that science and technology are falling short of these goals. Earlier assessments identified water fluoridation as one of the greatest public health accomplishments of the last century. Yet, failure to complete needed clinical and translational research has shortchanged the caries prevention agenda at a critical juncture. Science has firmly established the transmissible nature of tooth decay. However, there is evidence that tooth decay in young children is increasing, although progress has been made in other age groups. Studies of risk assessment have not been translated into improved practice. Antiseptics, chlorhexidine varnish, and polyvinylpyrrolidone iodine (PVI-I) may have value, but definitive trials are needed. Fluorides remain the most effective agents, but are not widely disseminated to the most needy. Fluoride varnish provides a relatively effective topical preventive for very young children, yet definitive trials have not been conducted. Silver diamine fluoride also has potential but requires study in the United States. Data support effectiveness and safety of xylitol, but adoption is not widespread. Dental sealants remain a mainstay of public policy, yet after decades of research, widespread use has not occurred. We conclude that research has established the public health burden of tooth decay, but insufficient research addresses the problems identified in the report Oral Health in America: A Report of the Surgeon General. Transfer of technology from studies to implementation is needed to prevent tooth decay among children. This should involve translational research and implementation of scientific and technological advances into practice.

Vaccines and photodynamic therapies for oral microbial-related diseases

The mouth is a favorable habitat for a great variety of bacteria. Microbial composition of dental plaque is the usual cause of various oral diseases in humans, including dental caries, periodontal disease and halitosis. In general, oral antibacterial agents such as antibiotics are commonly used to treat oral bacterial infection. Traditional periodontal surgery is painful and time-consuming. In addition, bacterial resistance and toxicity of antibiotics have become a global pandemic and unavoidable. Recently, vaccines for dental caries and periodontal disease have been developed and applied. Moreover, the use of photodynamic therapy has become an alternative to antibiotic drugs. The purpose of this article is to highlight the advantages of vaccine therapy and photodynamic therapy for oral microbial-related diseases compared to treatments with antimicrobial agents and traditional periodontal surgery.