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Improved understanding of antigenic components and their interaction with the immune system, as supported by computational tools, permits a sophisticated approach to modern vaccine design. Vaccine platforms provide an effective tool by which strategically designed peptide and protein antigens are modularized to enhance their immunogenicity. These modular vaccine platforms can overcome issues faced by traditional vaccine manufacturing and have the potential to generate safe vaccines, rapidly and at a low cost. This review introduces two promising platforms based on virus-like particle and liposome, and discusses the methodologies and challenges. [ABSTRACT FROM AUTHOR]

Virus-like particles are an established class of commercial vaccine possessing excellent function and proven stability. Exciting developments made possible by modern tools of synthetic biology has stimulated emergence of modular VLPs, whereby parts of one pathogen are by design integrated into a less harmful VLP which has preferential physical and manufacturing character. This strategy allows the immunologically protective parts of a pathogen to be displayed on the most-suitable VLP. However, the field of modular VLP design is immature, and robust design principles are yet to emerge, particularly for larger antigenic structures. Here we use a combination of molecular dynamic simulation and experiment to reveal two key design principles for VLPs. First, the linkers connecting the integrated antigenic module with the VLP-forming protein must be well designed to ensure structural separation and independence. Second, the number of antigenic domains on the VLP surface must be sufficiently below the maximum such that a “steric barrier” to VLP formation cannot exist. This second principle leads to designs whereby co-expression of modular protein with unmodified VLP-forming protein can titrate down the amount of antigen on the surface of the VLP, to the point where assembly can proceed. In this work we elucidate these principles by displaying the 18.1 kDa VP8* domain from rotavirus on the murine polyomavirus VLP, and show functional presentation of the antigenic structure. [ABSTRACT FROM AUTHOR]

Abstract: Faster and cheaper vaccine manufacture based on modern technologies is increasingly needed to effectively mitigate the burden of disease caused by highly contagious and mutagenic pathogens, such as influenza viruses. This study describes an approach to synthetically engineer a new influenza vaccine system by antigenic modularization of a carrier viral capsomere, coupled with microbial processing of the sub-unit vaccine. This approach leads to a system optimized with respect to both biological and process criteria. Murine polyomavirus VP1 protein, which self assembles into a pentameric sub-unit capsomere of a virus-like particle (VLP), was engineered to inhibit VLP assembly and to allow modular insertion of influenza M2e antigen at multiple sites within the protein. The yield, solubility, and immunogenicity of the resulting modular capsomeres could be optimized by varying the module insertion site and the number of M2e modules per site. This study demonstrated, for the first time, an innovative strategy of inserting multiple antigenic modules, up to 45 M2e modules, in a single capsomere. Modularization of M2e antigen was shown to improve its immunogenicity by more than an order of magnitude over that attained by immunization with an equivalent mass of non-modularized M2e peptide. Vaccination of mice using modular capsomeres induced high antigen-specific antibody levels suggestive of protective efficacy. This modular vaccine design approach, inspired by synthetic biology approaches to new system development, is conducive to technologies rapidly adaptable to pathogenic variations. [Copyright &y& Elsevier]

Infection with Group A streptococcus (GAS)—an oropharyngeal pathogen—leads to mortality and morbidity, primarily among developing countries and indigenous populations in developed countries. The development of safe and affordable GAS vaccines is challenging, due to the presence of various unique GAS serotypes, antigenic variation within the same serotype, and potential auto-immune responses. In the present study, we evaluated the use of a sublingual freeze-dried (FD) formulation based on immunogenic modular virus-like particles (VLPs) carrying the J8 peptide (J8-VLPs) as a potential safe and cost-effective GAS vaccine for inducing protective systemic and mucosal immunity. By using in vivo tracing of the sublingual J8-VLPs, we visualized the draining of J8-VLPs into the submandibular lymph nodes, in parallel with its rapid absorption into the systemic circulation, which support the induction of effective immune responses in both systemic and mucosal compartments. The sublingual administration of J8-VLPs resulted in a high serum IgG antibody level, with a good balance of Th1 and Th2 immune responses. Of note, sublingual vaccination with J8-VLPs elicited high levels of IgA antibody in the saliva. The co-administration of mucosal adjuvant cholera toxin (CT) further enhanced the increase in salivary IgA antibody levels induced by the J8-VLPs formulation. Moreover, the levels of salivary IgA and serum IgG observed following the administration of the CT-adjuvanted FD formulation of J8-VLPs (FD-J8-VLPs) and non-FD formulation of J8-VLPs were comparable. In fact, the saliva isolated from mice immunized with J8-VLPs and FD-J8-VLPs with CT demonstrated opsonizing activity against GAS in vitro . Thus, we observed that the sublingually delivered FD formulation of microbially produced modular VLPs could prevent and control GAS diseases in endemic areas in a cost-effective manner. [ABSTRACT FROM AUTHOR]

Highly pathogenic avian influenza (HPAI) causes significant economic loss, reduced food security and poses an ongoing pandemic threat. Poultry vaccination significantly decreases these problems and recognizes that the health of humans, animals and ecosystems are connected. Low-cost manufacture of poultry vaccine matched quickly to the ever-changing circulating strain is needed for effective vaccination. Here, we re-engineered the process to manufacture bacterially synthesized modular capsomere comprising influenza M2e, previously shown to confer complete protection in challenged mice, for application in poultry. Modular capsomere was prepared using a simplified non-chromatographic salting-out precipitation method and its immunogenicity tested in vivo in poultry. Modular capsomere crudely purified by precipitation ( p CapM2e) contained more contaminants than equivalent product purified by chromatography ( c CapM2e). Unadjuvanted p CapM2e containing 80 EU of endotoxin per dose was inferior to highly purified and adjuvanted c CapM2e (2 EU per dose). However, addition of adjuvant to p CapM2e resulting in high immunogenicity after only a single dose of vaccination, yet without any local adverse reaction. This finding suggests a strong synergy between adjuvant, antigen and contaminants, and the possible existence of a “Goldilocks” level of contaminants, where high immunogenicity and low reactogenicity can be obtained in a single-shot vaccination. The simplified process offers potential cost and speed advantages to address the needs in influenza poultry vaccination in low-cost veterinary markets. [ABSTRACT FROM AUTHOR]

Highlights: [•] Silica nanoparticles were used to adjuvant sub-unit protein antigen. [•] Nanoparticles boosted antigen immune response without protein conjugation. [•] Non-carrier nanoparticles adjuvanting efficacy depends on particle size. [ABSTRACT FROM AUTHOR]

Highlights: [•] Investigation of a modular capsomere vaccine presenting multiple M2e elements. [•] Protective efficacy demonstrated. [•] Rapid matching of broadly cross-protecting epitope to threat virus. [•] Extends coverage and possible impact of broadly cross-protecting eptiopes. [•] Synergy of manufacturing ease and protection opens new opportunities. [ABSTRACT FROM AUTHOR]

Highlights: [•] Helix 190 (H190) from influenza virus modularized onto unrelated polyomavirus VLP. [•] Antigen module design affected response quality (level of binding to HA1). [•] Flanking H190 element with GCN4 gave a low-quality response (low HA1 binding). [•] Modularizing multiple tandem repeats of H190 gave a high-quality antibody response. [•] Biomolecular engineering offers a future alternative to whole pathogen vaccines. [ABSTRACT FROM AUTHOR]

Abstract: Group A streptococcus (GAS) causes a wide range of diseases, some of them related to autoimmune diseases triggered by repeated GAS infections. Despite the fact that GAS primarily colonizes the mucosal epithelium of the pharynx, the main mechanism of action of most vaccine candidates is based on development of systemic antibodies that do not cross-react with host tissues, neglecting the induction of mucosal immunity that could potentially block disease transmission. Peptide antigens from GAS M-surface protein can confer protection against infection; however, translation of such peptides into immunogenic mucosal vaccines that can be easily manufactured remains a challenge. In this work, a modular murine polyomavirus (MuPyV) virus-like particle (VLP) was engineered to display a GAS antigenic peptide, J8i. Heterologous modules containing one or two J8i antigen elements were integrated with the MuPyV VLP, and produced using microbial protein expression, standard purification techniques and in vitro VLP assembly. Both modular VLPs, when delivered intranasally to outbred mice without adjuvant, induced significant titers of J8i-specific IgG and IgA antibodies, indicating significant systemic and mucosal responses, respectively. GAS colonization in the throats of mice challenged intranasally was reduced in these immunized mice, and protection against lethal challenge was observed. This study shows that modular MuPyV VLPs prepared using microbial synthesis have potential to facilitate cost-effective vaccine delivery to remote communities through the use of mucosal immunization. [Copyright &y& Elsevier]

Abstract: Studies on a platform technology able to deliver low-cost viral capsomeres and virus-like particles are described. The technology involves expression of the VP1 structural protein from murine polyomavirus (MuPyV) in Escherichia coli, followed by purification using scaleable units and optional cell-free VLP assembly. Two insertion sites on the surface of MuPyV VP1 are exploited for the presentation of the M2e antigen from influenza and the J8 peptide from Group A Streptococcus (GAS). Results from testing on mice following subcutaneous administration demonstrate that VLPs are self adjuvating, that adding adjuvant to VLPs provides no significant benefit in terms of antibody titre, and that adjuvanted capsomeres induce an antibody titre comparable to VLPs but superior to unadjuvanted capsomere formulations. Antibodies raised against GAS J8 peptide following immunization with chimeric J8-VP1 VLPs are bactericidal against a GAS reference strain. E. coli is easily and widely cultivated, and well understood, and delivers unparalleled volumetric productivity in industrial bioreactors. Indeed, recent results demonstrate that MuPyV VP1 can be produced in bioreactors at multi-gram-per-litre levels. The platform technology described here therefore has the potential to deliver safe and efficacious vaccine, quickly and cost effectively, at distributed manufacturing sites including those in less developed countries. Additionally, the unique advantages of VLPs including their stability on freeze drying, and the potential for intradermal and intranasal administration, suggest this technology may be suited to numerous diseases where adequate response requires large-scale and low-cost vaccine manufacture, in a way that is rapidly adaptable to temporal or geographical variation in pathogen molecular composition. [Copyright &y& Elsevier]