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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]

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]

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]