Enabling rapid conversion of antigen to vaccine, applied to multi-stage malaria vaccination

Vaccination is one of the most cost-effective ways to save lives and improve health. Despite the great success-stories of many human and animal vaccines, we still lack effective vaccines against major global killers such as malaria, tuberculosis and HIV. New vaccines are often developed from Virus-like particles (VLPs). VLPs resemble viruses in their size and shape, but carry no pathogenic genetic material and so do not cause disease. VLPs can be engineered to display a protein from a pathogen on their surface, to create an effective and safe vaccine. Decorating VLPs with such proteins from pathogens is one of the central challenges in the field of vaccine development, requiring expensive trial-and-error experiments and taking months to years. We have validated initial steps to overcome this key challenge. We engineered a "bacterial superglue" so that decorating VLPs simply requires mixing the VLP with the pathogenic protein. This attachment is fast, irreversible and broadly applicable. Due to the ease of the process, we have termed this platform Plug-and-Display vaccination. The pathogenic proteins we have focused on attaching to VLPs come from the malaria parasite. Malaria is one of the largest global health challenges, each year infecting approximately two million people and killing half a million people. With the difficulty in distributing effective drugs and the increase in drug resistance, there is urgent need to develop a malaria vaccine. We have investigated proteins on the surface of the malaria parasite at different stages of its life cycle and established key targets that could help create a more effective vaccine. In this proposal we will advance the Plug-and-Display vaccination approach in several ways, to maximise the immune responses to these malarial proteins. We will establish the use of our bacterial superglue for decoration of a different kind of VLP frequently used in the clinic. We will create new VLPs able to display three times more copies of the malarial protein, since that could stimulate an even stronger immune response. Also, VLPs will be precisely decorated with two different malarial proteins, to help generate a vaccine effective against a wider range of malaria strains. Since our Plug-and-Display VLPs could be useful not just for malaria but for a range of human and animal diseases, we will also increase the scale and stability of VLPs we produce, so that they can be a general resource for scientists worldwide and speed up the creation of effective vaccines against major health challenges.

Virus-like particles (VLPs) are non-infectious self-assembling nanoparticles, ideal for multimerising foreign antigens to create safe and effective vaccines. However, decorating VLPs with target-antigens is time-consuming and often leads to capsid misassembly or antigen misfolding; this is a major limiting factor for vaccine development. We have recently established a platform for irreversibly decorating VLPs simply by mixing with protein antigen. SpyCatcher is a genetically-encoded protein we designed to form a spontaneous irreversible isopeptide bond to its peptide-partner SpyTag. We expressed in E. coli VLPs from the bacteriophage AP205 genetically fused to SpyCatcher. We demonstrated quantitative covalent coupling to SpyCatcher-VLPs after mixing with SpyTag-linked to malaria and cancer antigens. This gave potent antibody responses in mice after only a single immunisation. Here we will greatly enhance the stability, purity and scale of production of this "Plug-and-display" vaccination platform. We will make major advances to the platform by establishing super-high VLP valency, twin conjugation using a second unique covalent labelling technology, and Plug-and-display on the clinically validated Hepatitis B VLP platform. Using recently established blood-stage antigens from Plasmodium falciparum, we will test the activity of the platform for generating high level protection from red blood cell invasion. By optimising a synergistic immune response from co-display of two different antigens at high density on VLPs, we will help the progress towards a broadly protective malaria vaccine. Beyond malaria, establishing the simple, efficient and modular decoration of antigen onto VLPs should accelerate and enhance vaccine development to a wide range of human and animal diseases.

Who will benefit from this research?
Apart from academic scientists, the beneficiaries will include the human and veterinary vaccine industry, which may include leading UK companies such as GlaxoSmithKline and AstraZeneca. Plug-and-display platforms developed here may be part of a final vaccine, or may accelerate the identification of antigens used in the resultant vaccine. In the long-term, the ultimate end-users of such a product for malaria would be the target population - most importantly infants in endemic areas who would be vaccinated against malaria in the first year of life.

Biotechnology and Pharmaceutical companies in diverse areas are in discussions with us about licensing SpyTag/SpyCatcher. Developing the novel VLPs through this proposal will greatly extend the ability for rapid functionalisation of nanoparticles, with potential beyond vaccines, such as in imaging, diagnosis and therapeutic delivery. Enhanced detection should have impact on disease diagnosis in animals and humans, which may be beneficial to the general public, the farming community and the National Health Service.

How will they benefit from this research?
The new platform for rapid vaccination should make it possible to explore vaccination with a wider range of candidate antigens. This will help to identify antigens giving the strongest and most protective responses and so accelerate generation of highly effective vaccines. The strong response even without boosting using SpyCatcher-VLP platforms may allow initial analysis of certain responses in half the time frequently needed when using only antigen with adjuvant.

Understanding the importance of antigen density in VLP immunisation will have general relevance in manipulation of the immune system, relevant to infectious disease, autoimmunity and chronic disease in human and veterinary medicine.
The likely time-scale for commercial licensing of intellectual property (IP) arising is in the last 6 months of the award and the year following the end of the award. In the light of positive results with novel immunogens and platforms, we will seek further research council, charitable, European Commission, or public/private partnership funding to support over the subsequent 3 years the early-phase clinical development.

This project will provide important training for the postdoctoral researchers in:
-developing and executing a project spanning disciplines from protein engineering, nanoassembly, and parasite biology to immune monitoring.
-development of presentation skills, through presenting within the University and at conferences, and discussing science and commercialisation with Human and Veterinary vaccine companies.
-taking the course in Entrepreneurship at Oxford University Business School
-assisting with protection of IP
-communicating their findings to non-expert audiences, including at the Oxfordshire Science Festival.

What will be done to ensure that they benefit from this research?
Publishing in high impact open access international journals is an effective way for us to communicate our findings to potential industrial partners. We will work with Isis Innovation, who look after Oxford University IP, to ensure protection of all new IP arising. As we achieve key results, we will communicate with the University of Oxford press office and the MRC and with our existing industrial contacts, to ensure that significant findings are communicated to the public and potential industrial partners. We will publish detailed protocols to facilitate adoption of the new multiprotein assembly and vaccine technologies by other users, as we have done previously in Nature Protocols and Methods in Molecular Biology for recent technologies we have developed.