Development of a cost-effective protein-based combined glycoconjugate meningococcal-pneumococcal vaccine

The bacteria, Neisseria meningitidis (Nm) and Streptococcus pneumoniae (Sp), normally live in the back of the throat of man. However, they can also infect the blood and the brain causing a range of diseases such as pneumonia and meningitis. Meningitis is a deadly disease that can kill in less than 4 hours. The main sufferers of meningitis are children under the age of four. Some vaccines exist against Nm and Sp and have been used for many years, with a degree of success in limiting disease and preventing death. However, these vaccines do not provide full protection and are expensive. Thus, it is sensible to continue the search for new, cheaper Nm and Sp vaccines. In the first of two proof-of-principle studies, antibodies (molecules that protect us from harmful germs) were reproduced in the laboratory from patients recovering from meningitis. Antibodies taken from a Nm patient were able to kill a broad selection of Nm types; the killing ability of antibodies recognising Sp are currently being assessed. The Nm and Sp proteins recognised by these killer antibodies may be good vaccine candidates. In the second proof-of-principle study, a well-known Nm vaccine component was modified in the lab using advanced methods known as protein-glycan coupling technology (PGCT). This PGCT will allow for the production of cheaper-to-produce and effective vaccines. From the foregoing, the aims of this study are: to extend these promising preliminary studies and find more antibodies that kill Nm and Sp strains, especially those that are not covered by currently-available vaccines. Next, the the identity of the proteins on the surface of Nm and Sp to which the antibodies bind will be unequivocally determined - these are promising vaccine candidates. Subsequently, these proteins (preference will be given to those that are present in as many Nm and Sp types as possible) will be modified with PGCT. Finally, the ability of these promising vaccine candidates to induce the production of antibodies in animals will be tested - a necessary step prior to testing in humans. The ideal end-result of this study will be the identification of Nm and Sp proteins that can compose a cheaper combined vaccine that will prevent meningitis.

Despite vaccination, the ongoing threat from bacterial meningitis is unquestionable, especially in low-to-middle income countries where cost is a significant factor, justifying the search for novel approaches to vaccine candidate discovery. In proof-of-principle studies, evidence was provided for the potential utilisation of a sequential approach involving reverse vaccinology 2.0- RV 2.0 - (cloning of human monoclonal antibodies [hmAbs] from convalescing patients) followed by protein-glycan coupling technology (PGCT) to produce a cost-effective combined meningococcal-pneumococcal vaccine with broad coverage. From four ml of patient blood samples, bactericidal antibodies targeting antigens not currently included in licensed meningococcal vaccines were cloned. The functional activity of a pneumococcal antibody with broad serotype-independent specificity is currently being assessed. Furthermore, preliminary data using PGCT (cheaper and time-saving alternative to conventional in vitro chemical coupling systems) shows the successful expression and potential glycosylation of recombinant meningococcal factor-H binding protein in an Escherichia coli mutant expressing the pneumococcal serotype 4 glycan. This study will extend investigations using both RV 2.0 and PGCT to identify functionally-immunogenic protein antigens that will compose a vaccine targeting both meningococcal and pneumococcal strains. Specifically, the study will: (1) Clone and express recombinant hmAbs from patients convalescing from meningococcal and pneumococcal diseases; (2) Assess functional activity of specific hmAbs; (3) Determine antigen targets (and their sequence conservation) of functional hmAbs; (4) Couple antigens of interest to glycan; and (5) Conduct animal efficacy studies (immunogenicity and SBA/OPA) in mice to determine candidate antigens that can progress to Phase 1 human clinical trials.

There is an urgent need for cost-effective, broadly cross-protective vaccines to combat bacterial meningitis, which is responsible for substantial morbidity and mortality throughout the world. This proposal aims to identify such efficacious cross-protective protein vaccine antigens through an innovative sequential approach using advanced pre-clinical vaccine development tools: reverse vaccinology 2.0 and protein-glycan coupling technology. Success would offer a step change in capability for combating bacterial meningitis, but would potentially have far reaching impact for the development of vaccines for prevention of bacterial diseases more broadly. Potential immediate academic beneficiaries span multiple disciplines and institutions within the UK and internationally. Whilst it is impossible to predict all future beneficiaries, key areas include:

- Those directly involved in meningococcal and pneumococcal vaccine, virulence and host-interactive pathogen biology research including those based in Universities, Research Institutes, Government Agencies and Industry throughout the world. In the long term, the work will contribute to the development of cheaper vaccines targeting bacterial meningitis thereby reducing the substantial morbidity, mortality and economic losses throughout the world (and especially in resource-limited countries). Thus, in addition to vaccine researchers within Universities, Government Agencies and Industry, the work will be of interest to healthcare workers, policy makers and stakeholders e.g. Charities and those affected by the disease.

- Those directly involved in research with human pathogens where antibodies mediate protection. The results and/or methods used in the proposed study will/may be translatable to other human and, with minor modifications, animal pathogens.

- Tools for vaccine research: This work will generate optimised protocols and a pipeline for use with Gram-negative and positive bacteria. Protocols will be made available through publications, available on request, and via dedicated web-pages.

- Antimicrobial Resistance (AMR): There are concerns about AMR in N. meningitidis and S. pneumoniae facilitated by the highly recombinogenic nature of both bacteria. The development of a broadly cross-protective vaccine would result in a reduction in the amount of antibiotics used to treat bacterial meningitis due to N. meningitidis and S. pneumoniae.

- Training and development: Those working directly on the project will gain a broad portfolio of highly transferable skills, applicable to successful future careers in both academic research and within alternative settings. Exposure of BSc and MSc students, working on bacterial meningitis-related projects, will result in early exposure of the next generation of researchers in the areas of bacteriology\proteomics\vaccinology.