Modulating affinity maturation during in vivo immunisation

During the 20th century, the ability to induce antibody responses via vaccination had a huge impact on livestock husbandry and human life expectancy. However, there remain many unanswered basic biological questions about how antibodies are generated and how this process can be manipulated. For example, (1) Can we increase in vivo affinity maturation of antibodies against complex antigens by co-delivery of antigen-specific antibody? (2) Can we increase diversity of the antibody response against complex antigens by modulating B cell signalling? Antibodies are produced when antigen-specific B cells undergo multiple rounds of mutation and selection for progressively improved antigen binding (affinity maturation). This process is self-limiting following immunisation and there is postulated to be an affinity "ceiling" above which there is no selective advantage for additional antibody mutations. However, higher levels of antibody mutation (up to 45%) are possible and have been observed during chronic infection. Therefore, this project aims to establish mechanisms to manipulate the response to produce a more diverse population of highly mutated antibodies. Specifically, by addressing the two questions above to test the following hypothesis: the antibody response to complex antigens can be improved by co-administration of antigen-specific antibodies and modulation of B cell signalling.

Project milestones: (1) Three groups of ten mice will be immunised with the multi-subunit HIV envelope protein (Env) as follows: (A) control arm; (B) Antigen-specific antibody co-delivery arm; (C) mTor inhibitor treated arm. In total, each group will receive five adjuvanted immunogen doses at two-week intervals. (2) Single cell FACS to isolate immunogen-specific monoclonal antibodies (mAbs) will allow assessment of affinity maturation at the level of individual clones. (3) Affinity maturation across the repertoire and also clonal diversity will be evaluated by NGS analysis of bulk B cell populations.

Timeline: The student will spend the first 6 months at UCL producing immunisation reagents, they will then spend 8 months at GSK to process post-immunisation samples, generate NGS data. They will then return to UCL to isolate mAbs and optimise methods to analyse the NGS data.

Relevance: The knowledge generated in this project will be important both for development of vaccines and mAbs. Thus, this proposal is aligned with two of the BBSRC's strategic research priorities: Industrial Biotechnology and Bioenergy and Bioscience for health. It will take advantage of key research opportunities to develop basic bioscience underlying the development of biologics (one of four key outputs identified as targets for industrial research collaborations). This work will also address the challenge areas (BBSRC Bioscience for Health Strategic Framework) by providing new understanding of fundamental biological mechanisms and develop innovative research tools using big data technology, namely NGS.

Partnership: The UCL team have all the skills and equipment required to analyse both the post immune serum samples and mAbs, including access to extensive bioinformatics infrastructure, and a fully operational containment level III laboratory. The in vivo selections team at GSK has extensive expertise in performing in vivo immunisations of mice and have developed methodology (with Dr McCoy on secondment at GSK) to generate antibody repertoire libraries for Illumina NGS analysis.