Charell-Dennis, Marie Catherine Francoise; (2002) Characterisation of B cell epitopes on human chorionic gonadotropin. Doctoral thesis (Ph.D), UCL (University College London).

Preview

Text out.pdf Download (23MB) | Preview

Abstract

A B cell epitope is defined as part of the antigen that is recognised by any given antibody. Despite the identification of common features, such as size or general shape, by the analysis of crystal structures of antigen/antibody complexes, relatively little is understood concerning B cell epitopes compared to T cell epitopes. This project aimed to characterise B cell epitopes on the β-subunit of human chorionic gonadotropin (hCG), because the availability of a crystal structure and a well-defined panel of monoclonal antibodies made β-hCG an ideal model. The production of hCG is largely restricted to pregnancy and its presence is necessary for the implantation of the fertilised egg. It has thus been employed in clinical trials as a potential contraceptive vaccine. The information gained during this project could increase our general knowledge concerning B cell epitopes, which ultimately could be helpful in the design of a safe birth control vaccine. Four separate approaches toward defining B cell epitopes on β-hCG were investigated: o The feasibility of identifying antibody-protected amino acids on a linear peptide epitope was examined using mass spectrometry in deuterium exchange experiments. The results obtained revealed the limitations of this technique, particularly in relation to the proportion of amide hydrogens engaged in hydrogen bonds and the presence of water molecules at the antibody/antigen interface. o A peptide library was screened with hCG-specific monoclonal antibodies to identify and characterise mimotopes of the relevant epitope. Although peptides mimicking the antigenicity were identified and information concerning the antigenic profile of this epitope were gained, the peptides did not elicit hCG-reactive antibody responses in vivo. o Site-specific mutagenesis of β-hCG combined with expression on the surface of mammalian cells was employed to define residues involved in an hCG-specific epitope. o Comparison of binding affinities of antibodies mapping various epitopes on hCG for one mutant was precisely determined using surface plasmon resonance technology. The results compared with previous immunogenicity studies emphasised the distinction between antigenicity and immunogenicity.

Download activity - last month

Export as JSONXMLCSV

Download activity - last 12 months

Export as XMLJSONCSV

Downloads by country - last 12 months

Export as CSVJSONXML

Archive Staff Only

View Item