This thesis aims to investigate human antibody responses to dengue virus. Dengue virus is a mosquito-borne flavivirus that circulates as 4 distinct serotypes in tropical and sub-tropical regions of the world. It is known that immunity to one serotype of the virus can be life-long but upon infection with a different serotype there is a much higher incidence of severe disease. Antibodies play an important role in this immunopathogenesis. Serotype cross-reactive antibodies have been shown to enhance the uptake of virus by Fc receptor-bearing host cells, thereby increasing the number of cells infected and the viral load. The work presented will address this concept of antibody-dependent enhancement as part of a study of the antibody repertoire in patients with primary and secondary infections. The antibody response to dengue virus was investigated by producing monoclonal antibodies from patients. Antibody variable region sequences were cloned from B cells and expressed as whole human IgG; allowing the specificity, neutralisation and enhancement features to be identified. By generating a range of antibodies it was possible to investigate the breadth of the B cell response. The B cell response was highly diverse, with a range of clones stimulated. The antibody variable region sequences were analysed to identify features within the repertoire of antibodies stimulated.
Additionally, this work describes production of an antigen display tool for characterisation of antibody target epitopes. Dengue virus envelope protein was expressed on the surface of yeast cells and a mutant library was created to map epitopes of monoclonal antibody binding. This work dissects the humoral immune response to dengue virus and contributes to the understanding of the immunopathology. This information could be used in creation of therapeutic antibodies or to assist in vaccine design and evaluation
