Identification and characterisation of novel human monoclonal antibodies to chlamydia trachomatis
File(s)
Author(s)
Pinder, Christopher
Type
Thesis
Abstract
Chlamydia trachomatis (Ct) is a gram-negative, obligate intracellular pathogen responsible for a range of diseases in humans. The ocular infection, trachoma, is a leading infectious cause of blindness, whereas genital infection is the most prevalent bacterial STI worldwide.
Our group recently completed a phase I clinical trial of a candidate vaccine against chlamydia trachomatis based on the immunodominant MOMP, using a novel protein construct designed to elicit a cross-serovar response.
The primary aim of this thesis was to characterise in detail the humoral response to this vaccine by isolating antigen-specific B cells and recombinantly producing human monoclonal antibodies against MOMP. To accomplish this, several novel assays were developed to successfully isolate these antigen-specific B cells.
The first was the immunoglobulin capture assay, a protocol developed to probe the antigen specificity of IgG-secreting plasmablasts and aid in their sorting. This was accomplished through the design and testing of a cell surface-based affinity matrix to capture secreted IgG and facilitate its staining with a fluorescent antigen probe.
The second was a method of isolating chlamydia-specific B cells using fluorescently labelled bacteria, allowing for native presentation of MOMP as well as other surface-expressed chlamydial antigens.
This latter method was then used to isolate chlamydia-specific memory B cells from participants in the vaccine clinical trial, as well as from a cohort of previous trachoma-infected individuals, which led us to produce the first 18 human monoclonal antibodies to Ct, two of which were capable of neutralising chlamydia in vitro.
Characterisation of these mAbs allows a detailed look at the features required for cross-serovar protection and neutralisation, which will inform future vaccine design. The knowledge gained from this project will also assist in analysis of the humoral response to other pathogens by allowing a more detailed analysis of the acute plasmablast response to vaccination or infection.
Our group recently completed a phase I clinical trial of a candidate vaccine against chlamydia trachomatis based on the immunodominant MOMP, using a novel protein construct designed to elicit a cross-serovar response.
The primary aim of this thesis was to characterise in detail the humoral response to this vaccine by isolating antigen-specific B cells and recombinantly producing human monoclonal antibodies against MOMP. To accomplish this, several novel assays were developed to successfully isolate these antigen-specific B cells.
The first was the immunoglobulin capture assay, a protocol developed to probe the antigen specificity of IgG-secreting plasmablasts and aid in their sorting. This was accomplished through the design and testing of a cell surface-based affinity matrix to capture secreted IgG and facilitate its staining with a fluorescent antigen probe.
The second was a method of isolating chlamydia-specific B cells using fluorescently labelled bacteria, allowing for native presentation of MOMP as well as other surface-expressed chlamydial antigens.
This latter method was then used to isolate chlamydia-specific memory B cells from participants in the vaccine clinical trial, as well as from a cohort of previous trachoma-infected individuals, which led us to produce the first 18 human monoclonal antibodies to Ct, two of which were capable of neutralising chlamydia in vitro.
Characterisation of these mAbs allows a detailed look at the features required for cross-serovar protection and neutralisation, which will inform future vaccine design. The knowledge gained from this project will also assist in analysis of the humoral response to other pathogens by allowing a more detailed analysis of the acute plasmablast response to vaccination or infection.
Version
Open Access
Date Issued
2021-08
Date Awarded
2022-03
Copyright Statement
Creative Commons Attribution NonCommercial NoDerivatives Licence
Advisor
McKay, Paul
Shattock, Robin
Sponsor
European Commission
Bill and Melinda Gates Foundation
Publisher Department
Infectious Disease
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)