The development of an antibody based therapy for Clostridium difficile
Introduction
Summary
The spore forming bacterium Clostridium difficile is a significant cause of illness amongst hospitalized patients in Wales accounting for 2,473 laboratory confirmed cases in 2005 and contributing to 105 deaths. In addition to the substantial human cost the estimated financial burden of this healthcare associated infection to Wales exceeds £10 million annually. Studies have shown that the stimulation of a robust antibody based immune response plays a key role in mediating protection. Animals studies have confirmed the feasibility of using antibodies to confer passive protection.
Aims of Project
Research objectives
1.Clone previously identified protective immunogens for C.difficile into an E.coli based expression system. It has previously been demonstrated that the C terminal receptor binding domains of the C.difficile major virulence facrtors, toxins A (tcdA) and B (tcdB), stimulate the production of protective antibodies in animals. In addition vegetative cell surface associated S layer proteins have been shown to induce the production of antibodies which inhibit the binding of the vegetative bacterium to human gut cells. We propose to clone and express codon optimized versions of these immunogens from E.coli and isolate recombinant proteins.
2. Characterize the immune response of individuals exposed to C.difficile and identify immunodominant epitopes. To identify immunodominant epitopes within each recombinant protein we will probe E.coli expressed C.difficile derived immunogens with antisera obtained from infected patients attending the University Hospital of Wales in Cardiff by 2D gel electrophoresis. Immunodominant spots will be identified by N terminal sequencing and epitope library mapping. Confirmational epitopes will be characterized using a phage display approach. This information will underpin the develop of antibody assays with which to determine the immune status of infected and immunized individuals and will enable clinicians to identify individuals likely to succumb to repeated episodes of infection as a consequence of a sub-optimal immune response. It will also provide the means to screen for toxin neutralizing antibodies.
3. The identification of toxin neutralizing antibodies. We will immunize mice with the recombinant proteins and determine the ability of the resulting polyclonal antibody response to neutralize toxin activity and inhibit bacterial binding using established cell culture based assays. We will then determine the ability of individual immunodomominant epitopes identified during the human serum screening process to inhibit toxin neutralization using a competition assay. Finally we will determine the ability of selected epitopes to inhibit the toxin neutralizing activity of human serum.
Training benefit to the student.
The proposed program of research will enable the student to develop a multidisciplinary research skill set encompassing microbiology, molecular biology and immunology. The involvement of clinical and industrial partners is expected to create opportunities for the researcher to venture out from the laboratory and interact with professionals in other disciplines. It would also enable them to gain an appreciation of the multiple steps involved in drug development.
Research fit
The organism Clostridium difficile is a significant causes of morbidity and mortality amongst hospitalized patients in Wales accounting for considerably more infections than MRSA. To combat the threat posed by C.difficile there is thus a pressing need to identify effective hospital decontamination strategies and to develop tools and therapeutics which can be used to treat at risk and infected individuals. To address theses issues we are in the process of establishing a new C.difficile research group which will, in collaboration with healthcare, academic and industrial partners, develop three complimentary research focuses namely detection, decontamination and treatment/anti-infectives.
To underpin this effort we have established a strategic link with Dr Jon Brazier the head of the National Anaerobe Reference Unit which is based at the Heath and hosts an extensively collection of C.difficile isolates. We have also established a link with Dr Robin Howe a consultant Microbiologist at the National Public Health Service Microbiology Laboratory which is also based at the University Hospital. Robin has a long term interest in C.difficile and has kindly agreed to provide access to clinical samples in addition to acting as a co-supervisor of the student. Building collaborative links with our public health and clinical colleagues across the university can only strengthen the relevance of our research effort and its is our expectation that it will lead to future joint research in this and other areas.
Finally the involvement of an industrial co-sponsor, IQ Corporation, with a track record of developing human antibody based therapeutics, provides us with a clear pathway with which to translate the research effort and develop a licensed therapeutic. Indeed Robin has indicated that their would be interest in performing the associated follow on clinical trails at the University Hospital.
IQ Corporation is a global biopharmaceutical company based in the Netherlands. Their mission is the development and commercialization of innovative products for diagnosis and therapy. The arm of the company that will be involved in this project is IQ Therapeutics which has a track record of developing fully human monoclonal antibodies for the treatment of infectious disease based on its novel and proprietary human antibody-based-technology. I have previously worked with the company during my time the US and as a consequence are familiar with their capabilities.
Funder
IQ Corporation based in the Netherlands
Project Value
£15,000 pA
Duration
3 years
