Soil-transmitted helminths are a major cause of morbidity for humans and their livestock. A combination of better sanitation, anthelminthic drugs and vaccines are predicted to reduce the morbidity of these parasites in humans. The drugs currently used to treat these infections, albendazole and mebendazole, are fairly ineffective against Trichuris trichiura (human whipworm), and there are reports of drug resistance arising within parasite populations in Vietnam and Zanzibar. There are also no commercially available vaccines against human STH species, and very few against their veterinary counterparts. The murine whipworm, T. muris, has been used for over 50 years as a model for T. trichiura. These parasites share homology at the genomic and transcriptomic levels, and the immune responses associated with both acute and chronic infection have been well studied using the T. muris mouse model. T. muris excretory/secretory products have been studied in the context of vaccination for over four decades, however relatively little progress has been made towards identifying the molecular components that stimulate protective immunity following vaccination or during acute infection. Here, a stringent selection protocol was developed using chromatography and mass spectrometry methods combined with a measurement of T cell cytokine production. The work presented in this thesis provides a novel framework for identifying potential immunogenic candidates within adult T.muris excretory/secretory products. Exosome-like vesicles isolated from adult T. muris ES were also explored as a source of host protective material. Vaccination with exosome-like vesicles protected male C57BL/6 mice from a subsequent low dose infection, which would ordinarily progress to chronicity, and a number of potential immunogenic candidates were identified. Over the course of this thesis, several important observations were made relating to characteristics of the immune response induced by vaccination with ES. Firstly, proteinaceous material is likely to be responsible for the host protective properties of ES. Secondly, vaccination with ES products stimulates long-lasting immunity. Thirdly, vaccination with ES collected from both larval and adult stages stimulates protective immunity. The number of potential immunogenic candidates has also been narrowed down from over four hundred to just eleven. Given the homology between T. muris and T. trichiura at both the genomic and transcriptomic levels, this work has the potential to advance vaccine design for T. trichiura and other Trichuris parasites.
|Date of Award||31 Dec 2017|
- The University of Manchester
|Supervisor||Richard Grencis (Supervisor) & David Thornton (Supervisor)|
- Trichuris muris