Parasitic nematode infections worldwide cause a significant impact on human health, as well as economic and welfare losses to the animal and agriculture industries. The principal method of control for parasitic nematode infections is currently limited to repeated treatments with anthelmintic drugs, but widespread resistance to all major classes of these drugs is a growing problem. As a result, there is an urgent need for alternative methods of controlling these infections, and the development of molecular vaccines and novel drugs represent two possible approaches. However, both these approaches require a deeper understanding of gene function in order to identify suitable control targets. This project examines RNA interference (RNAi) in the parasitic nematode Haemonchus contortus to determine if this could be developed as a functional tool and advance the discovery of novel control targets for parasitic nematodes. RNAi has proven less effective in parasitic nematodes than in the free-living model nematode Caenorhabditis elegans and it is unclear why this is so. This project examined the reliability of RNAi in H. contortus, and several genes were successfully silenced using RNAi. Further analysis of RNAi susceptible genes revealed that RNAi silencing appears to be related to the site of expression of the target gene; genes expressed in tissues which are accessible to the environment such as intestine, excretory cell and amphids were silenced by RNAi. Upstream promoter regions of RNAi susceptible genes were examined for the presence of motifs which may regulate spatial gene expression, an approach that could be used to predict gene susceptibility to RNAi. RNAi treated larvae were subsequently used to infect sheep in the first in vivo RNAi study, resulting in a significant impact on worm survival in vivo. In addition, several components of the RNAi pathway in H. contortus were characterised in this project, demonstrating the presence of a functional RNAi pathway that is capable of reliably silencing genes. In conclusion, the findings presented in this project suggest that RNAi may be used in the future to evaluate the function of a novel vaccine or drug target for controlling H. contortus infections in sheep.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:601515 |
| Date | January 2010 |
| Creators | Samarasinghe, Buddhini |
| Publisher | University of Glasgow |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://theses.gla.ac.uk/1957/ |
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