Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.743522
Title: Characterisation of a poxvirus associated with the decline of red squirrels in the UK
Author: Thomas, Kathryn
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2003
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Abstract:
Competition between the red and grey squirrels and an epidemic disease caused by a Squirrel parapoxvirus (SPPV) both play a crucial role in the replacement of red squirrels by the grey species. Serological evidence suggests that the grey squirrel may act as a reservoir host for SPPV, however no route of transmission between the two species has been identified. The aims of this study were to characterise the SPPV genome and to identify other potential host species. Knowledge gained from this will be invaluable for the future development of a vaccine against SPPV, which could be used in conjunction with red squirrel conservation programmes. A preliminary investigation to identify rodent species that may act as a reservoir for SPPV was carried out. Sera collected from wood mice and bank voles were screened for antibodies to SPPV using an enzyme-linked immunosorbent assay. No alternative hosts were identified using this approach. Viral DNA was purified from scab material collected from a red squirrel found dead in the wild during an epidemic of SPPV in Northumbria. The composition of the SPPV genome is G+C-rich at approximately 66%, and the genome is estimated to be 158kb in size. The G+C content is comparable with parapox and molluscipox viruses, but the genome does not correspond in size to viruses belonging to either of these genera. DNA hybridisation studies indicate that the central regions of the SPPV and Orf virus (ORFV) genomes are highly related; however the two viruses are divergent towards the genome ends. Twenty-eight previously identified poxvirus genes were identified and mapped on to the SPPV genome, including two genes previously believed to be unique to the molluscipox virus Molluscum contagiosum (MOCV). Comparison of the organisation of genes in SPPV with Vaccinia (VACV), MOCV and ORFV revealed an overall conservation in the order of genes, but differences in the spatial distribution. Further characterisation revealed that three known parapoxvirus-specific genes that are associated with virus virulence and immuno-modulation (homologues of interleukin-10 and vascular endothelial growth factor and the granulocyte macrophage colony stimulating factor inhibitory protein) appear to be absent in SPPV. In addition, sequence analysis of a putative SPPV homologue of the conserved poxvirus interferon (IFN) inhibitory gene suggests that this gene is disrupted in SPPV and not involved in the inhibition of IFN-induced anti-viral pathways. The genomic inconsistencies between SPPV and the other parapoxviruses suggest that the initial classification of SPPV as a parapoxvirus may be incorrect. Preliminary phylogenetic analysis suggests that SPPV does not belong in any of the previously described poxvirus genera.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.743522  DOI: Not available
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