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Interaction of African Swine Fever Virus With its Tick Vector.

Nix, Rebecca Jane. (2006) Interaction of African Swine Fever Virus With its Tick Vector. Doctoral thesis, University of Surrey (United Kingdom)..

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African Swine Fever virus (ASFV) is a large, double-stranded DNA virus which causes an acute haemorrhagic fever in domestic swine, but is apathogenic in its natural hosts, the warthog, bushpig and Ornithodoros ticks; O. moubata in Africa and O. erraticus in the Iberian Peninsula. The first aim of this thesis was to investigate the capacity of O. erraticus to act as vectors of ASFV and their ability to provide a reservoir of disease. This was studied by membrane-feeding ticks recent European ASFV isolates and monitoring the infection rate and viral titres recovered from ticks at different times post ingestion. Results have indicated differences in the ability of three European isolates’ ability to establish a persistent infection in the tick vector and provides a more comprehensive view into whether O. erraticus continue to pose a threat by acting as reservoirs of ASFV. ASFV encodes several proteins that are likely to contribute to virulence and host range. One of these proteins, CD2v, is similar to the T cell surface adhesion protein CD2. CD2v is required for the haemadsorption of swine erythrocytes to ASFV-infected cells and to extracellular virus particles. To investigate the role of CD2v in virus replication in the tick, O. erraticus were infected with a non-haemadsorbing field isolate and two recombinant isolates derived from this isolate whose haemadsorbing phenotype has been restored. The haemadsorbing recombinant isolates were found to replicate to higher titres than the non-haemadsorbing parental isolate. Inoculation of the non-haemadsorbing isolate across the gut wall was found to significantly increase viral replication within the tick. Furthermore, disruption of the interaction of CD2v with its ligand on the surface of red blood reduced the viral titres recovered from ticks. Combined, these results suggest a novel role for CD2v in virus uptake across the tick gut wall. A third objective was to establish a standard procedure to group ASFV isolates from different geographical locations. Previous analysis enabled virus isolates to be placed in broad groups by partial sequencing of a conserved gene. In this thesis, four variable regions of the ASFV genome have been identified that can be used to differentiate between closely related isolates. This procedure facilitates the analysis of lineages of infection which is of importance in understanding epidemiology of the virus and in controlling disease.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors : Nix, Rebecca Jane.
Date : 2006
Additional Information : Thesis (Ph.D.)--University of Surrey (United Kingdom), 2006.
Depositing User : EPrints Services
Date Deposited : 06 May 2020 14:15
Last Modified : 06 May 2020 14:19

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