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Genetic analyses, molecular epidemiology and diagnostic systems for bluetongue and related orbiviruses - SE2621

Description
This project will bring together research by the ‘Arbovirus Molecular Research Group’ (AMRG) and the Non-vesicular Reference Laboratory (NVRL) at The Pirbright Institute (TPI), involving genetic analyses and molecular-epidemiology studies of bluetongue virus (BTV), African horse sickness virus (AHSV), epizootic haemorrhagic disease virus (EHDV), equine encephalosis virus (EEV) and related orbiviruses. Data generated concerning the origins, movement, genetic composition and evolution of economically important orbiviruses that threaten Europe and the UK, provides a basis for development of novel diagnostic assays and risk assessment. Relevant data and analyses will be provided to Defra, the EU, OIE and other national authorities to inform policy decisions concerning appropriate surveillance and control strategies.
The global ‘Orbivirus Reference Collection’ (ORC) and sequence-databases (http://www.reoviridae.org/dsRNA_virus_proteins/ReoID/orbiviruses.htm) will be maintained. These important national and international resources, provide data and materials for molecular epidemiology studies and the design / validation of diagnostic assays and vaccines. The European BTV Reference Laboratory, Headed by Dr Carrie Batten has helped detect, type and trace the origins of European BTV outbreak-strains from each year since 1998, including BTV-8 which spread to the UK during 2007. A novel 26th serotype of BTV was identified in Kuwait during 2010, which does not infect adult Culicoides or a Culicoides cell line (KC cells) but can be transmitted horizontally between goats. The recent re-emergence of BTV-8 in central France (in 2015) and continuing transmission of BTV-4 in South Eastern Europe highlight threats posed by BT incursions into central and northern Europe (including the UK). The transmission of both AHSV and EHDV by the same insect-vectors (Culicoides spp.) suggests that they could also spread to/in Europe. Phylogenetic studies of European BTV isolates recently demonstrated the significance of genome-segment exchange (reassortment) in the evolution and emergence of these viruses.
The project will isolate and characterise orbivirus strains from outbreaks in Europe and other geographic regions of the world, maintaining the ORC and sequence-database. Full-genome sequences for novel viruses will provide information concerning their origins, movements and evolution. Reassortant genotypes will be identified and characterised, to help assess the risks they represent to Europe and the UK. Specific reassortant strains (e.g. between BTV-1 and BTV-26) will also be generated by reverse-genetics to assess the role of individual genome-segments and viral-proteins (genetic-markers) in control/restriction of infection and replication in Culicoides cells. These data and reassortant-strains will be made available to other projects to determine the significance of individual genome-segments / proteins in transmission by adult Culicoides, or horizontal spread between ruminants.
The major outcome of this programme will be provision of data and reference materials to maintain, improve, and validate molecular assays (maintaining diagnostic capability), and for selection, development and testing of novel vaccines by commercial partners. Multiplex typing assays will be developed to increase the speed and reduce costs of surveillance; also reducing the risk that mixed BTV infections will go undetected. Outer-capsid protein VP2 from different BTV serotypes will be expressed in plants and evaluated in serotype-specific ELISA that could potentially replace neutralisation tests to identifying BTV serotype, or BTV serotype-specific antibodies.
Objective
1: Full genome sequence analyses of orbivirus isolates/serotypes from Europe and other geographic areas: for molecular epidemiology and genome segment reassortment studies.
2. Maintain and continue to expand the Orbivirus Reference Collection (ORC).
3. Identify BTV genes and proteins involved in control or restriction of insect vector transmission.
4: Generate genome sequence data for representative isolates of other Orbivirus species: to support strain identification, differential diagnosis and analyses of genetic relationships.
5: Design and maintain oligonucleotide primers and probes for real-time RT PCR assays to detect and identify the serotypes of BTV, AHSV, EEV and EHDV.
6: Develop and validate multiplex assays for identification of different BTV serotypes.
7: Design generic RT-PCR assays to detect and identify different Orbivirus groups, and individual Orbivirus species (species-specific / group-specific assays).
8. Express VP2 proteins from different BTV serotypes for development of BTV type specific serological assays (ELISA).
9: Evaluate and provide relevant diagnostic assays / support for the Non-vesicular Reference Laboratory at TPI.
Time-Scale and Cost
From: 2016

To: 2019

Cost: £1,011,256
Contractor / Funded Organisations
IAH - Institute for Animal Health
Keywords
Animals              
Bluetongue              
Diagnosis              
Vector-Borne Viral Diseases              
Fields of Study
Animal Health