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Aquatic Herpes & other Large DNA Viruses - FC1202

Defra has a priority to ensure the high health status of wild animal populations. This project will employ a range of approaches and tools to improve the scientific basis for management and control of aquatic disease in both wild and farmed fish and shellfish populations and maintain that high health status.

For a number of decades the OIE list of serious aquatic animal diseases contained only one disease caused by a DNA virus, namely Channel catfish virus. The OIE list in 2011 now includes seven serious diseases caused by DNA viruses, three iridoviruses, two herpesviruses, a parvovirus and a baculovirus. There are also emerging serious diseases with DNA virus aetiology that are currently not listed. It is expected that the effects of climate change will result in new pathogens emerging, which will very likely include more DNA viruses. Research on serious viral pathogens at the Cefas Weymouth laboratory has very largely focused on RNA viruses, with no studies on DNA viruses until the emergence of koi herpesvirus (KHV) at the end of the 1990s. The emergence of more DNA viruses has presented new diagnostic challenges for the Cefas Weymouth laboratory and underlined the importance of characterising these viruses to help produce effective risk assessments for disease control. In response to this, Defra has funded a number of KHV research projects over the past decade and, more recently, studies of other emerging DNA viruses.

This project will continue productive research study areas begun under the previous Defra funded research projects. In particular, the KHV research project (FC1193) and the molecular epidemiology project (FC1191). The aim will be to exploit knowledge gained from these projects to improve methods for diagnosis, detection and molecular epidemiology of emerging herpesviruses and other large DNA viruses.

This project will also provide evidence to support Defra’s position regarding the control of serious emerging pathogens. A particular example is Ostreid herpesvirus. A new variant of OsHV1 emerged in France in 2008. It rapidly spread to all oyster production areas in France and other EU member states. It has caused high levels of mortality and significant declines in oyster production. The virus is found at only one location in the UK (Whitstable). Research to support the UK control policy is proposed.

As well as new virus pathogens emerging, new strains or variants of viruses arise, which may differ in certain characteristics from the original strains. A further aim will be to characterise new virus strains to assess such factors as pathogenicity and prevalence in aquatic environments to provide information for risk assessment purposes.

The project has nine objectives arranged under three themes. Under the theme of herpesvirus latency the objectives include, investigation of herpesvirus reactivation and development of assays to detect latent herpesvirus. Under the theme of improving capabilities for diagnostic & epidemiological investigation the objectives include, further characterisation of cyprinid herpesvirus (CyHV) variants and emerging putative CyHVs, improving detection of emerging virus pathogens and Improvement and further validation of antibody detection assays for disease surveillance. Under the theme of emerging herpesviruses and other large DNA viruses the objectives include studies on ostreid herpesvirus (OsHV) and OsHVmicrovar, development of a challenge model
for OsHV and studies on crustacean herpesviruses and on other large DNA viruses.
01. Investigation of herpesvirus reactivation...
02. Development of assays to detect latent herpesvirus...
03. Further characterisation of cyprinid herpesvirus variants and emerging putative cypriniviruses...
04. Improving detection of emerging cirus pathogens...
05. Improvement and further validation of antibody detection assays for disease surveillance...
06. Studies on Ostreid herpesvirus (OsHV) and microvar...
07. Develop a challenge model for infection of oysters with OsHV/OsHVuvar
08. Studies on crustacean herpesviruses...
Studies on other large DNA viruses...
Time-Scale and Cost
From: 2012

To: 2015

Cost: £390,000
Contractor / Funded Organisations
Animal Health              
Fish Disease