Orbiviruses
What are orbiviruses?
The two viruses of major veterinary importance are African horse sickness virus (AHSV) and bluetongue virus (BTV). Both are arboviruses, meaning they are transmitted by insects, in both cases, Culicoides biting midges.
African horse sickness virus (AHSV)
African horse sickness is one of the most debilitating and lethal viral infections of horses that was mostly restricted to African countries in the past. However, like its close relative bluetongue virus, AHSV appears to be expanding in range. In southern Africa, an attenuated viral vaccine is used, but this is of limited effectiveness and, due to safety concerns, is prohibited in Europe. The virus occurs as nine distinct serotypes, which further complicates diagnosis and vaccine design. There is thus a strong need for a safe, highly effective new generation vaccine.
What are we doing?
We currently have two projects that focus on the development of reagents and vaccines for AHSV:
A 3-year project funded by the Horserace Betting Levy Board aims to develop improved vaccines by applying plant expression technology to produce individual AHSV proteins and proteins assembled into virus-like particles (VLPs) in collaboration with Professor George Lomonossoff at the John Innes Centre (UK) and Dr Maretha O'Kennedy, a Special Scientist at CSIR Biosciences (South Africa). These will provide safe and effective vaccines that can be individually rapidly and cheaply produced in the face of an outbreak or formulated to provide protection against all nine serotypes.
We are also part of the EU-funded SPIDVAC (Safe Priority Infectious Diseases VACcines) consortium to develop innovative vaccines and companion DIVA diagnostic tests for three priority animal diseases on the World Organisation for Animal Health (WOAH) list of notifiable terrestrial diseases including African horse sickness. For more information please visit the SPIDVAC website.
Bluetongue virus (BTV)
Bluetongue virus is a highly pathogenic virus that affects ruminants and has a mortality rate in sheep of up to 70%. Only the minority of cases develop the blue tongue for which the virus was named. It’s a result of damage to blood vessels and tissue swelling, which reduce the amount of oxygenated blood reaching the tongue, leading to cyanosis.
The virus was first described in Africa in the late 18th Century and has since been identified in Australia, the United States, Asia and Europe. In 2007/8, the virus reached the UK from Europe when infected midges were blown across the English Channel.
Although the virus was eradicated after that outbreak, the UK remains on high alert for it re-occurring. There are vaccines available, but a major challenge for virus diagnosis and control is that there are at least 27 distinct serotypes.
What are we doing?
Professor Peter Mertens has focused his research on BTV for many years. While at the Pirbright Institute, his group developed the diagnostic assays and molecular epidemiology systems that were used to identify and track virus movements during recent bluetongue outbreaks in Europe. This played an important part in the eradication of the virus from the UK in 2008.
Peter also played a central role in determining the atomic structure of the bluetongue virus core particle.
The two viruses of major veterinary importance are African horse sickness virus (AHSV) and bluetongue virus (BTV). Both are arboviruses, meaning they are transmitted by insects, in both cases, Culicoides biting midges.
African horse sickness virus (AHSV)
African horse sickness is one of the most debilitating and lethal viral infections of horses that was mostly restricted to African countries in the past. However, like its close relative bluetongue virus, AHSV appears to be expanding in range. In southern Africa, an attenuated viral vaccine is used, but this is of limited effectiveness and, due to safety concerns, is prohibited in Europe. The virus occurs as nine distinct serotypes, which further complicates diagnosis and vaccine design. There is thus a strong need for a safe, highly effective new generation vaccine.
What are we doing?
We currently have two projects that focus on the development of reagents and vaccines for AHSV:
A 3-year project funded by the Horserace Betting Levy Board aims to develop improved vaccines by applying plant expression technology to produce individual AHSV proteins and proteins assembled into virus-like particles (VLPs) in collaboration with Professor George Lomonossoff at the John Innes Centre (UK) and Dr Maretha O'Kennedy, a Special Scientist at CSIR Biosciences (South Africa). These will provide safe and effective vaccines that can be individually rapidly and cheaply produced in the face of an outbreak or formulated to provide protection against all nine serotypes.
We are also part of the EU-funded SPIDVAC (Safe Priority Infectious Diseases VACcines) consortium to develop innovative vaccines and companion DIVA diagnostic tests for three priority animal diseases on the World Organisation for Animal Health (WOAH) list of notifiable terrestrial diseases including African horse sickness. For more information please visit the SPIDVAC website.
Bluetongue virus (BTV)
Bluetongue virus is a highly pathogenic virus that affects ruminants and has a mortality rate in sheep of up to 70%. Only the minority of cases develop the blue tongue for which the virus was named. It’s a result of damage to blood vessels and tissue swelling, which reduce the amount of oxygenated blood reaching the tongue, leading to cyanosis.
The virus was first described in Africa in the late 18th Century and has since been identified in Australia, the United States, Asia and Europe. In 2007/8, the virus reached the UK from Europe when infected midges were blown across the English Channel.
Although the virus was eradicated after that outbreak, the UK remains on high alert for it re-occurring. There are vaccines available, but a major challenge for virus diagnosis and control is that there are at least 27 distinct serotypes.
What are we doing?
Professor Peter Mertens has focused his research on BTV for many years. While at the Pirbright Institute, his group developed the diagnostic assays and molecular epidemiology systems that were used to identify and track virus movements during recent bluetongue outbreaks in Europe. This played an important part in the eradication of the virus from the UK in 2008.
Peter also played a central role in determining the atomic structure of the bluetongue virus core particle.