UK research team leads international fight against African Swine Fever

Pioneering research by a team of UK researchers has helped to provide two of the world’s best hopes of a vaccine for African Swine Fever (ASF).

The team at The Pirbright Institute, which is based in Surrey, has already come up with two pioneering findings with the potential to slow the spread of the deadly disease.

In its latest situation assessment, Defra upgraded the ASF threat to the UK from pork imports from ‘low’ to ‘medium’.

To raise awareness amongst veterinarians and farmers, Pirbright scientists have collaborated with APHA to produce a resource detailing the clinical signs of infection.

Dr. Linda Dixon, African Swine Fever expert at Pirbright, said: “We hope that by creating resources such as these, we can increase the likelihood of vets and farmers identifying the disease quickly should an outbreak occur in the UK.

“Thorough surveillance and rapid diagnosis of ASF are essential for its control, services which Pirbright provides globally as the World Organisation for Animal Health (OIE) Reference Laboratory for ASF.

“Using our expertise, we can advise Defra and OIE as well as improving tests to detect the virus more accurately and rapidly.”

Vaccination hopes

Understanding this disease is now more critical than ever, and Pirbright researchers are working to find out how the virus evades the host’s immune system and how it is transmitted.

Development of a safe and effective vaccine has recently made significant progress through the work of researchers led by Dr. Dixon.

The team has come up with two promising ways to make ASF vaccine candidates.

In the first study, they genetically modified the ASF virus so that it had a reduced ability to cause infection – known as a ‘live-attenuated’ vaccine.

Pigs that were exposed to the modified strain in a small trial were protected against further infection by a natural ASF virus, indicating this vaccine candidate has the potential for further development and trials.

The second method involved screening ASF virus genes for their ability to produce proteins that create an immune response in pigs, and the team is now looking to insert the most promising genes into a vaccine.

Rapidly spreading internationally

The recent spate of ASF outbreaks in China represents a significant development in the progression of the disease internationally.

So far, more than 38,000 pigs have been slaughtered in the country in a bid to rapidly contain the outbreak.

If ASF were to circulate in such a substantial pig population, neighbouring countries would be at risk as would other parts of the world through global trade and movement of infected pork products.

With around 500 million pigs, China is home to over half the world’s pig population, so any potential spread throughout China and neighbouring countries would be devastating for global pork supplies.

It comes as more than 740 outbreaks of the disease have also been confirmed in western Europe and Russia over the last two months.

Importance of biosecurity

In addition to the lack of a vaccine, control of ASF is hindered by the many transmission routes through which the virus can spread.

Wild boar act as a reservoir for the disease, enabling the virus to circulate unchecked. Boar carcasses can remain infectious for long periods given the right conditions.

Jef Grainger, head of sector bioscience for health at the Biotechnology and Biological Sciences Research Council (BBSRC), said: “African Swine Fever is a globally emerging disease that is particularly worrying due to the broad spectrum of transmission routes for domestic and wild pig breeds affected.

With no existing means of control beyond strict biosecurity and eradication measures, there are clearly enormous economic, social and animal welfare costs associated with its spread.

Pig keepers can also help prevent infection by practising good biosecurity. Routinely providing dedicated clothing and boots for workers and visitors, limiting visitors to a minimum, and preventing outside vehicles which may be contaminated from coming on to pig premises, are valuable procedures for keeping out African swine fever.

The Animal and Plant Health Agency (APHA) has reiterated that it is illegal to feed domestic food waste or catering waste of any description to farm animals in the UK.

African Swine Fever virus does not cause disease in humans but it poses a significant threat to food security and has a substantial impact on the economy, especially on trade and farming.