ASF protein discovery offers vaccine development potential

Scientists have identified specific proteins in the African swine fever virus (ASF) that could pave the way for development of a vaccine against the deadly disease.

Researchers at the Pirbright Institute in the UK screened proteins in the virus to pinpoint the ones that are most likely to trigger an immune response in pigs.

By utilizing those proteins, they hope they will eventually be able to protect herds against the disease, which has led to the culling of millions of pigs worldwide.

In a study published in Frontiers in Immunology, scientists looked for virus proteins that activated an immune response in pigs that had been previously infected with a weakened form of ASF.

Those 18 proteins were then transferred into viral vectors — viruses which deliver the ASF proteins to pig cells but are not harmful to the animals.

Dr. Chris Netherton, head of Pirbright’s ASF vaccination group, said the virus has more than 150 proteins, and understanding which of those triggers an immune response is vital to developing this type of vaccine.

“Now we have identified proteins that activate pig immune cells, we can work on optimizing the vaccine components to ensure pigs are protected against virulent ASF strains,” he said.

ASF infects all pigs and wild boar and can cause fever, loss of appetite, vomiting and bloody diarrhea. The disease is often deadly, with some strains approaching case fatality rates of 100%.

ASF has already resulted in the culling of over 1.1m pigs in China and nearly 2.5m pigs in Vietnam alone.

Culling, quarantine and strict biosecurity measures are currently the only defenses farmers can use to prevent ASF from spreading, making the development of a safe and effective vaccine critical.

While there are various types of ASF vaccine in development, progress is slow because relatively little is known about the virus and how the immune system responds to it, a Pirbright spokesman said.

Vaccines made with inactivated viruses have not offered protection to domestic pigs, and although live attenuated vaccines — which contain weakened versions of a live virus — show promise for protection, more testing is needed to ensure their safety.

Pirbright researchers therefore hope these vector vaccines will provide an alternative, which could help to control the spread of the disease, the spokesman added.

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