May 23, 2020


Pirbright scientists test vaccine that immunises pigs against African swine fever


Scientists from The Pirbright Institute in the UK are developing a vaccine for African swine fever (http://), which the World Organisation for Animal Health (OIE) has warned could kill a quarter of the world's pigs, partly due to the absence of a commercially available vaccine.


In a press release, the institute revealed that 100% of pigs immunised with the new vaccine were protected from a lethal dose of ASF virus (ASFV).


The team of scientists created what is known as a vectored vaccine by inserting eight strategically selected ASFV genes into a non-harmful virus, known as vector. Vectors are used to deliver the genes to pig cells where they produce viral proteins that prime the pig immune system to rapidly respond to an ASF infection.


The combination of eight virus genes protected pigs from severe disease after challenge with an otherwise fatal strain of ASFV, although clinical signs of disease did develop.   


According to Pirbright, this is the first time that a vectored vaccine has shown a protective effect against ASF. "Further development is needed, but if successful, this vaccine would enable the differentiation of infected animals from those that have received a vaccine (DIVA), which would allow vaccination programmes to be established without sacrificing the ability to trade", it added.


 "Demonstrating that our vaccine has the potential to fully protect pigs against ASF is a huge step in our vaccine development programme. We have already begun work to refine the genes included in the vaccine to improve its effectiveness and provide more protection", said Dr Chris Netherton, head of Pirbright's ASF Vaccinology Group.


For Christine Middlemiss, the UK's chief veterinary officer, the creation of the vectored vaccine "is a very encouraging breakthrough and it means we are one step closer to safeguarding the health of our pigs and the wider industry's role in global food supply from African swine fever". 


Over seven million pigs died worldwide due to ASF in 2019, Pirbright said. The ASF virus can cause fever, loss of appetite, vomiting and bloody diarrhoea in pigs and wild boar. The disease is often deadly, with some strains approaching case fatality rates of 100%.