Experimental vaccine for swine fever virus shows promise

Researchers have developed a vaccine against African swine fever that appears to be far more effective than previously developed vaccines.

Currently, there is no commercially available vaccine against African swine fever, which has been devastating the swine industry in Eastern Europe and Southeast Asia.

African swine fever virus (ASFV) is highly contagious and often lethal to domestic and wild pigs, according to the the study, published in the Journal of Virology.

"This new experimental ASFV vaccine shows promise, and offers complete protection against the current strain currently producing outbreaks throughout Eastern Europe and Asia," said study researcher Douglas P Gladue from Plum Island Animal Disease Center, Agricultural Research Service, US Department of Agriculture.

The research was motivated by the 2007 outbreak of African swine fever in the Republic of Georgia.

"This was the first outbreak in recent history outside of Africa and Sardinia--where swine fever is endemic--and this particular strain has been highly lethal and highly contagious, spreading quickly to neighboring countries," Gladue said.

"This is also a new strain of the virus, now known as ASFV-G (the G stands for Georgia)," Gladue added.

For the findings, researchers set out to develop a vaccine. Part of the process of developing whole virus vaccines involves deleting virulence genes from the virus.

But when the researchers deleted genes similar to those that had been deleted in older ASFV strains to attenuate them, "it became clear that ASFV-G was much more virulent" than the other, historical isolates, because it retained a higher level of virulence, said Gladue.

The researchers then realised they needed a different genetic target in order to attenuate ASFV-G.

They used a predictive methodology called a computational pipeline to predict the roles of proteins on the virus. The computational pipeline predicted that a protein called I177l could interfere with the immune system of the pig.

When they deleted this gene, ASFV-G was completely attenuated.

In the study, both low and high doses of the vaccine were 100 per cent effective against the virus when the pigs were challenged 28 days post-inoculation, the researchers said.