African swine fever vaccine to protect wild boar

A vaccine delivered to wild boar in their food can immunise them against African swine fever, and this immunity may be able to be passed on to others, University of Madrid researchers suggest.

“Our study demonstrates the effectiveness of the first oral vaccine against this disease on Eurasian wild boar. Overall, we demonstrate that oral immunisation of wild boar conferred 92% protection against a highly pathogenic strain of African swine fever, which is currently circulating in Asia and Europe,” said Dr Jose Angel Barasona, a researcher at the VISAVET Health Surveillance Centre and co-author of the research.

African swine fever is a highly contagious, deadly disease that poses a worldwide threat to the pig industry. It has spread to more than 55 countries on three continents, and it affects more than 77% of the world swine population. The disease spreads via contaminated feed and pork products, as well as by the movement of infected livestock and across wild boar populations.

The complex nature of the virus, gaps in knowledge concerning infection and immunity, and technical difficulties have hindered vaccine development in the past. In the new study, published in Frontiers in Veterinary Science, researchers created a vaccine using serum from a wild boar hunted in Latvia in 2017 which tested positive for African swine fever.

“This was a weakly virulent strain of the disease, which enabled us to produce a live vaccine. When we inoculated wild boar in our laboratories with this live strain, they showed no symptoms of this disease but produced antibodies against the virus, ultimately giving them protection against the more dangerous form,” Barasona said.

Testing of the vaccine showed it was not only effective against one of the most dangerous strains of African swine fever, but that this immunity could be passed on to other wild boar through contact with vaccinated animals.

“The ‘shedding’ of this vaccine might help amplify vaccination coverage, reducing the need for expensive production and large-scale administration of vaccine in the field,” explained Barasona.

According to the researchers, the vaccine could be administered in bait to the wild animals to control the disease, similar to how the outbreak of classical swine fever in Europe in the 2000s has been addressed. However, further research is needed before it can be used widely.

“If the safety of the vaccine can be established, then it may help mitigate the uncontrolled spread of African swine fever across Europe and Asia, like the success so far in halting the spread of classical swine fever. Future studies should examine the vaccine’s safety following repeated administration, the process of shedding, and its genetic stability during passage from one animal to another.”

Image credit: ©stock.adobe.com/au/wojciech nowak