Veterinary scientists make ‘first report’ of ASF vaccine

A group of veterinary scientists has made what it believes is the “first report” of a “promising” vaccine for African swine fever (ASF).

In a study published in the Frontiers in Veterinary Science journal, researchers found that oral immunisation of wild boar with an attenuated ASF virus, resulted in 92% protection against the illness.

“This is, to our knowledge, the first report of a promising vaccine against ASF virus in wild boar by oral administration,” said the researchers.

The group of scientists said that further testing would be necessary to assess the safety of repeated administrations, the genetic stability of the vaccine, and how long it will take the host to “shed” it.

The team notes that developing vaccines for ASF has been hindered by the genetic complexity of the virus, as well as gaps in knowledge concerning infection and immunity, and a lack of stable cell lines.

Interest in finding a vaccine increased with the re-emergence of the virus in Europe; nine EU member states have reported cases of ASF in the last five years.

Up to now, attempts to develop vaccinations, including through inactivated viruses and “subunit” vaccines, had failed to bring about protective immunity.

The strain of attenuated ASF used in the vaccine came from a wild boar that was hunted in Latvia in 2017.

Experimental use of this strain on domestic pigs was previously shown to provide “complete protection” against the virulent version of ASF.

The researchers identified the movement of infected wild-boar between European regions as one of the main reasons for the spread of ASF on the continent.

The virus has ravaged the pig industry in China, and has had a knock-on effect in other parts of the world.

Ciarán Carroll, editor of the Teagasc Advisory Newsletter, explained: “65% of all meat produced in China is pig meat and the two main regions for pig meat production [Guangdong and Shandong] are both reporting sow herd culling at 30%.”

He also noted that, in one region, culling could be as high as 50%.

Carroll says that the 117 reported cases of ASF in China have “caused the reduction in the Chinese sow herd of 6.5 million sows and approximately 50 million pigs to date”.