French lab makes progress with ASF vaccine

A vaccine against ASF can be prepared based on research done by the Ploufragan-Plouzané-Niort ANSES laboratory. "Initial results are promising and pave the way for effective control of this disease, which is responsible for high levels of swine mortality in Europe, Asia and the Caribbean," the French Food Agency said.

Georgia 2007/1 Virus Strain
The Department of Porcine Virology and Immunology (VIP) of the ANSES Laboratory has inactivated the Georgia 2007/1 virus strain that is currently circulating in the European Union. This strain has only caused mild fever in infected animals, whereas infection with the Georgia strain is usually 100% fatal.

Mild symptoms
The team conducted a series of studies with this attenuated strain and confirmed that the majority of pigs vaccinated with this virus intramuscularly or orally show only mild symptoms. Although the safety was not perfect, the survival rate was much better than the original strain of the virus. "Intramuscular vaccination is the method most commonly used on farms," ​​explains Marie-Frédéric Le Pottier, head of the VIP department. "Oral vaccination can be used to inoculate kknur with bait. This method was used for classical swine fever in the early 2000s and eradicated the disease in regions of France where it was present. Therefore, we tested both routes of vaccination from the very beginning."

Immune Response
Another promising result is that infected pigs develop an immune response that allows them to resist ASF infection without showing any symptoms as early as 2 weeks after vaccination. These results were published in the journal Viruses in December 2022.

ANSES scientists continued to work on an attenuated strain, specifically so that it could replicate in cell lines produced in vitro rather than in cells that had to be taken from pigs, as was the case initially. The move was successful, raising the possibility of producing the vaccine on a large scale. As an added bonus, the strain of virus thus produced caused fewer symptoms than the original attenuated strain, but was still effective.

Retransmission
Research is still ongoing, in particular to ensure that this attenuated strain is not transmitted from one animal to another or becomes virulent again. Scientists will also evaluate the vaccine's ability to prevent retransmission of the virus in animals that have been vaccinated and then exposed to the pathogenic ASF virus.

No Genetic Manipulation
The vaccine developed by ANSES scientists has the advantage of not being produced through genetic manipulation, making it easier to allow its use in nature. In order for these discoveries to lead to efficient industrial development and eventually vaccine production, it must be possible to transfer them to the veterinary pharmaceutical industry. To this end, the laboratory applied for a vaccine patent, which was published last August. The Ouest Valorisation Technology Transfer Office (TTO) supports ANSES in encouraging interested manufacturers to use this patent.