The study was conducted by specialists from the Plum Island Animal Disease Centre (USDA, USA) in collaboration with the International Livestock Research Institute (ILRI). They tested the commercial live attenuated vaccine candidate ASFV-G-ΔI177L on ASF strains collected from different regions of Africa.
The results showed a significant difference in the protective effect of the drug:
- Strong protection. Pigs vaccinated and exposed to the same strain on which the vaccine was based remained healthy, while unvaccinated pigs died quickly.
- Partial protection. About 80% of vaccinated pigs survived when infected with a genetically different strain from Ghana.
- No protection. The vaccine was not effective against several different strains from Malawi, Kenya, South Africa and Uganda, despite a strong immune response.
These results proved that the current classification of the virus based on a single gene (p72) does not allow predicting the effect of the vaccine. For example, two strains, Georgia2010 and Pret4, had identical p72 sequences but showed completely different responses in vaccinated animals.
USDA scientists have proposed a new classification method that takes into account all genes that encode viral proteins. This allows for more accurate selection of vaccines for strains circulating in specific regions.
‘Although much research is still needed, this classification will be the only rational approach to determining effective vaccination schedules and controlling ASF outbreaks,’ said Dr Manuel Borca, a USDA scientist.
“A universal vaccine strategy will not work. We need targeted vaccines developed for specific regional virus biotypes. This will help to more effectively contain the spread of ASF,” added Anna Lacasta, a leading scientist at ILRI.
ASF remains a global threat to the pig industry. In Africa, the disease has been decimating livestock for decades, and in recent years it has caused significant losses in Asia and Europe. It is estimated that millions of pigs have been lost, impacting food security and the economic stability of farms.
ASF also poses a serious threat to North America. In 2023, the US pig industry generated more than $27 billion in revenue, while in Canada, this figure reached C$6.3 billion in 2024.
Scientists emphasise that without regionally adapted vaccines, the risks remain extremely high. Further research and development will help to create more universal or combination solutions that can provide broader protection and reduce economic losses in global pig farming.