Nairobi: An international team of scientists has discovered that a promising African swine fever (ASF) vaccine can protect pigs against some strains of the virus but offers little or no protection against others. The findings indicate a necessity for region-specific vaccines to address one of the world's most devastating animal diseases.
According to Kenya News Agency, the research led by the U.S. Department of Agriculture's Plum Island Animal Disease Center and the International Livestock Research Institute (ILRI) tested a commercial live-attenuated vaccine candidate, ASFV-G-?I177L, against several ASFV strains collected from across Africa. Results demonstrated that while the vaccine was highly effective against certain strains, its performance varied significantly depending on the virus type.
USDA scientist Manuel Borca stated that although further experimental work is needed, the developed classification is likely the only available rational approach for deciding vaccination procedures to control and manage ASFV outbreaks. ASF is a highly contagious and often fatal disease affecting domestic and wild boars, with no globally commercially licensed vaccine available.
The disease is endemic in many parts of Africa, and recent outbreaks have devastated pig populations in Africa, Asia, and Europe, causing severe economic losses, threatening food security, and undermining the livelihoods of communities reliant on pig farming. Anna Lacasta, ILRI Senior Scientist, emphasized the need to rethink ASF vaccine strategies, noting that a one-size-fits-all solution is unlikely.
Lacasta further explained the importance of targeted vaccines aligned with regional virus biotypes to maximize protection and control outbreaks. She highlighted the necessity to support the development and licensing of vaccines based on circulating ASFV biotypes. Smallholder farmers in low- and middle-income countries (LMICs), particularly women and young people, are heavily affected by ASF. Beyond LMICs, the spread of ASF poses a significant threat to North America.
In the United States, the swine industry is crucial to the economy, generating more than USD 27 billion in gross cash receipts in 2023. Similarly, Canada's pig industry contributed CAD 6.3 billion in 2024, underscoring the region's significant economic exposure.
The study revealed that pigs vaccinated and exposed to the same strain used to make the vaccine remained healthy, while unvaccinated pigs quickly succumbed to disease. Approximately 80 percent of vaccinated pigs survived when challenged with a genetically different strain isolated in Ghana. However, the vaccine failed against several other genetically distinct strains from Malawi, Kenya, South Africa, and Uganda, despite triggering strong immune responses.
The results underscore that the traditional method of classifying ASF viruses by a single gene (p72) is insufficient to predict vaccine effectiveness. USDA scientists have developed a new classification method that analyzes the virus's entire set of protein-coding genes, offering a more precise way to match vaccines to regional virus types. The team recommends continued research into matching vaccines to virus types and exploring new vaccine designs that could provide broader protection against ASF.