Evaluation of cross-protection of African swine fever vaccine ASFV-G-ΔI177L between ASFV biotypes
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Published on
19.08.25
- Challenges
Vaccine development for the prevention of African swine fever has been very challenging due to the extensive genetic and largely unknown antigenic diversity.
Inactivated vaccines, using different inactivation methods and a variety of adjuvants, have been consistently inefficacious.
Historically, animals recovering from an infection with an attenuated virus became protected from the development of a clinical disease caused by an antigenically related strain.
Therefore, immunization of susceptible animals with attenuated virus strains has become a common method of vaccination with the first two commercially available vaccines based on recombinant live-attenuated viruses.
Limitation
An important limitation is that the efficacy of the live-attenuated virus is restricted to those strains that are antigenically related and, in most cases, only provide protection against homologous strains.
Due to the unknown antigenic heterogeneity among all African swine fever virus field isolates, the development of broad-spectrum vaccines is a challenge.
Besides the anecdotal data, there is not a large amount of information describing patterns of cross-protection between different ASFV strains.
A team of researchers from the International Livestock Research Institute (ILRI), Oak Ridge Institute for Science and Education and the United States Department of Agriculture evaluated the cross-protection induced by the African swine fever virus live-attenuated vaccine ASFV-G-ΔI177L against different biotypes of African swine fever virus and compared their genomic sequences to determine potential genetic mutations that could cause the lack of cross-protection.
The study is published in Vaccines (Aug 2025).
Results
The results demonstrate different patterns of protection when ASFV-G-ΔI177L vaccinated pigs were challenged with six different African swine fever virus field isolates belonging to different biotypes.
The presence of cross-protection cannot be predicted solely by the classical methodology for genotyping-based B646L ORF only.
Biotyping, considering the entire virus proteome, appears to be a more promising prediction tool, although additional gathering of experimental data will be necessary to fully validate it.
Until then, the presence of cross-protection needs to be confirmed in efficacy trials challenging vaccinated animals.
Citation
Borca, M.V., Ramirez-Medina, E., Mutisya, C., Ojuok, R., Odaba, J., Dihbol, M., Lacasta, A. and Gladue, D.P. 2025. Evaluation of cross-protection of African swine fever vaccine ASFV-G-ΔI177L between ASFV biotypes. Vaccines 13(8): 858.
Photo: Improved pigs on a farm in Hoima district, Uganda (ILRI/Karen Marshall)