As vaccine development advances, this article focuses on how VAX4ASF is developing companion DIVA diagnostics to ensure that vaccination and surveillance work hand in hand for effective ASF control.
As efforts intensify to develop safe and effective vaccines against African swine fever virus (ASFV), another piece of the puzzle becomes increasingly important: diagnostics. In a future where vaccination forms part of ASF control, the ability to distinguish infection from vaccination will define the success of surveillance systems.
For VAX4ASF, vaccine innovation and diagnostic development go hand in hand.
African swine fever remains one of the most challenging animal diseases affecting the pig sector worldwide. Strict biosecurity measures, movement controls and stamping-out policies have been essential in limiting its spread. However, as new limited-replication vaccine candidates move closer to practical application, disease management enters a new phase.
Vaccinated animals will develop antibodies, but so will infected animals. Without a reliable way to tell the difference, surveillance systems risk losing accuracy and trust. Authorities would struggle to detect new outbreaks within vaccinated populations, and trade could be affected by uncertainty. For vaccination to become a more powerful and responsible tool against ASF, it must be supported by precise diagnostics.
What is a DIVA test and why is it essential?
DIVA stands for Differentiating Infected from Vaccinated Animals. It refers to diagnostic tests specifically designed to distinguish immune responses caused by natural infection from those induced by vaccination.
In practical terms, a DIVA test allows veterinarians to analyse a blood sample and determine whether antibodies are linked to exposure to the wild virus or to a vaccine. This distinction is crucial for maintaining effective surveillance, safeguarding trade and ensuring rapid response if the virus re-emerges.
DIVA diagnostics provide reassurance in trade contexts, demonstrating that vaccination does not mask infection and that monitoring systems remain robust and transparent.
Without DIVA diagnostics, vaccination could unintentionally blur the epidemiological picture. With them, vaccination becomes a controlled and transparent tool within broader ASF management strategies.
Designing diagnostics alongside vaccine innovation
Within VAX4ASF, the DIVA strategy is developed in parallel with the vaccine candidates to ensure that vaccination and surveillance remain fully compatible. The limited-replication vaccine approach relies on selecting specific viral components, where diagnostic markers capable of distinguishing vaccination from natural infection may be then explored.
By focusing on immune responses linked to specific ASFV antigens, the DIVA test is designed to detect patterns that differ between infected and vaccinated animals. This differential approach enables reliable identification while preserving the clarity and robustness of surveillance systems.
VAX4ASF is contributing to a comprehensive approach to ASF control: one that balances scientific innovation, animal health protection and economic stability.
Developing such a companion diagnostic is challenging and requires complex processes with multiple tests and adaptations, which may provide unexpected results. Among others, the work includes identifying and characterising suitable ASFV antigens, generating the necessary immunological tools, and developing immunoassay prototypes —primarily ELISA-based formats— designed to achieve high sensitivity and specificity.
Once established, these assay prototypes will undergo performance evaluation using well-characterised samples from infected, vaccinated and non-infected animals. This validation phase will verify that the future test performs reliably under different epidemiological conditions, including both domestic pig populations and relevant wild suid contexts, supporting its potential future use in real-world surveillance programmes.
A fundamental element surveillance and policy
The impact of a DIVA test extends far beyond the laboratory. Reliable diagnostics underpin epidemiological modelling, risk-based surveillance and vaccination strategies. They allow authorities to monitor vaccine coverage, detect virus circulation early and adapt control measures accordingly.
Equally importantly, DIVA diagnostics provide reassurance in trade contexts, demonstrating that vaccination does not mask infection and that monitoring systems remain robust and transparent. They have also historically played a key role in eradication programmes, such as those targeting Aujeszky’s Disease (Pseudorabies).
By advancing both next-generation vaccines and a companion DIVA diagnostic test, VAX4ASF is contributing to a comprehensive approach to ASF control: one that balances scientific innovation, animal health protection and economic stability.
In the fight against African swine fever, diagnostics do not simply support vaccination. They make its responsible implementation possible.