DIVA Marker
DIVA Strategy
DIVA strategies are designed to support differentiation between infected animals and vaccinated animals. This can be important for surveillance, outbreak control, trade and regulatory decision-making.
Many GeminiVax vaccine candidates are designed to induce strong cytotoxic T-cell responses. However, this type of immune response is difficult to monitor under field conditions. Therefore, after vaccination, at least two key questions should be easy to answer: whether the vaccine was successfully delivered, and whether the animal has been exposed to the wild-type pathogen.
For this purpose, responses to influenza vector proteins cannot be used as reliable vaccination markers, since in pigs they may also result from natural infection with circulating influenza viruses. Similarly, responses to neutralising epitopes of the target pathogen may indicate vaccination, but may also reflect ongoing or previous exposure to the wild-type pathogen.
To provide a reliable marker of successful vaccination, GeminiVax introduces a synthetic DIVA marker into the vector sequence. This marker is designed to induce a strong humoral response that can be detected by IFA or rapid strip tests, giving farmers and veterinarians a practical confirmation that vaccination has been successfully performed.
The image shows an example of such a synthetic peptide epitope incorporated into the hemagglutinin protein of the vector. Several DIVA marker candidates are currently being tested for their applicability under field conditions.
The presence of the wild-type pathogen can usually be detected by IFA tests measuring antibody responses to pathogen proteins that are not included in the vaccine. Since GeminiVax vaccines use selected B-cell epitopes and T-cell epitope cassettes rather than whole pathogen proteins, it is possible to design diagnostic assays that clearly distinguish vaccinated animals from naturally infected animals.
Our partner company, LT Biotech UAB, based in Lithuania, specialises in IFA test development and can design the required diagnostic assay sets to support DIVA-based vaccination programmes.
