A live vaccine platform under development by University of Missouri researchers could address one of the major barriers preventing widespread vaccination for highly pathogenic avian influenza (HPAI) in the U.S. poultry industry: the inability to distinguish vaccinated birds from infected ones for international trade purposes.
Wenjun Ma, professor of molecular microbiology and immunology in the Department of Pathobiology and Integrative Biomedical Sciences and Department of Molecular Microbiology and Immunology at the University of Missouri, is leading the project to develop a Newcastle disease virus (NDV)-vectored vaccine that simultaneously protects against both HPAI H5N1 and Newcastle disease while providing critical DIVA (Differentiating Infected from Vaccinated Animals) functionality.
Export market protection key to adoption
DIVA capability is essential for maintaining export markets.
Current killed whole-virus H5 vaccines cannot differentiate between birds with infection-induced antibodies versus vaccination-induced antibodies, meaning positive H5 antibody tests trigger trade restrictions regardless of actual disease status. This limitation has kept the U.S. from deploying H5 vaccines commercially, leaving the industry to rely solely on biosecurity measures to combat the ongoing outbreak.
"International trade rules say if you have H5 antibodies, they assume you have an outbreak and will ban international trade," Ma explained. "This is why currently in the U.S., we still don't use H5 vaccines for this outbreak with significant economic losses."
The vaccine in development addresses this trade barrier by incorporating DIVA markers that allow officials to distinguish vaccinated flocks from infected ones, potentially opening the door for vaccine deployment without jeopardizing export access.
The live vaccine platform offers additional industry advantages beyond DIVA functionality. Because it replicates within the bird, production costs per dose are significantly lower than killed vaccines. The live platform also enables mass application through water systems and aerosol delivery, reducing labor costs compared to individual bird injection protocols.
"This live vaccine makes this vaccine much cheaper per dose," Ma said. "We can do mass application because we can go through the water, through aerosol. We can save a lot of labor costs."
Building on previous NDV-vector approaches
Testing will be conducted at BSL-3 facilities at the University of Missouri and Kansas State University, with collaboration from Icahn School Medicine at Mount Sinai researchers.
The project builds on Ma's previous research from the 2014-2015 H5N2 outbreak, which demonstrated the safety and efficacy of the NDV-vectored approach. That foundational work, published in NPJ Vaccines, provided the preliminary data necessary to secure funding from a Highly Pathogenic Avian Influenza (HPAI) Poultry Innovation Grand Challenge Award.
"Our former study already demonstrated this kind of vaccine is safe, very effective, and we can do mass application," Ma said.
To learn more about HPAI cases in commercial poultry flocks in the United States, Mexico and Canada, see an interactive map on WATTPoultry.com.
View our continuing coverage of the global avian influenza situation.
