06 November 2026
Researchers led by the University of Cambridge and DIOSynVax have engineered a multi-antigen mRNA vaccine, DVX-panH5Nx, which conferred 100% survival in preclinical models following lethal challenges with multiple H5N1 clades, outperforming conventional strain-matched vaccine candidates.
Conventional pre-pandemic preparedness relies heavily on single-strain, whole-inactivated virus (WIV) candidate vaccine viruses (CVVs) recommended by the World Health Organization (WHO). However, these traditional vaccines predominantly target hemagglutinin (HA) from a single isolate. As static representations of an evolving pathogen, they can rapidly lose efficacy against heterologous, antigenically drifted, or reassorted strains.
To overcome these evolutionary constraints, Del Rosario and colleagues employed the Digitally Immune-Optimized Synthetic Vaccine (DIOSynVax) technology. Rather than selecting a naturally occurring strain or a simple consensus sequence, the researchers applied phylogenetic modeling to extensive global sequence repositories, including GISAID and NCBI, to computationally design antigens incorporating conserved and critical variable epitopes.
The resulting platform, DVX-panH5Nx, comprises two polycistronic mRNA constructs co-formulated in lipid nanoparticles (LNPs):
- Strand 1: Encodes the computationally designed antigens DVX-H5-1 (representing globally distributed historical and contemporary human-infecting clades), DVX-N1, and the conserved matrix protein 2 (DVX-M2), linked through self-cleaving 2A peptides.
- Strand 2: Encodes DVX-H5-2 (designed to capture the rapid evolutionary trajectory of clade 2.3.4.4), DVX-N6, and DVX-M2.
This polycistronic architecture enables coordinated expression of HA, NA, and M2 within the same transfected host cell while simplifying manufacturing and quality-control processes.
Immunogenicity studies in mice and ferrets, the latter being a well-established model of human influenza pathogenesis, demonstrated remarkable antigenic breadth. DVX-panH5Nx elicited high half-maximal neutralizing antibody titers against a wide panel of pseudotyped viruses representing divergent clades, including ancestral clade 1, clade 2.3.2.1e, and multiple clade 2.3.4.4 subclades, including recent bovine and human genotype D.1.1 isolates. In contrast, stockpiled CVV vaccines, including A/Vietnam/1194/2004 and A/Astrakhan/3212/2020, demonstrated substantially narrower, clade-restricted neutralization. Furthermore, unlike whole-inactivated vaccines, which induced negligible anti-neuraminidase responses, DVX-panH5Nx stimulated potent neuraminidase inhibition (NI) titers against diverse N1 and N6 lineages.
Mice immunized with DVX-panH5Nx achieved 100% survival, with no significant weight loss or clinical signs, following lethal challenges with three antigenically distinct H5N1 viruses: A/Vietnam/1203/2004 (clade 1), A/Cambodia/NPH230032/2023 (clade 2.3.2.1e), and A/British Columbia/PHL-2032/2024 (clade 2.3.4.4b). In contrast, the stockpiled clade 2.3.4.4b CVV provided only 50% survival against clade 1 and 67% against clade 2.3.2.1e. At four days post-challenge, viral titers in the lungs and spleens of DVX-panH5Nx-vaccinated mice were below the limit of detection.
Ferret challenge studies: Following lethal challenge with HPAI A/chicken/Italy/23VIR3799-1/2023 (clade 2.3.4.4b), DVX-panH5Nx conferred 100% survival, with minimal clinical signs and no detectable viral dissemination to extrapulmonary organs, including the liver, spleen, and pancreas. In comparison, 50% of ferrets vaccinated with the adjuvanted clade 2.3.4.4b CVV succumbed by day 8.
These findings demonstrate that rational, multivalent antigen design can overcome important limitations of single-isolate, HA-centric vaccines. The study highlights the potential benefits of combining HA-mediated viral entry neutralization with NA-mediated inhibition of viral release, providing a complementary, two-tiered immune defense.
Del Rosario et al. (2026). Broad vaccine protection against globally diverse influenza A/H5Nx viruses. Cell Reports Medicine, 7(11), 103131.
