Longhorn Vaccines and Diagnostics has introduced a novel single-composite peptide vaccine that offers broad protection against human, avian, and swine influenza strains including pandemic variants such as H5N1. The unconjugated vaccine combines highly conserved epitopes from key influenza proteins, hemagglutinin (HA), neuraminidase (NA), and matrix proteins (M1, M2, M2e), with the ALFQ adjuvant to stimulate a strong immune response.
Preclinical Performance Demonstrates Cross-Species Efficacy
In preclinical trials, the LHNVD-110 vaccine demonstrated robust serum IgG1 antibody responses, effectively neutralizing and inhibiting hemagglutination in both Group 1 and Group 2 influenza viruses. According to Jeff Fischer, president of Longhorn Vaccines & Diagnostics, the pig data presented at ESCMID 2025 matches previous results in mice.
"In both pigs and mice, the vaccine consistently generates high, durable IgG levels that bind and neutralize across influenza strains. There has also been no sign of reactogenicity," Fischer stated. The inclusion of a universal T cell epitope further supports the development of long-term immune protection.
Manufacturing and Deployment Advantages
The vaccine's design offers significant advantages over current seasonal flu vaccines. As Fischer explained, "LHNVD-110 durability and consistency across strains suggests it should have significant advantages over current seasonal vaccines. As a composite peptide vaccine, it is easy to scale manufacturing."
The likely durability of a year or more would allow the vaccine to be administered at any time during the year, compared to seasonal vaccines that must be closely timed to the expected flu season. For manufacturers, production can be spread throughout the year, and unused doses can be carried over annually, eliminating waste.
Pandemic Preparedness Strategy
Fischer outlined multiple roles the universal vaccine could play in pandemic preparedness: "It could be stockpiled for deployment once a pandemic strain is identified, providing at least a baseline level of protection while a strain-specific vaccine is developed. It could also replace the seasonal vaccine to generate coverage in advance of a pandemic and potentially prevent pandemics from ever happening."
Clinical Development Timeline
LHNVD-110 generates monoclonal antibodies that have been modified for extended half-life, positioning the vaccine for clinical advancement. The objective will be to demonstrate the targeted epitopes' effectiveness in providing immunocompromised patients potent protection against influenza that is not currently available.
As a cocktail, those antibodies are expected to move into IND-enabling studies in the second half of 2025. The vaccine will follow and could be expedited if concerns grow over a pandemic.
One Health Approach
Longhorn's strategy incorporates a One Health perspective covering global populations of humans and animals. "Targeting multiple antigens on the influenza virus allows the vaccine to provide broad species protection and overcome viral mutations," Fischer noted. The vaccine design is easily scalable to allow for cost-effective immunization for large populations and can be scaled regionally to bring production and access to both developed and developing regions.
The company will present data on LHNVD-110's broad strain coverage in pigs at ESCMID 2025, along with information about LHNVD-202, a dual peptide universal influenza and SARS-CoV-2 vaccine candidate that provides durable strain coverage for both respiratory infections.
