Tonix Pharmaceuticals Announces Presentation of New Data on Mpox and Smallpox Vaccine Candidate TNX-801 at the Vaccine Congress 2025
July 10, 2025
Tonix Pharmaceuticals has presented compelling preclinical data on TNX-801, a recombinant horsepox vaccine designed for mpox and smallpox prevention. At the 2025 Vaccine Congress, researchers highlighted TNX-801’s capacity to generate durable immunity from a single subcutaneous dose—offering strong protection without the safety risks associated with traditional vaccinia vaccines. In nonhuman primates, TNX-801 conferred complete protection against Clade I mpox challenge. With promising immunogenicity and attenuation, TNX-801 could be a game-changer in outbreak preparedness. Tonix aims to move into clinical trials soon, positioning this novel candidate as a critical asset in global orthopox virus control strategies.
Tonix Pharmaceuticals’ presentation at the 2025 Vaccine Congress in Vienna introduced promising new data on TNX-801, a recombinant live horsepox virus vaccine designed to prevent orthopoxvirus infections, including mpox and smallpox. The vaccine, TNX-801, demonstrated robust immunogenicity and strong attenuation across preclinical models, potentially offering a safer alternative to traditional vaccinia-based vaccines.
According to Tonix CEO Dr. Seth Lederman, TNX-801’s ability to be administered subcutaneously—rather than via percutaneous scarification—marks a major advantage, potentially reducing adverse events like bacterial superinfection and inadvertent virus spread. Preclinical data revealed that TNX-801 replicates 27–119 times less in primary human dermal cells and is up to 100,000 times less virulent in interferon receptor knockout mice compared to legacy vaccinia strains.
Most notably, a single dose of TNX-801 provided full protection in cynomolgus macaques against a lethal Clade I mpox challenge, with no lesions observed. Durable immunity was also maintained in rabbits for up to 14 months post-vaccination. This efficacy, combined with a favorable safety profile in immunocompromised models, sets TNX-801 apart as a next-generation orthopox vaccine candidate.
Dr. Sina Bavari, Executive VP for Infectious Disease R&D at Tonix, emphasized the vaccine’s potential to “dissociate immune protection from adverse effects associated with traditional live-virus vaccines,” a key concern for both civilian and biodefense applications. Given the resurgence of mpox and persistent global biosecurity concerns over smallpox reintroduction, TNX-801 may become a vital tool in future outbreak containment.
Tonix plans to advance TNX-801 into human clinical trials soon and is seeking collaboration with public health partners. As single-dose, broad-coverage vaccines become increasingly necessary in emergency settings, TNX-801’s development aligns with calls for next-generation countermeasures in global infectious disease preparedness.