Data show clade IIb from 2022 outbreak is 100 to 100,000-fold less virulent than clade IIa from 2003 outbreak
Three new models for investigating mpox infection and pathogenesis identified
Tonix is advancing TNX-801, a live, attenuated, minimally replicative investigational vaccine candidate based on horsepox virus to protect against mpox disease
BERKELEY HEIGHTS, N.J., July 15, 2026 (GLOBE NEWSWIRE) -- Tonix Pharmaceuticals Holding Corp. (Nasdaq: TNXP) ("Tonix" or the "Company"), a fully integrated, commercial-stage biotechnology company, today announced the publication of a paper, "Monkeypox virus clade IIb isolate exhibits reduced virulence relative to clade IIa isolates in multiple murine models," in the Journal of Virology, the peer-reviewed publication of the American Society for Microbiology (ASM). The research, conducted at Tonix, found new animal models for investigating mpox pathogenesis and demonstrated significant differences in virulence between the clade IIb circulating in the U.S. and the historic 2003 clade IIa. The manuscript can be accessed at:
https://doi.org/10.1128/jvi.00247-26.
"Global mpox outbreaks that have caused severe human disease continue to occur due to previously unrecognized subclades," said Seth Lederman, M.D., Chief Executive Officer of Tonix Pharmaceuticals. "New approaches to understand and mitigate the spread of emerging mpox subclades are urgently needed. To examine the pathogenesis of emerging mpox clades, we identified three new murine models susceptible to mpox clade II infection, which revealed significant differences in virulence between clades. As Tonix investigates TNX-801 (live attenuated horsepox vaccine) for the prevention of mpox and smallpox, establishing additional foundational models are important to categorize and ultimately protect against the disease."
"The decreased virulence of clade IIb may have contributed to its ability to spread worldwide," said Sina Bavari, Ph.D., Executive Vice President of Tonix and site head of Tonix's Research and Development Center (RDC) in Frederick, Maryland. "Indolent subclinical infection is a risk factor for unintentional spread. Importantly, a deeper understanding of mpox virus (MPXV) pathogenesis will help guide the continued development and positioning of the TNX-801 vaccine platform, a vaccine candidate against mpox. Tonix is committed to advancing the understanding of emerging mpox disease and to developing TNX-801 platform as a potential vaccine candidate to address the continuing global threat posed by mpox."