Three powerful antibodies discovered with potential to treat mpox
September 3, 2025
Researchers at Mount Sinai have identified three monoclonal antibodies that block mpox viral spread and prevent severe disease. Published in Cell, the study shows that these antibodies, isolated from a recovered patient, target the conserved viral protein A35, halting infection in lab models and fully protecting rodents. Importantly, individuals recovering from mpox naturally produce these antibodies, and their presence correlates with milder illness and fewer hospitalizations. With no approved drugs for mpox and failed clinical trials of existing candidates, this discovery offers a promising pathway toward targeted therapies that could address urgent global health and biodefense needs.
The search for effective mpox treatments has taken a major step forward. Scientists at the Icahn School of Medicine at Mount Sinai have identified three monoclonal antibodies capable of blocking viral spread and shielding against severe disease, results that could transform the clinical management of orthopoxvirus infections.
The antibodies, detailed in Cell, were derived from a person who recovered from mpox and specifically target the A35 protein. In laboratory and animal studies, they not only halted viral replication but also prevented death in rodents exposed to the virus. Further analysis of human samples revealed that individuals naturally produce high levels of these antibodies after infection, and their presence correlates with reduced severity and fewer hospitalizations.
This discovery arrives at a critical moment. Since the global mpox outbreak in 2022, the World Health Organization has twice declared the virus a public health emergency of international concern. Despite widespread vaccination campaigns, there are still no approved drugs for treatment. Clinical trials of the most advanced antiviral candidates, such as tecovirimat, have failed to demonstrate meaningful benefit, leaving a glaring gap in care for vulnerable populations.
What makes these antibodies particularly compelling is their binding site. Researchers mapped the first crystal structure of a human antibody bound to an mpox protein, showing that A35 is highly conserved across orthopoxviruses. Because this site is unlikely to mutate, the antibodies are less susceptible to immune escape and could have utility beyond mpox, potentially offering protection against the wider poxvirus family.
Although the antibodies are still early in development, with preclinical safety testing and human trials ahead, the team has already patented them, signaling confidence in their clinical potential. This discovery not only highlights a new therapeutic strategy for mpox but also sets the stage for broader pandemic preparedness against emerging and reemerging poxviruses.