H84T-BanLec is derived from a carbohydrate-binding protein called lectin, isolated from bananas. H84T-BanLec binds to high-mannose glycans -- polysaccharides that are present on virus surfaces, but rarely on healthy human cells. After binding, the virus is effectively blocked from entering and infecting cells.

Atomic force microscopy helped the researchers confirm that H84T-BanLec develops multiple strong bonds with the spike protein, deterring lectin resistance. Therapeutic lectin use has previously been avoided, as it may stimulate the immune system in potentially harmful ways. However, when H84T-BanLec is modified to remove this effect, animal models show no detrimental effects.

Current COVID-19 treatments, including remdesivir, Paxlovid, and monoclonal antibodies, have varying side effects and effectiveness, particularly as SARS-CoV-2 evolves. The researchers contend that H84T-BanLec holds unique promise and hope to see its testing transition from animal models to humans. They also hope to investigate H84T-BanLec's effectiveness against cancer, since cancer cells, like viruses, also have high-mannose glycans on their surfaces.

"When COVID-19 occurred, we of course wanted to study the therapy's potential and discovered it was effective against every type of coronavirus, in vitro and in vivo," Dr. David Markovitz, internal medicine professor at the University of Michigan, said in a statement. "Whether delivered systemically or through the nose in animal models, or prophylactically or therapeutically early on in the illness, it worked."