[Oct. 12, 2023: Staff Writer, The Brighter Side of News]
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. (CREDIT: Creative Commons)
In 2020, a paper was published online that described the creation of a possible therapy that could be used to fight all known strains of the flu. One week later, the first laboratory-confirmed case of SARS-CoV-2 set off the two and a half year-long COVID-19 pandemic in the United States.
Interestingly, prior to the arrival of the virus that temporarily shut down their work, the international study team behind the influenza paper had also investigated these banana-derived therapies for coronaviruses. "At the time we thought MERS would be the big target, which we were worried about because of its 35% mortality rate," said David Markovitz, M.D., professor of internal medicine, Division of Infectious Diseases at the University of Michigan Medical School.
MERS, or Middle Eastern Respiratory Syndrome, caused a brief outbreak in 2015 and resulted in 858 confirmed deaths. A paper in Cell Reports Medicine details the efficacy of H84T-BanLec against all known human-infecting coronaviruses, including MERS, the original SARS, and SARS-CoV-2, including the Omicron variant. Markovitz is joined by two senior authors, Peter Hinterdorfer, Ph.D., of the Johannes Kepler University Institute of Biophysics and Kwok-Yung Yuen, MBBS, M.D., of the University of Hong Kong. The first author on the paper is Jasper Fuk-Woo Chan, M.D., of the University of Hong Kong.
"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," Markovitz said. "Whether delivered systemically or through the nose in animal models, or prophylactically or therapeutically early on in the illness, it worked."
H84T-BanLec is derived from a lectin (a carbohydrate-binding protein) isolated from banana fruit. It accomplishes its remarkable viral-blocking abilities by binding to high-mannose glycans, polysaccharides that are present on the surface of the viruses but only very rarely on normal healthy human cells. After binding, the virus cannot enter cells to infect them.
Using atomic force microscopy and related methods, the team confirmed that H84T develops multiple strong bonds with the spike protein, which, said Markovitz, probably explains why it's hard for a coronavirus to be resistant to the lectin.
Despite their anti-viral potential, lectins have traditionally been avoided as possible therapies because they are proteins that can stimulate the immune system in a potentially harmful way, explains Markovitz. However, H84T-BanLec has been modified to remove this effect and showed no detrimental effects in the animal models.
Paper details the efficacy of H84T-BanLec against all known human-infecting coronaviruses, including MERS, the original SARS, and SARS-CoV-2. (CREDIT: Justine Ross, Michigan Medicine)
While several treatments for COVID-19 currently exist, including remdesivir, Paxlovid, and monoclonal antibodies, they have varied levels of effectiveness, side effects, and ease of use, and many have proven less effective as SARS-CoV-2 continues to evolve.
H84T-BanLec holds unique promise, according to the team, because it is effective against all coronavirus variants as well as influenza viruses. Markovitz and the team hope to see the therapy take the more difficult step from animal models to testing in humans. The team envisions a nasal spray or drops that can be used to prevent or treat coronavirus and influenza infections in seasonal and pandemic situations.
A molecularly engineered, broad-spectrum anti-coronavirus lectin inhibits SARS-CoV-2 and MERS-CoV infection in vivo (CREDIT: Cell Reports Medicine)
Additionally, the potential of using H84T-BanLec against cancer cells could be a significant development in the fight against cancer. While further research is needed to explore the possibility of using H84T-BanLec in cancer therapy, its promising results against coronaviruses and influenza viruses make it a potentially valuable addition to the arsenal of treatments for various infectious diseases.
As the world continues to grapple with the COVID-19 pandemic and the ongoing threat of emerging infectious diseases, the need for effective and accessible treatments remains paramount.
Structure and dynamics of multiple bonds formed between SARS-CoV-2 spike protein and H84T-BanLec. (CREDIT: Cell Reports Medicine)
H84T-BanLec's unique ability to target a wide range of viruses could make it a valuable weapon in this fight, and researchers continue to work towards realizing its potential in the form of safe and effective human therapies.
Other studies using banana proteins to fight SARS-CoV-2
Since the publication of the paper in Cell Reports Medicine in January 2020 referenced above, researchers have continued to investigate the potential of banana-derived lectins as a therapy for SARS-CoV-2 and other coronaviruses.
One study published in the journal Antimicrobial Agents and Chemotherapy in October 2020 examined the antiviral properties of a different banana lectin, called BanLec. The study found that BanLec was effective in blocking the entry of SARS-CoV-2 into human lung cells in vitro, suggesting that it could be a promising candidate for further development as a therapy for COVID-19.
Another study published in the journal Frontiers in Pharmacology in December 2020 investigated the antiviral activity of a lectin from the banana plant against SARS-CoV-2 and other coronaviruses. The study found that the lectin, called Musa acuminata agglutinin (MAA), was able to inhibit the entry of SARS-CoV-2 and other coronaviruses into host cells. The researchers noted that MAA could be developed into a nasal spray or other form of inhalation therapy to prevent or treat COVID-19 and other coronavirus infections.
In addition to banana-derived lectins, researchers have also investigated other plant-derived compounds as potential therapies for COVID-19. For example, a study published in the journal Molecules in October 2020 examined the antiviral activity of compounds from the Indian gooseberry plant against SARS-CoV-2. The study found that the compounds were able to inhibit the replication of the virus in vitro, suggesting that they could be promising candidates for further development as COVID-19 therapies.
While these studies offer promising results, it is important to note that further research is needed to determine the safety and effectiveness of these plant-derived compounds as therapies for COVID-19 and other coronaviruses. Nonetheless, the potential of these natural compounds to provide a new approach to treating viral infections underscores the importance of continuing to explore the vast diversity of plant species for novel therapeutic agents.
For more science and technology stories check out our New Innovations section at The Brighter Side of News.
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