A chewing gum made with a plant-grown protein "traps" the SARS-CoV-2 virus, reducing viral load in saliva and potentially tamping down transmission, according to a study led by Henry Daniell at Penn Dental Medicine.
The work, performed in collaboration with the Perelman School of Medicine and School of Veterinary Medicine, as well as The Wistar Institute and Fraunhofer USA, could lead to a low-cost tool in the arsenal against the COVID-19 pandemic. Their study appeared in Molecular Therapy.
"SARS-CoV-2 replicates in the salivary glands, and we know that when someone infected sneezes, coughs, or speaks some of that virus can be expelled," says Daniell. "Indeed, speaking four words releases more virus particles than breathing without a mask for one hour. This gum offers an opportunity to neutralize the virus in the saliva, giving us a simple way to possibly cut down on a source of transmission."
Pre-pandemic, Daniell was studying the angiotensin-converting enzyme 2 (ACE2) protein in the context of treating hypertension. His lab had grown this protein, as well as many others that may have therapeutic potential, using a patented plant-based production system. The plant material, freeze-dried and ground-up, could be used to deliver the protein.
Daniell's past work on ACE2 proved fortuitous in the context of the COVID-19 pandemic. The receptor for ACE2 on human cells also happens to bind the SARS-CoV-2 spike protein and ACE2 enzyme is naturally present in saliva. Meanwhile, another line of work by Daniell involved research to develop a chewing gum infused with plant-grown enzymes to disrupt dental plaque. Pairing his insights about ACE2 with this technology, Daniell wondered if such a gum, infused with plant-grown ACE2 proteins, could neutralize SARS-CoV-2 in the oral cavity.
To find out, he contacted Ronald Collman at Penn Medicine, whose team had been collecting biospecimens from COVID patients for research. To test the gum, the team grew ACE2 in plants, paired with another compound that enables the protein to block gates of viral entry and incorporated the resulting plant material into cinnamon-flavored gum tablets. Among various tests, the team exposed saliva samples from COVID-19 patients to the ACE2 gum and found that levels of viral RNA fell so dramatically to be almost undetectable.
The research team is currently working toward obtaining permission for a clinical trial to evaluate safety and efficacy when tested in people infected with SARS-CoV-2.
