Debulking SARS-COV-2 in saliva using angiotensin converting enzyme 2 in the chewing gum to decrease oral virus transmission and infection

Abstract

To advance a novel concept of debulking virus in the oral cavity, the primary site of viral replication, virus trapping proteins CTB-ACE2 were expressed in chloroplasts and clinical grade plant material was developed to meet FDA requirements. Chewing gum (2 grams) containing plant cells expressed CTB-ACE2 up to17.2 mg ACE2/g DW (11.7% leaf protein) have physical characteristics, taste/flavor like conventional gums and no protein was lost during gum compression. CTB-ACE2 gum efficiently (>95%) inhibited entry of Lentivirus-Spike or VSV-Spike pseudovirus into Vero/CHO cells, when quantified by luciferase or red fluorescence. Incubation of CTB-ACE2 microparticles reduced SARS-CoV- 2 virus count in COVID-19 swab/saliva samples >95%, when evaluated by microbubbles (femtomolar concentration) or qPCR, demonstrating both virus trapping and blocking of cellular entry. COVID-19 saliva samples showed low or undetectable ACE2 activity when compared to healthy individuals (2582 vs 50126 ΔRFU; 27 vs 225 enzyme units), confirming greater susceptibility of infected patients for viral entry. CTB-ACE2 activity was completely inhibited by pre-incubation with SARS-COV-2 RBD, offering an explanation for reduced saliva ACE2 activity among COVID-19 patients. Chewing gum with virus trapping proteins offers a general affordable strategy to protect patients from most oral virus reinfections through debulking or minimizing transmission to others.

Graphical Abstract