Recep Ahan and colleagues evaluated the activity of griffithsin lectin protein (GRFT) from Griffithsia sp. against the novel human coronavirus, SARS-CoV-2. They demonstrated that this protein can not only block the entry of the Sars-CoV-2 but also inhibit its infection by attaching to spike protein of the Sars-CoV-2, both in vitro VeroE6 cell line and in vivo mouse model. Their study recently appeared in BioRxiv.
Lectin proteins isolated from seaweeds are shown to be potent antiviral agents against enveloped viruses e.g., HIV-1, herpes virus as well as two deadly human coronaviruses, SARS-CoV and MERS-CoV. Antiviral activity of seaweed lectins arises from their affinity to surface glycoproteins on viruses such as gp-120 protein of HIV-1 and spike proteins of SARS-CoV and MERS-CoV. Upon binding to surface proteins, lectins generally block the viral internalization step and thereby prevent the viral infection.
Now, Recep Ahan and colleagues evaluated the activity of griffithsin lectin protein (GRFT) from Griffithsia sp. against the novel human coronavirus, SARS-CoV-2.
For this purpose, they recombinantly expressed GRFT in E. coli with histidine tag and purified. Later, they validated and characterized binding of recombinant GRFT to whole inactivated SARS-CoV-2 as well as purified spike protein from HEK293 with the help of ELISA, ITC and QCM. Finally, they assessed the activity of GRFT in vitro with Vero6 cells, and in vivo with Syrian hamsters.
They demonstrated that griffithsin protein from Griffithsia sp. recombinantly produced in E. coli can bind spike (S) protein of SARS-CoV-2 in vitro and inhibit its infection both in vitro VeroE6 cell line and in vivo mouse model when applied prophylactically. In addition, toxicity assays of rGRFT with mouse models indicated that, it is a tolerable agent even at concentrations higher than its therapeutic concentration window.
“Our results indicate that GRFT is a potent non-mutagenic antiviral agent against SARS-CoV-2, reducing virus transmission through blocking its entry into the cells.”— they said.
Finally, upon very promising results from in vitro and in vivo assays and experiments, they formulated GRFT as a nasal spray for upcoming human phase trials.
“We believe that GRFT protein-based drugs will have a high impact in preventing the transmission both on Wuhan strain as well as any other emerging variants including delta variant causing high speed spread of COVID-19.”— they concluded.
Reference: Recep Erdem Ahan, Alireza Hanifehnezhad, Ebru Şahin Kehribar, Tuba Cigdem Oguzoglu, Katalin Földes, Cemile Elif Özçelik, Nazlican Filazi, Sıdıka Öztop, Sevgen Önder, Eray Ulaş Bozkurt, Koray Ergünay, Aykut Özkul, Urartu Özgür Şafak Şeker, “A Highly Potent SARS-CoV-2 Blocking Lectin Protein”, bioRxiv 2021.07.22.453309; doi: https://doi.org/10.1101/2021.07.22.453309
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