Griffithsin
Griffithsin, a lectin derived from red algae, binds on the surface of
various viral glycoproteins to oligosaccharides including HIV
glycoprotein 120 and SARS-CoV spike glycoprotein2. Griffithsin has low
cytotoxicity, is likely to interfere with any coronavirus spike protein
due to it is highly glycosylated nature, and may impede the role of
coronavirus spike protein. GRFT has been shown to inhibit
SARS-CoVreplicationand cytopathicity, as well as other coronaviridae
viruses [48] [49]. In particular, in Vero 76 cells, GRFT
inhibited various strains of SARS - infectionwith a low nanomolar EC50
with limited toxicity on control cells. GRFT can bind with glycans to
the surface of the glycoprotein (S protein). A total of three GRFT
molecules are capable of binding the S with very high affinity in a
dose, a lower number compared to HIV which is presumably due to the
lower number of high glycans on the S surface. Interestingly, such an
association does not restrict the binding of SARS-CoV S glycoprotein to
the human angiotensin I conversion enzyme 2 (ACE2) host cell [49].
Griffithsin has been studied as a gel or enema for HIV prevention in
phase I trials, but the efficacy and delivery mechanisms of spike
inhibitors should be re-evaluated for the 2019-nCoV treatment or
prevention.