Background and purpose
Currently, there are no licensed vaccines and limited antivirals for the treatment of COVID-19. Heparin (delivered systemically) is currently used to treat anticoagulant anomalies in COVID-19 patients. Additionally, in the United Kingdom, Brazil and Australia, nebulised unfractionated heparin (UFH) is being trialled in COVID-19 patients as a potential treatment. A systematic comparison of the potential antiviral effect of various heparin preparations on live wild type SARS-CoV-2, in vitro, is needed. Experimental approach: Seven different heparin preparations including UFH and low MW heparins (LMWH) of porcine or bovine origin were screened for antiviral activity against live SARS-CoV-2 (Australia/VIC01/2020) using a plaque inhibition assay with Vero E6 cells. Interaction of heparin with spike protein RBD was studied using differential scanning fluorimetry and the inhibition of RBD binding to human ACE2 protein using elisa assays was examined. Key
Purpose
Currently, there are no licensed vaccines and limited antivirals for the treatment of COVID-19. Heparin (delivered systemically) is currently used to treat anticoagulant anomalies in COVID-19 patients. Additionally, in the United Kingdom, Brazil and Australia, nebulised unfractionated heparin (UFH) is being trialled in COVID-19 patients as a potential treatment. A systematic comparison of the potential antiviral effect of various heparin preparations on live wild type SARS-CoV-2, in vitro, is needed. Experimental approach: Seven different heparin preparations including UFH and low MW heparins (LMWH) of porcine or bovine origin were screened for antiviral activity against live SARS-CoV-2 (Australia/VIC01/2020) using a plaque inhibition assay with Vero E6 cells. Interaction of heparin with spike protein RBD was studied using differential scanning fluorimetry and the inhibition of RBD binding to human ACE2 protein using elisa assays was examined. Key
Results
All the UFH preparations had potent antiviral effects, with IC50 values ranging between 25 and 41 μg·ml-1 , whereas LMWHs were less inhibitory by ~150-fold (IC50 range 3.4-7.8 mg·ml-1 ). Mechanistically, we observed that heparin binds and destabilizes the RBD protein and furthermore, we show heparin directly inhibits the binding of RBD to the human ACE2 protein receptor.