ACE2 is a crucial receptor target of SARS-CoV-2, which plays a vital role in the pathogenesis of COVID-19, as it enables viral entry into target cells (Fig. 1). The binding affinity between ACE2 and the receptor-binding domain (RBD) of the SARS-CoV-2 spike glycoprotein is 10- to 20-fold higher compared to that with the RBD of SARS-CoV, which likely underpins the higher pathogenesis of SARS-CoV-2 infections. […] ACE2 is expressed in several human organs at varying levels. It is highly expressed in the lungs (on the surface of type II alveolar epithelial cells), heart (on myocardial cells, coronary vascular endothelial cells, and vascular smooth muscle), kidney (on proximal tubule cells), and small intestine (on the enterocytes).
While promising, we must be mindful that this represents a single observation. Nonetheless, the results, in this instance, clearly demonstrate that SARS-CoV-2 disappeared rapidly from the serum and gradually from the nasal cavity and lungs following hrsACE2 treatment. Whether this marked reduction in viral load reflects the effect of hrsACE2 or the natural course of the disease in this patient is unknown. Most importantly, the use of hrsACE2 did not reduce the generation of neutralizing antibodies. Similar data were observed in a second patient with severe COVID-19 symptoms that received two doses of hrsACE2 for 1 day. Rapid reduction of viral load in the serum along with the generation of antiviral antibodies were observed in this second patient.
Abd El-Aziz, T.M., Al-Sabi, A. & Stockand, J.D.
An interesting approach for combating viruses that I have not heard of previously: treating the patient with a synthetic emzyme mimicking the receptors used by the virus to enter human cells. Some of the viral particles will then bind to the synthetic molecule – in this case hrsACE2 – instead of living cells, thus preventing infection! The preliminary results certainly look promising, both in vitro and in phase-I studies. Hopefully this can be developed into an approved treatment available at large scale – certainly a topic to be followed closely.
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