A Combination of Ivermectin and Doxycycline Possibly Blocks the Viral Entry and Modulate the Innate Immune Response in COVID-19 Patients

The current outbreak of the corona virus disease 2019 (COVID-19), has affected almost entire world and become pandemic now. Currently, there is neither any FDA approved drugs nor any vaccines available to control it. Very recently in Bangladesh, a group of doctors reported astounding success in treating patients suffering from COVID-19 with two commonly used drugs, Ivermectin and Doxycycline. In the current study we have explored the possible mechanism by which these drugs might have worked for the positive response in the COVID-19 patients. To explore the mechanism we have used molecular docking and molecular dynamics simulation approach. Effectiveness of Ivermectin and doxycycline were evaluated against Main Protease (Mpro), Spike (S) protein, Nucleocapsid (N), RNA-dependent RNA polymerase (RdRp, NSP12), ADP Ribose Phosphatase (NSP3), Endoribonuclease (NSP15) and methyltransferase (NSP10-NSP16 complex) of SARS-CoV-2 as well as human angiotensin converting enzyme 2 (ACE2) receptor. Our study shows that both Ivermectin and doxycycline have significantly bind with SARS-CoV-2 proteins but Ivermectin was better binding than doxycycline. Ivermectin showed a perfect binding site to the Spike-RBD and ACE2 interacting region indicating that it might be interfering in the interaction of spike with ACE2 and preventing the viral entry in to the host cells. Ivermectin also exhibited significant binding affinity with different SARS-CoV-2 structural and non-structural proteins (NSPs) which have diverse functions in virus life cycle. Significant binding of Ivermectin with RdRp indicate its role in the inhibition of the viral replication and ultimately impeding the multiplication of the virus. Ivermectin also possess significant binding affinity with NSP3, NSP10, NSP15 and NSP16 which helps virus in escaping from host immune system. Molecular dynamics simulation study shows that binding of the Ivermectin with Mpro, Spike, NSP3, NSP16 and ACE2 was quiet stable. Thus, our docking and simulation studies reveal that combination of Ivermectin and doxycycline might be executing the effect by inhibition of viral entry and enhance viral load clearance by targeting various viral functional proteins.