A graphical illustration of the antiviral mechanisms of Chloroquine (CQ) and hydroxychloroquine (HCQ). Both chemicals can interfere with the glycosylation of ACE2 and reduce the binding efficiency between ACE2 on the host cells and the spike protein on the surface of the coronavirus. They can also increase the pH of endosomes and lysosomes, through which the fusion process of the virus with host cells and subsequent replication are prevented. When HCQ enters APCs, it prevents antigen processing and MHC class II-mediated autoantigen presentation to T cells. The subsequent activation of T cells and expression of CD154 and other cytokines are repressed. In addition, HCQ disrupts the interaction of DNA/RNA with TLRs and the nucleic acid sensor cGAS and therefore the transcription of pro-inflammatory genes cannot be stimulated. As a result, administration of CQ or HCQ not only blocks the invasion and replication of coronavirus, but also attenuates the possibility of cytokine storm. #hydroxychloroquine #HCQ #antiviral #pathophysiology #pharmacology #mechanism #moa
