Strategies to target SARS-CoV-2 entry and infection using dual mechanisms of inhibition by acidification inhibitors |
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| Authors: | Chaitra Prabhakara Rashmi Godbole Parijat Sil Sowmya Jahnavi Shah-e-Jahan Gulzar Thomas S. van Zanten Dhruv Sheth Neeraja Subhash Anchal Chandra Akshatha Shivaraj Patricia Panikulam Ibrahim U Vijay Kumar Nuthakki Theja Parassini Puthiyapurayil Riyaz Ahmed Ashaq Hussain Najar Sai Manoz Lingamallu Snigdhadev Das Bhagyashri Mahajan Praveen Vemula Sandip B. Bharate Parvinder Pal Singh Ram Vishwakarma Arjun Guha Varadharajan Sundaramurthy Satyajit Mayor |
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| Affiliation: | 1. National Centre for Biological Sciences (TIFR), Bengaluru, India;2. University of Trans-Disciplinary Health Sciences and Technology (TDU), Bengaluru, India;3. SASTRA University, Thanjavur, India;4. CSIR—Indian Institute of Integrative Medicine, Jammu, India;5. Institute for Stem Cell Science and Regenerative Medicine (inSTEM), Bengaluru, India;6. Manipal Academy of Higher Education (MAHE), Madhav Nagar, Manipal, Karnataka, India;Icahn School of Medicine at Mount Sinai, UNITED STATES |
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| Abstract: | Many viruses utilize the host endo-lysosomal network for infection. Tracing the endocytic itinerary of SARS-CoV-2 can provide insights into viral trafficking and aid in designing new therapeutic strategies. Here, we demonstrate that the receptor binding domain (RBD) of SARS-CoV-2 spike protein is internalized via the pH-dependent CLIC/GEEC (CG) endocytic pathway in human gastric-adenocarcinoma (AGS) cells expressing undetectable levels of ACE2. Ectopic expression of ACE2 (AGS-ACE2) results in RBD traffic via both CG and clathrin-mediated endocytosis. Endosomal acidification inhibitors like BafilomycinA1 and NH4Cl, which inhibit the CG pathway, reduce the uptake of RBD and impede Spike-pseudoviral infection in both AGS and AGS-ACE2 cells. The inhibition by BafilomycinA1 was found to be distinct from Chloroquine which neither affects RBD uptake nor alters endosomal pH, yet attenuates Spike-pseudovirus entry. By screening a subset of FDA-approved inhibitors for functionality similar to BafilomycinA1, we identified Niclosamide as a SARS-CoV-2 entry inhibitor. Further validation using a clinical isolate of SARS-CoV-2 in AGS-ACE2 and Vero cells confirmed its antiviral effect. We propose that Niclosamide, and other drugs which neutralize endosomal pH as well as inhibit the endocytic uptake, could provide broader applicability in subverting infection of viruses entering host cells via a pH-dependent endocytic pathway. |
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