Department of Biotechnology
inStem (Institute for Stem Cell Science and Regenerative Medicine)

Strategies to target SARS-CoV-2 entry and infection using dual mechanisms of inhibition by acidification inhibitors.

Publication Type

Journal Article

Date of Publication

July 1, 2021

Journal

PLoS pathogens

Volume/Issue

17/7

ISSN

1553-7374

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.

Alternate Journal

PLoS Pathog

PubMed ID

34252168

PubMed Central ID

PMC8297935

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

Keywords

Endosomes
Virus Internalization
Hydrogen-Ion Concentration
Clathrin
Hydroxychloroquine
Animals
Endocytosis
Macrolides
Niclosamide
Protein Domains
Humans
Ammonium Chloride
Vero Cells
Protein Binding
Angiotensin-Converting Enzyme 2
COVID-19 Drug Treatment
Cell Line
Antiviral Agents
Spike Glycoprotein, Coronavirus
Chlorocebus aethiops
SARS-CoV-2
Chloroquine
COVID-19
Drug Synergism