A BSL-2 chimeric system designed to screen SARS-CoV-2 E protein ion channel inhibitors

A major hindrance to the identification of new drug targets and the large-scale testing of new or existing compound libraries against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is that research on the virus is restricted to biosafety level 3 (BSL-3) laboratories. In such cases, BSL-2 surrogate systems or chimeric and attenuated versions of the virus are developed for safer, faster, and cheaper examination of the stages of the virus life cycle and specific drug targets. In this study, we describe a BSL-2 chimeric viral system utilizing a Sindbis virus background as a tool to study one such target, the SARS-CoV-2 Envelope (E) protein channel activity. This protein is fully conserved between SARS-CoV and SARS-CoV-2 variants of concern (VOCs), except for a threonine to isoleucine mutation in the Omicron variant, making the E ion channel domain an attractive antiviral target for combination therapy. Using a BSL-2-chimeric system, we have been able to show similar inhibition profiles using channel inhibitors as previously reported for E-channel inhibition in authentic SARS-CoV-2. This system has the potential to allow faster initial screening of E-channel inhibitors and can be useful in developing broad-spectrum antivirals against viral channel proteins.IMPORTANCEDespite its importance in viral infections, no antivirals exist against the ion channel activity of the SARS-CoV-2 Envelope (E) protein. The E protein is highly conserved among SARS-CoV-2 variants, making it an attractive target for antiviral therapies. Research on SARS-CoV-2 is restricted to BSL-3 laboratories, creating a bottleneck for screening potential antiviral compounds. This study presents a BSL-2 chimeric system using a Sindbis virus background to study the ion channel activity of the E protein. This novel BSL-2 system bypasses this limitation, offering a safer and faster approach for the initial screening of ion channel inhibitors. By replicating the channel inhibition profiles of authentic SARS-CoV-2 in a more accessible system, this research paves the way for the development of broad-spectrum antivirals against viral channel proteins, potentially expediting the discovery of life-saving treatments for COVID-19 and other viral diseases.