In collaboration with researchers at Sunnybrook Research Institute and the University of Toronto, they were the first to isolate the SARS-CoV-2 virus in Canada from two COVID-19 patients in Toronto. They have since shared the isolated virus stock with research institutions across the country which has enabled and supported research and development of COVID-19 diagnostics and therapies in Canada. In a paper first-authored by Dr. Banerjee and recently published in the journal Emerging Infectious Diseases, they report on the successful isolation of the virus and genomic sequencing of each isolate. Furthermore, using the isolated virus, they investigated the susceptibility of different human cell types to infection by SARS-CoV-2. They found that while SARS-CoV-2 propagates to high viral titers in certain epithelial cells, it does not productively infect human immune cells. Read the full paper here.

In addition to identifying which cell types can be infected, Drs. Mossman and Banerjee are also investigating how cells respond to SARS-CoV-2 infection. In a study deposited in bioRxiv and currently undergoing peer review, they used RNA-sequencing and immunoblot analyses to characterize the dynamics of the early cellular response to SARS-CoV-2 infection in human lung cells. They found that although SARS-CoV-2 induces only a mild type I IFN antiviral response in host cells, it is unable to efficiently shut down type I IFN production and signaling from exogenous stimuli. The inability of SARS-CoV-2 to shut down antiviral responses may contribute to its low case-fatality rate compared to highly pathogenic coronaviruses that cause severe acute respiratory distress syndrome (SARS) and Middle East respiratory syndrome (MERS). Furthermore, their findings indicate that exogenous treatment with recombinant type I IFN may be a promising antiviral therapy for COVID-19. Read the full paper here.

Dr. Banerjee is leading a number of other SARS-CoV-2 projects in the Mossman lab. For one of the projects, the team is using bat cells to investigate how cells from a potential reservoir species respond to SARS-CoV-2 infection compared to human cells. This work will contribute to our understanding of how reservoir species such as bats can coexist with coronaviruses, which holds potential to uncover new therapeutic targets for coronavirus infections.

This article is part of a series highlighting research being conducted at MIRC as part of the global response to the COVID-19 pandemic

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