In-vitro studies of relative intracellular alterations caused by three variants of Severe Acute Respiratory Syndrome Corona Virus-2 (SARS-CoV-2)

BACKGROUND: The comparative understanding between cellular basis of transmission and clinical severities caused by Wuhan, Delta and Omicron strains of SARS-CoV-2 is important. OBJECTIVE: To conduct In-Vitro studies on cellular infection caused by different variants by performing cytotoxic assays and studying the live microscopic observations. METHODS: The swab samples positive for Wuhan, Delta and Omicron strains were inoculated in the Vero cell lines and their rate of infectivity and nature of cytopathy was observed. RESULTS: The study showed maximum inter cellular connectivity among cells infected by Delta variant, followed by Wuhan and least inter cellular connections in the cells infected by Omicron variant. The Delta strain causing highest mortality as per reported epidemiological trends, showed highest inter cellular connections and maximum cell damage supporting the fastest cell to cell spread of infection and causing most mortality among patients. CONCLUSIONS: The paper reports that numerous inter cellular connections is the cause of spread of infection among cells and maximum cell damage as the cause of clinical severities. The paper sensitizes the issue that 52 subunit of viral Spike Protein could act as fusion enzyme causing the numerous inter cellular connections. Study suggests that the S2 subunit of the viral Spike Protein could be the drug target for therapeutic intervention.