ABSTRACT
Background: The CoV-2 envelope (E) protein plays an important role in virus assembly, budding, immunopathogenesis and disease severity. E protein has ion channel activity, is located in Golgi and ER membranes of infected cells and is associated with inflammasome activation and immune dysregulation. Here we report that BIT225, an investigational HIV clinical compound, inhibits E ion channel activity and prevents body weight loss and mortality and reduces inflammation in lethally infected K18-hACE2 transgenic mice. BIT225 efficacy was observed when dosing was initiated before or 24 h or 48 h after infection. Method(s): SARS-CoV-2 E protein ion channel activity and Xenopus TMEM16A were measured in Xenopus oocytes. K18-hACE2 transgenic mice were infected intranasally with 104 pfu SARS CoV 2 (US-WA1/2020) and dosed orally twice daily with BIT225 for up to 12 Days. Dosing was initiated 12 h pre-infection or 24 h or 48 h post-infection. Disease parameters measured were survival, body weight, viral RNA by qPCR and infectious virus titre (plaque assay) in lung tissue homogenates and serum. In addition, levels of pro-inflammatory cytokines (IL-6, IL-1alpha, IL-1beta, TNFalpha & TGFbeta, MCP-1) were measured in lung and serum samples. Result(s): BIT225 inhibited ion channel activity of E-protein, but not that of TMEM16A in Xenopus oocytes. BIT225 dosed at 300mg/kg BID for 12 days starting 12 h pre-infection completely prevented body weight loss and mortality in SARS-CoV-2 infected K18 mice (n=12), while all vehicle-dosed animals reached a mortality endpoint by day 9 across two studies (n=12). Figure 1 shows results from a time of addition study: When treatment with BIT225 started at 24 h post-infection, body weight loss and mortality was also prevented (100% survival, n=5). In the group of mice where treatment started at 48 h after infection, body weight loss and mortality were prevented in 4 of 5 mice. Treatment efficacy was associated with significant reduction in lung viral load (3.5 log10), virus titer (4000 pfu/ml) and lung and serum cytokine levels. Conclusion(s): BIT225 is an inhibitor of SARS-CoV-2 E-protein viroporin activity. In the K18 model BIT225 protected mice from weight loss and death, inhibited virus replication and reduced inflammation. These effects were noted when treatment with BIT225 was initiated before or 24-48 hours after infection and validate viroporin E as a viable antiviral target and support the clinical study of BIT225 in treatment of SARS-CoV-2.