Interferon-induced transmembrane protein 3 (IFITM3) limits lethality of SARS-CoV-2 in mice (preprint)

Interferon-induced transmembrane protein 3 (IFITM3) is a host antiviral protein that alters cell membranes to block fusion of viruses. Published reports have identified conflicting pro- and anti-viral effects of IFITM3 on SARS-CoV-2 in cultured cells, and its impact on viral pathogenesis in vivo remains unclear. Here, we show that IFITM3 knockout (KO) mice infected with mouse-adapted SARS-CoV-2 experienced extreme weight loss and lethality, while wild type (WT) mice lost minimal weight and recovered. KO mice had higher lung viral titers and increases in lung inflammatory cytokine levels, CD45-positive immune cell infiltration, and histopathology, compared to WT mice. Mechanistically, we observed disseminated viral antigen staining throughout the lung tissue and pulmonary vasculature in KO mice, while staining was observed in confined regions in WT lungs. Global transcriptomic analysis of infected lungs identified upregulation of gene signatures associated with interferons, inflammation, and angiogenesis in KO versus WT animals, highlighting changes in lung gene expression programs that precede severe lung pathology and fatality. Corroborating the protective effect of IFITM3 in vivo, K18-hACE2/IFITM3 KO mice infected with non-adapted SARS-CoV-2 showed enhanced, rapid weight loss and early death compared to control mice. Increased heart infection was observed in both mouse models in the absence of IFITM3, indicating that IFITM3 constrains extrapulmonary dissemination of SARS-CoV-2. Our results establish IFITM3 KO mice as a new animal model for studying severe SARS-CoV-2 infection of the lung and cardiovascular system, and overall demonstrate that IFITM3 is protective in SARS-CoV-2 infections of mice.

Strategies for the development of drugs targeting novel coronavirus 2019-nCoV / 药学学报

@# There is no specific drug that has been approved for 2019-nCoV. There are a number of factors that pose major challenges in their development. Approaches to the development of anti-2019-nCoV include screening existing broad-spectrum antiviral drugs, repositioning of readily available clinical compounds, and <italic>de novo</italic> development of novel and specific agents for 2019-nCoV. Candidate compounds can be developed either to inhibit virus-based targets, such as RNA proteases, polymerase, spike glycoproteins, and viral envelop and membrane proteins, or to inhibit host-based targets, such as receptors and proteases that are utilized by virus for viral entry and endocytosis. Recently, the RNA polymerase remdesivir had demonstrated clinical efficacy in one patient with severe novel coronavirus pneumonia (NCP). The broad-spectrum viral protease inhibitor Kaletra^® is also recommended in the current NCP clinical practice. Both drugs had lately been proceeded into multiple controlled phase III clinical trials to test their safety and efficacy in NCP. Combinational therapies consisting of multiple drugs provide other viable options against 2019-nCoV, based on scientific and clinical rationales. Using bioinformatics and database analysis, we have identified 75 clinically compounds, including 20 marketed compounds, that are efficacious in inhibiting key targets in virus- and host-based approaches, which may facilitate the development of new therapeutic options for 2019-nCoV.