Article Extended Data Fig. 7 | Analysis of 2019-nCoV receptor usage. Determination of virus infectivity in HeLa cells with or without the expression of human APN and DPP4. The expression of ACE2, APN and DPP4 plasmids with S tag were detected using mouse anti-S tag monoclonal antibody. ACE2, APN and DPP4 proteins (green), viral protein (red) and nuclei (blue) are shown. Scale bars, 10 μm.

Viral infection triggers activation of transcription factors such as NF-kappaB and IRF3, which collaborate to induce type I interferons (IFNs) and elicit innate antiviral response. Here, we identified MITA as a critical mediator of virus-triggered type I IFN signaling by expression cloning. Overexpression of MITA activated IRF3, whereas knockdown of MITA inhibited virus-triggered activation of IRF3, expression of type I IFNs, and cellular antiviral response. MITA was found to localize to the outer membrane of mitochondria and to be associated with VISA, a mitochondrial protein that acts as an adaptor in virus-triggered signaling. MITA also interacted with IRF3 and recruited the kinase TBK1 to the VISA-associated complex. MITA was phosphorylated by TBK1, which is required for MITA-mediated activation of IRF3. Our results suggest that MITA is a critical mediator of virus-triggered IRF3 activation and IFN expression and further demonstrate the importance of certain mitochondrial proteins in innate antiviral immunity.

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Bacterial biofilms can be programmed to produce living materials with self-healing and evolvable functionalities. However, the wider use of artificial biofilms has been hindered by limitations on processability and functional protein secretion capacity. We describe a highly flexible and tunable living functional materials platform based on the TasA amyloid machinery of the bacterium Bacillus subtilis. We demonstrate that genetically programmable TasA fusion proteins harboring diverse functional proteins or domains can be secreted and can assemble into diverse extracellular nano-architectures with tunable physicochemical properties. Our engineered biofilms have the viscoelastic behaviors of hydrogels and can be precisely fabricated into microstructures having a diversity of three-dimensional (3D) shapes using 3D printing and microencapsulation techniques. Notably, these long-lasting and environmentally responsive fabricated living materials remain alive, self-regenerative, and functional. This new tunable platform offers previously unattainable properties for a variety of living functional materials having potential applications in biomaterials, biotechnology, and biomedicine.

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Recognition of human cytomegalovirus (HCMV) DNA by the cytosolic sensor cGAS initiates STING-dependent innate antiviral responses. HCMV can antagonize host immune responses to promote latency infection. However, it is unknown whether and how HCMV targets the cGAS-STING axis for immune evasion. Here we identified the HCMV tegument protein UL82 as a negative regulator of STING-dependent antiviral responses. UL82 interacted with STING and impaired STING-mediated signaling via two mechanisms. UL82 inhibited the translocation of STING from the ER to perinuclear microsomes by disrupting the STING-iRhom2-TRAPβ translocation complex. UL82 also impaired the recruitment of TBK1 and IRF3 to the STING complex. The levels of downstream antiviral genes induced by UL82-deficient HCMV were higher than those induced by wild-type HCMV. Conversely, wild-type HCMV replicated more efficiently than the UL82-deficient mutant. These findings reveal an important mechanism of immune evasion by HCMV.

, a novel coronavirus that is related to severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV) in phylogenetic distance was identified. 1 This virus, which was later designated as SARS-CoV-2, also causes acute respiratory disease syndrome (ARDS) termed coronavirus disease 2019 (COVID-19), which was declared as a pandemic by the World Health Organization in March 2020. Although the majority of patients of COVID-19 show moderate symptoms such as dry cough and fatigue, up to 20% cases develop severe symptoms characterized as ARDS, a clinical pulmonary phenomenon marked by the development of bilateral infiltrates and hypoxemia. 2 The median incubation period of SARS-CoV-2 infection is~4-5 days before symptom onset, and the majority of symptomatic patients develop symptoms within 11.5 days. Within 5-6 days of symptom onset, SARS-CoV-2 viral load reaches its peak, which is much earlier than SARS-CoV. 3 Severe COVID-19 cases progress to ARDS with hypoxemia around 8-12 days after symptom onset. 2 Although various independent factors such as older age and existing diseases contribute to mortality, the majority of fatal patients die of complications such as ARDS, myocardial injury, acute kidney injury, and sepsis. 2,3 The pathogenesis of COVID-19 has been heavily investigated in the past months. Pathophysiology in COVID-19 is characterized by diffuse alveolar damage, focal reactive hyperplasia of pneumocytes, inflammatory cellular infiltration, vasculitis, hypercoagulability, neutrophilia, and lymphopenia. 4 Studies have suggested that hyper-inflammation is linked to more severe disease of COVID-19, which is characterized by a cytokine releasing syndrome (CRS). 3,5 It has been reported that some inflammatory cytokines (such as IL-6, IL-10, and TNF-α) and chemokines (such as CXCL10/ IP-10, CCL2/MCP-1, and CCL3/MIP-1α) are upregulated in COVID-19 patients. 2 However, these studies are limited by the small sample size, narrowed cytokine and chemokine spectrum, and absence of temporal kinetic analysis of these factors with disease progression. Currently, limited information is available on host factors and biomarkers affecting individual outcomes in COVID-19. Identification of host plasma factors that are correlated to COVID-19 progression may provide potential biomarkers and targets for developing therapeutics. To systematically investigate the kinetic changes of plasma levels of cytokines, chemokines and growth factors (CCGFs) over the disease courses in COVID-19 patients as well as the correlations between the CCGF profiles and disease severity, we measured levels of 48 CCGFs in plasma of mild, severe and fatal COVID-19 patients collected at different stages of disease courses. We collected sera from 6 fatal, 7 severe, and 10 mild patients at day 1, 5, 10, and 14 after diagnosis. One sample was collected from each of the 4 healthy donors. We measured the levels of

Viral DNA sensing within the cytosol of infected cells activates type I interferon (IFN) expression. MITA/STING plays an essential role in this pathway by acting as both a sensor for the second messenger cGAMP and as an adaptor for downstream signaling components. In an expression screen for proteins that can activate the IFNB1 promoter, we identified the ER-associated protein ZDHHC1 as a positive regulator of virus-triggered, MITA/STING-dependent immune signaling. Zdhhc1(-/-) cells failed to effectively produce IFNs and other cytokines in response to infection with DNA but not RNA viruses. Zdhhc1(-/-) mice infected with the neurotropic DNA virus HSV-1 exhibited lower cytokine levels and higher virus titers in the brain, resulting in higher lethality. ZDHHC1 constitutively associated with MITA/STING and mediates dimerization/aggregation of MITA/STING and recruitment of the downstream signaling components TBK1 and IRF3. These findings support a role for ZDHHC1 in mediating MITA/STING-dependent innate immune response against DNA viruses.