BACKGROUNDNo therapeutics have yet been proven effective for the treatment of severe illness caused by SARS-CoV-2. METHODSWe conducted a randomized, controlled, open-label trial involving hospitalized adult patients with confirmed SARS-CoV-2 infection, which causes the respiratory illness Covid-19, and an oxygen saturation (Sao 2 ) of 94% or less while they were breathing ambient air or a ratio of the partial pressure of oxygen (Pao 2 ) to the fraction of inspired oxygen (Fio 2 ) of less than 300 mm Hg. Patients were randomly assigned in a 1:1 ratio to receive either lopinavir-ritonavir (400 mg and 100 mg, respectively) twice a day for 14 days, in addition to standard care, or standard care alone. The primary end point was the time to clinical improvement, defined as the time from randomization to either an improvement of two points on a seven-category ordinal scale or discharge from the hospital, whichever came first. RESULTSA total of 199 patients with laboratory-confirmed SARS-CoV-2 infection underwent randomization; 99 were assigned to the lopinavir-ritonavir group, and 100 to the standard-care group. Treatment with lopinavir-ritonavir was not associated with a difference from standard care in the time to clinical improvement (hazard ratio for clinical improvement, 1.24; 95% confidence interval [CI], 0.90 to 1.72). Mortality at 28 days was similar in the lopinavir-ritonavir group and the standard-care group (19.2% vs. 25.0%; difference, −5.8 percentage points; 95% CI, −17.3 to 5.7). The percentages of patients with detectable viral RNA at various time points were similar. In a modified intention-to-treat analysis, lopinavir-ritonavir led to a median time to clinical improvement that was shorter by 1 day than that observed with standard care (hazard ratio, 1.39; 95% CI, 1.00 to 1.91). Gastrointestinal adverse events were more common in the lopinavir-ritonavir group, but serious adverse events were more common in the standard-care group. Lopinavir-ritonavir treatment was stopped early in 13 patients (13.8%) because of adverse events. CONCLUSIONS

To face SARS-CoV-2 pandemic various attempts are made to identify potential effective treatments by repurposing available drugs. Among them, indomethacin, an anti-inflammatory drug, was shown to have potent in-vitro antiviral properties on human SARS-CoV-1, canine CCoV, and more recently on human SARS-CoV-2 at low micromolar range. Our objective was to show that indomethacin could be considered as a promising candidate for the treatment of SARS-CoV-2 and to provide criteria for comparing benefits of alternative dosage regimens using a model-based approach. A multi-stage model-based approach was developed to characterize % of recovery and viral load in CCoVinfected dogs, to estimate the PK of indomethacin in dog and human using published data after administration of immediate (IR) and sustained-release (SR) formulations, and to estimate the expected antiviral activity as a function of different assumptions on the effective exposure in human. Different dosage regimens were evaluated for IR formulation (25 mg and 50 mg three-times-a-day, and 25 mg four-times-a-day), and SR formulation (75 mg once and twice-a-day). The best performing dosing regimens were: 50 mg three-times-a-day for the IR formulation, and 75 mg twice-a-day for the SR formulation. The treatment with the SR formulation at the dose of 75 mg twice-a-day is expected to achieve a complete response in three days for the treatment in patients infected by the SARS-CoV-2 coronavirus. These results suggest that indomethacin could be considered as a promising candidate for the treatment of SARS-CoV-2 whose potential therapeutic effect needs to be further assessed in a prospective clinical trial.

Long-term antibody responses and neutralizing activities in response to SARS-CoV-2 infection are not yet clear. Here we quantify immunoglobulin M (IgM) and G (IgG) antibodies recognizing the SARS-CoV-2 receptor-binding domain (RBD) of the spike (S) or the nucleocapsid (N) protein, and neutralizing antibodies during a period of 6 months from COVID-19 disease onset in 349 symptomatic COVID-19 patients who were among the first be infected world-wide. The positivity rate and magnitude of IgM-S and IgG-N responses increase rapidly. High levels of IgM-S/N and IgG-S/N at 2-3 weeks after disease onset are associated with virus control and IgG-S titers correlate closely with the capacity to neutralize SARS-CoV-2. Although specific IgM-S/N become undetectable 12 weeks after disease onset in most patients, IgG-S/N titers have an intermediate contraction phase, but stabilize at relatively high levels over the 6 month observation period. At late time points, the positivity rates for binding and neutralizing SARS-CoV-2-specific antibodies are still >70%. These data indicate sustained humoral immunity in recovered patients who had symptomatic COVID-19, suggesting prolonged immunity.

Kindlins and talins are integrin-binding proteins that are critically involved in integrin activation, an essential process for many fundamental cellular activities including cell-matrix adhesion, migration, and proliferation. As FERM-domain-containing proteins, talins and kindlins, respectively, bind different regions of β-integrin cytoplasmic tails. However, compared with the extensively studied talin, little is known about how kindlins specifically interact with integrins and synergistically enhance their activation by talins. Here, we determined crystal structures of kindlin2 in the apo-form and the β1-and β3-integrin bound forms. The apo-structure shows an overall architecture distinct from talins. The complex structures reveal a unique integrin recognition mode of kindlins, which combines two binding motifs to provide specificity that is essential for integrin activation and signaling. Strikingly, our structures uncover an unexpected dimer formation of kindlins. Interrupting dimer formation impairs kindlin-mediated integrin activation. Collectively, the structural, biochemical, and cellular results provide mechanistic explanations that account for the effects of kindlins on integrin activation as well as for how kindlin mutations found in patients with Kindler syndrome and leukocyte-adhesion deficiency may impact integrin-mediated processes.I ntegrins, composed of α-and β-subunits, are the major receptors mediating the cell-extracellular matrix (ECM) adhesion (1-3). By connecting specific ECM proteins and diverse cytoskeletal regulators, integrins mediate bidirectional transmembrane signaling (4, 5). Stable integrin-ECM interaction and subsequent signaling require integrin activation, which was reported to be mediated by talin, a 4.1-protein/ezrin/radixin/moesin (FERM) domain-containing protein (6). Recently, kindlins, another family of FERM-containing proteins, were found to play crucial roles in integrin activation and signaling (7-12).The kindlin family consists of three members in vertebrates, kindlin1/2/3, each containing a FERM domain and a PH domain (Fig. 1A) (13). Compared with the typical FERM domain that consists of three lobes (F1, F2, and F3), kindlin-FERM contains an additional N-terminal F0 lobe. In kindlins, the F1 and F2 lobes are split by a largely unstructured insertion and the PH domain, respectively (Fig. 1A). Kindlins, although sharing high sequence similarity (SI Appendix, Fig. S1), show distinct tissue distributions and nonredundant functions. Kindlin1 is expressed mainly in epithelia, and nonfunctional kindlin1 mutations lead to Kindler syndrome, a congenital skin disease (14-16). Expression of kindlin3 is restricted to the hematopoietic system, and mutations in kindlin3 were found to associate with leukocyte-adhesion deficiency type III (LADIII) (17, 18). Kindlin2 is ubiquitously expressed, and loss of kindlin2 in mice leads to peri-implantation lethality (11). Kindlins are also involved in tumorigenesis and metastasis (19). The kindlin-associated diseases are due, at least in part...