COVID-19 is a new respiratory illness caused by SARS-CoV-2, and has constituted a global public health emergency. Cat is susceptible to SARS-CoV-2. However, the prevalence of SARS-CoV-2 in cats remains largely unknown. Here, we investigated the infection of SARS-CoV-2 in cats during COVID-19 outbreak in Wuhan by serological detection methods. A cohort of serum samples were collected from cats in Wuhan, including 102 sampled after COVID-19 outbreak, and 39 prior to the outbreak. Fifteen sera collected after the outbreak were positive for the receptor binding domain (RBD) of SARS-CoV-2 by indirect enzyme linked immunosorbent assay (ELISA). Among them, 11 had SARS-CoV-2 neutralizing antibodies with a titer ranging from 1/20 to 1/1080. No serological cross-reactivity was detected between SARS-CoV-2 and type I or II feline infectious peritonitis virus (FIPV). In addition, we continuously monitored serum antibody dynamics of two positive cats every 10 days over 130 days. Their serum antibodies reached the peak at 10 days after first sampling, and declined to the limit of detection within 110 days. Our data demonstrated that SARS-CoV-2 has infected cats in Wuhan during the outbreak and described serum antibody dynamics in cats, providing an important reference for clinical treatment and prevention of COVID-19.

The recent outbreaks of SARS-CoV-2 pose a global health emergency. The SARS-CoV-2 trimeric spike (S) glycoprotein interacts with the human ACE2 receptor to mediate viral entry into host cells. We report the cryo-EM structures of a tightly closed SARS-CoV-2 S trimer with packed fusion peptide and an ACE2-bound S trimer at 2.7- and 3.8-Å resolution, respectively. Accompanying ACE2 binding to the up receptor-binding domain (RBD), the associated ACE2-RBD exhibits continuous swing motions. Notably, the SARS-CoV-2 S trimer appears much more sensitive to the ACE2 receptor than the SARS-CoV S trimer regarding receptor-triggered transformation from the closed prefusion state to the fusion-prone open state, potentially contributing to the superior infectivity of SARS-CoV-2. We defined the RBD T470-T478 loop and Y505 as viral determinants for specific recognition of SARS-CoV-2 RBD by ACE2. Our findings depict the mechanism of ACE2-induced S trimer conformational transitions from the ground prefusion state toward the postfusion state, facilitating development of anti–SARS-CoV-2 vaccines and therapeutics.

This article describes the synthesis and functions of a porous catalytic framework based on conjugated micro- and mesoporous polymers with metalloporphyrin building blocks (FeP-CMP). FeP-CMP was newly synthesized via a Suzuki polycondensation reaction and was developed as a heterogeneous catalyst for the activation of molecular oxygen to convert sulfide to sulfoxide under ambient temperature and pressure. FeP-CMP is intriguing because the polymer skeleton itself is built from catalytic moieties and serves as built-in catalysts, bears inherent open nanometer-scale pores that are accessible for substrates, and possesses large surface areas (1270 m(2) g(-1)) that facilitate the transformation reaction. It is highly efficient with high conversion (up to 99%) and a large turnover number (TON = 97,320), is widely applicable to various sulfides covering from aromatic to alkyl and cyclic substrates, displays high selectivity (up to 99%) to form corresponding sulfoxides, and is highly chemoselective for the oxidation of a sulfide group even in the coexistence of other oxidative functionalities. Owing to the covalent linkages between catalytic sites in the frameworks, FeP-CMP can be recycled with good retention of its porous structure and allows for large-scale transformation. These unique characteristics clearly originate from the covalent porous catalytic framework structure and demonstrate the usefulness of CMPs in the exploration of built-in heterogeneous catalysts, a new potential of these materials that have thus far been reported to exhibit noteworthy gas adsorption functions.

Recent achievements in semiconductor surface‐enhanced Raman scattering (SERS) substrates have greatly expanded the application of SERS technique in various fields. However, exploring novel ultra‐sensitive semiconductor SERS materials is a high‐priority task. Here, a new semiconductor SERS‐active substrate, Ta 2 O 5 , is developed and an important strategy, the “coupled resonance” effect, is presented, to optimize the SERS performance of semiconductor materials by energy band engineering. The optimized Mo‐doped Ta 2 O 5 substrate exhibits a remarkable SERS sensitivity with an enhancement factor of 2.2 × 10 7 and a very low detection limit of 9 × 10 −9 m for methyl violet (MV) molecules, demonstrating one of the highest sensitivities among those reported for semiconductor SERS substrates. This remarkable enhancement can be attributed to the synergistic resonance enhancement of three components under 532 nm laser excitation: i) MV molecular resonance, ii) photoinduced charge transfer resonance between MV molecules and Ta 2 O 5 nanorods, and iii) electromagnetic enhancement around the “gap” and “tip” of anisotropic Ta 2 O 5 nanorods. Furthermore, it is discovered that the concomitant photoinduced degradation of the probed molecules in the time‐scale of SERS detection is a non‐negligible factor that limits the SERS performance of semiconductors with photocatalytic activity.

To investigate factors associated with the duration of viral shedding in patients with COVID-19, outside of Wuhan. Methods: In this retrospective cohort study, patients with laboratory-confirmed COVID-19 in Changsha, China were included. Clinical characteristics, laboratory findings, treatment, and outcome were retrieved. Univariate and multivariate analyses were performed to explore potential factors. Results: Overall, 147 patients with COVID-19 were included. The median duration of viral shedding (the number of days from symptoms onset until the successive negative detection of SARS-CoV-2 RNA) was 17 days (interquartile range [IQR], 12-21). Multivariate Logistic regression analysis indicated that the highest temperature at admission (odds ratio [OR], 5.200; 95% confidence interval [CI]: 1.190À22.726; p = 0.028), time from symptom onset to admission (OR, 1.740; 95% CI: 1.296À2.337; p < 0.001) and hospital length of stay (OR, 1.604; 95% CI: 1.262À2.040; p < 0.001) were risk factors for prolonged duration of viral shedding. Conclusions: This study, with a relatively large sample size, focused on the duration of viral shedding and related factors in patients with COVID-19, outside of Wuhan, China. Potential risk factors were identified and should be taken into consideration for the strategy of quarantining infected patients.

Comparing hospitalised, community and staff COVID-19 infection rates during the early phase of the evolving COVID-19 epidemic Dear Editor, a descriptive and modelling study. Lancet Infect Dis 2020 Apr 2 pii: S1473-3099(20)30230-9[Epub ahead of print].

The ongoing pandemic of coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Neutralizing antibodies against SARS-CoV-2 are an option for drug development for treating COVID-19. Here, we report the identification and characterization of two groups of mouse neutralizing monoclonal antibodies (MAbs) targeting the receptor-binding domain (RBD) on the SARS-CoV-2 spike (S) protein. MAbs 2H2 and 3C1, representing the two antibody groups, respectively, bind distinct epitopes and are compatible in formulating a noncompeting antibody cocktail. A humanized version of the 2H2/3C1 cocktail is found to potently neutralize authentic SARS-CoV-2 infection in vitro with half inhibitory concentration (IC50) of 12 ng/mL and effectively treat SARS-CoV-2-infected mice even when administered at as late as 24 h post-infection. We determine an ensemble of cryo-EM structures of 2H2 or 3C1 Fab in complex with the S trimer up to 3.8 Å resolution, revealing the conformational space of the antigen–antibody complexes and MAb-triggered stepwise allosteric rearrangements of the S trimer, delineating a previously uncharacterized dynamic process of coordinated binding of neutralizing antibodies to the trimeric S protein. Our findings provide important information for the development of MAb-based drugs for preventing and treating SARS-CoV-2 infections.

The outbreak of coronavirus disease 2019 has seriously threatened human health. Rapidly and sensitively detecting SARS-CoV-2 viruses can help control the spread of viruses. However, it is an arduous challenge to apply semiconductor-based substrates for virus SERS detection due to their poor sensitivity. Therefore, it is worthwhile to search novel semiconductor-based substrates with excellent SERS sensitivity. Herein we report, for the first time, Nb2C and Ta2C MXenes exhibit a remarkable SERS enhancement, which is synergistically enabled by the charge transfer resonance enhancement and electromagnetic enhancement. Their SERS sensitivity is optimized to 3.0 × 106 and 1.4 × 106 under the optimal resonance excitation wavelength of 532 nm. Additionally, remarkable SERS sensitivity endows Ta2C MXenes with capability to sensitively detect and accurately identify the SARS-CoV-2 spike protein. Moreover, its detection limit is as low as 5 × 10−9 M, which is beneficial to achieve real-time monitoring and early warning of novel coronavirus. This research not only provides helpful theoretical guidance for exploring other novel SERS-active semiconductor-based materials but also provides a potential candidate for the practical applications of SERS technology.