Structure-Based Discovery of Inhibitors of the SARS-CoV-2 Nsp14 N7-Methyltransferase.

An under-explored target for SARS-CoV-2 is the S-adenosyl methionine (SAM)-dependent methyltransferase Nsp14, which methylates the N7-guanosine of viral RNA at the 5'-end, allowing the virus to evade host immune response. We sought new Nsp14 inhibitors with three large library docking strategies. First, up to 1.1 billion lead-like molecules were docked against the enzyme's SAM site, leading to three inhibitors with IC50 values from 6 to 50 µM. Second, docking a library of 16 million fragments revealed 9 new inhibitors with IC50 values from 12 to 341 µM. Third, docking a library of 25 million electrophiles to covalently modify Cys387 revealed 7 inhibitors with IC50 values from 3.5 to 39 µM. Overall, 32 inhibitors encompassing 11 chemotypes had IC50 values < 50 µM and 5 inhibitors in 4 chemotypes had IC50 values < 10 µM. These molecules are among the first non-SAM-like inhibitors of Nsp14, providing starting points for future optimization.

Design and synthesis of naturally-inspired SARS-CoV-2 inhibitors.

A naturally inspired chemical library of 25 molecules was synthesised guided by 3-D dimensionality and natural product likeness factors to explore a new chemical space. The synthesised chemical library, consisting of fused-bridged dodecahydro-2a,6-epoxyazepino[3,4,5-c,d]indole skeletons, followed lead likeness factors in terms of molecular weight, C-sp3 fraction and Clog P. Screening of the 25 compounds against lung cells infected with SARS-CoV-2 led to the identification of 2 hits. Although the chemical library showed cytotoxicity, the two hits (3b, 9e) showed the highest antiviral activity (EC50 values of 3.7 and 1.4 µM, respectively) with an acceptable cytotoxicity difference. Computational analysis based on docking and molecular dynamics simulations against main protein targets in SARS-CoV-2 (main protease Mpro, nucleocapsid phosphoprotein, non-structural protein nsp10-nsp16 complex and RBD/ACE2 complex) were performed. The computational analysis proposed the possible binding targets to be either Mpro or the nsp10-nsp16 complex. Biological assays were performed to confirm this proposition. A cell-based assay for Mpro protease activity using a reverse-nanoluciferase (Rev-Nluc) reporter confirmed that 3b targets Mpro. These results open the way towards further hit-to-lead optimisations.

SS148 and WZ16 inhibit the activities of nsp10-nsp16 complexes from all seven human pathogenic coronaviruses.

Seven coronaviruses have infected humans (HCoVs) to-date. SARS-CoV-2 caused the current COVID-19 pandemic with the well-known high mortality and severe socioeconomic consequences. MERS-CoV and SARS-CoV caused epidemic of MERS and SARS, respectively, with severe respiratory symptoms and significant fatality. However, HCoV-229E, HCoV-NL63, HCoV-HKU1, and HCoV-OC43 cause respiratory illnesses with less severe symptoms in most cases. All coronaviruses use RNA capping to evade the immune systems of humans. Two viral methyltransferases, nsp14 and nsp16, play key roles in RNA capping and are considered valuable targets for development of anti-coronavirus therapeutics. But little is known about the kinetics of nsp10-nsp16 methyltransferase activities of most HCoVs, and reliable assays for screening are not available. Here, we report the expression, purification, and kinetic characterization of nsp10-nsp16 complexes from six HCoVs in parallel with previously characterized SARS-CoV-2. Probing the active sites of all seven by SS148 and WZ16, the two recently reported dual nsp14 / nsp10-nsp16 inhibitors, revealed pan-inhibition. Overall, our study show feasibility of developing broad-spectrum dual nsp14 / nsp10-nsp16-inhibitor therapeutics.

Adverse environmental effects of disposable face masks due to the excess usage.

The widespread use of disposable face masks as a preventative strategy to address transmission of the SARS-CoV-2 virus has been a key environmental concern since the pandemic began. This has led to an unprecedented new form of contamination from improperly disposed masks, which liberates significant amounts of heavy metals and toxic chemicals in addition to volatile organic compounds (VOCs). Therefore, this study monitored the liberation of heavy metals, VOCs, and microfibers from submerged disposable face masks at different pH (4, 7 and 12), to simulate distinct environmental conditions. Lead (3.238% ppb), cadmium (0.672 ppb) and chromium (0.786 ppb) were found in the analyzed leachates. By pyrolysis, 2,4-dimethylhept-1-ene and 4-methylheptane were identified as the VOCs produced by the samples. The chemically degraded morphology in the FESEM images provided further evidence that toxic heavy metals and volatile organic compounds had been leached from the submerged face masks, with greater degradation observed in samples submerged at pH 7 and higher. The results are seen to communicate the comparable danger of passively degrading disposable face masks and the release of micro- or nanofibers into the marine environment. The toxicity of certain heavy metals and chemicals released from discarded face masks warrants better, more robust manufacturing protocols and increased public awareness for responsible disposal to reduce the adverse impact on ecology and human health.

Analyzing Trends in the Global Surge of Coronavirus Disease 2019 Pandemic Submissions to The Journal of Pediatrics.

During February to December 2020, there were 498 coronavirus disease 2019 (COVID-19) pandemic-focused brief report and original article submissions to The Journal of Pediatrics. The majority were from international authors (68.1%). Early in the pandemic, geographic origin of the corresponding author paralleled the path of COVID-19 infection both within the US and around the globe.

Impact of the Coronavirus Disease 2019 Pandemic on Authorship Gender in The Journal of Pediatrics: Disproportionate Productivity by International Male Researchers.

OBJECTIVE: To assess the impact of the coronavirus disease 2019 (COVID-19) pandemic on authorship gender in articles submitted to The Journal of Pediatrics. STUDY DESIGN: Using gender-labeling algorithms and human inspection, we inferred the gender of corresponding authors of original articles submitted in January-February and April-May of 2019 and 2020 noting those articles related to the COVID-19 pandemic. We used Pearson χ2 tests to determine differences in gender proportions during the selected periods in the US and internationally. RESULTS: We analyzed 1521 original articles. Submissions increased 10.9% from January-February 2019 to January-February 2020 and 61.6% from April-May 2019 to April-May 2020. Women accounted for 56.0% of original articles in April-May 2019 but only 49.8% of original articles in April-May 2020. Original articles focused on COVID-19 represented a small percentage of additional articles submitted in January-February 2020 (1/33 or 3.0%) and (53/199 or 26.6%) in April-May 2020 compared with the number of submissions in the same months in 2019. International male corresponding authors submitted a significantly larger proportion of original articles compared with international female corresponding authors in April-May 2020 compared to April-May 2019 (P = .043). There was no difference in corresponding author gender proportion in the US (US in April-May of 2020 vs April-May of 2019; P = .95). There was no significant difference in final dispositions based on corresponding author gender for original articles from 2019 and 2020 (P = .17). CONCLUSIONS: Original article submissions to The Journal increased in April-May 2020, with the greatest increase by international male corresponding authors. The majority of the submission growth was not related to COVID-19.

Reopening K-12 Schools in the Era of Coronavirus Disease 2019: Review of State-Level Guidance Addressing Equity Concerns.

OBJECTIVE: To determine how state guidance documents address equity concerns in K-12 schools during the coronavirus disease 2019 pandemic. STUDY DESIGN: Using online searches, we collected state-level documents from all 50 states and the District of Columbia discussing reopening plans for K-12 schools in the 2020-2021 academic year. We examined whether these documents explicitly mentioned equity as a concern, as well as if and how they addressed the following equity issues: food insecurity and child nutrition, homelessness or temporary housing, lack of access to Internet/technology, students with disabilities or special needs, English-language learners, students involved with or on the verge of involvement with the Department of Children and Family Services or an equivalent agency, mental health support, students/staff at greater risk of severe illness from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and students/staff living with someone at greater risk of severe illness from SARS-CoV-2 infection. RESULTS: Forty-four of 51 states (86%) explicitly mentioned equity as a concern or guiding principle. At least 90% of states offered guidance for 7 equity issues. Fewer than 75% of states addressed homelessness or temporary housing, students involved with or on the verge of involvement with Department of Children and Family Services or an equivalent agency, and students/staff living with someone at greater risk of severe illness from SARS-CoV-2 infection. CONCLUSIONS: Wide variability exists in state-level guidance to help K-12 schools develop reopening plans that protect those who are most vulnerable to learning loss or reduced access to basic needs. Interpretation and implementation by local educational agencies will need to be assessed.