A COVID-19 antibody curbs SARS-CoV-2 nucleocapsid protein-induced complement hyper-activation

Although human antibodies elicited by severe acute respiratory distress syndrome coronavirus-2 (SARS-CoV-2) nucleocapsid (N) protein are profoundly boosted upon infection, little is known about the function of N-directed antibodies. Herein, we isolated and profiled a panel of 32 N protein-specific monoclonal antibodies (mAb) from a quick recovery coronavirus disease-19 (COVID-19) convalescent, who had dominant antibody responses to SARS-CoV-2 N protein rather than to Spike protein. The complex structure of N protein RNA binding domain with the highest binding affinity mAb nCoV396 reveals the epitopes and antigens allosteric changes. Functionally, a virus-free complement hyper-activation analysis demonstrates that nCoV396 specifically compromises N protein-induced complement hyper-activation, a risk factor for morbidity and mortality in COVID-19, thus paving the way for functional anti-N mAbs identification. One Sentence SummaryB cell profiling, structural determination, and protease activity assays identify a functional antibody to N protein.

Preliminary evidence from a multicenter prospective observational study of the safety and efficacy of chloroquine for the treatment of COVID-19

BackgroundEffective therapies are urgently needed for the SARS-CoV-2 pandemic. Chloroquine has been proved to have antiviral effect against coronavirus in vitro. In this study, we aimed to assess the efficacy and safety of chloroquine with different doses in COVID-19. MethodIn this multicenter prospective observational study, we enrolled patients older than 18 years old with confirmed SARS-CoV-2 infection excluding critical cases from 12 hospitals in Guangdong and Hubei Provinces. Eligible patients received chloroquine phosphate 500mg, orally, once (half dose) or twice (full dose) daily. Patients treated with non-chloroquine therapy were included as historical controls. The primary endpoint is the time to undetectable viral RNA. Secondary outcomes include the proportion of patients with undetectable viral RNA by day 10 and 14, hospitalization time, duration of fever, and adverse events. ResultsA total of 197 patients completed chloroquine treatment, and 176 patients were included as historical controls. The median time to achieve an undetectable viral RNA was shorter in chloroquine than in non-chloroquine (absolute difference in medians -6.0 days; 95% CI -6.0 to -4.0). The duration of fever is shorter in chloroquine (geometric mean ratio 0.6; 95% CI 0.5 to 0.8). No serious adverse events were observed in the chloroquine group. Patients treated with half dose experienced lower rate of adverse events than with full dose. ConclusionsAlthough randomised trials are needed for further evaluation, this study provides evidence for safety and efficacy of chloroquine in COVID-19 and suggests that chloroquine can be a cost-effective therapy for combating 102 the COVID-19 pandemic.

Application and optimization of RT-PCR in diagnosis of SARS-CoV-2 infection

BackgroundCoronavirus Disease 2019 (COVID-19) caused by Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global threat to public health. Aiming to construct an efficient screening pattern, we comprehensively evaluated the performances of RT-PCR and chest CT in diagnosing COVID-19. MethodsThe records including demographics, RT-PCR, and CT from 87 confirmed COVID-19 cases and 481 exclusion cases were collected. The diagnostic accuracy of the pharyngeal swab RT-PCR, CT, combination with the second pharyngeal swab RT-PCR or with CT were evaluated individually. Besides, all the stool RT-PCR results were plotted by time to explore the value of stool RT-PCR. FindingsCombination of RT-PCR and CT has the higher sensitivity (91.9%,79/86) than RT-PCR alone (78.2%,68/87) or CT alone (66.7%, 54 of 81) or combination of two RT-PCR tests (86.2%,75/87). There was good agreement between RT-PCR and CT (kappa-value, 0.430). In 34 COVID-19 cases with inconsistent results, 94.1% (n=32) are mild infection, 62.5% of which (20/32) showed positive RT-PCR. 46.7% (35/75) COVID-19 patients had at least one positive stool during the course. Two cases had positive stool earlier than the pharyngeal swabs. Importantly, one patient had consecutive positive stool but negative pharyngeal swabs. InterpretationCombination of RT-PCR and CT with the highest sensitivity is an optimal pattern to screen COVID-19. RT-PCR is superior to CT in diagnosing mild infections. Stool RT-PCR should be considered as an item for improving discovery rate and hospital discharge. This study shed light for optimizing scheme of screening and monitoring of SARS-CoV-2 infection. FundingThis work was supported by the National Natural Science Foundation of China (No. 81502104), National Program on Key Basic Research Project (No. 2018YFC0910600),the Nature Science Foundation of Guangdong Province, China (Grant No: 2017A030313771 and 2020A151501001) and the Young Teachers Nurturing Program of Sun Yat-Sen University (Grant No:17ykpy62)

Evidence for gastrointestinal infection of SARS-CoV-2

The new coronavirus (SARS-CoV-2) outbreak originating from Wuhan, China, poses a threat to global health. While its evident that the virus invades respiratory tract and transmits from human to human through airway, other viral tropisms and transmission routes remain unknown. We tested viral RNA in stool from 73 SARS-CoV-2-infected hospitalized patients using rRT-PCR. 53.42% of the patients tested positive in stool. 23.29% of the patients remained positive in feces even after the viral RNA decreased to undetectable level in respiratory tract. The viral RNA was also detected in gastrointestinal tissues. Furthermore, gastric, duodenal and rectal epithelia showed positive immunofluorescent staining of viral host receptor ACE2 and viral nucleocapsid protein in a case of SARS-CoV-2 infection. Our results provide evidence for gastrointestinal infection of SARS-CoV-2, highlighting its potential fecal-oral transmission route.

Suberoylanilide hydroxamic acid (SAHA) suppresses JAK/STAT1 signal pathway to down-regulate the expression of indoleamine 2, 3-dioxygenuse in gallbladder carcinoma cells / 中华肝胆外科杂志

Objective To investigate the mechanism on JAK/STAT1 signal pathway in SAHA down-regulation of indoleamine 2,3-dioxygenase (IDO) in gallbladder carcinoma cells.MethodsWe treated gallbladder carcinoma SGC-996 cells with IFN-γ and SAHA.Western blotting was used to detect the expression of IDO,signal transducer and activator of transcription 1 (STAT1) phosphorylation and interferon regulatory factor genes-1 (IRF-1).Confocal microscopy analysis was used to detect STAT1 translocation.Transient transfections and reporter genes assay was used in detecting the activation of γ-activated sites (GAS) and interferon stimulated response elements (ISRE).ResultsIDO expressed in SGC-996 cells in dose- and time-dependent manners when stimulated with IFN-γ.SAHA down-regulated the expression of IDO induced by IFN-γ in a dose-dependent manner.SAHA blocked the expression of IRF-1 induced by IFN-γ.SAHA inhibited the IFN-γ-induced STAT1 phosphorylation and nuclear translocation.SAHA down-regulated IFN-γ-induced activation of GAS and ISRE.ConclusionsSAHA may down-regulate IDO expression through inhibiting the activation of members in JAK/STAT1 signal pathway.This may provide a new immunotherapeutic strategy to break tumor immune tolerance in gallbladder carcinoma.