SARS-CoV-2 NSP13 interacts with host IRF3, blocking antiviral immune responses.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), poses an unprecedented threat to human health since late 2019. Notably, the progression of the disease is associated with impaired antiviral interferon (IFN) responses. Although multiple viral proteins were identified as potential IFN antagonists, the underlying molecular mechanisms remain to be fully elucidated. In this study, we firstly demonstrate that SARS-CoV-2 NSP13 protein robustly antagonizes IFN response induced by the constitutively active form of transcription factor IRF3 (IRF3/5D). This induction of IFN response by IRF3/5D is independent of the upstream kinase, TBK1, a previously reported NSP13 target, thus indicating that NSP13 can act at the level of IRF3 to antagonize IFN production. Consistently, NSP13 exhibits a specific, TBK1-independent interaction with IRF3, which, moreover, is much stronger than that of NSP13 with TBK1. Furthermore, the NSP13-IRF3 interaction was shown to occur between the NSP13 1B domain and IRF3 IRF association domain (IAD). In agreement with the strong targeting of IRF3 by NSP13, we then found that NSP13 blocks IRF3-directed signal transduction and antiviral gene expression, counteracting IRF3-driven anti-SARS-CoV-2 activity. These data suggest that IRF3 is likely to be a major target of NSP13 in antagonizing antiviral IFN responses and provide new insights into the SARS-CoV-2-host interactions that lead to viral immune evasion.

Effective prevention and management of COVID-19 in outpatient hemodialysis patients.

The authors introduce a mobile phone app that may effectively prevent and manage coronavirus disease 2019 (COVID-19) in outpatient hemodialysis patients in Sichuan Province, China.

Immune evasion of SARS-CoV-2 from interferon antiviral system.

The on-going pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to unprecedented medical and socioeconomic crises. Although the viral pathogenesis remains elusive, deficiency of effective antiviral interferon (IFN) responses upon SARS-CoV-2 infection has been recognized as a hallmark of COVID-19 contributing to the disease pathology and progress. Recently, multiple proteins encoded by SARS-CoV-2 have been shown to act as potential IFN antagonists with diverse possible mechanisms. Here, we summarize and discuss the strategies of SARS-CoV-2 for evasion of innate immunity (particularly the antiviral IFN responses), understanding of which will facilitate not only the elucidation of SARS-CoV-2 infection and pathogenesis but also the development of antiviral intervention therapies.

Hybridoma-derived neutralizing monoclonal antibodies against Beta and Delta variants of SARS-CoV-2 in vivo.

Neutralizing monoclonal antibodies (mAb) are a major therapeutic strategy for the treatment of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. The continuous emergence of new SARS-CoV-2 variants worldwide has increased the urgency for the development of new mAbs. In this study, we immunized mice with the receptor-binding domain (RBD) of the SARS-CoV-2 prototypic strain (WIV04) and screened 35 RBD-specific mAbs using hybridoma technology. Results of the plaque reduction neutralization test showed that 25 of the mAbs neutralized authentic WIV04 strain infection. The 25 mAbs were divided into three categories based on the competitive enzyme-linked immunosorbent assay results. A representative mAb was selected from each category (RD4, RD10, and RD14) to determine the binding kinetics and median inhibitory concentration (IC50) of WIV04 and two variants of concern (VOC): B.1.351 (Beta) and B.1.617.2 (Delta). RD4 neutralized the B.1.617.2 variant with an IC50 of 2.67 â€‹ng/mL; however, it completely lost neutralizing activity against the B.1.351 variant. RD10 neutralized both variants with an IC50 exceeding 100 â€‹ng/mL; whereas RD14 neutralized two variants with a higher IC50 (>1 â€‹mg/mL). Animal experiments were performed to evaluate the protective effects of RD4 and RD10 against various VOC infections. RD4 could protect Adv-hACE2 transduced mice from B.1.617.2 infection at an antibody concentration of 25 â€‹mg/kg, while RD10 could protect mice from B.1.351 infection at an antibody concentration of 75 â€‹mg/kg. These results highlight the potential for future modifications of the mAbs for practical use.

Antiviral activity and mechanism of the antifungal drug, anidulafungin, suggesting its potential to promote treatment of viral diseases.

BACKGROUND: The severe fever with thrombocytopenia syndrome disease (SFTS), caused by the novel tick-borne SFTS virus (SFTSV), was listed among the top 10 priority infectious disease by World Health Organization due to the high fatality rate of 5-30% and the lack of effective antiviral drugs and vaccines and therefore raised the urgent need to develop effective anti-SFTSV drugs to improve disease treatment. METHODS: The antiviral drugs to inhibit SFTSV infection were identified by screening the library containing 1340 FDA-approved drugs using the SFTSV infection assays in vitro. The inhibitory effect on virus entry and the process of clathrin-mediated endocytosis under different drug doses was evaluated based on infection assays by qRT-PCR to determine intracellular viral copies, by Western blot to characterize viral protein expression in cells, and by immunofluorescence assays (IFAs) to determine virus infection efficiencies. The therapeutic effect was investigated in type I interferon receptor defective A129 mice in vivo with SFTSV infection, from which lesions and infection in tissues caused by SFTSV infection were assessed by H&E staining and immunohistochemical analysis. RESULTS: Six drugs were identified as exerting inhibitory effects against SFTSV infection, of which anidulafungin, an antifungal drug of the echinocandin family, has a strong inhibitory effect on SFTSV entry. It suppresses SFTSV internalization by impairing the late endosome maturation and decreasing virus fusion with the membrane. SFTSV-infected A129 mice had relieving symptoms, reduced tissue lesions, and improved disease outcomes following anidulafungin treatment. Moreover, anidulafungin exerts an antiviral effect in inhibiting the entry of other viruses including SARS-CoV-2, SFTSV-related Guertu virus and Heartland virus, Crimean-Congo hemorrhagic fever virus, Zika virus, and Herpes simplex virus 1. CONCLUSIONS: The results demonstrated that the antifungal drug, anidulafungin, could effectively inhibit virus infection by interfering with virus entry, suggesting it may be utilized for the clinical treatment of infectious viral diseases, in addition to its FDA-approved use as an antifungal. The findings also suggested to further evaluate the anti-viral effects of echinocandins and their clinical importance for patients with infection of viruses, which may promote therapeutic strategies as well as treatments and improve outcomes pertaining to various viral and fungal diseases.

Increasing trans-cleavage catalytic efficiency of Cas12a and Cas13a with chemical enhancers: Application to amplified nucleic acid detection

The exceptional programable trans-cleavage ability of type V and VI CRISPR/Cas nucleases paved the way for ultrasensitive CRISPR/Cas based sensing of nucleic acid and alternative targets. However, the enhancement of the trans-cleavage activity of Cas effector with organic chemical agents has not been explored thus far. We report here chemically enhanced trans-cleavage activity of Cas12a and Cas13a nucleases which improves sensor performance in CRISPR/Cas biosensing. Improved trans-ssDNA cleavage of Cas12a and trans-ssRNA cleavage of Cas13a were demonstrated by using sulfhydryl reductants and non-ionic surfactants. DTT and PVA were demonstrated to be the most effective chemical enhancers in both cases. By using a fluorescence resonance energy transfer (FRET)-based intramolecular distance measurements, we identified the mechanism of this enhancement to be the conformation change of the ribonucleoprotein and quantified it to be major (about 50% increase of a relevant intramolecular distance). These chemical enhancers have been integrated into the established CRISPR/Cas biosensing protocols without additional modifications. For the detection of Helicobacter Pylori DNA and SARS-CoV-2 RNA, we found a decreased reaction time by 75–83% and 4–6-fold increased sensitivity. These results indicate that chemical enhancers provide a versatile and broadly applicable approach to break through the barriers of long reaction time and sensitivity in CRISPR/Cas sensors.

Immunogenicity and safety of a recombinant fusion protein vaccine (V-01) against coronavirus disease 2019 in healthy adults: a randomized, double-blind, placebo-controlled, phase II trial.

BACKGROUND: Innovative coronavirus disease 2019 (COVID-19) vaccines, with elevated global manufacturing capacity, enhanced safety and efficacy, simplified dosing regimens, and distribution that is less cold chain-dependent, are still global imperatives for tackling the ongoing pandemic. A previous phase I trial indicated that the recombinant COVID-19 vaccine (V-01), which contains a fusion protein (IFN-PADRE-RBD-Fc dimer) as its antigen, is safe and well tolerated, capable of inducing rapid and robust immune responses, and warranted further testing in additional clinical trials. Herein, we aimed to assess the immunogenicity and safety of V-01, providing rationales of appropriate dose regimen for further efficacy study. METHODS: A randomized, double-blind, placebo-controlled phase II clinical trial was initiated at the Gaozhou Municipal Centre for Disease Control and Prevention (Guangdong, China) in March 2021. Both younger (n = 440; 18-59 years of age) and older (n = 440; ≥60 years of age) adult participants in this trial were sequentially recruited into two distinct groups: two-dose regimen group in which participants were randomized either to follow a 10 or 25 µg of V-01 or placebo given intramuscularly 21 days apart (allocation ratio, 3:3:1, n = 120, 120, 40 for each regimen, respectively), or one-dose regimen groups in which participants were randomized either to receive a single injection of 50 µg of V-01 or placebo (allocation ratio, 3:1, n = 120, 40, respectively). The primary immunogenicity endpoints were the geometric mean titers of neutralizing antibodies against live severe acute respiratory syndrome coronavirus 2, and specific binding antibodies to the receptor binding domain (RBD). The primary safety endpoint evaluation was the frequencies and percentages of overall adverse events (AEs) within 30 days after full immunization. RESULTS: V-01 provoked substantial immune responses in the two-dose group, achieving encouragingly high titers of neutralizing antibody and anti-RBD immunoglobulin, which peaked at day 35 (161.9 [95% confidence interval [CI]: 133.3-196.7] and 149.3 [95%CI: 123.9-179.9] in 10 and 25 µg V-01 group of younger adults, respectively; 111.6 [95%CI: 89.6-139.1] and 111.1 [95%CI: 89.2-138.4] in 10 and 25 µg V-01 group of older adults, respectively), and remained high at day 49 after a day-21 second dose; these levels significantly exceed those in convalescent serum from symptomatic COVID-19 patients (53.6, 95%CI: 31.3-91.7). Our preliminary data show that V-01 is safe and well tolerated, with reactogenicity predominantly being absent or mild in severity and only one vaccine-related grade 3 or worse AE being observed within 30 days. The older adult participants demonstrated a more favorable safety profile compared with those in the younger adult group: with AEs percentages of 19.2%, 25.8%, 17.5% in older adults vs. 34.2%, 23.3%, 26.7% in younger adults at the 10, 25 µg V-01 two-dose group, and 50 µg V-01 one-dose group, respectively. CONCLUSIONS: The vaccine candidate V-01 appears to be safe and immunogenic. The preliminary findings support the advancement of the two-dose, 10 µg V-01 regimen to a phase III trial for a large-scale population-based evaluation of safety and efficacy. TRIAL REGISTRATION: http://www.chictr.org.cn/index.aspx (No. ChiCTR2100045107, http://www.chictr.org.cn/showproj.aspx?proj=124702).

Analysis of Clinical Characteristics and Virus Strains Variation of Patients Infected With SARS-CoV-2 in Jiangsu Province—A Retrospective Study

Background: At present, the global sever acute respiratory syndrome coronavirus 2 (SARS-CoV-2) situation is still grim, and the risk of local outbreaks caused by imported viruses is high. Therefore, it is necessary to monitor the genomic variation and genetic evolution characteristics of SARS-CoV-2. The main purpose of this study was to detect the entry of different SARS-CoV-2 variants into Jiangsu Province, China. Methods: First, oropharyngeal swabs were collected from 165 patients (55 locally confirmed cases and 110 imported cases with confirmed and asymptomatic infection) diagnosed with SARS-CoV-2 infection in Jiangsu Province, China between January 2020 and June 2021. Then, whole genome sequencing was used to explore the phylogeny and find potential mutations in genes of the SARS-CoV-2. Last, association analysis among clinical characteristics and SARS-CoV-2 Variant of Concern, pedigree surveillance analysis of SARS-COV-2, and single nucleotide polymorphisms (SNPs) detection in SARS-COV-2 samples was performed. Results: More men were infected with the SARS-CoV-2 when compared with women. The onset of the SARS-CoV-2 showed a trend of younger age. Moreover, the number of asymptomatic infected patients was large, similar to the number of common patients. Patients infected with Alpha (50%) and Beta (90%) variants were predominantly asymptomatic, while patients infected with Delta (17%) variant presented severe clinical features. A total of 935 SNPs were detected in 165 SARS-COV-2 samples. Among which, missense mutation (58%) was the dominant mutation type. About 56% of SNPs changes occurred in the open reading frame 1ab (ORF1ab) gene. Approximately, 20% of SNP changes occurred in spike glycoprotein (S) gene, such as p.Asp501Tyr, p.Pro681His, and p.Pro681Arg. In total, nine SNPs loci in S gene were significantly correlated with the severity of patients. It is worth mentioning that amino acid substitution of p.Asp614Gly was significantly positively correlated with the clinical severity of patients. The amino acid replacements of p.Ser316Thr and p.Lu484Lys were significantly negatively correlated with the course of disease. Conclusion: Sever acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may further undergo a variety of mutations in different hosts, countries, and weather conditions. Detecting the entry of different virus variants of SARS-CoV-2 into Jiangsu Province, China may help to monitor the spread of infection and the diversity of eventual recombination or genomic mutations.

Antibody neutralization to SARS-CoV-2 and variants after 1 year in Wuhan, China.

Most COVID-19 convalescents can build effective anti-SARS-CoV-2 humoral immunity, but it remains unclear how long it can maintain and how efficiently it can prevent the reinfection of the emerging SARS-CoV-2 variants. Here, we tested the sera from 248 COVID-19 convalescents around 1 year post-infection in Wuhan, the earliest known epicenter. SARS-CoV-2 immunoglobulin G (IgG) was well maintained in most patients and potently neutralizes the infection of the original strain and the B.1.1.7 variant. However, varying degrees of immune escape was observed on the other tested variants in a patient-specific manner, with individuals showing remarkably broad neutralization potency. The immune escape can be largely attributed to several critical spike mutations. These results suggest that SARS-CoV-2 can elicit long-lasting immunity but this is escaped by the emerging variants.

IFP35 as a promising biomarker and therapeutic target for the syndromes induced by SARS-CoV-2 or influenza virus.

Previous studies have shown that the high mortality caused by viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza virus primarily results from complications of a cytokine storm. Therefore, it is critical to identify the key factors participating in the cytokine storm. Here we demonstrate that interferon-induced protein 35 (IFP35) plays an important role in the cytokine storm induced by SARS-CoV-2 and influenza virus infection. We find that the levels of serum IFP35 in individuals with SARS-CoV-2 correlates with severity of the syndrome. Using mouse model and cell assays, we show that IFP35 is released by lung epithelial cells and macrophages after SARS-CoV-2 or influenza virus infection. In addition, we show that administration of neutralizing antibodies against IFP35 considerably reduces lung injury and, thus, the mortality rate of mice exposed to viral infection. Our findings suggest that IFP35 serves as a biomarker and as a therapeutic target in virus-induced syndromes.

Reviving chloroquine for anti-SARS-CoV-2 treatment with cucurbit[7]uril-based supramolecular formulation.

The wide-spreading SARS-CoV-2 virus has put the world into boiling water for more than a year, however pharmacological therapies to act effectively against coronavirus disease 2019 (COVID-19) remain elusive. Chloroquine (CQ), an antimalarial drug, was found to exhibit promising antiviral activity in vitro and in vivo at a high dosage, thus CQ was approved by the FDA for the emergency use authorization (EUA) in the fight against COVID-19 in the US, but later was revoked the EUA status due to the severe clinical toxicity. Herein, we show that supramolecular formulation of CQ by a macrocyclic host, curcurbit[7]uril (CB[7]), reduced its non-specific toxicity and improved its antiviral activity against coronavirus, working in synergy with CB[7]. CB[7] was found to form 1:1 host-guest complexes with CQ, with a binding constant of ∼104 L/mol. The CQ-CB[7] formulation decreased the cytotoxicity of CQ against Vero E6 and L-02 cell lines. In particular, the cytotoxicity of CQ (60 µmol/L) against both Vero E6 cell line and L-02 cell lines was completely inhibited in the presence of 300 µmol/L and 600 µmol/L CB[7], respectively. Furthermore, the CB[7] alone showed astonishing antiviral activity in SARS-CoV-2 infected Vero E6 cells and mouse hepatitis virus strain A59 (MHV-A59) infected N2A cells, and synergistically improved the antiviral activity of CQ-CB[7], suggesting that CB[7]-based CQ formulation has a great potential as a safe and effective antiviral agent against SARS-CoV-2 and other coronavirus.

Crimean-Congo Hemorrhagic Fever Virus: Current Advances and Future Prospects of Antiviral Strategies.

Crimean-Congo hemorrhagic fever virus (CCHFV) is a widespread, tick-borne pathogen that causes Crimean-Congo hemorrhagic fever (CCHF) with high morbidity and mortality. CCHFV is transmitted to humans through tick bites or direct contact with patients or infected animals with viremia. Currently, climate change and globalization have increased the transmission risk of this biosafety level (BSL)-4 virus. The treatment options of CCHFV infection remain limited and there is no FDA-approved vaccine or specific antivirals, which urges the identification of potential therapeutic targets and the design of CCHF therapies with greater effort. In this article, we discuss the current progress and some future directions in the development of antiviral strategies against CCHFV.

Occurrence of COVID-19 Symptoms During SARS-CoV-2 Infection Defines Waning of Humoral Immunity.

Approximately half of the SARS-CoV-2 infections occur without apparent symptoms, raising questions regarding long-term humoral immunity in asymptomatic individuals. Plasma levels of immunoglobulin G (IgG) and M (IgM) against the viral spike or nucleoprotein were determined for 25,091 individuals enrolled in a surveillance program in Wuhan, China. We compared 405 asymptomatic individuals who mounted a detectable antibody response with 459 symptomatic COVID-19 patients. The well-defined duration of the SARS-CoV-2 endemic in Wuhan allowed a side-by-side comparison of antibody responses following symptomatic and asymptomatic infections without subsequent antigen re-exposure. IgM responses rapidly declined in both groups. However, both the prevalence and durability of IgG responses and neutralizing capacities correlated positively with symptoms. Regardless of sex, age, and body weight, asymptomatic individuals lost their SARS-CoV-2-specific IgG antibodies more often and rapidly than symptomatic patients did. These findings have important implications for immunity and favour immunization programs including individuals after asymptomatic infections.