Predictive Systems Biology Modeling: Unraveling Host Metabolic Disruptions and Potential Drug Targets in SARS-CoV-2 and Its Variants (preprint)

Background: Host response is critical to the onset, progression, and outcome of viral infections. Since viruses hijack the host cellular metabolism for their replications, we hypothesized that restoring host cell metabolism can efficiently reduce viral production. Here, we present a viral-host Metabolic Modeling (vhMM) method to systematically evaluate the disturbances in host metabolism in viral infection and computationally identify targets for modulation by integrating genome-wide precision metabolic modeling and cheminformatics. Results: In SARS-CoV-2 infections, we identified consistent changes in host metabolism and gene and endogenous metabolite targets between the original SARS-COV-2 and different variants (Alpha, Delta, and Omicron). Among six compounds predicted for repurposing, methotrexate, cinnamaldehyde, and deferiprone were tested in vitro and effective in inhibiting viral production with IC50 less than 4uM. Further, an analysis of real-world patient data showed that cinnamon usage significantly reduced the SARS-CoV-2 infection rate with an odds ratio of 0.65 [95%CI: 0.55~0.75]. Conclusions: These results demonstrated that vhMM is an efficient method for predicting targets and drugs for viral infections.

Pegloticase efficacy and safety in kidney transplant recipients; results of the phase IV, open-label PROTECT clinical trial.

INTRODUCTION: Kidney transplant (KT) recipients have a high prevalence and severity of gout. Pegloticase (pegylated recombinant uricase) rapidly metabolizes serum uric acid (sUA), and its efficacy is not impacted by kidney function. METHODS: This open-label, Phase 4 trial (PROTECT NCT04087720) examined safety and efficacy of pegloticase in 20 participants with KT > 1 year prior to enrollment and with uncontrolled gout (sUA ≥7 mg/dL, intolerance/inefficacy to urate lowering therapy, and ≥1 of the following: tophi, chronic gouty arthritis, ≥2 flares in past year) and functioning KT (estimated glomerular filtration rate [eGFR] ≥15 mL/min/1.73 m2 ) on stable immunosuppression therapy. RESULTS: The primary endpoint was sUA response during month 6 (sUA < 6 mg/dL for ≥80% of time). The study enrolled 20 participants (mean ± SD); age: 53.9 ± 10.9 years, time since KT: 14.7 ± 6.9 years, sUA: 9.4 ± 1.5 mg/dL, gout duration: 8.4 ± 11.6 years; all on ≥2 stable doses of immunosuppression agents. Pegloticase (8 mg intravenous every 2 weeks) in KT recipients with uncontrolled gout showed a high response rate of 89% (16/18 responders). Two participants discontinued treatment solely due to COVID-19 concerns prior to month 6 were not included in the primary analysis. Pegloticase exposures were higher than those historically observed with pegloticase monotherapy, and no anaphylaxis or infusion reaction events occurred during the study. CONCLUSIONS: This improved response rate to pegloticase in the KT population reflects observations from other trials and reports on immunomodulation with pegloticase. As the KT population has a high prevalence of gout and limitations with oral urate lowering medication options, these findings suggest a potential option for uncontrolled gout therapy in KT participants.

Ferrets: A powerful model of SARS-CoV-2.

The rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in recent years not only caused a global pandemic but resulted in enormous social, economic, and health burdens worldwide. Despite considerable efforts to combat coronavirus disease 2019 (COVID-19), various SARS-CoV-2 variants have emerged, and their underlying mechanisms of pathogenicity remain largely unknown. Furthermore, effective therapeutic drugs are still under development. Thus, an ideal animal model is crucial for studying the pathogenesis of COVID-19 and for the preclinical evaluation of vaccines and antivirals against SARS-CoV-2 and variant infections. Currently, several animal models, including mice, hamsters, ferrets, and non-human primates (NHPs), have been established to study COVID-19. Among them, ferrets are naturally susceptible to SARS-CoV-2 infection and are considered suitable for COVID-19 study. Here, we summarize recent developments and application of SARS-CoV-2 ferret models in studies on pathogenesis, therapeutic agents, and vaccines, and provide a perspective on the role of these models in preventing COVID-19 spread.

Characteristics of patients with SARS-COV-2 PCR re-positivity after recovering from COVID-19.

The purpose of this study was to analyse the clinical characteristics of patients with severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) PCR re-positivity after recovering from coronavirus disease 2019 (COVID-19). Patients (n = 1391) from Guangzhou, China, who had recovered from COVID-19 were recruited between 7 September 2021 and 11 March 2022. Data on epidemiology, symptoms, laboratory test results and treatment were analysed. In this study, 42.7% of recovered patients had re-positive result. Most re-positive patients were asymptomatic, did not have severe comorbidities, and were not contagious. The re-positivity rate was 39%, 46%, 11% and 25% in patients who had received inactivated, mRNA, adenovirus vector and recombinant subunit vaccines, respectively. Seven independent risk factors for testing re-positive were identified, and a predictive model was constructed using these variables. The predictors of re-positivity were COVID-19 vaccination status, previous SARs-CoV-12 infection prior to the most recent episode, renal function, SARS-CoV-2 IgG and IgM antibody levels and white blood cell count. The predictive model could benefit the control of the spread of COVID-19.

Transcription regulation of SARS-CoV-2 receptor ACE2 by Sp1: a potential therapeutic target (preprint)

Angiotensin-converting enzyme 2 (ACE2) is a major cell entry receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Induction of ACE2 expression may represent an effective tactic employed by SARS-CoV-2 to facilitate its own propagation. However, the regulatory mechanisms of ACE2 expression after viral infection remain largely unknown. By employing an array of 45 different luciferase reporters, we identify that the transcription factor Sp1 positively and HNF4 negatively regulate the expression of ACE2 at the transcriptional levels in HPAEpiC cells, a human lung epithelial cell line. SARS-CoV-2 infection promotes and inhibits the transcription activity of Sp1 and HNF4, respectively. The PI3K/AKT signaling pathway, which is activated by SARS-CoV-2 infection, is a crucial node for induction of ACE2 expression by increasing Sp1 phosphorylation, an indicator of its activity, and reducing HNF4 nuclear location. Furthermore, we show that colchicine could inhibit the PI3K/AKT signaling pathway, thereby suppressing ACE2 expression. Inhibition of Sp1 by either its inhibitor mithramycin A or colchicine reduces viral replication and tissue injury in Syrian hamsters infected with SARS-CoV-2. In summary, our study uncovers a novel function of Sp1 in regulating ACE2 expression and suggests that Sp1 is a potential target to reduce SARS-CoV-2 infection.

Extracellular vesicles mediate antibody-resistant transmission of SARS-CoV-2.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a global pandemic. Antibody resistance dampens neutralizing antibody therapy and threatens current global Coronavirus (COVID-19) vaccine campaigns. In addition to the emergence of resistant SARS-CoV-2 variants, little is known about how SARS-CoV-2 evades antibodies. Here, we report a novel mechanism of extracellular vesicle (EV)-mediated cell-to-cell transmission of SARS-CoV-2, which facilitates SARS-CoV-2 to escape from neutralizing antibodies. These EVs, initially observed in SARS-CoV-2 envelope protein-expressing cells, are secreted by various SARS-CoV-2-infected cells, including Vero E6, Calu-3, and HPAEpiC cells, undergoing infection-induced pyroptosis. Various SARS-CoV-2-infected cells produce similar EVs characterized by extra-large sizes (1.6-9.5 µm in diameter, average diameter > 4.2 µm) much larger than previously reported virus-generated vesicles. Transmission electron microscopy analysis and plaque assay reveal that these SARS-CoV-2-induced EVs contain large amounts of live virus particles. In particular, the vesicle-cloaked SARS-CoV-2 virus is resistant to neutralizing antibodies and able to reinfect naïve cells independent of the reported receptors and cofactors. Consistently, the constructed 3D images show that intact EVs could be taken up by recipient cells directly, supporting vesicle-mediated cell-to-cell transmission of SARS-CoV-2. Our findings reveal a novel mechanism of receptor-independent SARS-CoV-2 infection via cell-to-cell transmission, provide new insights into antibody resistance of SARS-CoV-2 and suggest potential targets for future antiviral therapeutics.

Research on Influencing Factors of Knowledge Hiding Behavior in Socialized Q&A Communities: Taking Zhihu as an Example

With the normalization of epidemic prevention and control, the expression of the public’s demand for health information on online platforms continues to increase, while knowledge hiding behavior has seriously hindered the communication and dissemination of epidemic prevention knowledge and has a negative impact on public communication and access to health information in the socialized Q&A communities. Therefore, further stimulating diving users' activity and reducing their knowledge hiding behavior have become the key to the sustainable development of epidemic prevention and control and communities. Based on the social cognition theory, from the perspective of individual cognition and external environment, this study constructs a theoretical model of the influencing factors of users’ knowledge hiding behavior in the socialized Q&A communities in the post-epidemic era and puts forward relevant assumptions. 151 effective questionnaires are collected and an empirical analysis is carried out by using the structural equation model. The results show that outcome expectation, community atmosphere, and requesting negatively affect knowledge hiding behavior;self-efficacy, outcome expectation, and community atmosphere negatively affect the three different types of knowledge hiding behavior, which are evasive hiding, playing dumb, and rationalized hiding;community atmosphere positively affects outcome expectation, which plays a significant intermediary effect between community atmosphere and knowledge hiding behavior. The research content and relevant conclusions of this study deepen and expand the connotation and extension of knowledge hiding behavior in the negative performance of Q&A communities. From the perspective of practical application, it can also effectively reduce knowledge hiding behavior, grasp the development direction of public health needs, and strengthen the dissemination of epidemic prevention and control knowledge.

A nanomaterial targeting the spike protein captures SARS-CoV-2 variants and promotes viral elimination.

The global emergency caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic can only be solved with effective and widespread preventive and therapeutic strategies, and both are still insufficient. Here, we describe an ultrathin two-dimensional CuInP2S6 (CIPS) nanosheet as a new agent against SARS-CoV-2 infection. CIPS exhibits an extremely high and selective binding capacity (dissociation constant (KD) < 1 pM) for the receptor binding domain of the spike protein of wild-type SARS-CoV-2 and its variants of concern, including Delta and Omicron, inhibiting virus entry and infection in angiotensin converting enzyme 2 (ACE2)-bearing cells, human airway epithelial organoids and human ACE2-transgenic mice. On association with CIPS, the virus is quickly phagocytosed and eliminated by macrophages, suggesting that CIPS could be successfully used to capture and facilitate virus elimination by the host. Thus, we propose CIPS as a promising nanodrug for future safe and effective anti-SARS-CoV-2 therapy, and as a decontamination agent and surface-coating material to reduce SARS-CoV-2 infectivity.

Induction of Broadly Cross-Reactive Antibody Responses to SARS-CoV-2 Variants by S1 Nanoparticle Vaccines.

Despite the rapid deployment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines, the emergence of SARS-CoV-2 variants and reports of their immune evasion characteristics have led to an urgent need for novel vaccines that confer potent cross-protective immunity. In this study, we constructed three different SARS-CoV-2 spike S1-conjugated nanoparticle vaccine candidates that exhibited high structural homogeneity and stability. Notably, these vaccines elicited up to 50-times-higher neutralizing antibody titers than the S1 monomer in mice. Crucially, it was found that the S1-conjugated nanoparticle vaccine could elicit comparable levels of neutralizing antibodies against wild-type or emerging variant SARS-CoV-2, with cross-reactivity to SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV), the effect of which could be further enhanced using our designed nanoparticles. Our results indicate that the S1-conjugated nanoparticles are promising vaccine candidates with the potential to elicit potent and cross-reactive immunity against not only wild-type SARS-CoV-2, but also its variants of concern, variants of interest, and even other pathogenic betacoronaviruses. IMPORTANCE The emergence of SARS-CoV-2 variants led to an urgent demand for a broadly effective vaccine against the threat of variant infection. The spike protein S1-based nanoparticle designed in our study could elicit a comprehensive humoral response toward different SARS-CoV-2 variants of concern and variants of interest and will be helpful to combat COVID-19 globally.

Screening the hub genes and analyzing the mechanisms in discharged COVID-19 patients retesting positive through bioinformatics analysis.

BACKGROUND: After encountering COVID-19 patients who test positive again after discharge, our study analyzed the pathogenesis to further assess the risk and possibility of virus reactivation. METHODS: A separate microarray was acquired from the Gene Expression Omnibus (GEO), and its samples were divided into two groups: a "convalescent-RTP" group consisting of convalescent and "retesting positive" (RTP) patients (group CR) and a "healthy-RTP" group consisting of healthy control and RTP patients (group HR). The enrichment analysis was performed with R software, obtaining the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Subsequently, the protein-protein interaction (PPI) networks of each group were established, and the hub genes were discovered using the cytoHubba plugin. RESULTS: In this study, 6622 differentially expressed genes were identified in the group CR, among which RAB11B-AS1, DISP1, MICAL3, PSMG1, and DOCK4 were up-regulated genes, and ANAPC1, IGLV1-40, SORT1, PLPPR2, and ATP1A1-AS1 were down-regulated. 7335 genes were screened in the group HR, including the top 5 up-regulated genes ALKBH6, AMBRA1, MIR1249, TRAV18, and LRRC69, and the top 5 down-regulated genes FAM241B, AC018529.3, AL031963.3, AC006946.1, and FAM149B1. The GO and KEGG analysis of the two groups revealed a significant enrichment in immune response and apoptosis. In the PPI network constructed, group CR and group HR identified 10 genes, respectively, and TP53BP1, SNRPD1, and SNRPD2 were selected as hub genes. CONCLUSIONS: Using the messenger ribonucleic acid (mRNA) expression data from GSE166253, we found TP53BP1, SNRPD1, and SNRPD2 as hub genes in RTP patients, which is vital to the management and prognostic prediction of RTP patients.

Harnessing Natural Products by a Pharmacophore-Oriented Semisynthesis Approach for the Discovery of Potential Anti-SARS-CoV-2 Agents.

Natural products possessing unique scaffolds may have antiviral activity but their complex structures hinder facile synthesis. A pharmacophore-oriented semisynthesis approach was applied to (-)-maoelactone A (1) and oridonin (2) for the discovery of anti-SARS-CoV-2 agents. The Wolff rearrangement/lactonization cascade (WRLC) reaction was developed to construct the unprecedented maoelactone-type scaffold during semisynthesis of 1. Further mechanistic study suggested a concerted mechanism for Wolff rearrangement and a water-assisted stepwise process for lactonization. The WRLC reaction then enabled the creation of a novel family by assembly of the maoelactone-type scaffold and the pharmacophore of 2, whereby one derivative inhibited SARS-CoV-2 replication in HPA EpiC cells with a low EC50 value (19±1 nM) and a high TI value (>1000), both values better than those of remdesivir.

A Novel Y-Shaped, S-O-N-O-S-Bridged Crosslink between Three Residues C22, C44, and K61 Is a Redox Switch of the SARS-CoV-2 Main Protease (preprint)

As the COVID-19 pathogen, SARS-CoV-2 relies on its main protease (MPro) for pathogenesis and replication. During the crystallographic analyses of MPro crystals that were exposed to the air, a uniquely Y-shaped, S-O-N-O-S-bridged posttranslational crosslink that connects three residues C22, C44, and K61 at their side chains was frequently observed. As a novel posttranslational modification, this crosslink serves as a redox switch to regulate the catalytic activity of MPro, a demonstrated drug target of COVID-19. The formation of this linkage leads to a much more opened active site that can be potentially targeted for the development of novel SARS-CoV-2 antivirals. The inactivation of MPro by this crosslink indicates that small molecules that lock MPro in the crosslinked form can be potentially used with other active site-targeting molecules such as paxlovid for synergistic effects in inhibiting the SARS-CoV-2 viral replication. Therefore, this new finding reveals a unique aspect of the SARS-CoV-2 pathogenesis and is potentially paradigm-shifting in our current understanding of the function of MPro and the development of its inhibitors as COVID-19 antivirals.

Neuroradiological Basis of COVID-19 Olfactory Dysfunction: A Systematic Review and Meta-Analysis.

OBJECTIVE: Olfactory dysfunction (OD) is a common presenting symptom of COVID-19 infection. Radiological imaging of the olfactory structures in patients with COVID-19 and OD can potentially shed light on its pathogenesis, and guide clinicians in prognostication and intervention. METHODS: PubMed, Embase, Cochrane, SCOPUS were searched from inception to August 1, 2021. Three reviewers selected observational studies, case series, and case reports reporting radiological changes in the olfactory structures, detected on magnetic resonance imaging, computed tomography, or other imaging modalities, in patients aged ≥18 years with COVID-19 infection and OD, following preferred reporting items for systematic reviews and meta-analyses guidelines and a PROSPERO-registered protocol (CRD42021275211). We described the proportion of radiological outcomes, and used random-effects meta-analyses to pool the prevalence of olfactory cleft opacification, olfactory bulb signal abnormalities, and olfactory mucosa abnormalities in patients with and without COVID-19-associated OD. RESULTS: We included 7 case-control studies (N = 353), 11 case series (N = 154), and 12 case reports (N = 12). The pooled prevalence of olfactory cleft opacification in patients with COVID-19 infection and OD (63%, 95% CI = 0.38-0.82) was significantly higher than that in controls (4%, 95% CI = 0.01-0.13). Conversely, similar proportions of cases and controls demonstrated olfactory bulb signal abnormalities (88% and 94%) and olfactory mucosa abnormalities (2% and 0%). Descriptive analysis found that 55.6% and 43.5% of patients with COVID-19 infection and OD had morphological abnormalities of the olfactory bulb and olfactory nerve, respectively, while 60.0% had abnormal olfactory bulb volumes. CONCLUSION: Our findings implicate a conductive mechanism of OD, localized to the olfactory cleft, in approximately half of the affected COVID-19 patients. Laryngoscope, 132:1260-1274, 2022.

CoVac501, a self-adjuvanting peptide vaccine conjugated with TLR7 agonists, against SARS-CoV-2 induces protective immunity.

Safe, effective, and economical vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are needed to achieve adequate herd immunity and end the pandemic. We constructed a novel SARS-CoV-2 vaccine, CoVac501, which is a self-adjuvanting peptide vaccine conjugated with Toll-like receptor 7 (TLR7) agonists. The vaccine contains immunodominant peptides screened from the receptor-binding domain (RBD) and is fully chemically synthesized. It has been formulated in an optimized nanoemulsion formulation and is stable at 40 °C for 1 month. In non-human primates (NHPs), CoVac501 elicited high and persistent titers of protective neutralizing antibodies against multiple RBD mutations, SARS-CoV-2 original strain, and variants (B.1.1.7 and B.1.617.2). Specific peptides booster immunization against the B.1.351 variant has also been shown to be effective in improving protection against B.1.351. Meanwhile, CoVac501 elicited the increase of memory T cells, antigen-specific CD8+ T-cell responses, and Th1-biased CD4+ T-cell immune responses in NHPs. Notably, at an extremely high SARS-CoV-2 challenge dose of 1 × 107 TCID50, CoVac501 provided near-complete protection for the upper and lower respiratory tracts of cynomolgus macaques.

Public Health Measures During the COVID-19 Pandemic Reduce the Spread of Other Respiratory Infectious Diseases.

Background: Public health measures (such as wearing masks, physical distancing, and isolation) have significantly reduced the spread of the coronavirus disease-2019 (COVID-19), but the impact of public health measures on other respiratory infectious diseases is unclear. Objective: To assess the correlation between public health measures and the incidence of respiratory infectious diseases in China during the COVID-19 pandemic. Methods: We collected the data from the National Health and Construction Commission in China on the number of patients with six respiratory infectious diseases (measles, tuberculosis, pertussis, scarlet fever, influenza, and mumps) from 2017 to 2020 and assessed the correlation between public health measures and the incidence of respiratory infectious diseases. Finally, we used the data of the six respiratory infectious diseases in 2021 to verify our results. Results: We found public health measures significantly reduced the incidence of measles (p = 0.002), tuberculosis (p = 0.002), pertussis (p = 0.004), scarlet fever (p = 0.002), influenza (p = 0.034), and mumps (p = 0.002) in 2020, and prevented seasonal peaks. Moreover, the effects of public health measures were most marked during the peak seasons for these infections. Of the six respiratory infectious diseases considered, tuberculosis was least affected by public health measures. Conclusion: Public health measures were very effective in reducing the incidence of respiratory infectious diseases, especially when the respiratory infectious diseases would normally have been at their peak.

Novel nucleocapsid protein-targeting phenanthridine inhibitors of SARS-CoV-2.

The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is unprecedented in human history. As a major structural protein, nucleocapsid protein (NPro) is critical to the replication of SARS-CoV-2. In this work, 17 NPro-targeting phenanthridine derivatives were rationally designed and synthesized, based on the crystal structure of NPro. Most of these compounds can interact with SARS-CoV-2 NPro tightly and inhibit the replication of SARS-CoV-2 in vitro. Compounds 12 and 16 exhibited the most potent anti-viral activities with 50% effective concentration values of 3.69 and 2.18 µM, respectively. Furthermore, site-directed mutagenesis of NPro and Surface Plasmon Resonance (SPR) assays revealed that 12 and 16 target N-terminal domain (NTD) of NPro by binding to Tyr109. This work found two potent anti-SARS-CoV-2 bioactive compounds and also indicated that SARS-CoV-2 NPro-NTD can be a target for new anti-virus agents.

Screening the Hub Genes and Analyzing the Mechanisms in Discharged COVID-19 Patients Retesting Positive through Bioinformatics Analysis (preprint)

Background: With the worldwide spread of COVID-19, people’s health and social order have been exposed to enormous risks. After encountering patients who test positive again after discharge, our study analyzed the pathogenesis to further assess the risk and possibility of virus reactivation. Methods: : A separate microarray was acquired from the Integrated Gene Expression System (GEO), and its samples were divided into two groups: a “convalescent-RTP” group consisting of recovery and “retesting-positive” (RTP) patients (group CR) and a “health-RTP” group consisting of healthy control and RTP patients (group HR). The enrichment analysis was performed with R software, obtaining the gene ontology (GO) and Kyoto pluripotent stem cells (KEGG) of the genes and genomes. Subsequently, the protein–protein interaction (PPI) networks of each group were established and the hub genes were discovered using the cytoHubba plug-in. Results: : In this study, 20 differentially expressed genes were identified, and 6622 genes were identified in the group CR, consisting of 5003 up-regulated and 1619 down-regulated genes. Meanwhile, 7335 genes were screened in the group HR, including 4323 up-regulated and 3012 down-regulated ones. The GO and KEGG analysis of the two groups revealed significant enrichment of these differentially expressed genes in pathways associated with immune response and apoptosis. In the PPI network constructed, 10 hub genes in group CR were identified, including TP53BP1, SNRPD1, SNRPD2, SF3B1, SNRNP200, MRPS16, MRPS9, CALM1, PPP2R1A, YWHAZ. Similarly, TP53BP1, RPS15, EFTUD2, MRPL16, MRPL17, MRPS14, RPL35A, MRPL32, MRPS6, POLR2G were selected as hub genes. Conclusions: : Using the messenger ribonucleic acid (mRNA) expression data from GSE166253, we explore the pathogenesis of retesting positive in COVID-19 from the immune mechanism and molecular level. We found TP53BP1, SNRPD1 and SNRPD2 as hub genes in RTP patients. Hence, their regulatory pathway is vital to the management and prognostic prediction of RTP patients, rendering the further study of these hub genes necessary.