COVID-19 represents the most serious public health event in the past few decades of the 21^st century. The development of vaccines, neutralizing antibodies, and small molecule chemical agents have effectively prevented the rapid spread of COVID-19. However, the continued emergence of SARS-CoV-2 variants have weakened the efficiency of these vaccines and antibodies, which brought new challenges for searching novel anti-SARS-CoV-2 drugs and methods. In the process of SARS-CoV-2 infection, the virus firstly attaches to heparan sulphate on the cell surface of respiratory tract, then specifically binds to hACE2. The S protein of SARS-CoV-2 is a highly glycosylated protein, and glycosylation is also important for the binding of hACE2 to S protein. Furthermore, the S protein is recognized by a series of lectin receptors in host cells. These finding implies that glycosylation plays important roles in the invasion and infection of SARS-CoV-2. Based on the glycosylation pattern and glycan recognition mechanisms of SARS-CoV-2, it is possible to develop glycan inhibitors against COVID-19. Recent studies have shown that sulfated polysaccharides originated from marine sources, heparin and some other glycans display anti-SARS-CoV-2 activity. This review summarized the function of glycosylation of SARS-CoV-2, discoveries of glycan inhibitors and the underpinning molecular mechanisms, which will provide guidelines to develop glycan-based new drugs against SARS-CoV-2.
Antibodies, Neutralizing ; Glycosylation ; Heparin ; Heparitin Sulfate ; Humans ; Polysaccharides/chemistry* ; Receptors, Mitogen/metabolism* ; SARS-CoV-2 ; Spike Glycoprotein, Coronavirus/metabolism* ; COVID-19 Drug Treatment

To explore the expression potential of heterogeneous genes using the backbone of infectious bronchitis virus (IBV) Beaudette strain, the ectodomain region of the Spike gene (1,302 bp) of IBV H120 strain was amplified by RT-PCR and replaced into the corresponding location of the IBV Beaudette strain full-length cDNA. This recombinant was designated as BeauR-H120(S1). BeauR-H120(S1) was directly used as the DNA template for the transcription of viral genomic RNA in vitro. Then, the transcription product was transfected into Vero cells by electroporation. At 48 h post-transfection, the transfected Vero cells were harvested, and passaging continued. A syncytium was not observed until the recombinant virus had passed through four passages. The presence of rBeau-H120(S1) was verified by the detection of the replaced ectodomain region of the H120 Spike gene using RT-PCR. Western blot analysis of rBeau-H120 (S1)-infected Vero cell lysates demonstrated that the nucleocapsid (N) protein was expressed, which implied that rBeau-H120(S1) could propagate in Vero cells. The TCIDs0 and EIDs0 data demonstrated that the titer levels of rBeau-H120(S1) reached 10(590+/-0.22)TCID50/mL and 10(6.13+/-0.23)EID50/mL in Vero cells and 9-day-old SPF chicken embryos, respectively. Protection studies showed that the percentage of antibody-positive chickens, which were vaccinated with rBeau-H120(S1) at 7 days after hatching, rose to 90% at 21 days post-inoculation. Inoculation provided an 85% rate of immune protection against a challenge of the virulent IBV M41 strain (103EID50/chicken). This recombinant virus constructed using reverse genetic techniques could be further developed as a novel genetic engineering vaccine against infectious bronchitis.
Animals ; Cercopithecus aethiops ; Chick Embryo ; Chickens ; Coronavirus Infections ; veterinary ; virology ; Infectious bronchitis virus ; chemistry ; genetics ; growth & development ; metabolism ; Poultry Diseases ; virology ; Protein Structure, Tertiary ; Spike Glycoprotein, Coronavirus ; chemistry ; genetics ; metabolism ; Transfection ; Vero Cells

The spike (S) glycoprotein of HCoV-NL63 is a major target in the development of diagnostic assays and vaccines, but its antigenic and immunogenic properties remain unclear. Four fragments coding spike proteins (S1, S2, RL and RS) from HCoV-NL63 were amplified and cloned into the expression vector derived from vaccinia virus (Tiantan strain), and recombinant vaccinia viruses expressing four segments of spike proteins were generated (vJSC1175-S1; vJSC1175-S2; vJSC1175-RL; vJSC1175-RS), respectively. Their expression location in cell and level were characterized using indirect immune fluorescence assay (IFA) and Western-Blot, respectively. The expressions of four segments of spike proteins in recombinant vaccinia viruses were showed at appropriate level and with posttranslational modification (glycosylation), and S1, RL and RS were mainly distributed in the cell membrane, while the S2 was mainly distributed in the cytoplasm. Our results provide a basis for further exploring diagnostic role and vaccine development of different spike segments from HCoV-NL63.
Base Sequence ; Blotting, Western ; Coronavirus NL63, Human ; chemistry ; Fluorescent Antibody Technique, Indirect ; Humans ; Membrane Glycoproteins ; biosynthesis ; genetics ; Molecular Sequence Data ; Plasmids ; Recombinant Proteins ; biosynthesis ; Spike Glycoprotein, Coronavirus ; Vaccinia virus ; genetics ; Viral Envelope Proteins ; biosynthesis ; genetics

We wished to ascertain the prevalence as well as the genetic and antigenic variation of infectious bronchitis viruses (IBVs) circulating in the Guangxi Province of China in recent years. The S1 gene of 15 IBV field isolates during 2012-2013 underwent analyses in terms of the similarity of amino-acid sequences, creation of phylogenetic trees, recombination, and serologic identification. Similarities in amino-acid sequences among the 15 isolates of the S1 gene were 54.3%-99.6%, and 43.3%-99.3% among 15 isolates and reference strains. Compared with the vaccine strain H120, except for GX-YL130025, the other 14 isolates showed a lower similarity of amino-acid sequences of the S1 gene (65.1-81.4%). Phylogenetic analyses of the S1 gene suggested that 15 IBV isolates were classified into eight genotypes, with the predominant genotype being new-type II. Recombination analyses demonstrated that the S1 gene of the GX-NN130048 isolate originated from recombination events between vaccine strain 4/91 and a LX4-like isolate. Serotyping results suggested that seven serotypes prevailed during 2012-2013 in Guangxi Province, and that only one isolate was consistent with the vaccine strain H120 in serotype (which has been used widely in recent years). The serotype of recombinant isolate GX-NN130048 was different from those of its parent strains. These results suggested that not only the genotype, but also the serotype of IBV field isolates in Guangxi Province had distinct variations, and that increasing numbers of genotypes and serotypes are in circulation. We showed that recombination events can lead to the emergence of new serotypes. Our study provides new evidence for understanding of the molecular mechanisms of IBV variations, and the development of new vaccines against IBVs.
Animals ; Antibodies, Viral ; blood ; Chickens ; China ; Coronavirus Infections ; blood ; veterinary ; virology ; Genetic Variation ; Genotype ; Infectious bronchitis virus ; classification ; genetics ; immunology ; isolation & purification ; Molecular Sequence Data ; Phylogeny ; Poultry Diseases ; blood ; virology ; Sequence Homology, Amino Acid ; Spike Glycoprotein, Coronavirus ; chemistry ; genetics ; immunology

The S1 gene hypervariable region I (HVR I) of 22 infectious bronchitis virus (IBV) strains isolated in Guangxi during the period of 1985-2007 were sequenced and compared to that of the other IBV reference strains and the pigeon coronavirus isolates. A phylogenetic tree based on nucleotide sequences of HVR I of all the IBV showed that they were classified into 5 distinct Clusters. 16 out of 22 IBV isolates were grouped into Cluster I, and had higher homology with pigeon coronavirus isolates but lower homology with the Massachusetts (Mass) type vaccine strains. There were 4 and 3 amino-acid residues inserted at the sites of 33-34 and 34-35 respectively within HVR I in 15 isolates, except in isolate GX-NN6 there had 4 amino-acid residues inserted at the both sites; isolates GX-YL1 and GX-NN2 had close relationship with Mass type vaccine strains, and they shared Cluster II; isolates GX-G and GX-XD of Cluster III had close relationship with the Japanese strain JP Miyazaki 89 which was isolated at the same period; isolates GX-YL6 and GX-NN7 of Cluster V had close relationship with the European strain 4/91. The results showed that there were high phylogenetic diversity among the IBVs prevailed in the field in Guangxi resulting from the commonly occurred mutation or insertion within the S1 gene HVR I of the viruses, and majority of the isolates had lower homology with the commonly used Mass type vaccine strains. There was much higher homology among viruses isolated in the same period of time, but without distinct difference in geographical origins.
Amino Acid Sequence ; Animals ; Chickens ; virology ; Genetic Variation ; Infectious bronchitis virus ; classification ; genetics ; isolation & purification ; Membrane Glycoproteins ; chemistry ; genetics ; Molecular Sequence Data ; Phylogeny ; Spike Glycoprotein, Coronavirus ; Viral Envelope Proteins ; chemistry ; genetics

To identify the epitope of SARS-CoV spike protein specific neutralizing monoclonal antibody (MAb) 2C5. The antibody was used as target and three rounds of bio-panning were conducted with phage-display peptide library. After the third panning, 20 phage-plague clones were randomly picked and analyzed for the binding ability with the MAb 2C5 by ELISA. The display sequence analysis demonstrated that among the twenty phage clones, eight clones displayed the same seven-peptide TPEQQFT. All these eight phage-clones showed strongest binding activity with 2C5 in phage ELISA analysis. Furthermore, phages displaying peptide TPEQQFT could specifically inhibit the binding of MAb 2C5 with SARS-CoV spike protein. The results demonstrated that TPEQQFT is a mimic epitope peptide containing neutralizing MAb 2C5. This study may provide information for further structural and functional analysis of spike protein and development vaccine for severe acute respiratory syndrome.
Amino Acid Sequence ; Antibodies, Monoclonal ; immunology ; Enzyme-Linked Immunosorbent Assay ; Epitopes ; Membrane Glycoproteins ; chemistry ; immunology ; Molecular Sequence Data ; Peptide Library ; SARS Virus ; immunology ; Spike Glycoprotein, Coronavirus ; Viral Envelope Proteins ; chemistry ; immunology

The coronavirus disease 2019(COVID-19) is raging in China and more than 20 other countries and regions since the middle of December 2019. Currently, there is no specific drug or vaccine besides symptomatic supportive therapy. Taking full advantage of the clinical experience of traditional Chinese medicine(TCM) in preventing and controlling major epidemics such as SARS, it is an important mission for TCM to propose effective formula with immediate response and solid evidence by using modern biomedical knowledge and techniques(molecular docking assisted TCM formulation for short). In view of the high homology between the gene sequences of the novel coronavirus and SARS virus, and the similarities between the two in terms of pathogenic mechanism and clinical manifestations, our team established a rapid screening and optimization model for the prevention and treatment of the novel coronavirus based on clinical experience and molecular docking technology. Firstly, the clinical team and the research team pre-developed and screened TCM formula by using "back-to-back" manner. Then, the formula was optimized and determined by comparing and analyzing the results of the two groups. The results showed that the research team screened out 46 active ingredients from candidate TCMs that could act on the novel coronavirus S-protein-binding site of human ACE2 protein, which were mainly attributed to 7 herbs such as Lonicerae Japonicae Flos and Mori Folium. The result was largely consistent with the formula raised by the clinical group, verifying and supporting its rationality. This provides evidence for the scientific and potential efficacy of the TCM prescription from the perspective of treatment target analysis, and also suggests that the TCM prescription has the potential to directly inhibit viral infection in addition to improving clinical symptoms or syndromes. Based on this, our team optimized and formed a new anti-coronavirus TCM prescription "Keguan Yihao", immediately providing the TCM prescription with certain clinical experience and objective evidence support for the prevention and treatment of new emergent infectious diseases in our hospital. The TCM prescription was combined with modern medicine symptomatic supportive treatment for clinical treatment, preliminary results showed better effect than symptomatic supportive therapy alone. This research has innovated the method mode in clinical practice and basic research integration of traditional Chinese medicine for the prevention and control of new emerging infectious diseases. It is of great significance to further improve the rapid response mechanism of TCM in face of major epidemics, and further improve the capability level of TCM to prevent and treat new emerging infectious diseases.
Angiotensin-Converting Enzyme 2 ; Angiotensin-Converting Enzyme Inhibitors/pharmacology* ; Betacoronavirus ; COVID-19 ; China ; Coronavirus Infections/drug therapy* ; Drugs, Chinese Herbal/pharmacology* ; Humans ; Medicine, Chinese Traditional ; Molecular Docking Simulation ; Pandemics ; Peptidyl-Dipeptidase A/chemistry* ; Pneumonia, Viral/drug therapy* ; SARS-CoV-2 ; Spike Glycoprotein, Coronavirus/chemistry* ; COVID-19 Drug Treatment

Pneumonia caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection emerged in Wuhan City, Hubei Province, China in December 2019. By Feb. 11, 2020, the World Health Organization (WHO) officially named the disease resulting from infection with SARS-CoV-2 as coronavirus disease 2019 (COVID-19). COVID-19 represents a spectrum of clinical manifestations that typically include fever, dry cough, and fatigue, often with pulmonary involvement. SARS-CoV-2 is highly contagious and most individuals within the population at large are susceptible to infection. Wild animal hosts and infected patients are currently the main sources of disease which is transmitted via respiratory droplets and direct contact. Since the outbreak, the Chinese government and scientific community have acted rapidly to identify the causative agent and promptly shared the viral gene sequence, and have carried out measures to contain the epidemic. Meanwhile, recent research has revealed critical aspects of SARS-CoV-2 biology and disease pathogenesis; other studies have focused on epidemiology, clinical features, diagnosis, management, as well as drug and vaccine development. This review aims to summarize the latest research findings and to provide expert consensus. We will also share ongoing efforts and experience in China, which may provide insight on how to contain the epidemic and improve our understanding of this emerging infectious disease, together with updated guidance for prevention, control, and critical management of this pandemic.
Amino Acid Motifs ; Animals ; Antiviral Agents ; Betacoronavirus ; genetics ; China ; epidemiology ; Communicable Disease Control ; methods ; Coronavirus Infections ; diagnosis ; epidemiology ; physiopathology ; prevention & control ; therapy ; Humans ; Immunization, Passive ; Medicine, Chinese Traditional ; Pandemics ; Pneumonia, Viral ; diagnosis ; epidemiology ; physiopathology ; therapy ; Protein Domains ; Spike Glycoprotein, Coronavirus ; chemistry ; Viral Vaccines

BACKGROUNDTo investigate the interaction between the host cell and the truncated S fragments to identify the receptor-binding domain of the spike (S) protein of SARS-associated coronavirus (SARS-CoV).

METHODSTwo different fragments S260-600 and S397-796 of the SARS-CoV S protein were expressed in Escherichia coli (E.coli) using a pET expression vector, respectively. The two recombinant proteins were separately verified by Western blot, purified by nickel-affinity chromatography, and incubated with Vero cells, a susceptible cell line of SARS-CoV infection, for cell binding assay. After the sequential probing with sera from convalescent SARS-patients and FITC-labeled anti-human IgG, the cells were analyzed by flow cytometry. The NIH 3T3 cell, a non-permissive cell line of SARS-CoV infection, was used as controls.

RESULTSThe recombinant proteins S260-600 and S397-796 were efficiently expressed in an insoluble form in E.coli. The appropriate expression of the proteins was confirmed by Western blotting using both SARS patients' sera and anti-6 x histidine antibody. The flow cytometry results showed that the both proteins were able to bind Vero cells, but the binding ability of S260-600 was somewhat stronger than that of S397-796. In contrast, the S260-600 protein did not bind NIH3T3 cells.

CONCLUSIONBoth S260-600 and S397-796 exhibited different receptor binding activity. The S260-600 fragment probably contains the important receptor binding domain and could be a potential candidate for the development of SARS vaccine and anti-SARS therapeutics.

Animals ; Binding, Competitive ; Blotting, Western ; Cercopithecus aethiops ; Escherichia coli ; genetics ; metabolism ; Membrane Glycoproteins ; chemistry ; genetics ; metabolism ; Mice ; NIH 3T3 Cells ; Peptide Fragments ; chemistry ; genetics ; metabolism ; Protein Binding ; Receptors, Cell Surface ; metabolism ; Recombinant Proteins ; isolation & purification ; metabolism ; SARS Virus ; genetics ; metabolism ; Spike Glycoprotein, Coronavirus ; Vero Cells ; Viral Envelope Proteins ; chemistry ; genetics ; metabolism

In the face of the worldwide threat of severe acute respiratory syndrome (SARS) to human life, some of the most urgent challenges are to develop fast and accurate analytical methods for early diagnosis of this disease as well as to create a safe anti-viral vaccine for prevention. To these ends, we investigated the antigenicity of the spike protein (S protein), a major structural protein in the SARS-coronavirus (SARS-CoV). Based upon the theoretical analysis for hydrophobicity of the S protein, 18 peptides were synthesized. Using Enzyme-Linked Immunosorbent Assay (ELISA), these peptides were screened in the sera from SARS patients. According to these results, two fragments of the S gene were amplified by PCR and cloned into pET-32a. Both S fragments were expressed in the BL-21 strain and further purified with an affinity chromatography. These recombinant S fragments were confirmed to have positive cross-reactions with SARS sera, either by Western blot or by ELISA. Our results demonstrated that the potential epitope regions were located at Codons 469-882 in the S protein, and one epitope site was located at Codons 599-620. Identification of antigenic regions in the SARS-CoV S protein may be important for the functional studies of this virus or the development of clinical diagnosis.
Antigens, Viral ; immunology ; Chromatography, High Pressure Liquid ; Cloning, Molecular ; Electrophoresis, Polyacrylamide Gel ; Enzyme-Linked Immunosorbent Assay ; Genetic Vectors ; Humans ; Mass Spectrometry ; Membrane Glycoproteins ; genetics ; immunology ; metabolism ; Molecular Weight ; Peptide Fragments ; chemistry ; Recombinant Proteins ; genetics ; immunology ; SARS Virus ; genetics ; immunology ; metabolism ; Spike Glycoprotein, Coronavirus ; Viral Envelope Proteins ; genetics ; immunology ; metabolism