Objective The study aims to investigate the immunological functions of the nucleocapsid (N) protein of the novel coronavirus Omicron (BA.1, BA.2) and evaluate the differences among different N proteins of mutant strains in immunogenicity. Methods By aligning sequences, the mutation sites of the Omicron (BA.1, BA.2) N protein relative to prototype strain of the novel coronavirus (Wuhan-Hu-1) were determined. The pET-28a-N-Wuhan-Hu-1 plasmid was used as template to construct pET-28a-BA.1/BA.2-N through single point mutation or homologous recombination. The three kinds of N protein were expressed in prokaryotic system, purified through Ni-NTA affinity chromatography, and then immunized into mice. The titer and reactivity of the polyclonal antibody, as well as the expression level of IL-1β and IFN-γ in mouse spleen cells, were detected using indirect ELISA and Western blot assay. Results The constructed prokaryotic expression plasmids were successfully used to express the Wuhan-Hu-1 N, BA.1 N, and BA.2 N proteins in E.coli BL21(DE3) at 37 DegreesCelsius for 4 hours. The indirect ELISA test showed that the titers of polyclonal antibody prepared by three N proteins were all 1:51 200. All three N proteins can increase the expression of IFN-γ and IL-1β cytokines, but the effect of Omicron N protein in activing two cytokines was more obvious than that of Wuhan-Hu-1 N protein. Conclusion The study obtained three new coronavirus N proteins and polyclonal antibodies, and confirmed that mutations in the amino acid sites of the N protein can affect its immunogenicity. This provides a basis for developing rapid diagnostic methods targeting N protein of different novel coronavirus variants.
Animals ; Mice ; SARS-CoV-2/genetics* ; Coronavirus Nucleocapsid Proteins/immunology* ; Nucleocapsid Proteins/isolation & purification* ; COVID-19/immunology* ; Antibodies, Viral/immunology* ; Mice, Inbred BALB C ; Interferon-gamma/metabolism* ; Interleukin-1beta/metabolism* ; Female ; Escherichia coli/metabolism* ; Mutation ; Humans

This study aims to establish an antibody detection method for porcine deltacoronavirus (PDCoV). The recombinant proteins PDCoV-N1 and PDCoV-N2 were expressed via the prokaryotic plasmid pColdII harboring the N gene sequence of the PDCoV strain CH/XJYN/2016. The reactivity and specificity of PDCoV-N1 and PDCoV-N2 with anti-PEDV sera were analyzed after the recombinant proteins were analyzed by SDS-PAGE and purified by the Ni-NTA Superflow Cartridge. Meanwhile, Western blotting and indirect immunofluorescence assay were carried out separately to validate the recombinant proteins PDCoV-N1 and PDCoV-N2. Finally, we established an indirect ELISA method based on the recombinant protein PDCoV-N2 after optimizing the conditions and tested the sensitivity, specificity, and reproducibility of the method. Then, the established method was employed to examine 102 clinical serum samples. The recombinant protein PDCoV-N2 showed low cross-reactivity with anti-PEDV sera. The optimal conditions of the indirect ELISA method based on PDCoV-N2 were as follows: the antigen coating concentration of 1.25 μg/mL and coating at 37 ℃ for 1 h; blocking by BSA overnight at 4 ℃; serum sample dilution at 1:50 and incubation at 37 ℃ for 1 h; secondary antibody dilution at 1:80 000 and incubation at 37 ℃ for 1 h; color development with TMB chromogenic solution at 37 ℃ for 10 min. The S/P value ≥ 0.45, ≤0.38, and between 0.45 and 0.38 indicated that the test sample was positive, negative, and suspicious, respectively. The testing results of the antisera against porcine epidemic diarrhea virus (PEDV), porcine circovirus 2 (PCV2), transmissible gastroenteritis virus (TGEV), foot-and-mouth disease virus (FMDV), and African swine fever virus (ASFV) showed that the S/P values were all less than 0.38. The testing results of the 800-fold diluted anti-PDCoV sera were still positive. The results of the inter- and intra-batch tests showed that the coefficients of variation of this method were less than 10%. Clinical serum sample test results showed the coincidence rate between this method and neutralization test was 94.12%. In this study, an ELISA method for the detection of anti-PDCoV antibodies was successfully established based on the truncated N protein of PDCoV. This method is sensitive, specific, stable, and reproducible, serving as a new method for the clinical diagnosis of PDCoV.
Animals ; Enzyme-Linked Immunosorbent Assay/methods* ; Swine ; Antibodies, Viral/blood* ; Recombinant Proteins/genetics* ; Deltacoronavirus/isolation & purification* ; Coronavirus Infections/virology* ; Swine Diseases/diagnosis* ; Coronavirus Nucleocapsid Proteins ; Sensitivity and Specificity

A new coronavirus (SARS-CoV-2) has been identified as the etiologic agent for the COVID-19 outbreak. Currently, effective treatment options remain very limited for this disease; therefore, there is an urgent need to identify new anti-COVID-19 agents. In this study, we screened over 6,000 compounds that included approved drugs, drug candidates in clinical trials, and pharmacologically active compounds to identify leads that target the SARS-CoV-2 papain-like protease (PLpro). Together with main protease (M
Antiviral Agents/therapeutic use* ; Binding Sites ; COVID-19/virology* ; Coronavirus Papain-Like Proteases/metabolism* ; Crystallography, X-Ray ; Drug Evaluation, Preclinical ; Drug Repositioning ; High-Throughput Screening Assays/methods* ; Humans ; Imidazoles/therapeutic use* ; Inhibitory Concentration 50 ; Molecular Dynamics Simulation ; Mutagenesis, Site-Directed ; Naphthoquinones/therapeutic use* ; Protease Inhibitors/therapeutic use* ; Protein Structure, Tertiary ; Recombinant Proteins/isolation & purification* ; SARS-CoV-2/isolation & purification*

The recently emerged novel coronavirus pneumonia, named the coronavirus disease 2019 (COVID-19), shares several clinical characteristics with severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), and spread rapidly throughout China in December of 2019 (Huang et al., 2020). The pathogen 2019 novel coronavirus (2019-nCoV) is now named SARS coronavirus 2 (SARS-CoV-2) and is highly infectious. As of Apr. 9, 2020, over 80 000 confirmed cases had been reported, with an estimated mortality rate of 4.0% (Chinese Center for Disease Control and Prevention, 2020). Person-to-person transmission and familial clustering have been reported (Chan et al., 2020; Nishiura et al., 2020; Phan et al., 2020). However, there is no evidence of fetal intrauterine infection in pregnant women who have been infected with SARS-CoV-2 in their third trimester (Chen et al., 2020). It is unclear whether breastfeeding transmits the virus from previously infected and recovered mothers to their babies. Here we report the clinical course of a pregnant woman with COVID-19. In order to determine whether SARS-CoV-2 can be transmitted to newborns through breastfeeding, we measured viral RNA in the patient's breastmilk samples at different time points after delivery.
Adult ; Betacoronavirus ; Breast Feeding ; China ; Coronavirus Infections ; diagnosis ; Female ; Humans ; Infant, Newborn ; Infectious Disease Transmission, Vertical ; Milk, Human ; virology ; Pandemics ; Pneumonia, Viral ; diagnosis ; Pregnancy ; Pregnancy Complications, Infectious ; virology ; RNA, Viral ; isolation & purification

Since the global outbreak of severe acute respiratory syndrome (SARS) in 2003, China has gradually built a robust prevention and control system for sudden infectious diseases. All large hospitals have a fever clinic that isolates patients with all kinds of acute communicable diseases as the first line of medical defense. The emergency department, as the second line of medical defense in hospitals, is constantly shouldering the heavy responsibility of screening communicable diseases while also treating all kinds of other non-communicable acute and critical diseases (Zhang et al., 2012; Zhu et al., 2015; Wang et al., 2017; Feng et al., 2018; Lu, 2018; Xu and Lu, 2019). An outbreak of pneumonia of unknown etiology that began in Wuhan city (China) has spread rapidly in China since December 2019 (Huang et al., 2020; WHO, 2020; Zhu et al., 2020). In February 2020, the National Health Commission of China named the disease a novel coronavirus pneumonia (NCP); then, it was formally named the coronavirus disease 2019 (COVID-19) by the World Health Organization (WHO) on Feb. 11, 2020. The Coronavirus Study Group of the International Committee on Taxonomy of Viruses designated this causative virus as SARS coronavirus 2 (SARS-CoV-2). SARS-CoV-2 belongs to the β coronavirus genus, and its pathogenic mechanism has not been clarified, which requires further study. To better understand the clinical characteristics of COVID-19 and more effectively prevent and control this disease, we retrospectively analyzed four representative cases of COVID-19 that had recently been screened and diagnosed in our emergency department.
Adult ; Betacoronavirus ; China ; epidemiology ; Coronavirus Infections ; diagnosis ; Emergency Service, Hospital ; Female ; Humans ; Lung ; diagnostic imaging ; Male ; Middle Aged ; Pandemics ; Patient Isolation ; Pneumonia, Viral ; diagnosis ; Tomography, X-Ray Computed

We optimized a fluorescent quantitative polymerase chain reaction (qPCR) assay system for rapid and real time detection of SARS-CoV-2 RNA. The results show that the lowest dilution of RNA samples used for the detection of SARS-CoV-2 RNA could reach 1/10 000 (the initial value is set as 10 ng/μL). Moreover, the cycle threshold (Ct) for samples of clinically diagnosed COVID-19 was lower than 35 or 40. The sensitivity of this method was satisfactory. The results were consistent with those of the COVID-19 detection kit on the market under the same conditions, but the number of cycles required was shortened by about 2. Therefore, the optimized assay developed in this study can be used in screening and early clinical diagnosis. Our work provides a tool to facilitate rapid clinical diagnosis of COVID-19.
Betacoronavirus ; genetics ; isolation & purification ; Coronavirus Infections ; diagnosis ; virology ; Early Diagnosis ; Humans ; Pandemics ; Pneumonia, Viral ; diagnosis ; virology ; Polymerase Chain Reaction ; methods ; standards ; RNA, Viral ; analysis ; genetics ; Sensitivity and Specificity ; Time Factors

Betacoronavirus ; isolation & purification ; pathogenicity ; Bile Acids and Salts ; metabolism ; Bile Ducts, Intrahepatic ; pathology ; virology ; Cell Culture Techniques ; Coronavirus Infections ; complications ; pathology ; Cytokine Release Syndrome ; etiology ; physiopathology ; Cytopathogenic Effect, Viral ; Epithelial Cells ; enzymology ; pathology ; virology ; Humans ; Hyperbilirubinemia ; etiology ; Liver ; pathology ; Organoids ; pathology ; virology ; Pandemics ; Peptidyl-Dipeptidase A ; analysis ; Pneumonia, Viral ; complications ; pathology ; Receptors, Virus ; analysis ; Serine Endopeptidases ; analysis ; Viral Load

OBJECTIVES: To analyze the clinical characteristics of fecal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acid-positive in patients with coronavirus dasease 2019 (COVID-19) and to provide a scientific basis for the prevention and control of this disease. METHODS: The clinical data of 16 patients with fecal SARS-CoV-2 nucleic acid positive, who hospitalized in the North Branch of the First Hospital of Changsha (Changsha Public Health Rescue Center) from January to February 2020, were retrospectively analyzed. Their clinical manifestations, laboratory data and imaging data were summarized. RESULTS: Among the 16 patients, there were 9 males (56.25%) and 7 females (43.75%), the ratio of males to females was 1∶1.29. The age of onset was (43.3±14.6) years. There were 15 patients with contact history of Wuhan, 1 patient with contact history of local patient.Twelve patients were common type (75%), and 4 patients were severe type (25%). Clinical symptoms included fever in 14 patients (87.5%), cough in 12 patients (75%), shortness of breath in 5 patients (31.25%), pharyngalgia in 10 patients (62.5%), fatigue in 7 patients (43.75%), and diarrhea in 4 patients (25%). There were 14 patients (87.5%) with normal or decreased white blood cell count, 11 patients (68.75%) with decreased lymphocyte count, 15 patients (93.75%) with increased erythrocyte sedimentation rate, 13 patients (81.25%) with increased hypersensitivity C-reactive protein, 5 patients (31.25%) with increased procalcitonin, and 8 patients (50%) with increased serum ferritin in peripheral blood, and stool routine was basically normal. Compared with the common type, there was significant difference in the white blood cell and lymphocyte counts in the severe type (<0.01); the infection indicators, such as hypersensitivity C-reactive protein and serum ferritin, were significantly increased, with significant difference (all <0.01); but the procalcitonin and erythrocyte sedimentation rate was not significantly different (both >0.05). Chest CT mainly showed patchy shadows and interstitial changes. According to imaging examination, 4 patients (25%) showed unilateral pneumonia and 12 patients (75%) showed bilateral pneumonia. CONCLUSIONS The patients have the clinical symptoms of COVID-19, but gastrointestinal symptoms (such as diarrhea) are more common, and the changes of white blood cell count, lymphocyte count, hypersensitivity C-reactive protein, ferritin are more obvious in severe patients.The positivity of fecal nucleic acid suggests the possibility of digestive tract transmission of SARS-CoV-2, and fecal nucleic acid testing can be used as a routine testing method in clinical practice.
Adult ; Betacoronavirus ; isolation & purification ; C-Reactive Protein ; analysis ; China ; Coronavirus Infections ; diagnosis ; physiopathology ; Diarrhea ; virology ; Feces ; virology ; Female ; Ferritins ; analysis ; Humans ; Leukocyte Count ; Male ; Middle Aged ; Pandemics ; Pneumonia, Viral ; diagnosis ; physiopathology ; Retrospective Studies

BACKGROUND: Human infections with zoonotic coronaviruses (CoVs), including severe acute respiratory syndrome (SARS)-CoV and Middle East respiratory syndrome (MERS)-CoV, have raised great public health concern globally. Here, we report a novel bat-origin CoV causing severe and fatal pneumonia in humans. METHODS: We collected clinical data and bronchoalveolar lavage (BAL) specimens from five patients with severe pneumonia from Wuhan Jinyintan Hospital, Hubei province, China. Nucleic acids of the BAL were extracted and subjected to next-generation sequencing. Virus isolation was carried out, and maximum-likelihood phylogenetic trees were constructed. RESULTS: Five patients hospitalized from December 18 to December 29, 2019 presented with fever, cough, and dyspnea accompanied by complications of acute respiratory distress syndrome. Chest radiography revealed diffuse opacities and consolidation. One of these patients died. Sequence results revealed the presence of a previously unknown β-CoV strain in all five patients, with 99.8% to 99.9% nucleotide identities among the isolates. These isolates showed 79.0% nucleotide identity with the sequence of SARS-CoV (GenBank NC_004718) and 51.8% identity with the sequence of MERS-CoV (GenBank NC_019843). The virus is phylogenetically closest to a bat SARS-like CoV (SL-ZC45, GenBank MG772933) with 87.6% to 87.7% nucleotide identity, but is in a separate clade. Moreover, these viruses have a single intact open reading frame gene 8, as a further indicator of bat-origin CoVs. However, the amino acid sequence of the tentative receptor-binding domain resembles that of SARS-CoV, indicating that these viruses might use the same receptor. CONCLUSION A novel bat-borne CoV was identified that is associated with severe and fatal respiratory disease in humans.
Adult ; Aged ; Betacoronavirus ; genetics ; isolation & purification ; Coronavirus Infections ; diagnostic imaging ; therapy ; virology ; Female ; Humans ; Male ; Middle Aged ; Pandemics ; Pneumonia, Viral ; diagnostic imaging ; therapy ; virology ; Tomography, X-Ray ; Treatment Outcome

OBJECTIVE: To investigate the clinical outcome of patients with moderate type of coronavirus disease 2019 (COVID-19) after discharge by retesting viral nucleic acid. METHODS: Seven patients with moderate COVID-19 met the discharge criteria enacted by National Health Commission were quarantined in hospital for 7 days, then continuously quarantined at home for 4 weeks after discharged. During the quarantined period, the symptoms and signs were documented, and sputum or nasal swab and feces samples were collected to test SARS-CoV-2 nucleic acid by RT-PCR method. RESULTS: There was no symptoms and signs during the quarantine period in all 7 patients. However, respiratory swabs from 3 patients were confirmed positive of SARS-CoV-2 nucleic acid at 5 to 7 days after they met the discharge criteria. CONCLUSIONS There is a relatively high incidence of positive viral nucleic acid in patients met the discharge criteria, and it is suggested that patients met the current discharge criteria should be quarantined in hospital for another 7 days and the follow-up viral testing is necessary.
Betacoronavirus ; isolation & purification ; Coronavirus Infections ; diagnosis ; Feces ; chemistry ; virology ; Follow-Up Studies ; Humans ; Pandemics ; Patient Discharge ; statistics & numerical data ; Pneumonia, Viral ; diagnosis ; Quarantine ; statistics & numerical data ; RNA, Viral ; analysis ; Reverse Transcriptase Polymerase Chain Reaction ; Time Factors