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

Adolescent ; Adult ; Aged ; COVID-19/virology* ; COVID-19 Nucleic Acid Testing/methods* ; Child ; Coronavirus Nucleocapsid Proteins/genetics* ; Feces/virology* ; Female ; Humans ; Male ; Middle Aged ; Phosphoproteins/genetics* ; RNA, Viral/genetics* ; SARS-CoV-2/isolation & purification* ; Young Adult

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

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 compare the diagnostic efficacy among three RT-PCR test kits for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acid detection. METHODS: The throat swab samples from 40 hospitalized patients clinically diagnosed as coronavirus disease 2019 (COVID-19) and 16 hospitalized non-COVID-19 patients were recruited. The SARS-CoV-2 nucleic acid was detected in throat swab samples with RT-PCR test kits from Sansure Biotech ("Sansure" for short), Jiangsu Bioperfectus Technologies ("Bioperfectus" for short) and BGI Genomics ("BGI" for short). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and Kappa value were analyzed. The viral nucleic acid was extracted from the throat swab samples by one-step cleavage and magnetic bead methods, and the efficacy of two extraction methods was also compared. The results of magnetic bead method for nucleic acid extraction by two different extractors (Sansure Natch CS S12C Fully Automated Nucleic Acid Extraction System vs. Tianlong NP968-C Nucleic Acid Extractor) were also compared. RESULTS: The sensitivity, specificity, PPV, NPV and kappa value were 95.00%, 87.50%, 95.00%, 87.50%and 0.825 for Sansure kit; 90.00%, 87.50%, 94.74%, 77.78%and 0.747 for the Bioperfectus kit, and 82.50%, 81.25%, 91.67%, 65.00%and 0.593 for the BGI kit, respectively. The positive, negative and total coincident rates and kappa value of viral nucleic acid detection results using the samples extracted by one-step cleavage and magnetic bead methods were 95.24%, 100.00%, 96.43%and 0.909, respectively, but the one-step cleavage method took only 25 min, while the magnetic bead method required 180 min. The positive, negative and total coincident rates and kappa value of viral nucleic acid detection results using the samples extracted by the two different nucleic acid extractors were 85.00%, 100.00%, 89.29% and 0.764, respectively. CONCLUSIONS The detection efficacy for SARS-CoV-2 nucleic acid by the Sansure kit is relatively higher and the one-step cleavage method has advantages of convenient operation and less time consuming.
Betacoronavirus ; genetics ; isolation & purification ; Coronavirus Infections ; diagnosis ; virology ; Humans ; Pandemics ; Pneumonia, Viral ; diagnosis ; virology ; RNA, Viral ; genetics ; isolation & purification ; Reagent Kits, Diagnostic ; standards

Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was found initially in Wuhan, China in early December 2019. The pandemic has spread to 216 countries and regions, infecting more than 23310 000 people and causing over 800 000 deaths globally by Aug. 24, 2020, according to World Health Organization (https://www.who.int/emergencies/diseases/ novel-coronavirus-2019). Fever, cough, and dyspnea are the three common symptoms of the condition, whereas the conventional transmission route for SARS-CoV-2 is through droplets entering the respiratory tract. To date, infection control measures for COVID-19 have been focusing on the involvement of the respiratory system. However, ignoring potential faecal transmission and the gastrointestinal involvement of SARS-CoV-2 may result in mistakes in attempts to control the pandemic.
Betacoronavirus/isolation & purification* ; COVID-19 ; China/epidemiology* ; Coronavirus Infections/virology* ; Environmental Microbiology ; Feces/virology* ; Gastrointestinal Diseases/virology* ; Humans ; Models, Biological ; Pandemics ; Pneumonia, Viral/virology* ; RNA, Viral/genetics* ; SARS-CoV-2 ; Virus Shedding

No abstract available.
Coronavirus Infections/*diagnosis/virology ; Humans ; Middle East Respiratory Syndrome Coronavirus/genetics/isolation & purification ; Nasopharynx/virology ; RNA, Viral/genetics/metabolism ; Real-Time Polymerase Chain Reaction ; Viral Envelope Proteins/genetics

The deltacoronavirus is a new member of the subfamily Coronaviridae of the family Coronaviridae. Deltacoronaviruses can infect birds and mammals. Deltacoronaviruses were detected in early 2007 in Asian leopard cats and Chinese ferret badgers. In 2014, porcine deltacoronavirus (PDCoV) infection spread rapidly in the USA. Moreover, cell culture-adapted PDCoV has been obtained from infected piglets. Animal experiments have confirmed that the isolated PDCoV is highly pathogenic and causes severe diarrhea in piglets. Thus, the PDCoV can be considered to be a good model to study the deltacoronavirus. In this review, we discuss the etiology, epidemiology, pathogenicity, culture, and diagnostic methods of the PDCoV.
Animals ; Coronavirus ; classification ; genetics ; isolation & purification ; Coronavirus Infections ; veterinary ; virology ; Diarrhea ; veterinary ; virology ; Phylogeny ; Swine ; Swine Diseases ; virology

In July 2009, some farms of breeding Muscovy ducks on the peak of egg laying suffered the decrease of hatching rate and the quality of the eggs showing low mortality and no evident respiratory symptoms. The swelling and congestive ovary was visible after autopsy. This study was brought out for the diagnosis of these cases. The virus was isolated and identified by the methods of virus culture in chicken embryo, physical and chemical properties test, hemagglutinin test, NDV (Newcastle diseases Virus) interference test, electron microscope observation, pathogenicity test and the gene sequence analysis. The results indicated the virus showed the characters of inducing dwarf embryo after inocubation, the sensibility to lipid solvent and the hemagglutination capacity after pancreatic enzyme treatment, the typical morphology of coronavirus, the interference to NDV replication and the homology among 84.7% - 99% of the particial N gene sequences to the reference IBV (Avian infectious bronchitis virus) strains. The strain was identified as IBV isolate and this study confirmed the pathogenicity of IBV to Muscovy ducks.
Amino Acid Sequence ; Animals ; Chick Embryo ; Coronavirus Infections ; veterinary ; virology ; Ducks ; virology ; Female ; Infectious bronchitis virus ; classification ; genetics ; isolation & purification ; Molecular Sequence Data ; Phylogeny ; Poultry Diseases ; virology ; Sequence Alignment