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1.
Microbiol Spectr ; 10(1): e0061821, 2022 02 23.
Article in English | MEDLINE | ID: covidwho-1622002

ABSTRACT

The host transmembrane protein MARCH8 is a RING finger E3 ubiquitin ligase that downregulates various host transmembrane proteins, such as MHC-II. We have recently reported that MARCH8 expression in virus-producing cells impairs viral infectivity by reducing virion incorporation of not only HIV-1 envelope glycoprotein but also vesicular stomatitis virus G-glycoprotein through two different pathways. However, the MARCH8 inhibition spectrum remains largely unknown. Here, we show the antiviral spectrum of MARCH8 using viruses pseudotyped with a variety of viral envelope glycoproteins. Infection experiments revealed that viral envelope glycoproteins derived from the rhabdovirus, arenavirus, coronavirus, and togavirus (alphavirus) families were sensitive to MARCH8-mediated inhibition. Lysine mutations at the cytoplasmic tails of rabies virus-G, lymphocytic choriomeningitis virus glycoproteins, SARS-CoV and SARS-CoV-2 spike proteins, and Chikungunya virus and Ross River virus E2 proteins conferred resistance to MARCH8. Immunofluorescence showed impaired downregulation of the mutants of these viral envelope glycoproteins by MARCH8, followed by lysosomal degradation, suggesting that MARCH8-mediated ubiquitination leads to intracellular degradation of these envelopes. Indeed, rabies virus-G and Chikungunya virus E2 proteins proved to be clearly ubiquitinated. We conclude that MARCH8 has inhibitory activity on a variety of viral envelope glycoproteins whose cytoplasmic lysine residues are targeted by this antiviral factor. IMPORTANCE A member of the MARCH E3 ubiquitin ligase family, MARCH8, downregulates many different kinds of host transmembrane proteins, resulting in the regulation of cellular homeostasis. On the other hands, MARCH8 acts as an antiviral factor when it binds to and downregulates HIV-1 envelope glycoprotein and vesicular stomatitis virus G-glycoprotein that are viral transmembrane proteins. This study reveals that, as in the case of cellular membrane proteins, MARCH8 shows broad-spectrum inhibition against various viral envelope glycoproteins by recognizing their cytoplasmic lysine residues, resulting in lysosomal degradation.


Subject(s)
Antiviral Agents/pharmacology , Lysine/drug effects , Ubiquitin-Protein Ligases/pharmacology , Viral Envelope Proteins/chemistry , Blotting, Western , Down-Regulation , HEK293 Cells , HeLa Cells , Humans , Immunoprecipitation , Lysine/metabolism , Ubiquitination/physiology , Viral Envelope Proteins/drug effects
2.
Sci Rep ; 12(1): 364, 2022 01 10.
Article in English | MEDLINE | ID: covidwho-1617003

ABSTRACT

RNA-binding proteins (RBPs) interact with and determine the fate of many cellular RNAs directing numerous essential roles in cellular physiology. Nuclear Factor 90 (NF90) is an RBP encoded by the interleukin enhancer-binding factor 3 (ILF3) gene that has been found to influence RNA metabolism at several levels, including pre-RNA splicing, mRNA turnover, and translation. To systematically identify the RNAs that interact with NF90, we carried out iCLIP (individual-nucleotide resolution UV crosslinking and immunoprecipitation) analysis in the human embryonic fibroblast cell line HEK-293. Interestingly, many of the identified RNAs encoded proteins involved in the response to viral infection and RNA metabolism. We validated a subset of targets and investigated the impact of NF90 on their expression levels. Two of the top targets, IRF3 and IRF9 mRNAs, encode the proteins IRF3 and IRF9, crucial regulators of the interferon pathway involved in the SARS-CoV-2 immune response. Our results support a role for NF90 in modulating key genes implicated in the immune response and offer insight into the immunological response to the SARS-CoV-2 infection.


Subject(s)
COVID-19/metabolism , Immunoprecipitation/methods , Nuclear Factor 90 Proteins/metabolism , RNA-Binding Proteins/metabolism , RNA/metabolism , SARS-CoV-2/metabolism , COVID-19/virology , Cells, Cultured , HEK293 Cells , Humans , Interferon Regulatory Factor-3/genetics , Interferon Regulatory Factor-3/metabolism , Interferon-Stimulated Gene Factor 3, gamma Subunit/genetics , Interferon-Stimulated Gene Factor 3, gamma Subunit/metabolism , Nuclear Factor 90 Proteins/genetics , Protein Binding , RNA/genetics , RNA Interference , RNA Stability , RNA, Messenger/genetics , RNA, Messenger/metabolism , RNA-Binding Proteins/genetics , RNA-Seq/methods , SARS-CoV-2/genetics , SARS-CoV-2/physiology
3.
J Immunol ; 208(3): 753-761, 2022 02 01.
Article in English | MEDLINE | ID: covidwho-1614089

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), has seriously threatened global public health. Severe COVID-19 has been reported to be associated with an impaired IFN response. However, the mechanisms of how SARS-CoV-2 antagonizes the host IFN response are poorly understood. In this study, we report that SARS-CoV-2 helicase NSP13 inhibits type I IFN production by directly targeting TANK-binding kinase 1 (TBK1) for degradation. Interestingly, inhibition of autophagy by genetic knockout of Beclin1 or pharmacological inhibition can rescue NSP13-mediated TBK1 degradation in HEK-293T cells. Subsequent studies revealed that NSP13 recruits TBK1 to p62, and the absence of p62 can also inhibit TBK1 degradation in HEK-293T and HeLa cells. Finally, TBK1 and p62 degradation and p62 aggregation were observed during SARS-CoV-2 infection in HeLa-ACE2 and Calu3 cells. Overall, our study shows that NSP13 inhibits type I IFN production by recruiting TBK1 to p62 for autophagic degradation, enabling it to evade the host innate immune response, which provides new insights into the transmission and pathogenesis of SARS-CoV-2 infection.


Subject(s)
Autophagy , COVID-19/immunology , Interferon Type I/biosynthesis , Methyltransferases/physiology , RNA Helicases/physiology , SARS-CoV-2/physiology , Sequestosome-1 Protein/metabolism , Viral Nonstructural Proteins/physiology , Beclin-1/antagonists & inhibitors , Cell Line , Down-Regulation , Humans , Immune Evasion , Immunity, Innate , Immunoprecipitation , Interferon Type I/genetics , Multiprotein Complexes , Protein Aggregates , Protein Interaction Mapping
4.
STAR Protoc ; 3(1): 101067, 2022 03 18.
Article in English | MEDLINE | ID: covidwho-1595326

ABSTRACT

N 6 -methylation of adenosine (m6A) is the most abundant internal mRNA modification and is an important post-transcriptional regulator of gene expression. Here, we describe a protocol for methylated RNA immunoprecipitation sequencing (MeRIP-Seq) to detect and quantify m6A modifications in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA. The protocol is optimized for low viral RNA levels and is readily adaptable for other applications. For complete details on the use and execution of this protocol, please refer to Li et al. (2021).


Subject(s)
Adenosine/analogs & derivatives , Immunoprecipitation/methods , Sequence Analysis, RNA/methods , Adenosine/analysis , Adenosine/genetics , Animals , COVID-19/genetics , Caco-2 Cells , Chlorocebus aethiops , Gene Expression/genetics , Gene Expression Regulation/genetics , Genetic Techniques , HEK293 Cells , Humans , Methylation , RNA/chemistry , RNA/genetics , RNA Processing, Post-Transcriptional , RNA, Viral/metabolism , SARS-CoV-2/genetics , SARS-CoV-2/pathogenicity , Vero Cells
5.
mBio ; 12(5): e0131621, 2021 10 26.
Article in English | MEDLINE | ID: covidwho-1406604

ABSTRACT

Coronaviruses (CoVs) are emergent pathogens that may cause life-threatening respiratory diseases in humans. Understanding of CoV-host interactions may help to identify novel therapeutic targets. MOV10 is an RNA helicase involved in different steps of cellular RNA metabolism. Both MOV10 antiviral and proviral activities have been described in a limited number of viruses, but this protein has not been previously associated with CoVs. We found that during Middle East respiratory syndrome coronavirus (MERS-CoV) infection, MOV10 aggregated in cytoplasmic structures colocalizing with viral nucleocapsid (N) protein. MOV10-N interaction was confirmed by endogenous MOV10 coimmunoprecipitation, and the presence of other cellular proteins was also detected in MOV10 complexes. MOV10 silencing significantly increased both N protein accumulation and virus titer, with no changes in the accumulation of viral RNAs. Moreover, MOV10 overexpression caused a 10-fold decrease in viral titers. These data indicated that MOV10 has antiviral activity during MERS-CoV infection. We postulated that this activity could be mediated by viral RNA sequestration, and in fact, RNA immunoprecipitation data showed the presence of viral RNAs in the MOV10 cytoplasmic complexes. Expression of wild-type MOV10 or of a MOV10 mutant without helicase activity in MOV10 knockout cell lines, developed by CRISPR-Cas technology, indicated that the helicase activity of MOV10 was required for its antiviral effect. Interestingly MOV10-N interaction was conserved in other mildly or highly pathogenic human CoVs, including the recently emerged severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), although MOV10 antiviral activity was found only in highly pathogenic CoVs, suggesting a potential role of MOV10 in the modulation of human CoVs pathogenesis. IMPORTANCE Coronaviruses (CoVs) are emerging pathogens causing life-threatening diseases in humans. Knowledge of virus-host interactions and viral subversion mechanisms of host pathways is required for the development of effective countermeasures against CoVs. The interaction between cellular RNA helicase MOV10 and nucleocapsid (N) protein from several human CoVs is shown. Using MERS-CoV as a model, we demonstrate that MOV10 has antiviral function, requiring its helicase activity, most likely mediated by viral RNA sequestration in cytoplasmic ribonucleoprotein structures. Furthermore, we found that MOV10 antiviral activity may act only in highly pathogenic human CoVs, suggesting a role for MOV10 in modulating CoVs pathogenesis. The present study uncovers a complex network of viral and cellular RNAs and proteins interaction modulating the antiviral response against CoVs.


Subject(s)
Antiviral Agents/pharmacology , Coronavirus Nucleocapsid Proteins/metabolism , RNA Helicases/metabolism , RNA Helicases/pharmacology , Animals , Blotting, Western , Cell Line, Tumor , Chlorocebus aethiops , Fluorescent Antibody Technique , Humans , Immunoprecipitation , RNA, Viral/metabolism , Vero Cells , Virus Replication/drug effects
6.
Viruses ; 13(8)2021 08 19.
Article in English | MEDLINE | ID: covidwho-1367921

ABSTRACT

The recent emergence of SARS-CoV-2 in humans from a yet unidentified animal reservoir and the capacity of the virus to naturally infect pets, farmed animals and potentially wild animals has highlighted the need for serological surveillance tools. In this study, the luciferase immunoprecipitation systems (LIPS), employing the spike (S) and nucleocapsid proteins (N) of SARS-CoV-2, was used to examine the suitability of the assay for antibody detection in different animal species. Sera from SARS-CoV-2 naturally-infected mink (n = 77), SARS-CoV-2 experimentally-infected ferrets, fruit bats and hamsters and a rabbit vaccinated with a purified spike protein were examined for antibodies using the SARS-CoV-2 N and/or S proteins. From comparison with the known neutralization status of the serum samples, statistical analyses including calculation of the Spearman rank-order-correlation coefficient and Cohen's kappa agreement were used to interpret the antibody results and diagnostic performance. The LIPS immunoassay robustly detected the presence of viral antibodies in naturally infected SARS-CoV-2 mink, experimentally infected ferrets, fruit bats and hamsters as well as in an immunized rabbit. For the SARS-CoV-2-LIPS-S assay, there was a good level of discrimination between the positive and negative samples for each of the five species tested with 100% agreement with the virus neutralization results. In contrast, the SARS-CoV-2-LIPS-N assay did not consistently differentiate between SARS-CoV-2 positive and negative sera. This study demonstrates the suitability of the SARS-CoV-2-LIPS-S assay for the sero-surveillance of SARS-CoV-2 infection in a range of animal species.


Subject(s)
Antibodies, Viral/blood , COVID-19/veterinary , Mink/immunology , SARS-CoV-2/immunology , Animals , COVID-19/diagnosis , COVID-19/epidemiology , COVID-19/immunology , COVID-19 Serological Testing , Chiroptera/immunology , Coronavirus Nucleocapsid Proteins/immunology , Epidemiological Monitoring , Ferrets/immunology , Immunoprecipitation , Mesocricetus/immunology , Phosphoproteins/immunology , Rabbits/immunology , Seroepidemiologic Studies , Spike Glycoprotein, Coronavirus/immunology
7.
Nat Cell Biol ; 23(8): 846-858, 2021 08.
Article in English | MEDLINE | ID: covidwho-1309445

ABSTRACT

The integral membrane protein ATG9A plays a key role in autophagy. It displays a broad intracellular distribution and is present in numerous compartments, including the plasma membrane (PM). The reasons for the distribution of ATG9A to the PM and its role at the PM are not understood. Here, we show that ATG9A organizes, in concert with IQGAP1, components of the ESCRT system and uncover cooperation between ATG9A, IQGAP1 and ESCRTs in protection from PM damage. ESCRTs and ATG9A phenocopied each other in protection against PM injury. ATG9A knockouts sensitized the PM to permeabilization by a broad spectrum of microbial and endogenous agents, including gasdermin, MLKL and the MLKL-like action of coronavirus ORF3a. Thus, ATG9A engages IQGAP1 and the ESCRT system to maintain PM integrity.


Subject(s)
Autophagy-Related Proteins/metabolism , Cell Membrane/metabolism , Membrane Proteins/metabolism , Vesicular Transport Proteins/metabolism , Autophagosomes/metabolism , Autophagy-Related Proteins/genetics , HEK293 Cells , HeLa Cells , Humans , Immunoblotting , Immunoprecipitation , Membrane Proteins/genetics , Microscopy, Confocal , Protein Transport/physiology , Vesicular Transport Proteins/genetics
8.
EMBO J ; 40(11): e102277, 2021 06 01.
Article in English | MEDLINE | ID: covidwho-1194823

ABSTRACT

The ongoing outbreak of severe acute respiratory syndrome (SARS) coronavirus 2 (SARS-CoV-2) demonstrates the continuous threat of emerging coronaviruses (CoVs) to public health. SARS-CoV-2 and SARS-CoV share an otherwise non-conserved part of non-structural protein 3 (Nsp3), therefore named as "SARS-unique domain" (SUD). We previously found a yeast-2-hybrid screen interaction of the SARS-CoV SUD with human poly(A)-binding protein (PABP)-interacting protein 1 (Paip1), a stimulator of protein translation. Here, we validate SARS-CoV SUD:Paip1 interaction by size-exclusion chromatography, split-yellow fluorescent protein, and co-immunoprecipitation assays, and confirm such interaction also between the corresponding domain of SARS-CoV-2 and Paip1. The three-dimensional structure of the N-terminal domain of SARS-CoV SUD ("macrodomain II", Mac2) in complex with the middle domain of Paip1, determined by X-ray crystallography and small-angle X-ray scattering, provides insights into the structural determinants of the complex formation. In cellulo, SUD enhances synthesis of viral but not host proteins via binding to Paip1 in pBAC-SARS-CoV replicon-transfected cells. We propose a possible mechanism for stimulation of viral translation by the SUD of SARS-CoV and SARS-CoV-2.


Subject(s)
Coronavirus Papain-Like Proteases/metabolism , Gene Expression Regulation, Viral , Peptide Initiation Factors/metabolism , RNA-Binding Proteins/metabolism , RNA-Dependent RNA Polymerase/metabolism , SARS Virus/physiology , SARS-CoV-2/physiology , Viral Nonstructural Proteins/metabolism , Amino Acid Sequence , Bacterial Proteins , Chromatography, Gel , Coronavirus Papain-Like Proteases/chemistry , Crystallography, X-Ray , Genes, Reporter , HEK293 Cells , Humans , Immunoprecipitation , Luminescent Proteins , Models, Molecular , Peptide Initiation Factors/chemistry , Protein Binding , Protein Biosynthesis , Protein Conformation , Protein Domains , Protein Interaction Mapping , RNA, Viral/genetics , RNA-Binding Proteins/chemistry , RNA-Dependent RNA Polymerase/chemistry , Recombinant Fusion Proteins/chemistry , Recombinant Fusion Proteins/metabolism , Ribosome Subunits/metabolism , SARS Virus/genetics , SARS-CoV-2/genetics , Scattering, Small Angle , Sequence Alignment , Sequence Homology, Amino Acid , Viral Nonstructural Proteins/chemistry , X-Ray Diffraction
9.
J Biosci Bioeng ; 131(6): 696-702, 2021 Jun.
Article in English | MEDLINE | ID: covidwho-1141952

ABSTRACT

Monoclonal antibodies are extremely valuable functional biomaterials that are widely used not only in life science research but also in antibody drugs and test drugs. There is also a strong need to develop high-quality neutralizing antibodies as soon as possible in order to stop the rapid spread of new infectious diseases such as the SARS-CoV-2 virus. This study has developed a membrane-type immunoglobulin-directed hybridoma screening (MIHS) method for obtaining high-quality monoclonal antibodies with high efficiency and high speed. In addition to these advantages, this paper demonstrates that the MIHS method can selectively obtain monoclonal antibodies that specifically recognize the functional structure of proteins. The MIHS method is a useful technology that greatly contributes to the research community because it can be easily introduced in any laboratory that uses a flow cytometer.


Subject(s)
Antibodies, Monoclonal/analysis , Antibodies, Monoclonal/immunology , Antibody Specificity/immunology , Hybridomas/metabolism , Animals , Antibodies, Monoclonal/biosynthesis , Antibodies, Monoclonal/isolation & purification , Antibodies, Neutralizing/analysis , Antibodies, Neutralizing/biosynthesis , Antibodies, Neutralizing/immunology , Antibodies, Neutralizing/isolation & purification , Cell Line, Tumor , Enzyme-Linked Immunosorbent Assay/methods , Flow Cytometry/methods , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/immunology , Green Fluorescent Proteins/metabolism , Humans , Hybridomas/cytology , Immunoglobulin Isotypes , Immunoprecipitation , Mice , Time Factors
10.
Vet Microbiol ; 250: 108853, 2020 Nov.
Article in English | MEDLINE | ID: covidwho-779738

ABSTRACT

Coronaviruses (CoVs) is showing obvious interspecies transmission, such as the SARS-CoV, MERS-CoV and SARS-CoV-2. Here, the emerging porcine deltacoronavirus (PDCoV) strain, isolated from Shanghai, China, broadly infects porcine, human and chicken cells in vitro. Previously studies by our group and others have confirmed that PDCoV nucleocapsid (N) protein performs an important role in antagonizing retinoic acid-induced gene I-like receptor (RLR) activation. However, the mechanism of PDCoV N protein suppressing porcine type I IFN production remains unclear, especially the downstream of porcine RLR signaling pathway. In the present study, porcine IRF7 (poIRF7) was identified as the interaction protein of PDCoV N protein through LC-MS/MS. The poIRF7 (268-487aa) was the key region of binding PDCoV N protein. Although IRF7 is a conserved functional protein in species, the PDCoV N protein has been confirmed to interact with only poIRF7 and significantly decrease poIRF7-induced type I IFN production, but not human or chicken IRF7. Furthermore, PDCoV N protein can promote poIRF7 degradation via the ubiquitin-proteasome pathway, which directly increased the K6, K11, and K29-linked polyubiquitination of poIRF7. Lysine 359 of poIRF7 was a key site in PDCoV N protein inducing poIRF7 degradation. Taken together, our results reveal a novel mechanism that PDCoV N protein could species-specifically interact with poIRF7 and then promote its degradation to suppress porcine type I IFN production. The novel findings provide a new insight into PDCoV and other zoonotic coronavirus evading the innate immune response of different species.


Subject(s)
Coronavirus/chemistry , Interferon Regulatory Factor-7/immunology , Interferons/metabolism , Nucleocapsid Proteins/immunology , Animals , Blotting, Western , Cell Line , Chickens , China , Chromatography, Liquid , Coronavirus/classification , Fluorescent Antibody Technique, Indirect , HEK293 Cells , Humans , Immunoprecipitation , Interferons/immunology , LLC-PK1 Cells , Phylogeny , Plasmids , Proteasome Endopeptidase Complex/metabolism , Species Specificity , Swine , Tandem Mass Spectrometry , Ubiquitin/metabolism , Whole Genome Sequencing/veterinary
11.
Sci Transl Med ; 12(559)2020 09 02.
Article in English | MEDLINE | ID: covidwho-724557

ABSTRACT

It is of paramount importance to evaluate the prevalence of both asymptomatic and symptomatic cases of SARS-CoV-2 infection and their differing antibody response profiles. Here, we performed a pilot study of four serological assays to assess the amounts of anti-SARS-CoV-2 antibodies in serum samples obtained from 491 healthy individuals before the SARS-CoV-2 pandemic, 51 individuals hospitalized with COVID-19, 209 suspected cases of COVID-19 with mild symptoms, and 200 healthy blood donors. We used two ELISA assays that recognized the full-length nucleoprotein (N) or trimeric spike (S) protein ectodomain of SARS-CoV-2. In addition, we developed the S-Flow assay that recognized the S protein expressed at the cell surface using flow cytometry, and the luciferase immunoprecipitation system (LIPS) assay that recognized diverse SARS-CoV-2 antigens including the S1 domain and the carboxyl-terminal domain of N by immunoprecipitation. We obtained similar results with the four serological assays. Differences in sensitivity were attributed to the technique and the antigen used. High anti-SARS-CoV-2 antibody titers were associated with neutralization activity, which was assessed using infectious SARS-CoV-2 or lentiviral-S pseudotype virus. In hospitalized patients with COVID-19, seroconversion and virus neutralization occurred between 5 and 14 days after symptom onset, confirming previous studies. Seropositivity was detected in 32% of mildly symptomatic individuals within 15 days of symptom onset and in 3% of healthy blood donors. The four antibody assays that we used enabled a broad evaluation of SARS-CoV-2 seroprevalence and antibody profiling in different subpopulations within one region.


Subject(s)
Antibodies, Viral/blood , Betacoronavirus/immunology , Clinical Laboratory Techniques/methods , Coronavirus Infections/diagnosis , Pneumonia, Viral/diagnosis , Serologic Tests/methods , Adolescent , Adult , Aged , Aged, 80 and over , COVID-19 , COVID-19 Testing , Cohort Studies , Coronavirus Infections/epidemiology , Coronavirus Infections/immunology , Enzyme-Linked Immunosorbent Assay/methods , Female , Flow Cytometry/methods , France/epidemiology , Healthy Volunteers , Humans , Immunoprecipitation/methods , Luciferases , Male , Middle Aged , Neutralization Tests , Pandemics , Pneumonia, Viral/epidemiology , Pneumonia, Viral/immunology , SARS-CoV-2 , Seroepidemiologic Studies , Spike Glycoprotein, Coronavirus/immunology , Young Adult
12.
Emerg Microbes Infect ; 9(1): 1497-1505, 2020 Dec.
Article in English | MEDLINE | ID: covidwho-595010

ABSTRACT

In response to the coronavirus disease 2019 (COVID-19) outbreak, caused by SARS-CoV-2, multiple diagnostic tests are required for acute disease diagnosis, contact tracing, monitoring asymptomatic infection rates and assessing herd immunity. While PCR remains the frontline test of choice in the acute diagnostic setting, serological tests are urgently needed. Unlike PCR tests which are highly specific, cross-reactivity is a major challenge for COVID-19 antibody tests considering there are six other coronaviruses known to infect humans. SARS-CoV is genetically related to SARS-CoV-2 sharing approximately 80% sequence identity and both belong to the species SARS related coronavirus in the genus Betacoronavirus of family Coronaviridae. We developed and compared the performance of four different serological tests to comprehensively assess the cross-reactivity between COVID-19 and SARS patient sera. There is significant cross-reactivity when N protein of either virus is used. The S1 or RBD regions from the spike (S) protein offers better specificity. Amongst the different platforms, capture ELISA performed best. We found that SARS survivors all have significant levels of antibodies remaining in their blood 17 years after infection. Anti-N antibodies waned more than anti-RBD antibodies, and the latter is known to play a more important role in providing protective immunity.


Subject(s)
Antibodies, Viral/immunology , Betacoronavirus/immunology , Clinical Laboratory Techniques/methods , Coronavirus Infections/diagnosis , Pneumonia, Viral/diagnosis , SARS Virus/immunology , Serologic Tests/methods , Severe Acute Respiratory Syndrome/diagnosis , Antibodies, Viral/blood , Betacoronavirus/isolation & purification , COVID-19 , COVID-19 Testing , Coronavirus Nucleocapsid Proteins , Cross Reactions , Diagnosis, Differential , Enzyme-Linked Immunosorbent Assay/methods , HEK293 Cells , Humans , Immunoprecipitation , Nucleocapsid Proteins/immunology , Pandemics , Phosphoproteins , Protein Domains/immunology , SARS Virus/isolation & purification , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/immunology
13.
J Infect Dis ; 222(2): 206-213, 2020 06 29.
Article in English | MEDLINE | ID: covidwho-618807

ABSTRACT

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of coronavirus disease 2019 (COVID-19), is associated with respiratory-related disease and death. Assays to detect virus-specific antibodies are important to understand the prevalence of infection and the course of the immune response. METHODS: Quantitative measurements of plasma or serum antibodies to the nucleocapsid and spike proteins were analyzed using luciferase immunoprecipitation system assays in 100 cross-sectional or longitudinal samples from patients with SARS-CoV-2 infection. A subset of samples was tested both with and without heat inactivation. RESULTS: At >14 days after symptom onset, antibodies against SARS-CoV-2 nucleocapsid protein showed 100% sensitivity and 100% specificity, whereas antibodies to spike protein were detected with 91% sensitivity and 100% specificity. Neither antibody levels nor the rate of seropositivity were significantly reduced by heat inactivation of samples. Analysis of daily samples from 6 patients with COVID-19 showed anti-nucleocapsid and spike protein antibodies appearing between days 8 and 14 after initial symptoms. Immunocompromised patients generally had a delayed antibody response to SARS-CoV-2, compared with immunocompetent patients. CONCLUSIONS: Antibody to the nucleocapsid protein of SARS-CoV-2 is more sensitive than spike protein antibody for detecting early infection. Analyzing heat-inactivated samples with a luciferase immunoprecipitation system assay is a safe and sensitive method for detecting SARS-CoV-2 antibodies.


Subject(s)
Antibodies, Viral/blood , Betacoronavirus/immunology , Clinical Laboratory Techniques , Coronavirus Infections/immunology , Immunoprecipitation , Nucleocapsid Proteins/immunology , Pneumonia, Viral/immunology , Spike Glycoprotein, Coronavirus/immunology , Adult , COVID-19 , COVID-19 Testing , Coronavirus Infections/diagnosis , Coronavirus Nucleocapsid Proteins , Female , Hot Temperature , Humans , Immunocompetence , Immunocompromised Host , Luciferases , Male , Middle Aged , Pandemics , Phosphoproteins , Retrospective Studies , SARS-CoV-2 , Sensitivity and Specificity , Time Factors
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