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2.
Emerg Microbes Infect ; 11(1): 277-283, 2022 Dec.
Article in English | MEDLINE | ID: covidwho-1585239

ABSTRACT

The novel SARS-CoV-2 Omicron variant (B.1.1.529), first found in early November 2021, has sparked considerable global concern and it has >50 mutations, many of which are known to affect transmissibility or cause immune escape. In this study, we sought to investigate the virological characteristics of the Omicron variant and compared it with the Delta variant which has dominated the world since mid-2021. Omicron variant replicated more slowly than the Delta variant in transmembrane serine protease 2 (TMPRSS2)-overexpressing VeroE6 (VeroE6/TMPRSS2) cells. Notably, the Delta variant replicated well in Calu3 cell line which has robust TMPRSS2 expression, while the Omicron variant replicated poorly in this cell line. Competition assay showed that Delta variant outcompeted Omicron variant in VeroE6/TMPRSS2 and Calu3 cells. To confirm the difference in entry pathway between the Omicron and Delta variants, we assessed the antiviral effect of bafilomycin A1, chloroquine (inhibiting endocytic pathway), and camostat (inhibiting TMPRSS2 pathway). Camostat potently inhibited the Delta variant but not the Omicron variant, while bafilomycin A1 and chloroquine could inhibit both Omicron and Delta variants. Moreover, the Omicron variant also showed weaker cell-cell fusion activity when compared with Delta variant in VeroE6/TMPRSS2 cells. Collectively, our results suggest that Omicron variant infection is not enhanced by TMPRSS2 but is largely mediated via the endocytic pathway. The difference in entry pathway between Omicron and Delta variants may have an implication on the clinical manifestations or disease severity.


Subject(s)
COVID-19/virology , SARS-CoV-2/physiology , Serine Endopeptidases/metabolism , Virus Internalization , Virus Replication , Animals , Carcinoma, Non-Small-Cell Lung/pathology , Cell Line, Tumor , Chlorocebus aethiops , Chloroquine/pharmacology , Endocytosis/drug effects , Esters/pharmacology , Guanidines/pharmacology , Humans , Immune Evasion , Lung Neoplasms/pathology , Macrolides/pharmacology , Recombinant Proteins/metabolism , SARS-CoV-2/genetics , Vero Cells , Virus Cultivation , Virus Internalization/drug effects , Whole Genome Sequencing
3.
Blood ; 138(22): 2256-2268, 2021 12 02.
Article in English | MEDLINE | ID: covidwho-1443788

ABSTRACT

SARS-CoV-2 vaccine ChAdOx1 nCoV-19 (AstraZeneca) causes a thromboembolic complication termed vaccine-induced immune thrombotic thrombocytopenia (VITT). Using biophysical techniques, mouse models, and analysis of VITT patient samples, we identified determinants of this vaccine-induced adverse reaction. Super-resolution microscopy visualized vaccine components forming antigenic complexes with platelet factor 4 (PF4) on platelet surfaces to which anti-PF4 antibodies obtained from VITT patients bound. PF4/vaccine complex formation was charge-driven and increased by addition of DNA. Proteomics identified substantial amounts of virus production-derived T-REx HEK293 proteins in the ethylenediaminetetraacetic acid (EDTA)-containing vaccine. Injected vaccine increased vascular leakage in mice, leading to systemic dissemination of vaccine components known to stimulate immune responses. Together, PF4/vaccine complex formation and the vaccine-stimulated proinflammatory milieu trigger a pronounced B-cell response that results in the formation of high-avidity anti-PF4 antibodies in VITT patients. The resulting high-titer anti-PF4 antibodies potently activated platelets in the presence of PF4 or DNA and polyphosphate polyanions. Anti-PF4 VITT patient antibodies also stimulated neutrophils to release neutrophil extracellular traps (NETs) in a platelet PF4-dependent manner. Biomarkers of procoagulant NETs were elevated in VITT patient serum, and NETs were visualized in abundance by immunohistochemistry in cerebral vein thrombi obtained from VITT patients. Together, vaccine-induced PF4/adenovirus aggregates and proinflammatory reactions stimulate pathologic anti-PF4 antibody production that drives thrombosis in VITT. The data support a 2-step mechanism underlying VITT that resembles the pathogenesis of (autoimmune) heparin-induced thrombocytopenia.


Subject(s)
Antigen-Antibody Complex/immunology , Autoantibodies/immunology , COVID-19/prevention & control , Capsid Proteins/adverse effects , Drug Contamination , Genetic Vectors/adverse effects , HEK293 Cells/immunology , Immunoglobulin G/immunology , Platelet Factor 4/immunology , Purpura, Thrombocytopenic, Idiopathic/etiology , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/adverse effects , Adenoviridae/immunology , Animals , Antigen-Antibody Complex/ultrastructure , Autoantibodies/biosynthesis , Capillary Leak Syndrome/etiology , Capsid Proteins/immunology , Cell Line, Transformed , /immunology , Dynamic Light Scattering , Epitopes/chemistry , Epitopes/immunology , Extracellular Traps/immunology , Extravasation of Diagnostic and Therapeutic Materials/etiology , Genetic Vectors/immunology , HEK293 Cells/chemistry , Humans , Imaging, Three-Dimensional , Immunoglobulin G/biosynthesis , Inflammation , Mice , Microscopy/methods , Platelet Activation , Proteomics , Purpura, Thrombocytopenic, Idiopathic/blood , Purpura, Thrombocytopenic, Idiopathic/immunology , Sinus Thrombosis, Intracranial/diagnostic imaging , Sinus Thrombosis, Intracranial/immunology , Spike Glycoprotein, Coronavirus/immunology , Virus Cultivation
5.
Elife ; 102021 04 09.
Article in English | MEDLINE | ID: covidwho-1389777

ABSTRACT

Virus propagation methods generally use transformed cell lines to grow viruses from clinical specimens, which may force viruses to rapidly adapt to cell culture conditions, a process facilitated by high viral mutation rates. Upon propagation in VeroE6 cells, SARS-CoV-2 may mutate or delete the multibasic cleavage site (MBCS) in the spike protein. Previously, we showed that the MBCS facilitates serine protease-mediated entry into human airway cells (Mykytyn et al., 2021). Here, we report that propagating SARS-CoV-2 on the human airway cell line Calu-3 - that expresses serine proteases - prevents cell culture adaptations in the MBCS and directly adjacent to the MBCS (S686G). Similar results were obtained using a human airway organoid-based culture system for SARS-CoV-2 propagation. Thus, in-depth knowledge on the biology of a virus can be used to establish methods to prevent cell culture adaptation.


Subject(s)
Epithelial Cells , SARS-CoV-2/physiology , Spike Glycoprotein, Coronavirus/genetics , Virus Cultivation/methods , Virus Internalization , Animals , Cell Line , Chlorocebus aethiops , Epithelial Cells/cytology , Epithelial Cells/metabolism , Epithelial Cells/virology , Humans , Proteolysis , Respiratory System/cytology , Respiratory System/virology , Serine Proteases/metabolism
7.
J Med Virol ; 93(9): 5603-5607, 2021 09.
Article in English | MEDLINE | ID: covidwho-1363670

ABSTRACT

It has been estimated that individuals with COVID-19 can shed replication-competent virus up to a maximum of 20 days after initiation of symptoms. The majority of studies that addressed this situation involved hospitalized individuals and those with severe disease. Studies to address the possible presence of SARS-CoV-2 during the different phases of COVID-19 disease in mildly infected individuals, and utilization of viral culture techniques to identify replication-competent viruses, have been limited. This report describes two patients with mild forms of the disease who shed replication-competent virus for 24 and 37 days, respectively, after symptom onset.


Subject(s)
COVID-19/immunology , COVID-19/virology , SARS-CoV-2/growth & development , Virus Cultivation , Animals , Chlorocebus aethiops , Female , Humans , Middle Aged , SARS-CoV-2/pathogenicity , Vero Cells/ultrastructure , Vero Cells/virology , Viral Load , Virus Shedding
8.
Transfusion ; 60(9): 2038-2046, 2020 09.
Article in English | MEDLINE | ID: covidwho-1263879

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA could be detected in the blood of infected cases. From February 9, all blood establishments in Hubei province, China, implemented nucleic acid testing (NAT) for SARS-CoV-2 RNA among blood donors to ensure blood safety. STUDY DESIGN AND METHODS: Nucleic acid test screening individually (ID) or by minipool (MP) testing was performed according to the manufacturer's instructions. Inactivated culture supernatant of SARS-CoV-2-infected Vero cells was quantified by droplet digital polymerase chain reaction (ddPCR) and series diluted with negative plasma to evaluate the assay's performance. RESULTS: The limit of detection of the kit for MP testing was 62.94 and 33.14 copies/mL for N and ORF1ab region, respectively. ID testing could achieve 3.87 and 4.85 copies/mL for two regions using 1600 µL of plasma. Coefficients of variations of two different concentrations of reference samples were all less than 5% in MP testing. As of April 30, 2020, a total of 98,342 blood donations including 87,095 whole blood donations and 11,247 platelet donations were tested by ID or MP testing, and no RNAemia was found. In addition, Hubei province suffered precipitously decreased blood supply, especially in February: 86% reduction compared with the same period of 2019. CONCLUSION: Nucleic acid test screening of SARS-CoV-2 on blood donations is suitable in blood establishments using the commercial real-time PCR detection kit based on available instruments. The negative result indicated that SARS-CoV-2 appears to be no direct threat to blood safety but raises some serious issues for general blood supply.


Subject(s)
Blood Donors , COVID-19 Nucleic Acid Testing , COVID-19/epidemiology , RNA, Viral/blood , SARS-CoV-2/isolation & purification , Viremia/diagnosis , Animals , Blood Banks , Blood Donors/supply & distribution , COVID-19/diagnosis , China/epidemiology , Chlorocebus aethiops , Humans , Limit of Detection , RNA, Viral/isolation & purification , Real-Time Polymerase Chain Reaction/methods , SARS-CoV-2/physiology , Vero Cells , Viral Load , Virus Cultivation
9.
Viruses ; 13(6)2021 05 28.
Article in English | MEDLINE | ID: covidwho-1256666

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first identified in Wuhan, China, in late 2019 and is the causative agent of the coronavirus disease 2019 (COVID-19) pandemic. Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) represents the gold standard for diagnostic assays even if it cannot precisely quantify viral RNA copies. Thus, we decided to compare qRT-PCR with digital polymerase chain reaction (dPCR), which is able to give an accurate number of RNA copies that can be found in a specimen. However, the aforementioned methods are not capable to discriminate if the detected RNA is infectious or not. For this purpose, it is necessary to perform an endpoint titration on cell cultures, which is largely used in the research field and provides a tissue culture infecting dose per mL (TCID50/mL) value. Both research and diagnostics call for a model that allows the comparison between the results obtained employing different analytical methods. The aim of this study is to define a comparison among two qRT-PCR protocols (one with preliminary RNA extraction and purification and an extraction-free qRT-PCR), a dPCR and a titration on cell cultures. The resulting correlations yield a faithful estimation of the total number of RNA copies and of the infectious viral burden from a Ct value obtained with diagnostic routine tests. All these estimations take into consideration methodological errors linked to the qRT-PCR, dPCR and titration assays.


Subject(s)
COVID-19/therapy , COVID-19/virology , Polymerase Chain Reaction/methods , RNA, Viral/analysis , Reverse Transcriptase Polymerase Chain Reaction , SARS-CoV-2/isolation & purification , Viral Load/methods , Animals , Cells, Cultured , Chlorocebus aethiops , Digital Technology/methods , Humans , SARS-CoV-2/genetics , Vero Cells , Virus Cultivation
10.
mSphere ; 6(3)2021 05 12.
Article in English | MEDLINE | ID: covidwho-1230164

ABSTRACT

Human coronavirus (HCoV)-OC43 rarely shows a cytopathic effect (CPE) after infection of various cell lines, and the indirect immunoperoxidase assay (IPA), a relatively complex procedure, has long been used as an alternative assay. Because HCoV-OC43 uses cell-surface transmembrane protease serine 2 (TMPRSS2) for cell entry, VeroE6 cells expressing TMPRSS2 may show a clear CPE after HCoV-OC43 infection. The aim of this study was to construct a 50% tissue culture infectious dose (TCID50) assay for HCoV-OC43 based on CPE evaluation using VeroE6/TMPRSS2 cells. VeroE6/TMPRSS2 cells showed clear CPEs 3 to 4 days after low-titer HCoV-OC43 infection. Evaluation of viral kinetics indicated that the viral titer in the culture supernatant of VeroE6/TMPRSS2 cells in the early stages of infection was higher than that of other cells. In comparison, between the CPE-based and the IPA-based (i.e., the reference titer) methods, the titer measured with CPE evaluation 4 to 5 days after infection using VeroE6/TMPRSS2 cells showed a much smaller difference from the reference titer than that measured using other cells. Thus, the TCID50 assay using CPE evaluation with VeroE6/TMPRSS2 cells provides the correct titer value and will greatly contribute to future research on HCoV-OC43.IMPORTANCE HCoV-OC43 rarely shows a cytopathic effect (CPE) in infected cell lines, and thus the plaque and TCID50 assays by CPE observation are not applicable for titration; the indirect immunoperoxidase assay (IPA) is used instead. However, the IPA is relatively complex, time-consuming, costly, and not suitable for simultaneous titration of many samples. We developed a TCID50 assay using CPE evaluation with TMPRSS2-expressing VeroE6/TMPRSS2 cells that provides the same accuracy as the conventional IPA-based viral titration and does not require any staining procedures using antibodies or substrates. This titration method will greatly contribute to future research on HCoV-OC43 by allowing simple, low-cost, and accurate titration of this virus.


Subject(s)
Coronavirus OC43, Human/physiology , Cytopathogenic Effect, Viral , Receptors, Virus/metabolism , Serine Endopeptidases/metabolism , Viral Load/methods , Animals , Cell Line, Tumor , Chlorocebus aethiops , Coronavirus OC43, Human/isolation & purification , Humans , Immunoenzyme Techniques , Receptors, Virus/genetics , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Serine Endopeptidases/genetics , Vero Cells/virology , Virus Cultivation , Virus Internalization , Virus Replication
11.
Transfus Clin Biol ; 28(3): 264-270, 2021 Aug.
Article in English | MEDLINE | ID: covidwho-1201297

ABSTRACT

OBJECTIVES: The patients with hematological malignancies are a vulnerable group to COVID-19, due to the immunodeficiency resulting from the underlying disease and oncological treatment that significantly impair cellular and humoral immunity. Here we report on a beneficial impact of a passive immunotherapy with convalescent plasma to treat a prolonged, active COVID-19 infection in a patient with a history of nasopharyngeal diffuse large B-cell lymphoma treated with the therapy inducing substantial impairment of particularly humoral arm of immune system. The specific aim was to quantify SARS-CoV2 neutralizing antibodies in a patient plasma during the course of therapy. MATERIALS AND METHODS: Besides the standard of care treatment and monitoring, neutralizing antibody titers in patient's serum samples, calibrated according to the First WHO International Standard for anti-SARS-CoV-2 immunoglobulin (human), were quantified in a time-dependent manner. During the immunotherapy period peripheral blood flow cytometry immunophenotyping was conducted to characterize lymphocyte subpopulations. RESULTS: The waves of clinical improvements and worsening coincided with transfused neutralizing antibodies rises and drops in the patient's systemic circulation, proving their contribution in controlling the disease progress. Besides the patient's lack of own humoral immune system, immunophenotyping analysis revealed also the reduced level of helper T-lymphocytes and immune exhaustion of monocytes. CONCLUSION: Therapeutic approach based on convalescent plasma transfusion transformed a prolonged, active COVID-19 infection into a manageable chronic disease.


Subject(s)
Antibodies, Viral/biosynthesis , COVID-19/therapy , Immunocompromised Host , Lymphoma, Large B-Cell, Diffuse/complications , SARS-CoV-2/immunology , Animals , Antibodies, Neutralizing/blood , Antibodies, Neutralizing/therapeutic use , Antibodies, Viral/blood , Antibodies, Viral/therapeutic use , Antineoplastic Combined Chemotherapy Protocols/adverse effects , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , COVID-19/complications , COVID-19/diagnosis , COVID-19 Nucleic Acid Testing , Chlorocebus aethiops , Combined Modality Therapy , Hematopoietic Stem Cell Transplantation , Humans , Immunization, Passive , Immunophenotyping , Lymphocyte Subsets/drug effects , Lymphocyte Subsets/immunology , Lymphoma, Large B-Cell, Diffuse/immunology , Lymphoma, Large B-Cell, Diffuse/therapy , Lymphopenia/etiology , Lymphopenia/immunology , Male , Middle Aged , Monocytes/immunology , Nasopharynx/virology , RNA, Viral/analysis , RNA, Viral/blood , Radiotherapy, Adjuvant , Rituximab/administration & dosage , Rituximab/adverse effects , SARS-CoV-2/isolation & purification , Vero Cells , Virus Cultivation
12.
J Med Virol ; 93(9): 5603-5607, 2021 09.
Article in English | MEDLINE | ID: covidwho-1198392

ABSTRACT

It has been estimated that individuals with COVID-19 can shed replication-competent virus up to a maximum of 20 days after initiation of symptoms. The majority of studies that addressed this situation involved hospitalized individuals and those with severe disease. Studies to address the possible presence of SARS-CoV-2 during the different phases of COVID-19 disease in mildly infected individuals, and utilization of viral culture techniques to identify replication-competent viruses, have been limited. This report describes two patients with mild forms of the disease who shed replication-competent virus for 24 and 37 days, respectively, after symptom onset.


Subject(s)
COVID-19/immunology , COVID-19/virology , SARS-CoV-2/growth & development , Virus Cultivation , Animals , Chlorocebus aethiops , Female , Humans , Middle Aged , SARS-CoV-2/pathogenicity , Vero Cells/ultrastructure , Vero Cells/virology , Viral Load , Virus Shedding
13.
Int J Mol Med ; 47(6)2021 06.
Article in English | MEDLINE | ID: covidwho-1181666

ABSTRACT

The Coronavirus Disease 2019 (COVID­19) pandemic has forced the scientific community to rapidly develop highly reliable diagnostic methods in order to effectively and accurately diagnose this pathology, thus limiting the spread of infection. Although the structural and molecular characteristics of the severe acute respiratory syndrome coronavirus 2 (SARS­CoV­2) were initially unknown, various diagnostic strategies useful for making a correct diagnosis of COVID­19 have been rapidly developed by private research laboratories and biomedical companies. At present, rapid antigen or antibody tests, immunoenzymatic serological tests and molecular tests based on RT­PCR are the most widely used and validated techniques worldwide. Apart from these conventional methods, other techniques, including isothermal nucleic acid amplification techniques, clusters of regularly interspaced short palindromic repeats/Cas (CRISPR/Cas)­based approaches or digital PCR methods are currently used in research contexts or are awaiting approval for diagnostic use by competent authorities. In order to provide guidance for the correct use of COVID­19 diagnostic tests, the present review describes the diagnostic strategies available which may be used for the diagnosis of COVID­19 infection in both clinical and research settings. In particular, the technical and instrumental characteristics of the diagnostic methods used are described herein. In addition, updated and detailed information about the type of sample, the modality and the timing of use of specific tests are also discussed.


Subject(s)
COVID-19 Testing/methods , COVID-19/diagnosis , Animals , Biosensing Techniques/methods , Clustered Regularly Interspaced Short Palindromic Repeats , Humans , Inventions , Microscopy, Electron/methods , Nucleic Acid Amplification Techniques/methods , SARS-CoV-2/genetics , SARS-CoV-2/isolation & purification , Virus Cultivation/methods
14.
Methods Mol Biol ; 2203: 223-229, 2020.
Article in English | MEDLINE | ID: covidwho-729909

ABSTRACT

All viruses have to overcome the innate immune response in order to establish infection. Methods have been developed to assay if, and how, viruses overcome these responses, and many can be directly applied to coronaviruses. Here, in vitro methods to determine how coronaviruses overcome this response are described.


Subject(s)
Coronavirus/growth & development , Coronavirus/metabolism , Virus Cultivation/methods , Animals , Cell Line , Coronavirus/pathogenicity , Host-Pathogen Interactions , Humans , Immunity, Innate/immunology , Interferons , Middle East Respiratory Syndrome Coronavirus/growth & development , Middle East Respiratory Syndrome Coronavirus/pathogenicity , RNA, Viral , Viral Nonstructural Proteins , Virus Replication
15.
Jpn J Infect Dis ; 74(1): 48-53, 2021 Jan 22.
Article in English | MEDLINE | ID: covidwho-1116920

ABSTRACT

JC polyomavirus (JCPyV) causes progressive multifocal leukoencephalopathy (PML), a demyelinating disease of the central nervous system affecting immunocompromised patients. The study of PML-type JCPyV in vitro has been limited owing to the inefficient propagation of the virus in cultured cells. In this study, we carried out long-term culture of COS-7 cells (designated as COS-IMRb cells) transfected with PML-type M1-IMRb, an adapted viral DNA with a rearranged non-coding control region (NCCR). The JCPyV derived from COS-IMRb cells were characterized by analyzing the viral replication, amount of virus by hemagglutination (HA), production of viral protein 1 (VP1), and structure of the NCCR. HA assays indicated the presence of high amounts of PML-type JCPyV in COS-IMRb cells. Immunostaining showed only a small population of JCPyV carrying COS-IMRb cells to be VP1-positive. Sequencing analysis of the NCCR of JCPyV after long-term culture revealed that the NCCR of M1-IMRb was conserved in COS-IMRb cells without any point mutation. The JCPyV genomic DNA derived from a clone of COS-IMRb-3 cells was detected, via Southern blotting, as a single band of approximately 5.1 kbp without deletion. These findings suggest the potential of using COS-IMRb-3 cells as a useful tool for screening anti-JCPyV drugs.


Subject(s)
JC Virus/growth & development , JC Virus/genetics , Leukoencephalopathy, Progressive Multifocal/virology , Virus Cultivation/methods , Animals , Blotting, Southern/methods , COS Cells , Chlorocebus aethiops , DNA Replication , DNA, Viral/isolation & purification , Hemagglutination , Humans , Transfection , Viral Proteins/genetics , Viral Proteins/metabolism , Virus Replication
16.
Clin Microbiol Infect ; 27(6): 886-891, 2021 Jun.
Article in English | MEDLINE | ID: covidwho-1101160

ABSTRACT

OBJECTIVES: This study compares the infectivity of SARS-CoV-2 in respiratory samples from patients with mild COVID-19 with those from hospitalized patients with severe bilateral pneumonia. In severe COVID-19, we also analysed the presence of neutralizing activity in paired sera. METHODS: We performed cell cultures on 193 real-time reverse transcription polymerase chain reaction respiratory samples, positive for SARS-CoV-2, obtained from 189 patients at various times, from clinical diagnosis to follow-up. Eleven samples were obtained from asymptomatic individuals, 91 samples from 91 outpatients with mild forms of COVID-19 and 91 samples from 87 inpatients with severe pneumonia. In these patients, neutralizing activity was analysed in 30 paired sera collected after symptom onset >10 days. RESULTS: We detected a cytopathic effect (CPE) in 91/193 (47%) samples. Viral viability was maintained for up to 10 days in patients with mild COVID-19. In patients with severe COVID-19, the virus remained viable for up to 32 days after the onset of symptoms. Patients with severe COVID-19 presented infectious virus at a significantly higher rate in the samples with moderate to low viral load (cycle threshold value ≥ 26): 32/75 (43%) versus 14/63 (22%) for mild cases (p < 0.01). We observed a positive CPE despite the presence of clear neutralizing activity (NT50 > 1:1024 in 10% (3/30) of samples. DISCUSSION: Patients with severe COVID-19 might shed viable virus during prolonged periods of up to 4 weeks after symptom onset, even when presenting high cycle threshold values in their respiratory samples and despite having developed high neutralizing antibody titres.


Subject(s)
COVID-19/immunology , COVID-19/virology , SARS-CoV-2/growth & development , Virus Cultivation , Adult , Aged , Animals , Antibodies, Viral/blood , COVID-19 Nucleic Acid Testing , Cell Culture Techniques , Chlorocebus aethiops , Cytopathogenic Effect, Viral , Female , Hospitalization , Humans , Immunoglobulin G/blood , Immunoglobulin M/blood , Male , Microbial Viability , Middle Aged , Pneumonia, Viral , SARS-CoV-2/pathogenicity , Serologic Tests , Severity of Illness Index , Time Factors , Vero Cells , Viral Load , Virus Shedding , Young Adult
17.
J Clin Lab Anal ; 35(4): e23735, 2021 Apr.
Article in English | MEDLINE | ID: covidwho-1092109

ABSTRACT

BACKGROUND: The rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has generated a pandemic with alarming rates of fatality worldwide. This situation has had a major impact on clinical laboratories that have attempted to answer the urgent need for diagnostic tools, since the identification of coronavirus disease 2019 (COVID-19). Development of a reliable serological diagnostic immunoassay, with high levels of sensitivity and specificity to detect SARS-CoV-2 antibodies with improved differential diagnosis from other circulating viruses, is mandatory. METHODS: An enzyme-linked immunosorbent assay (ELISA) using whole inactivated virus cultured in vitro, was developed to detect viral antigens. WB and ELISA investigations were carried out with sera of convalescent patients and negative sera samples. Both analyses were concurrently performed with recombinant MABs to verify the findings. RESULTS: Preliminary data from 10 sera (5 patients with COVID-19, and 5 healthy controls) using this immunoassay are very promising, successfully identifying all of the confirmed SARS-CoV-2-positive individuals. CONCLUSION: This ELISA appears to be a specific and reliable method for detecting COVID-19 antibodies (IgG, IgM, and IgA), and a useful tool for identifying individuals which have developed immunity to the virus.


Subject(s)
Antigens, Viral , COVID-19 Serological Testing/methods , COVID-19/diagnosis , SARS-CoV-2 , Virus Cultivation/methods , Animals , Antibodies, Viral/blood , Antigens, Viral/chemistry , Antigens, Viral/immunology , Antigens, Viral/isolation & purification , Blotting, Western , COVID-19/immunology , COVID-19/virology , Chlorocebus aethiops , Coronavirus Nucleocapsid Proteins/chemistry , Coronavirus Nucleocapsid Proteins/immunology , Coronavirus Nucleocapsid Proteins/isolation & purification , Enzyme-Linked Immunosorbent Assay/methods , Humans , Phosphoproteins/chemistry , Phosphoproteins/immunology , Phosphoproteins/isolation & purification , SARS-CoV-2/chemistry , SARS-CoV-2/immunology , SARS-CoV-2/isolation & purification , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/isolation & purification , Vero Cells
18.
Appl Microbiol Biotechnol ; 105(4): 1421-1434, 2021 Feb.
Article in English | MEDLINE | ID: covidwho-1052958

ABSTRACT

Similar to the recent COVID-19 pandemic, influenza A virus poses a constant threat to the global community. For the treatment of flu disease, both antivirals and vaccines are available with vaccines the most effective and safest approach. In order to overcome limitations in egg-based vaccine manufacturing, cell culture-based processes have been established. While this production method avoids egg-associated risks in face of pandemics, process intensification using animal suspension cells in high cell density perfusion cultures should allow to further increase manufacturing capacities worldwide. In this work, we demonstrate the development of a perfusion process using Madin-Darby canine kidney (MDCK) suspension cells for influenza A (H1N1) virus production from scale-down shake flask cultivations to laboratory scale stirred tank bioreactors. Shake flask cultivations using semi-perfusion mode enabled high-yield virus harvests (4.25 log10(HAU/100 µL)) from MDCK cells grown up to 41 × 106 cells/mL. Scale-up to bioreactors with an alternating tangential flow (ATF) perfusion system required optimization of pH control and implementation of a temperature shift during the infection phase. Use of a capacitance probe for on-line perfusion control allowed to minimize medium consumption. This contributed to a better process control and a more economical performance while maintaining a maximum virus titer of 4.37 log10(HAU/100 µL) and an infectious virus titer of 1.83 × 1010 virions/mL. Overall, this study clearly demonstrates recent advances in cell culture-based perfusion processes for next-generation high-yield influenza vaccine manufacturing for pandemic preparedness. KEY POINTS: • First MDCK suspension cell-based perfusion process for IAV produciton was established. • "Cell density effect" was overcome and process was intensified by reduction of medium use and automated process control. • The process achieved cell density over 40 × 106 cells/mL and virus yield over 4.37 log10(HAU/100 µL).


Subject(s)
Influenza A Virus, H1N1 Subtype/physiology , Virus Cultivation/methods , Virus Replication/physiology , Animals , Bioreactors , Dogs , Madin Darby Canine Kidney Cells
19.
J Clin Microbiol ; 58(8)2020 07 23.
Article in English | MEDLINE | ID: covidwho-999208

ABSTRACT

Real-time reverse transcription-PCR (RT-PCR) is currently the most sensitive method to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes coronavirus disease 2019 (COVID-19). However, the correlation between detectable viral RNA and culturable virus in clinical specimens remains unclear. Here, we performed virus culture for 60 specimens that were confirmed to be positive for SARS-CoV-2 RNA by real-time RT-PCR. The virus could be successfully isolated from 12 throat and nine nasopharyngeal swabs and two sputum specimens. The lowest copy number required for virus isolation was determined to be 5.4, 6.0, and 5.7 log10 genome copies/ml sample for detecting the nsp12, E, and N genes, respectively. We further examined the correlation of genome copy number and virus isolation in different regions of the viral genome, demonstrating that culturable specimens are characterized by high copy numbers with a linear correlation observed between copy numbers of amplicons targeting structural and nonstructural regions. Overall, these results indicate that in addition to the copy number, the integrity of the viral genome should be considered when evaluating the infectivity of clinical SARS-CoV-2 specimens.


Subject(s)
Betacoronavirus/growth & development , Betacoronavirus/isolation & purification , Clinical Laboratory Techniques/methods , Coronavirus Infections/diagnosis , Coronavirus Infections/virology , Pneumonia, Viral/diagnosis , Pneumonia, Viral/virology , Virus Cultivation/methods , Betacoronavirus/genetics , COVID-19 , COVID-19 Testing , COVID-19 Vaccines , Correlation of Data , Humans , Nasopharynx/virology , Pandemics , Pharynx/virology , Real-Time Polymerase Chain Reaction/methods , Reverse Transcriptase Polymerase Chain Reaction/methods , SARS-CoV-2
20.
Infez Med ; 28(4): 486-499, 2020 Dec 01.
Article in English | MEDLINE | ID: covidwho-950623

ABSTRACT

To date, research on viral shedding (VS), live virus isolation and infection status remains ongoing as scientists and clinicians attempt to better understand the coronavirus disease of 2019 (COVID-19) pandemic. Viral RNA detection at different stages of the disease, quantitative changes and patterns of viral persistence and clearance all provide context for the pathogenesis and transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Given the highly infectious nature of SARS-CoV-2 and its impact on the global population and economy, clinicians continue to seek the best methods for controlling its spread, and data on public health preventative measures continue to emerge. In this paper we review the available evidence on the viral dynamics of SARS-CoV-2 in the URT to determine a timeline for infection based on molecular and viral culture findings and to assess the significance of persistently positive results. Keywords: viral shedding, viral load, viral culture, SARS-CoV-2, upper respiratory tract.


Subject(s)
COVID-19/virology , Nose/virology , Pharynx/virology , SARS-CoV-2/physiology , Saliva/virology , COVID-19/epidemiology , Female , Humans , Male , Nasopharynx/virology , Oropharynx/virology , Pandemics , Reverse Transcriptase Polymerase Chain Reaction , SARS-CoV-2/isolation & purification , Sex Distribution , Viral Load , Virus Activation , Virus Cultivation , Virus Replication , Virus Shedding
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