פרוטוקול טקסט מלא לגישה זו ניסיוני זמין <a href="http://www.springerprotocols.com/">הפרוטוקולים שפרינגר</a> .

The authors have nothing to disclose.

A correction was made to: <a href="http://www.jove.com/video/751/">Titration of Human Coronaviruses Using an Immunoperoxidase Assay</a>. A revised abstract was republished due to a publisher error.
Revised Abstract:
Determination of infectious viral titers is a basic and essential experimental approach for virologists. Classical plaque assays cannot be used for viruses that do not cause significant cytopathic effects, which is the case for prototype strains 229E and OC43 of human coronavirus (HCoV). Therefore, an alternative indirect immunoperoxidase assay (IPA) was developed for the detection and titration of these viruses and is described herein. Susceptible cells are inoculated with serial logarithmic dilutions of virus-containing samples in a 96-well plate format. After viral growth, viral detection by IPA yields the infectious virus titer, expressed as 'Tissue Culture Infectious Dose 50 percent' (TCID50). This represents the dilution of a virus-containing sample at which half of a series of laboratory wells contain infectious replicating virus. This technique provides a reliable method for the titration of HCoV-229E and HCoV-OC43 in biological samples such as cells, tissues and fluids. This article is based on work first reported in Methods in Molecular Biology (2008) volume 454, pages 93-102.
Original Abstract:
Calculation of infectious viral titers represents a basic and essential experimental approach for virologists. Classical plaque assays cannot be used for viruses that do not cause significant cytopathic effects, which is the case for strains 229E and OC43 of human coronavirus (HCoV). An alternative indirect immunoperoxidase assay (IPA) is herein described for the detection and titration of these viruses. Susceptible cells are inoculated with serial logarithmic dilutions of samples in a 96-well plate. After viral growth, viral detection by IPA yields the infectious virus titer, expressed as "Tissue Culture Infectious Dose" (TCID50). This represents the dilution of a virus-containing sample at which half of a series of laboratory wells contain replicating virus. This technique is a reliable method for the titration of HCoV in biological samples (cells, tissues or fluids).

A correction was made to: <a href="http://www.jove.com/video/751/">Titration of Human Coronaviruses Using an Immunoperoxidase Assay</a>. A revised abstract was republished due to a publisher error.

Erratum: Titration of Human Coronaviruses Using an Immunoperoxidase Assay

titration of human coronaviruses using an immunoperoxidase assay

חישוב titers ויראלית מדבקת מייצג גישה ניסויית בסיסי וחיוני וירולוגים. מבחני פלאק קלאסית אינו יכול לשמש לאיתור וירוסים שלא לגרום לתופעות cytopathic משמעותי, אשר במקרה של זנים 229E ו OC43 של קורונה האנושי (HCoV). Assay חלופה אימונו עקיף (IPA) מתואר במסמך לאיתור טיטרציה של וירוסים אלה. תאים רגישים הם מחוסן עם דילולים לוגריתמי הסידורי של דגימות צלחת 96-היטב. לאחר צמיחה ויראלי, זיהוי נגיפי ידי IPA התשואות titer וירוס מדבק, כפי שבאה לידי ביטוי &quot;מנה רקמות תרבות זיהומיות&quot; (TCID50). זה מייצג את הדילול של מדגם המכיל וירוסים בו חצי שורה של בארות מעבדה להכיל וירוס שכפול. טכניקה זו שיטה אמינה עבור טיטרציה של HCoV דגימות ביולוגיות (תאים, רקמות או נוזלי).

Watch this Scientific Journal Video about Titration of Human Coronaviruses Using an Immunoperoxidase Assay at JoVE.com

Titration of Human Coronaviruses Using an Immunoperoxidase Assay

בסרטון הזה, אנחנו מראים שיטה חלופית לזיהוי titering של וירוסים באמצעות זיהוי אנטיגן האנזימטית טכניקה המכונה assay אימונו. כאן, אנו יראה לכם כיצד לאסוף דגימות ויראליות שלך, להכין את התאים לבדיקה, ולבסוף assay באמצעות אימונו דילולים סדרתי כדי לקבוע את titer ויראלי.

טיטרציה של נגיפי קורונה האדם שימוש Assay אימונו

Determination of infectious viral titers is a basic and essential experimental approach for virologists. Classical plaque assays cannot be used for ...

titration-of-human-coronaviruses-using-an-immunoperoxidase-assay

Research

JoVE Journal

Biology

38.1K Views.  INRS-Institut Armand-Frappier. בסרטון הזה, אנחנו מראים שיטה חלופית לזיהוי titering של וירוסים באמצעות זיהוי אנטיגן האנזימטית טכניקה המכונה assay אימונו. כאן, אנו יראה לכם כיצד לאסוף דגימות ויראליות שלך, להכין את התאים לבדיקה, ולבסוף assay באמצעות אימונו דילולים סדרתי כדי לקבוע את titer ויראלי.

Video: Titration of Human Coronaviruses Using an Immunoperoxidase Assay

High-throughput Detection Method for Influenza Virus

Influenza virus is a respiratory pathogen that causes a high degree of morbidity and mortality every year in multiple parts of the world. Therefore, precise diagnosis of the infecting strain and rapid high-throughput screening of vast numbers of clinical samples is paramount to control the spread of pandemic infections. Current clinical diagnoses of influenza infections are based on serologic testing, polymerase chain reaction, direct specimen immunofluorescence and cell culture 1,2.
Here, we report the development of a novel diagnostic technique used to detect live influenza viruses. We used the mouse-adapted human A/PR/8/34 (PR8, H1N1) virus 3 to test the efficacy of this technique using MDCK cells 4. MDCK cells (104 or 5 x 103 per well) were cultured in 96- or 384-well plates, infected with PR8 and viral proteins were detected using anti-M2 followed by an IR dye-conjugated secondary antibody. M2 5 and hemagglutinin 1 are two major marker proteins used in many different diagnostic assays. Employing IR-dye-conjugated secondary antibodies minimized the autofluorescence associated with other fluorescent dyes. The use of anti-M2 antibody allowed us to use the antigen-specific fluorescence intensity as a direct metric of viral quantity. To enumerate the fluorescence intensity, we used the LI-COR Odyssey-based IR scanner. This system uses two channel laser-based IR detections to identify fluorophores and differentiate them from background noise. The first channel excites at 680 nm and emits at 700 nm to help quantify the background. The second channel detects fluorophores that excite at 780 nm and emit at 800 nm. Scanning of PR8-infected MDCK cells in the IR scanner indicated a viral titer-dependent bright fluorescence. A positive correlation of fluorescence intensity to virus titer starting from 102-105 PFU could be consistently observed. Minimal but detectable positivity consistently seen with 102-103 PFU PR8 viral titers demonstrated the high sensitivity of the near-IR dyes. The signal-to-noise ratio was determined by comparing the mock-infected or isotype antibody-treated MDCK cells.
Using the fluorescence intensities from 96- or 384-well plate formats, we constructed standard titration curves. In these calculations, the first variable is the viral titer while the second variable is the fluorescence intensity. Therefore, we used the exponential distribution to generate a curve-fit to determine the polynomial relationship between the viral titers and fluorescence intensities. Collectively, we conclude that IR dye-based protein detection system can help diagnose infecting viral strains and precisely enumerate the titer of the infecting pathogens.

This method describes the use of Infrared dye based imaging system for detection of H1N1 in bronchioalveolar lavage (BAL) fluid of infected mice at a high sensitivity. This methodology can be performed in a 96- or 384-well plate, requires &lt;10 &mu;l volume of test material and has the potential for concurrent screening of multiple pathogens.

תפוקה גבוהה איתור שיטת וירוס השפעת

Influenza virus is a respiratory pathogen that causes a high degree of morbidity and mortality every year in multiple parts of the world. Therefore, ...

Immunology and Infection

Measuring Influenza Neuraminidase Inhibition Antibody Titers by Enzyme-linked Lectin Assay

Antibodies to neuraminidase (NA), the second most abundant surface protein on influenza virus, contribute toward protection against influenza. Traditional methods to measure NA inhibiting (NI) antibody titers are not practical for routine serology. This protocol describes the enzyme-linked lectin assay (ELLA), a practical alternative method to measure NI titers that is performed in 96 well plates coated with a large glycoprotein substrate, fetuin. NA cleaves terminal sialic acids from fetuin, exposing the penultimate sugar, galactose. Peanut agglutinin (PNA) is a lectin with specificity for galactose and therefore the extent of desialylation can be quantified using a PNA-horseradish peroxidase conjugate, followed by addition of a chromogenic peroxidase substrate. The optical density that is measured is proportional to NA activity. To measure NI antibody titers, serial dilutions of sera are incubated at 37 &#176;C O/N on fetuin-coated plates with a fixed amount of NA. The reciprocal of the highest serum dilution that results in &#8805;50% inhibition of NA activity is designated as the NI antibody titer. The ELLA provides a practical format for routine evaluation of human antibody responses following influenza infection or vaccination.

We describe the enzyme-linked lectin assay (ELLA) for measuring influenza neuraminidase (NA)-inhibition antibody titers in sera. The assay uses peanut agglutinin to quantify galactose residues that become accessible when NA removes sialic acid from fetuin-coated, 96-well plates.

מדידת טיטר נוגדנים עיכוב Neuraminidase שפעת ידי enzyme-linked Assay לקטינים

Antibodies to neuraminidase (NA), the second most abundant surface protein on influenza virus, contribute toward protection against influenza. Traditional ...

Optimization of a Quantitative Micro-neutralization Assay

The micro-neutralization (MN) assay is a standard technique for measuring the infectivity of the influenza virus and the inhibition of virus replication. In this study, we present the protocol of an imaging-based MN assay to quantify the true antigenic relationships between viruses. Unlike typical plaque reduction assays that rely on visible plaques, this assay quantitates the entire infected cell population of each well. The protocol matches the virus type or subtype with the selection of cell lines to achieve maximum infectivity, which enhances sample contrast during imaging and image processing. The introduction of quantitative titration defines the amount of input viruses of neutralization and enables the results from different experiments to be comparable. The imaging setup with a flatbed scanner and free downloadable software makes the approach high throughput, cost effective, user friendly, and easy to deploy in most laboratories. Our study demonstrates that the improved MN assay works well with the current circulating influenza A(H1N1)pdm09, A(H3N2), and B viruses, without being significantly influenced by amino acid substitutions in the neuraminidase (NA) of A(H3N2) viruses. It is particularly useful for the characterization of viruses that either grow to low HA titer and/or undergo an abortive infection resulting in an inability to form plaques in cultured cells.

This study describes an imaging-based micro-neutralization assay to analyze the antigenic relationships between viruses. The protocol employs a flatbed scanner and has four steps, including titration, titration quantitation, neutralization, and neutralization quantitation. The assay works well with current circulating influenza A(H1N1)pdm09, A(H3N2), and B viruses.

אופטימיזציה של Assay כמותי מיקרו-נטרול

The micro-neutralization (MN) assay is a standard technique for measuring the infectivity of the influenza virus and the inhibition of virus replication. ...

Measuring Influenza Neutralizing Antibody Responses to A(H3N2) Viruses in Human Sera by Microneutralization Assays Using MDCK-SIAT1 Cells

Neutralizing antibodies against hemagglutinin (HA) of influenza viruses are considered the main immune mechanism that correlates with protection for influenza infections. Microneutralization (MN) assays are often used to measure neutralizing antibody responses in human sera after influenza vaccination or infection. Madine Darby Canine Kidney (MDCK) cells are the commonly used cell substrate for MN assays. However, currently circulating 3C.2a and 3C.3a A(H3N2) influenza viruses have acquired altered receptor binding specificity. The MDCK-SIAT1 cell line with increased &#945;-2,6 sialic galactose moieties on the surface has proven to provide improved infectivity and more faithful replications than conventional MDCK cells for these contemporary A(H3N2) viruses. Here, we describe a MN assay using MDCK-SIAT1 cells that has been optimized to quantify neutralizing antibody titers to these contemporary A(H3N2) viruses. In this protocol, heat inactivated sera containing neutralizing antibodies are first serially diluted, then incubated with 100 TCID50/well of influenza A(H3N2) viruses to allow antibodies in the sera to bind to the viruses. MDCK-SIAT1 cells are then added to the virus-antibody mixture, and incubated for 18 - 20 h at 37 &#176;C, 5% CO2 to allow A(H3N2) viruses to infect MDCK-SIAT1 cells. After overnight incubation, plates are fixed and the amount of virus in each well is quantified by an enzyme-linked immunosorbent assay (ELISA) using anti-influenza A nucleoprotein (NP) monoclonal antibodies. Neutralizing antibody titer is defined as the reciprocal of the highest serum dilution that provides &#8805;50% inhibition of virus infectivity.

Measuring Influenza Neutralizing Antibody Responses to AH3N2 Viruses in Human Sera by Microneutralization Assays Using MDCK-SIAT1 Cells

Influenza neutralizing antibodies correlate with protection of influenza infections. Microneutralization assays measure neutralizing antibodies in human sera and are often used for influenza human serology. We describe a microneutralization assay using MDCK-SIAT1 cells to measure neutralizing antibody titers to contemporary 3C.2a and 3C.3a A(H3N2) viruses following influenza vaccination or infection.

מבחני מדידת שפעת בנטרול תגובות נוגדנים וירוסים A(H3N2) סרה האנושי על-ידי Microneutralization באמצעות תאים MDCK-SIAT1

Neutralizing antibodies against hemagglutinin (HA) of influenza viruses are considered the main immune mechanism that correlates with protection for ...

An Optimized Hemagglutination Inhibition (HI) Assay to Quantify Influenza-specific Antibody Titers

Antibody titers are commonly used as surrogate markers for serological protection against influenza and other pathogens. Detailed knowledge of antibody production pre- and post-vaccination is required to understand vaccine-induced immunity. This article describes a reliable point-by-point protocol to determine influenza-specific antibody titers. The first protocol describes a method to specify the antigen amounts required for hemagglutination, which standardizes the concentrations for subsequent usage in the second protocol (hemagglutination assay, HA assay). The second protocol describes the quantification of influenza-specific antibody titers against different viral strains by using a serial dilution of human serum or cell culture supernatants (hemagglutination inhibition assay, HI assay).
As an applied example, we show the antibody response of a healthy cohort, which received a trivalent inactivated influenza vaccine. Additionally, the cross-reactivity between the different influenza viruses is shown and methods to minimize cross-reactivity by using different types of animal red blood cells (RBCs) are explained. The discussion highlights advantages and disadvantages of the presented assays and how the determination of influenza-specific antibody titers can improve the understanding of vaccine-related immunity.

An Optimized Hemagglutination Inhibition HI Assay to Quantify Influenza-specific Antibody Titers

The presented protocols describe how to perform a hemagglutination inhibition assay to quantify influenza-specific antibody titers from serum samples of influenza vaccine recipients. The first assay determines optimal viral antigen concentrations by hemagglutination. The second assay quantifies influenza-specific antibody titers by hemagglutination inhibition.

Assay עיכוב (איץ ' אי) Hemagglutination אופטימיזציה לכמת נוגדן ספציפי שפעת Titers

Antibody titers are commonly used as surrogate markers for serological protection against influenza and other pathogens. Detailed knowledge of antibody ...

Medicine

Use of Crystal Violet to Improve Visual Cytopathic Effect-based Reading for Viral Titration using TCID50 Assays

Viral titration is a key assay for virology research. The detection of cytopathic effect (CPE) via TCID50 assays and plaque-forming units (PFU) assays are the two main methods to calculate the titer of a virus stock and are often based on microscopy detection or cell staining for visualization. In the case of TCID50 assay, objective visualization is commonly based on immunocytochemical (ICC) staining of intracellular virus to calculate titers combined with visual CPE detection via microscopy. However, ICC staining is costly and time consuming. In this study, we compared visual CPE observation via microscopy, ICC staining and crystal violet staining to determine the titers of two CPE-forming viruses, Influenza A virus (IAV) of swine origin and Porcine Reproductive and Respiratory Syndrome virus (PRRSV). We show that both crystal violet and ICC staining are more accurate than visual CPE detection, presenting nearly identical levels of precision on both IAV and PRRSV. For this reason, here we present crystal violet staining as a faster and more affordable way to determine viral titrations on a TCID50 assay for CPE-forming viruses titrated in cell lines.

This protocol shows an accurate and objective approach to visualize viral titrations using crystal violet, by comparing it with optical microscopy and immunocytochemical staining.

שימוש קריסטל ויולט כדי לשפר קריאה חזותית אפקט ציטוטופתי מבוסס עבור טיטציה ויראלית באמצעות TCID50 Assays

Viral titration is a key assay for virology research. The detection of cytopathic effect (CPE) via TCID50 assays and plaque-forming units (PFU) assays are ...

כימות נוגדנים מנטרלים הנגרמים על ידי חיסון בגרסאות SARS-CoV-2

Application of Ha-CoV-2 Pseudovirus for Rapid Quantification of SARS-CoV-2 Variants and Neutralizing Antibodies

The coronavirus disease 2019 pandemic (COVID-19) has highlighted the need for rapid assays to accurately measure the infectivity of emerging SARS-CoV-2 variants and the effectiveness of vaccine-induced neutralizing antibodies against viral variants. These assays are essential for pandemic surveillance and validating vaccines and variant-specific boosters. This manuscript demonstrates the application of a novel hybrid alphavirus-SARS-CoV-2 pseudovirus (Ha-CoV-2) for quick quantification of SARS-CoV-2 variant infectivity and vaccine-induced neutralizing antibodies to viral variants. Ha-CoV-2 is a SARS-CoV-2 virus-like particle consisting of viral structural proteins (S, M, N, and E) and a fast-expressing RNA genome derived from an alphavirus, Semliki Forest Virus (SFV). Ha-CoV-2 also contains both green fluorescent protein (GFP) and luciferase reporter genes that allow for quick quantification of viral infectivity. As an example, the infectivity of the SARS-CoV-2 Delta (B.1.617.2) and the Omicron (B.1.1.529) variants are quantified, and their sensitivities to a neutralizing antibody (27VB) are also measured. These examples demonstrate the great potential of Ha-CoV-2 as a robust platform for rapid quantification of SARS-CoV-2 variants and their susceptibility to neutralizing antibodies.

זרקור המחבר: מערכת וירוס פסאודוטיפ להערכת תת-וריאנטים של אומיקרון ונטרול נוגדנים במחקר SARS-CoV-2

This protocol describes the application of a novel hybrid alphavirus-SARS-CoV-2 pseudovirus (Ha-CoV-2) as a platform for rapid quantification of infectivity of SARS-CoV-2 variants and their sensitivity to neutralizing antibodies.

יישום של Ha-CoV-2 Pseudovirus לכימות מהיר של גרסאות SARS-CoV-2 ונוגדנים מנטרלים

The coronavirus disease 2019 pandemic (COVID-19) has highlighted the need for rapid assays to accurately measure the infectivity of emerging SARS-CoV-2 ...

הערכת נטרול סרום נגד SARS-CoV-2 עם וירוסים פסאודוטיפיים

Pseudotyped Viruses As a Molecular Tool to Monitor Humoral Immune Responses Against SARS-CoV-2 Via Neutralization Assay

Pseudotyped viruses (PVs) are molecular tools that can be used to study host-virus interactions and to test the neutralizing ability of serum samples, in addition to their better-known use in gene therapy for the delivery of a gene of interest. PVs are replication defective because the viral genome is divided into different plasmids that are not incorporated into the PVs. This safe and versatile system allows the use of PVs in biosafety level 2 laboratories. Here, we present a general methodology to produce lentiviral PVs based on three plasmids as mentioned here: (1) the backbone plasmid carrying the reporter gene needed to monitor the infection; (2) the packaging plasmid carrying the genes for all the structural proteins needed to generate the PVs; (3) the envelope surface glycoprotein expression plasmid that determines virus tropism and mediates viral entry into the host cell. In this work, SARS-CoV-2 Spike is the envelope glycoprotein used for the production of non-replicative SARS-CoV-2 pseudotyped lentiviruses.
Briefly, packaging cells (HEK293T) were co-transfected with the three different plasmids using standard methods. After 48 h, the supernatant containing the PVs was harvested, filtered, and stored at -80 &#176;C. The infectivity of SARS-CoV-2 PVs was tested by studying the expression of the reporter gene (luciferase) in a target cell line 48 h after infection. The higher the value for relative luminescence units (RLUs), the higher the infection/transduction rate. Furthermore, the infectious PVs were added to the serially diluted serum samples to study the neutralization process of pseudoviruses' entry into target cells, measured as the reduction in RLU intensity: lower values corresponding to high neutralizing activity.

מחבר זרקור: חקר אינטראקציות וירוס מארח עם וירוסים מדומים 

Pseudotyped viruses (PVs) are replication-defective virions that are used to study host-virus interactions under safer conditions than handling authentic viruses. Presented here is a detailed protocol that shows how SARS-CoV-2 PVs can be used to test the neutralizing ability of patients' serum after COVID-19 vaccination.

וירוסים מדומים ככלי מולקולרי לניטור תגובות חיסוניות הומורליות נגד SARS-CoV-2 באמצעות בדיקת נטרול

Pseudotyped viruses (PVs) are molecular tools that can be used to study host-virus interactions and to test the neutralizing ability of serum samples, in ...

טיטרציה של נגיפי קורונה האדם שימוש Assay אימונו

Summary

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Chapters in this video

תפוקה גבוהה איתור שיטת וירוס השפעת

מדידת טיטר נוגדנים עיכוב Neuraminidase שפעת ידי enzyme-linked Assay לקטינים

אופטימיזציה של Assay כמותי מיקרו-נטרול

מבחני מדידת שפעת בנטרול תגובות נוגדנים וירוסים A(H3N2) סרה האנושי על-ידי Microneutralization באמצעות תאים MDCK-SIAT1

Assay עיכוב (איץ ' אי) Hemagglutination אופטימיזציה לכמת נוגדן ספציפי שפעת Titers

שימוש קריסטל ויולט כדי לשפר קריאה חזותית אפקט ציטוטופתי מבוסס עבור טיטציה ויראלית באמצעות TCID50 Assays

יישום של Ha-CoV-2 Pseudovirus לכימות מהיר של גרסאות SARS-CoV-2 ונוגדנים מנטרלים

יישום של Ha-CoV-2 Pseudovirus לכימות מהיר של גרסאות SARS-CoV-2 ונוגדנים מנטרלים

יישום של Ha-CoV-2 Pseudovirus לכימות מהיר של גרסאות SARS-CoV-2 ונוגדנים מנטרלים

וירוסים מדומים ככלי מולקולרי לניטור תגובות חיסוניות הומורליות נגד SARS-CoV-2 באמצעות בדיקת נטרול