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SARS-CoV-2 Serology Assays |
Detect and measure anti-SARS-CoV-2 antibodies
Serology assays enable researchers to determine if subjects have already been infected with severe acute respiratory coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19, by measuring the presence of antibodies against SARS-CoV-2 in blood (serum or plasma). Detectable anti-SARS-CoV-2 antibodies is dependent on the immune response and can be influenced by a variety of factors including dose of virus exposure, assessment stage post-symptom onset, age, gender, and health status. Thermo Fisher Scientific offers specific and sensitive serological assays that are important for accurate and reliable detection of anti-SARS-CoV-2 antibodies.
Targeted profiling of critically ill SARS-CoV-2 subjects: from transcriptome to proteome
Hear from Dr. Douglas Fraser at Western University, Canada, as he demonstrates the use of ProcartaPlex Human Coronavirus Ig Total Panel, 11plex to better understand the immune response to SARS-CoV-2 and ultimately develop strategic treatment plans for critically ill patients in intensive care unit (ICU) for COVID-19. Plasma samples were collected from subjects admitted to the ICU at day 1, 3, 7, and 10 and screened for antibody levels using the 11-plex panel.
Overview of SARS-CoV-2
Pathogen biology
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for the COVID-19 pandemic, belongs to the family of coronaviruses. It is an enveloped, positive-sense, single-stranded RNA virus. The genome of ~30 kilobases contains several open reading frames (ORFs) that encode four structural proteins, namely Spike (S), Envelope (E), Membrane (M), and Nucleocapsid (N), along with a diverse range of non-structural proteins.
Understanding the pathogen biology of SARS-CoV-2 is crucial in developing effective diagnostic tools, vaccines, and therapeutics. The virus enters host cells by binding to the angiotensin-converting enzyme 2 (ACE2) receptor on the cell surface. This receptor recognition is mediated by the spike (S) protein on the viral surface. Once inside the host cell, the viral RNA is released and serves as a template for viral replication and transcription. The virus then assembles new viral particles and is released from the infected cell, leading to the spread of infection.
Deciphering the viral replication pathways from host cell functions poses a challenge as viruses manipulate cellular machinery upon infection, altering the cellular environment to favor virus production.
Host response and cytokine storm
The host's response to SARS-CoV-2 infection encompasses a wide range of interactions and signaling events, influencing both innate and adaptive immune responses. This intricate interplay holds significant implications for human health studies. Infection by SARS-CoV-2 can result in an increase in cytokine levels, also known as a cytokine storm, and is considered to be one of the major causes of acute respiratory distress syndrome (ARDS) and multiple-organ failure. This cytokine storm, or cytokine release syndrome (CRS), is characterized by an imbalance in the cytokine network towards a pro-inflammatory response combined with an insufficient anti-inflammatory response, resulting in a loss of immune system homeostasis.
Currently, the treatment of SARS-CoV-2 infection focuses on palliative care, as respiratory failure from ARDS remains the primary cause of mortality [1]. Recent research suggests that managing the immune-mediated inflammatory cytokine response could prove beneficial. In severe cases, this response is often referred to as cytokine release storm or syndrome (CRS), which can lead to hyper-inflammation, multi-organ failure, and ultimately death. Notably, research indicates a significant variation in immune response factors among individuals, with some displaying stronger early defenses that prevent progression to severe cases. Understanding the cellular and biochemical variances in the innate and adaptive immune response is therefore crucial for patients experiencing asymptomatic, mild, or severe CRS symptoms [2, 3].
Learn more about cytokine storms
Learn more about inflammation and cytokine release syndrome
SARS-CoV-2 ELISA serology assays
We provide a variety of SARS-CoV-2 ELISA kits to measure Ig antibodies, neutralization antibodies and viral-related proteins. Invitrogen ELISA kits for popular targets such as SARS-CoV-2 Spike (Trimer), RBD, Nucleocapsid etc. are listed in Table 1.
Learn more about ELISA kits and components
Popular SARS-CoV-2 protein targets and ELISA performance data
Table 1. View our ELISA kits for the following popular targets:
Ig ELISA for serum and plasma
The Human SARS-CoV-2 Spike (Trimer) Ig ELISA kits are designed to measure the amount of Ig antibodies bound to SARS-CoV-2 Spike (Trimer). A trimerized Spike protein is pre-coated in the wells of the supplied microplate. Samples and controls, including a high control that can be used as a standard, are then added into these wells and bind to the immobilized (capture) Spike protein. The wells are washed, and anti-Ig conjugated to HRP are added and will bind to any captured antibodies. The wells are washed, and a substrate solution is added that reacts with the enzyme complex to produce measurable signal. The intensity of this signal is directly proportional to the concentration of antibody present in the original specimen.
Invitrogen SARS-CoV-2 ELISA kits are highly specific and sensitive. Figure 1 shows the principle of Invitrogen Ig Antibody ELISA for SARS-CoV-2. To demonstrate the specificity and sensitivity of Ig ELISAs, we screened SARS-CoV-2 PCR (+) and PCR (–) samples using Human SARS-CoV-2 Spike (Trimer) Ig Total ELISA Kit (Figure 2) and compared the performance to other supplier’s SARS-CoV-2 ELISA (Figure 3).
Figure 1. The fundamental principle of Invitrogen Ig Antibody ELISA for SARS-CoV-2.
Click image to enlarge
Figure 2. Specificity and sensitivity of Ig ELISA assay. Human serum samples were screened with PCR and validated to minimize false positives. The Ig levels were measured in 39 PCR (+) and 160 PCR (–) (control) samples using Human SARS-CoV-2 Spike (Trimer) Ig Total ELISA Kit and calibrator cut-off level was calculated. All PCR (+) samples are above the calibrator (dotted line) while all PCR (–) are below the calibrator. Two PCR (+) samples in the lower graph showed low antibody levels and were confirmed negative using another serology assay (data not shown).
Click image to enlarge
Figure 3. Comparison of Invitrogen Human SARS-CoV-2 Spike Ig ELISA and competitor ELISA. The Ig levels were measured in PCR (+), healthy and control samples using Human SARS-CoV-2 Spike (Trimer) Ig Total ELISA Kit and other supplier’s ELISA that also measures Ig antibodies against Spike S1 subunit antigen. Borderline healthy control samples were also included. Data was compared and discrepancies were found in the competitor ELISA where a healthy sample showed a false positive and 3 PCR (+) samples showed negative or borderline (indicated with red arrows). Evidently, there was a better correlation to the expected PCR results with our Invitrogen ELISA.
Neutralizing antibody ELISA for serum and plasma
The SARS-CoV-2 Neutralizing Ab ELISA kit is designed to measure the neutralizing portion of anti-SARS-CoV-2 antibodies. A receptor binding domain (RBD) protein is pre-coated in the wells of the supplied microplate. Samples or the positive control are added into the wells. Neutralizing antibodies present in a sample that specifically bind to RBD will block any interaction with biotinylated ACE2 that is subsequently added. Signal from SA-HRP is indirectly proportional to the amount of specific neutralizing antibody present.
Figure 4 shows the principle of Invitrogen Neutralizing Antibody ELISA for SARS-CoV-2. To evaluate the assay specificity and sensitivity, SARS-CoV-2 PCR (+) and PCR (–) samples were analyzed using SARS-CoV-2 Neutralizing Ab ELISA Kit (Figure 5) and performance was compared against competitor ELISA (Figure 6).
Figure 4. The fundamental principle of Invitrogen Neutralizing Antibody ELISA for SARS-CoV-2.
Click image to enlarge
Figure 5. Specificity and sensitivity of Neutralization Ab ELISA assay. Human serum samples were screened with PCR and validated to minimize false positives. To establish a calibrator for cut-off level of 20% neutralization, ELISA was performed on 114 PCR (+) and 12 PCR (–) (control) samples using SARS-CoV-2 Neutralizing Ab ELISA Kit to determine whether all PCR (–) samples are below the calibrator cut-off level.
Click image to enlarge
Figure 6. Comparison of Invitrogen Human SARS-CoV-2 Neutralizing Ab ELISA and competitor ELISA. SARS-CoV-2 surrogate Virus Neutralization Test (sVNT) and conventional VNT were performed using SARS-CoV-2 Neutralizing Ab ELISA Kit and other supplier’s ELISA. Data shows a strong correlation (rs=0.949) of Invitrogen ELISA to competitor’s ELISA and Plaque Reduction Neutralization Test (PRNT).
SARS-CoV-2 multiplex serology assays
ProcartaPlex Ig Total (Up to 15-plex including variants)
The proteins that serve as primary antigens to stimulate an immune response producing IgA, IgM, and IgG antibodies during SARS-CoV-2 infection include the nucleocapsid (N), the spike (S) protein, and sub-regions of the spike protein such as the receptor binding domain (RBD) and the S1 regions. The Nucleocapsid (N) protein has the highest homology (90%) between SARS-CoV-1 and SARS-CoV-2 [4]. Serology test kits available during the early phase of the SARS-CoV-2 pandemic were developed to detect antibodies against the Nucleocapsid, which displayed significant cross-reactivity, and thus higher false positive readings for subjects exposed to SARS-CoV-1 [4]. The SARS-CoV spike (S) protein assembles into a trimerized structure to form a crown-like (hence corona) appearance and is composed of a S1 and S2 subunit. Within S1, the receptor binding domain (RBD), which is located in the C-terminal subdomain, has higher identity (74%) between SARS-CoV and SARS-CoV-2 than the N-terminal domain, consistent with the view that SARS-CoV-2 may use ACE2 as its receptor for entry into host cells like SARS-CoV [5]. The RBD has been identified as one of the immunodominant sites of the SARS-CoV-2 spike protein, with antibodies against the spike protein correlating well with neutralization. In addition, it is important to test serologic cross-reactivity with endemic and seasonal coronaviruses to rule out false-positive results.
The ProcartaPlex Human Coronavirus Ig Total Panel, 11plex enables screening of four SARS-CoV-2 antibodies, mainly Spike trimer, S1 subunit, RBD and Nucleocapsid (Figure 7), six coronavirus strains, viz., SARS-CoV-1, MERS and 4 common cold coronaviruses (CoV-NL63, CoV-KHU1, CoV-229E, CoV-OC43) (Figure 8), and one negative control in a single well using Luminex xMAP technology. The panel offers high correlation with SARS-CoV-2 PCR (+) and PCR (–) samples and specificity with no false positive results when tested with pre-pandemic samples (Figure 9).
In addition, four variants can be plexed with this 11-plex panel to create a 15-plex assay. The four variant proteins include the variants originating from the UK (B.1.1.7) α, South Africa (B.1.351) β, Brazil (P.1) γ, and the delta variant (B.1.617.2). Simultaneous detection of anti-SARS-CoV-2 antibodies and related coronavirus antibodies in one assay can save time to provide a complete, holistic data set using plasma or serum samples.
Click image to enlarge
Figure 7. Screening of human samples for SARS-CoV-2 antigens. Human serum samples from 39 Covid PCR (+) and 168 healthy PCR (–) (controls) were screened for four SARS-CoV-2 antigens, viz., Spike timer, S1, RBD and Nucleocapsid using ProcartaPlex Human Coronavirus Ig Total Panel, 11plex. Results indicate that the antibody levels for these four antigens corresponded to the expected results of high antibody levels for PCR (+) and low antibody levels for PCR (-) samples.
Click image to enlarge
Figure 8. Screening of human samples for common cold coronaviruses. Human serum samples from 39 Covid PCR (+) and 168 healthy PCR (–) (controls) were screened for four common cold coronaviruses, viz., CoV-NL63, CoV-HKU1, CoV-229E and CoV-OC43 using ProcartaPlex Human Coronavirus Ig Total Panel, 11plex. These results highlight the ability of this ProcartaPlex 11-plex panel to also assess the relevance of common cold coronaviruses within a single assay.
Click image to enlarge
Figure 9. Benchmark comparison of Invitrogen ProcartaPlex Human Coronavirus Ig 11-plex panel to competitors’ assays. Human serum samples from 110 healthy controls collected in 2016 and 2017 prior to the COVID-19 pandemic were screened. The Ig levels for four SARS-CoV-2 antigens, viz., Spike timer, S1, RBD and Nucleocapsid were measured using ProcartaPlex Human Coronavirus Ig Total Panel, 11plex and two different supplier’s kits. Data showed that all these control samples were below cutoff values for the 4 antigens in the panel indicating no false positives. While data from 12 of these samples were above the cutoff values in other suppliers’ assays indicating ~10% false positives (data not shown).
Neutralizing Antibody 6-plex Panel
The ProcartaPlex Human SARS-CoV-2 Variants Neutralizing Antibody Panel, 6plex enables screening of six neutralizing anti-SARS-CoV-2 antibodies—original wild-type and five variants B.1.1.529 (o), B.1.617.2 (δ), P.1 (γ), B.1.351 (β), and B.1.1.7 (α) in a single well (Figure 10). This serological assay is designed with SARS-CoV-2 wild type or variant proteins conjugated to the bead. Samples or controls are added where neutralizing antibodies will bind to the proteins. This is a competitive assay where the detector antibody is a biotinylated ACE-2 that will bind to any unbound protein. Streptavidin-phycoerythrin (PE) is added and the signal is indirectly proportional to the amount of specific neutralizing antibody present. Negative controls will give the highest MFI values. Figure 11 shows screening of neutralizing antibodies against SARS-CoV-2 variants after vaccination.
Click image to enlarge
Figure 10. The fundamental principle of Invitrogen ProcartaPlex 6-plex Neutralizing Antibody panel for SARS-CoV-2.
Click image to enlarge
Figure 11. Screening of human samples for SARS-CoV-2 vaccine-induced neutralizing antibodies against SARS-CoV-2 variants. Human serum samples from SARS-CoV-2 vaccinated patients were collected after dose 1, 2 and 3. Six neutralizing antibodies against SARS-CoV-2 variants, viz., original wild-type (WT) and five variants—B.1.1.529 (o), B.1.617.2 (δ), P.1 (γ), B.1.351 (β), and B.1.1.7 (α) were measured in a single well using ProcartaPlex Human SARS-CoV-2 Variants Neutralizing Antibody Panel, 6plex
Omicron (B.1.1.529)
In addition to the Neutralizing Antibody 6-Plex panel, we also offer SARS-CoV-2 Spike Omicron (B.1.1.529) Neutralizing Antibody Human ProcartaPlex Simplex Kit. This assay enables the measurement of the neutralizing potential of antibodies towards the variant B.1.1.529 (o) in plasma and serum.
Overview of SARS-CoV-2
Pathogen biology
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for the COVID-19 pandemic, belongs to the family of coronaviruses. It is an enveloped, positive-sense, single-stranded RNA virus. The genome of ~30 kilobases contains several open reading frames (ORFs) that encode four structural proteins, namely Spike (S), Envelope (E), Membrane (M), and Nucleocapsid (N), along with a diverse range of non-structural proteins.
Understanding the pathogen biology of SARS-CoV-2 is crucial in developing effective diagnostic tools, vaccines, and therapeutics. The virus enters host cells by binding to the angiotensin-converting enzyme 2 (ACE2) receptor on the cell surface. This receptor recognition is mediated by the spike (S) protein on the viral surface. Once inside the host cell, the viral RNA is released and serves as a template for viral replication and transcription. The virus then assembles new viral particles and is released from the infected cell, leading to the spread of infection.
Deciphering the viral replication pathways from host cell functions poses a challenge as viruses manipulate cellular machinery upon infection, altering the cellular environment to favor virus production.
Host response and cytokine storm
The host's response to SARS-CoV-2 infection encompasses a wide range of interactions and signaling events, influencing both innate and adaptive immune responses. This intricate interplay holds significant implications for human health studies. Infection by SARS-CoV-2 can result in an increase in cytokine levels, also known as a cytokine storm, and is considered to be one of the major causes of acute respiratory distress syndrome (ARDS) and multiple-organ failure. This cytokine storm, or cytokine release syndrome (CRS), is characterized by an imbalance in the cytokine network towards a pro-inflammatory response combined with an insufficient anti-inflammatory response, resulting in a loss of immune system homeostasis.
Currently, the treatment of SARS-CoV-2 infection focuses on palliative care, as respiratory failure from ARDS remains the primary cause of mortality [1]. Recent research suggests that managing the immune-mediated inflammatory cytokine response could prove beneficial. In severe cases, this response is often referred to as cytokine release storm or syndrome (CRS), which can lead to hyper-inflammation, multi-organ failure, and ultimately death. Notably, research indicates a significant variation in immune response factors among individuals, with some displaying stronger early defenses that prevent progression to severe cases. Understanding the cellular and biochemical variances in the innate and adaptive immune response is therefore crucial for patients experiencing asymptomatic, mild, or severe CRS symptoms [2, 3].
Learn more about cytokine storms
Learn more about inflammation and cytokine release syndrome
SARS-CoV-2 ELISA serology assays
We provide a variety of SARS-CoV-2 ELISA kits to measure Ig antibodies, neutralization antibodies and viral-related proteins. Invitrogen ELISA kits for popular targets such as SARS-CoV-2 Spike (Trimer), RBD, Nucleocapsid etc. are listed in Table 1.
Learn more about ELISA kits and components
Popular SARS-CoV-2 protein targets and ELISA performance data
Table 1. View our ELISA kits for the following popular targets:
Ig ELISA for serum and plasma
The Human SARS-CoV-2 Spike (Trimer) Ig ELISA kits are designed to measure the amount of Ig antibodies bound to SARS-CoV-2 Spike (Trimer). A trimerized Spike protein is pre-coated in the wells of the supplied microplate. Samples and controls, including a high control that can be used as a standard, are then added into these wells and bind to the immobilized (capture) Spike protein. The wells are washed, and anti-Ig conjugated to HRP are added and will bind to any captured antibodies. The wells are washed, and a substrate solution is added that reacts with the enzyme complex to produce measurable signal. The intensity of this signal is directly proportional to the concentration of antibody present in the original specimen.
Invitrogen SARS-CoV-2 ELISA kits are highly specific and sensitive. Figure 1 shows the principle of Invitrogen Ig Antibody ELISA for SARS-CoV-2. To demonstrate the specificity and sensitivity of Ig ELISAs, we screened SARS-CoV-2 PCR (+) and PCR (–) samples using Human SARS-CoV-2 Spike (Trimer) Ig Total ELISA Kit (Figure 2) and compared the performance to other supplier’s SARS-CoV-2 ELISA (Figure 3).
Figure 1. The fundamental principle of Invitrogen Ig Antibody ELISA for SARS-CoV-2.
Click image to enlarge
Figure 2. Specificity and sensitivity of Ig ELISA assay. Human serum samples were screened with PCR and validated to minimize false positives. The Ig levels were measured in 39 PCR (+) and 160 PCR (–) (control) samples using Human SARS-CoV-2 Spike (Trimer) Ig Total ELISA Kit and calibrator cut-off level was calculated. All PCR (+) samples are above the calibrator (dotted line) while all PCR (–) are below the calibrator. Two PCR (+) samples in the lower graph showed low antibody levels and were confirmed negative using another serology assay (data not shown).
Click image to enlarge
Figure 3. Comparison of Invitrogen Human SARS-CoV-2 Spike Ig ELISA and competitor ELISA. The Ig levels were measured in PCR (+), healthy and control samples using Human SARS-CoV-2 Spike (Trimer) Ig Total ELISA Kit and other supplier’s ELISA that also measures Ig antibodies against Spike S1 subunit antigen. Borderline healthy control samples were also included. Data was compared and discrepancies were found in the competitor ELISA where a healthy sample showed a false positive and 3 PCR (+) samples showed negative or borderline (indicated with red arrows). Evidently, there was a better correlation to the expected PCR results with our Invitrogen ELISA.
Neutralizing antibody ELISA for serum and plasma
The SARS-CoV-2 Neutralizing Ab ELISA kit is designed to measure the neutralizing portion of anti-SARS-CoV-2 antibodies. A receptor binding domain (RBD) protein is pre-coated in the wells of the supplied microplate. Samples or the positive control are added into the wells. Neutralizing antibodies present in a sample that specifically bind to RBD will block any interaction with biotinylated ACE2 that is subsequently added. Signal from SA-HRP is indirectly proportional to the amount of specific neutralizing antibody present.
Figure 4 shows the principle of Invitrogen Neutralizing Antibody ELISA for SARS-CoV-2. To evaluate the assay specificity and sensitivity, SARS-CoV-2 PCR (+) and PCR (–) samples were analyzed using SARS-CoV-2 Neutralizing Ab ELISA Kit (Figure 5) and performance was compared against competitor ELISA (Figure 6).
Figure 4. The fundamental principle of Invitrogen Neutralizing Antibody ELISA for SARS-CoV-2.
Click image to enlarge
Figure 5. Specificity and sensitivity of Neutralization Ab ELISA assay. Human serum samples were screened with PCR and validated to minimize false positives. To establish a calibrator for cut-off level of 20% neutralization, ELISA was performed on 114 PCR (+) and 12 PCR (–) (control) samples using SARS-CoV-2 Neutralizing Ab ELISA Kit to determine whether all PCR (–) samples are below the calibrator cut-off level.
Click image to enlarge
Figure 6. Comparison of Invitrogen Human SARS-CoV-2 Neutralizing Ab ELISA and competitor ELISA. SARS-CoV-2 surrogate Virus Neutralization Test (sVNT) and conventional VNT were performed using SARS-CoV-2 Neutralizing Ab ELISA Kit and other supplier’s ELISA. Data shows a strong correlation (rs=0.949) of Invitrogen ELISA to competitor’s ELISA and Plaque Reduction Neutralization Test (PRNT).
SARS-CoV-2 multiplex serology assays
ProcartaPlex Ig Total (Up to 15-plex including variants)
The proteins that serve as primary antigens to stimulate an immune response producing IgA, IgM, and IgG antibodies during SARS-CoV-2 infection include the nucleocapsid (N), the spike (S) protein, and sub-regions of the spike protein such as the receptor binding domain (RBD) and the S1 regions. The Nucleocapsid (N) protein has the highest homology (90%) between SARS-CoV-1 and SARS-CoV-2 [4]. Serology test kits available during the early phase of the SARS-CoV-2 pandemic were developed to detect antibodies against the Nucleocapsid, which displayed significant cross-reactivity, and thus higher false positive readings for subjects exposed to SARS-CoV-1 [4]. The SARS-CoV spike (S) protein assembles into a trimerized structure to form a crown-like (hence corona) appearance and is composed of a S1 and S2 subunit. Within S1, the receptor binding domain (RBD), which is located in the C-terminal subdomain, has higher identity (74%) between SARS-CoV and SARS-CoV-2 than the N-terminal domain, consistent with the view that SARS-CoV-2 may use ACE2 as its receptor for entry into host cells like SARS-CoV [5]. The RBD has been identified as one of the immunodominant sites of the SARS-CoV-2 spike protein, with antibodies against the spike protein correlating well with neutralization. In addition, it is important to test serologic cross-reactivity with endemic and seasonal coronaviruses to rule out false-positive results.
The ProcartaPlex Human Coronavirus Ig Total Panel, 11plex enables screening of four SARS-CoV-2 antibodies, mainly Spike trimer, S1 subunit, RBD and Nucleocapsid (Figure 7), six coronavirus strains, viz., SARS-CoV-1, MERS and 4 common cold coronaviruses (CoV-NL63, CoV-KHU1, CoV-229E, CoV-OC43) (Figure 8), and one negative control in a single well using Luminex xMAP technology. The panel offers high correlation with SARS-CoV-2 PCR (+) and PCR (–) samples and specificity with no false positive results when tested with pre-pandemic samples (Figure 9).
In addition, four variants can be plexed with this 11-plex panel to create a 15-plex assay. The four variant proteins include the variants originating from the UK (B.1.1.7) α, South Africa (B.1.351) β, Brazil (P.1) γ, and the delta variant (B.1.617.2). Simultaneous detection of anti-SARS-CoV-2 antibodies and related coronavirus antibodies in one assay can save time to provide a complete, holistic data set using plasma or serum samples.
Click image to enlarge
Figure 7. Screening of human samples for SARS-CoV-2 antigens. Human serum samples from 39 Covid PCR (+) and 168 healthy PCR (–) (controls) were screened for four SARS-CoV-2 antigens, viz., Spike timer, S1, RBD and Nucleocapsid using ProcartaPlex Human Coronavirus Ig Total Panel, 11plex. Results indicate that the antibody levels for these four antigens corresponded to the expected results of high antibody levels for PCR (+) and low antibody levels for PCR (-) samples.
Click image to enlarge
Figure 8. Screening of human samples for common cold coronaviruses. Human serum samples from 39 Covid PCR (+) and 168 healthy PCR (–) (controls) were screened for four common cold coronaviruses, viz., CoV-NL63, CoV-HKU1, CoV-229E and CoV-OC43 using ProcartaPlex Human Coronavirus Ig Total Panel, 11plex. These results highlight the ability of this ProcartaPlex 11-plex panel to also assess the relevance of common cold coronaviruses within a single assay.
Click image to enlarge
Figure 9. Benchmark comparison of Invitrogen ProcartaPlex Human Coronavirus Ig 11-plex panel to competitors’ assays. Human serum samples from 110 healthy controls collected in 2016 and 2017 prior to the COVID-19 pandemic were screened. The Ig levels for four SARS-CoV-2 antigens, viz., Spike timer, S1, RBD and Nucleocapsid were measured using ProcartaPlex Human Coronavirus Ig Total Panel, 11plex and two different supplier’s kits. Data showed that all these control samples were below cutoff values for the 4 antigens in the panel indicating no false positives. While data from 12 of these samples were above the cutoff values in other suppliers’ assays indicating ~10% false positives (data not shown).
Neutralizing Antibody 6-plex Panel
The ProcartaPlex Human SARS-CoV-2 Variants Neutralizing Antibody Panel, 6plex enables screening of six neutralizing anti-SARS-CoV-2 antibodies—original wild-type and five variants B.1.1.529 (o), B.1.617.2 (δ), P.1 (γ), B.1.351 (β), and B.1.1.7 (α) in a single well (Figure 10). This serological assay is designed with SARS-CoV-2 wild type or variant proteins conjugated to the bead. Samples or controls are added where neutralizing antibodies will bind to the proteins. This is a competitive assay where the detector antibody is a biotinylated ACE-2 that will bind to any unbound protein. Streptavidin-phycoerythrin (PE) is added and the signal is indirectly proportional to the amount of specific neutralizing antibody present. Negative controls will give the highest MFI values. Figure 11 shows screening of neutralizing antibodies against SARS-CoV-2 variants after vaccination.
Click image to enlarge
Figure 10. The fundamental principle of Invitrogen ProcartaPlex 6-plex Neutralizing Antibody panel for SARS-CoV-2.
Click image to enlarge
Figure 11. Screening of human samples for SARS-CoV-2 vaccine-induced neutralizing antibodies against SARS-CoV-2 variants. Human serum samples from SARS-CoV-2 vaccinated patients were collected after dose 1, 2 and 3. Six neutralizing antibodies against SARS-CoV-2 variants, viz., original wild-type (WT) and five variants—B.1.1.529 (o), B.1.617.2 (δ), P.1 (γ), B.1.351 (β), and B.1.1.7 (α) were measured in a single well using ProcartaPlex Human SARS-CoV-2 Variants Neutralizing Antibody Panel, 6plex
Omicron (B.1.1.529)
In addition to the Neutralizing Antibody 6-Plex panel, we also offer SARS-CoV-2 Spike Omicron (B.1.1.529) Neutralizing Antibody Human ProcartaPlex Simplex Kit. This assay enables the measurement of the neutralizing potential of antibodies towards the variant B.1.1.529 (o) in plasma and serum.
Additional resources for SARS-CoV-2 Immunoassays
Related instruments
References
- Mehta P., McAuley D.F., Brown M., et. Al. COVID-19: consider cytokine storm syndromes and immunosuppression. Lancet, 2020. 395(10229): 1033-1034.
- Huang C., Wang Y., Li X., et. al. Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. Lancet, 2020. 395(10223): 497-506.
- Wang D, Hu B, Hu C, Zhu F, Liu X, Zhang J, Wang B, Xiang H, Cheng Z, Xiong Y, Zhao Y, Li Y, Wang X, Peng Z. Clinical Characteristics of 138 Hospitalized Patients With 2019 Novel Coronavirus-Infected Pneumonia in Wuhan, China. JAM,. 2020. 323(11): 1061-1069.
- Okba N.M.A., Müller M.A., Li W., et. al. Severe Acute Respiratory Syndrome Coronavirus 2-Specific Antibody Responses in Coronavirus Disease Patients. Emerg Infect Dis, 2020. 26(7): 1478-1488.
- Jaimes J.A., André N.M., Chappie J.S., et. al. Phylogenetic Analysis and Structural Modeling of SARS-CoV-2 Spike Protein Reveals an Evolutionary Distinct and Proteolytically Sensitive Activation Loop. J Mol Biol, 2020. 432(10): 3309-3325.
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