SARS-CoV-2 (COVID-19) IgA ELISA Kit
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SARS-CoV-2 (COVID-19) IgA ELISA Kit is an indirect ELISA for the qualitative detection of IgA class antibodies against SARS-CoV-2 (COVID-19) in human plasma and serum samples.
- Colorimetric readout - 450 nm - Works on any standard plate reader
- Easy results interpretation
View Alternative Names
Immunoglobulin alpha-2 heavy chain, Immunoglobulin alpha-2 heavy chain BUT
Reactivity data
Product details
SARS-CoV-2 (COVID-19) IgA ELISA Kit (ab277286) is intended for the qualitative determination of IgA class antibodies against SARS-CoV-2 in human serum or plasma (citrate, heparin) to support the diagnosis of COVID-19 disease and constitutes a supplement to direct pathogen detection. In addition, serology can be used to collect epidemiological information on the prevalence of SARS-CoV-2.
Microtiter plates are coated with specific antigens to bind corresponding antibodies of the sample. After washing the wells to remove all unbound sample material a horseradish peroxidase (HRP) labelled conjugate is added. This conjugate binds to the captured antibodies. In a second washing step unbound conjugate is removed. The immune complex formed by the bound conjugate is visualized by adding Tetramethylbenzidine (TMB) substrate which gives a blue reaction product. The intensity of this product is proportional to the amount of specific antibodies in the sample. Sulfuric acid is added to stop the reaction. This produces a yellow endpoint color. Absorbance at 450/620 nm is read using an ELISA Microtiter plate reader.
Antibody Isotypes and State of Infection:
| Serology | Significance |
| IgM |
Characteristic of the primary antibody response. High IgM titer: → suggests a current or very recent infection. |
| IgG |
Follows IgM production. Characteristic of the secondary antibody response. May persist for several years. High IgG titer with low IgM titer: → may indicate past infection. |
| IgA |
Produced in mucosal linings throughout the body (⇒ protective barrier). Usually produced early in the course of the infection. |
Diagnostic Specificity:
The diagnostic specificity is defined as the probability of the assay of scoring negative in the absence of the specific analyte. SARS-CoV-2 infections emerged in December 2019 in Wuhan, China. The expected prevalence values for German and US blood donor panels from before December 2019 therefore amount to 0 %. The determined positive results correspond to a specificity of 98.26 % (95 %-confidence interval: 93.86 % - 99.79 %).
| Sample panel | No. patients (n) | Positive | Equivocal | Negative | Specificity | 95% CI |
| Blood donors Germany | 66 | 0 | 0 | 66 | 100% | |
| Blood donors US | 50 | 2 | 1 | 47 | 95.92% | |
| Total | 116 | 2 | 1 | 113 | 98.26% | 93.86%-99.79% |
Diagnostic Sensitivity:
The diagnostic sensitivity is defined as the probability of the assay of scoring positive in the presence of the specific analyte. 42 samples from 25 patients tested positive for SARS-CoV-2 RNA by RT-PCR were tested.
| Days post symptom onset | No. samples (n) | Positive | Equivocal | Negative | Sensitivity (Eqv excluded) |
| 0-5 | 13 | 1 | 0 | 12 | 7.69% |
| 6-8 | 10 | 4 | 1 | 5 | 44.44% |
| 9-11 | 10 | 4 | 1 | 5 | 44.44% |
| greater than 12 | 9 | 8 | 1 | 0 | 100% |
Interferences:
Three clinical samples exhibiting differing reactivities were tested for interference with each substance listed in the Table below: a positive, a negative, and an equivocal sample. All samples exhibited a change of signal less than 15 % when tested with each potential interferant.
| Interferent | Conc. tested |
| Albumin | 60 mg/mL |
| Bilirubin conjugated | 0.4 mg/mL |
| Bilirubin unconugated | 0.4 mg/mL |
| Cholesterol | 4 mg/mL |
| Hemoglobin | 10 mg/mL |
| Triglycerides | 15 mg/mL |
Cross Reactivity:
105 samples with antibody activities to potentially cross reacting parameters (including antibodies to several respiratory pathogens) were tested to evaluate the cross reactivity of the assay.
| Samples +ve to antibodies to | No. of samples (n) | Positive | Equivocal | Negative |
| Adenovirus | 10 | 0 | 1 | 9 |
| Parainfluenzavirus | 9 | 0 | 0 | 9 |
| Candida albicans | 8 | 0 | 0 | 8 |
| Bordetella pertussis | 9 | 0 | 0 | 9 |
| Influenzavirus A | 9 | 0 | 0 | 9 |
| Influenzavirus B | 10 | 0 | 1 | 9 |
| Enterovirus | 10 | 0 | 0 | 10 |
| Respiratory syncytial virus | 10 | 0 | 0 | 10 |
| Chlamydia pneumoniae | 9 | 0 | 0 | 9 |
| Legionella pneumoniae | 8 | 0 | 0 | 8 |
| Mycoplasma pneumoniae | 9 | 0 | 0 | 9 |
| Haemophilus influenzae | 3 | 0 | 0 | 3 |
| Other Coronavirus | 1 | 0 | 0 | 1 |
Cross reactions with antibodies to adenovirus and influenzavirus cannot be excluded. Cross reactivity with other human coronaviruses should be considered for result interpretation.
Precision
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Properties and storage information
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Supplementary information
This supplementary information is collated from multiple sources and compiled automatically.
Biological function summary
The nucleocapsid protein of SARS-CoV-2 is involved in maintaining the integrity of the viral genome. It forms a ribonucleoprotein complex with the viral RNA which is necessary for viral replication. The nucleocapsid protein is integral in the formation of the virus's structure and assists in the assembly and release of new virus particles. It interacts with other viral proteins contributing to the stability and functioning of the virus.
Pathways
The nucleocapsid protein is involved in the viral life cycle and replication pathways. The protein participates in the RNA replication and transcription complex working alongside proteins such as the RNA-dependent RNA polymerase and other non-structural proteins. These interactions within the pathways are essential for the efficient replication of the viral genome and production of new viral particles which are key steps in the virus's lifecycle.
Product protocols
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Target data
Publications (1)
Recent publications for all applications. Explore the full list and refine your search
Nutrients 14: PubMed36014873
2022
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Species
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