SARS-CoV-2 (COVID-19) IgA ELISA试剂盒

产品详情

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:

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 %).

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.

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.

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.

Cross reactions with antibodies to adenovirus and influenzavirus cannot be excluded. Cross reactivity with other human coronaviruses should be considered for result interpretation.