Development of a model immunofiltration assay using a conjugate based on horseradish peroxidase

The aim of the study was to optimize the conditions for a model immunoassay in the immunofiltration format using diagnostic reagents based on horseradish peroxidase. Residual blood serum samples from patients in the red zone with a verified diagnosis of a new coronavirus infection were used as positive sera, and blood sera obtained before 2019 were used as negative samples. The procedure of immunofiltration analysis was carried out using a pool of negative and positive blood sera. Studies were carried out to optimize the analysis procedure and increase the significant characteristics of the test. Results. It has been shown that the addition of sodium dodecyl sulfate to a final concentration of 50 M in the substrate buffer makes it possible to achieve a higher analytical signal and a stable result 10 minutes after the end of the analysis procedure. Such conditions of immunofiltration analysis as dilutions of the diagnostic reagent, the volume of the introduced sample and the amount of the S-protein of the coronavirus applied to the nitrocellulose membrane were optimized. It has been determined that using immunofiltration analysis it is possible to detect antibodies against the coronavirus S-protein in a dilution of a serum sample of more than 1/1000. The results of immunofiltration analysis reproduce the results of ELISA.