DESCRIPTION

Used for the quantitative determination of Casirivimab concentration in serum and plasma.

PRINCIPLE OF THE ASSAY

This assay employs the quantitative competitive enzyme immunoassay technique. Recombinant SARS-CoV-2 RBD has been pre-coated onto a microplate. Standards or samples are premixed with biotin-labeled antibody and then pipetted into the wells. Casirivimab in the sample competitively binds to the pre-coated protein with biotin-labeled Casirivimab. After washing away any unbound substances, Streptavidin-HRP is added to the wells. Following a wash to remove any unbound enzyme reagent, a substrate solution is added to the wells and color develops in inversely proportion to the amount of Casirivimab bound in the initial step. The color development is stopped and the intensity of the color is measured.

PRECISION

Intra-Assay Precision (Precision within an assay): <20% Three samples of known concentration were tested sixteen times on one plate to assess intra-assay precision. Inter-Assay Precision (Precision between assays): <20% Three samples of known concentration were tested in twenty four separate assays to assess inter-assay precision.

Sample		1	2	3	1	2	3
n		16	16	16	24	24	24
Mean (ng/mL)		308.1	101.5	27.8	300.6	81.2	20.3
Standard deviation		34.6	13.8	2.7	46.1	8.2	2.6
CV \(%\)		11.2	13.6	9.7	15.3	10.1	13.0

RECOVERY

The recovery of Casirivimab spiked to three different levels in human serum samples throughout the range of the assay was evaluated.

Sample	Dilution factor	Average (%)	Range (%)
Human serum (n=3)	1:10	93	80-112
	1:20	99	91-107

LINEARITY

To assess the linearity of the assay, human serum samples were spiked with high concentrations of Casirivimab and diluted with the Standard Diluent to produce samples with values within the dynamic range of the assay.

Sample	Dilution factor	Average (%)	Range (%)
Human serum (n=3)	1:2	99	89-109
	1:4	105	93-114
	1:8	102	92-111
	1:16	106	85-128