Study On Immunoassay Determination Of Bovine Colostrum Immunoglobulin

Bovine colostrum refers to the milk produced by cows within seven days of delivery. It has many nutrients, immune factors and growth factors, which are much higher than normal milk. Immunoglobulin (IgG) is the most important component of immunity. IgG has antibody activity and its structure is similar to immunoglobulin antibody. It can bind with antigens and significantly increase the T lymphocyte proliferation, macrophage phagocytosis, thereby reducing the body damage by pathogens, improving immunity. It has become an imuportant content of IgG measure colostrum.The monoclonal antibodies (McAb) were obtained by ascites in mouse after resuscitating hybridoma cell of mouse anti-bovine immunoglobulin IgG. The ascites was purificated by caprylic acid-ammonium sulfate and affinity chromatography. The McAb was subclasses of IgG1, a concentration of 46.85 mg/mL, titer of 5.12×106. Its concentration was 10.88 mg/mL, titer was 2.56×106 by the method of caprylic acid-ammonium; further purificating by method of affinity chromatography, concentration was 2.21 mg/mL, titer was 2.56 x 106, the affinity constant was 8.92 x 108, a high-affinity antibodies.A double antibody sandwich ELISA technique was established for the detection of bovine colostrums IgG by using monoclonal antibodies after purificating. The linear regression equation of the method was y = 0.4703 Igx-0.1582 (R2= 0.9926). The limit of detection was 7.06 ng/mL, intra-assay coefficient of variation was 4.52%, inter-assay coefficient of variation of 4.94%. The average recovery rate was 95.87%. The research method was used to detect 10 parts colostrum samples, IgG contents were 50.29-79.68 mg/mL with an average was 65.40 mg/mL.The linear regression equation of the method was y= 0.3822 Igx-0.0648 (R2= 0.9736). The linear range is 7.8-1000 ng/mL, the limit of detection was 7.67 ng/mL, intra-assay coefficient of variation was 8.89%, inter-assay coefficient of variation of 9.81%. The average recovery rate was 95.87%. With this study was detected 10 parts of colostrum samples, IgG content were 58.64-82.66 mg/mL, with an average was 69.66 mg/mL.Magnetic beads double sandwich ELISA method was more quickly, but the accuracy was less accurate than double sandwich ELISA method. It was suitable for rapid detection, and double antibody sandwich ELISA method is suitable for accurate detection.