Verification and application of indirect ELISA for quantitative detection of content of antibody IgG against Shigella flexneri 2a and Shigella sonnei 0-specific polysaccharide in human serum / 中国生物制品学杂志

ABSTRACT

@#Objective To verify an ELISA method for quantitative detection of antibody IgG against Shigella flexneri 2a and Shigella sonnei O-specific polysaccharide in human serum and use it to detect human serum samples before and after immunization with flexneri and sonnei dysentery bivalent vaccine.Methods The reference serum and quality control serum were mixed in a certain proportion to prepare 10 serum samples of different concentrations(numbered as S1～S10),which was determined continuously for 6 d by the indirect ELISA quantitative detection method provided by the enterprise,and the recovery rate and coefficient of variation(CV) were calculated.The reference serum content with a recovery rate of CV less than 20% was used as the limit of quantitation(LOQ).The serum sample S10 and reference serum were measured by the same method for 6 d,3 times of repeated test a day,and the CV was calculated;The inhibition rate of serum to polysaccharide was calculated by using the competitive inhibition ELISA with reference serum.The reference serum was detected by the method provided by the enterprise,the linear range was determined,the curve equation was obtained,and the correlation coefficient(R~2) was calculated.The verified method was used to detect 1 842 human serum samples before and after immunization with flexneri and sonnei dysentery bivalent vaccine.Results The recovery rates of Shigella flexneri 2a and Shigella sonnei polysaccharide antibody IgG in 10 serum samples were 73.21%～222.68% and 83.67%～123.56%,respectively;CV of precision verification between and within tests were all less than 30%;The inhibition rates of reference serum on 100 μg/mL Shigella flexneri 2a and Shigella sonnei polysaccharide were 85.95% and 88.42%,respectively;The linear ranges of Shigella flexneri 2a and Shigella sonnei polysaccharide antibody IgG were 0.05～0.125 and 0.025～0.125 EU/mL,with the R~2 not less than 0.99,and the LOQ were 0.050 and 0.025 EU/mL,respectively.The content of antibody IgG in serum after immunization with flexneri and sonnei dysentery bivalent vaccine was significantly higher than that before immunization.Conclusion The ELISA quantitative detection method provided by the enterprise had good accuracy,precision and specificity,and might be used for the detection of clinical serum of dysentery vaccine.