Development and application of an ELISA kit for detecting human anti-capsular polysaccharides IgG of serogroup A meningococcus

ObjectiveDevelopment and application of an ELISA kit for detecting human anti-capsular polysaccharides antibody of serogroup A meningococcus.MethodsThe capsular polysaccharide(MenA PS)was purified from the supernatant by CTAB,phenol,and ethanol precipitation.MenA PS was conjugated with egg albumin(EA)by reductive amination,and purified by Sepharose CL-4B.We optimized the reaction conditions,developed the indirect ELISA method for the detection of human anti-serogroup A meningococcus polysaccharide IgG which with the purified MenA PS-EA as coating antigen.The kit was compared with SBA.ResultsThe purity of MenA PS-EA was 81.50% by high-performance liquid chromatography(HPLC).The diagnostic kit was assessed by a series of assays,the sensitivity and specificity and reproducibility(CV of positive quanlity control sera:4.26%～5.30%)were good.It has an excellent stabilization when it was deposited at 37℃ for 7 days or 4℃ for 12 months.192 sera were tested by serum bactericidal assay(SBA)and ELISA to evaluate the sensitivity and specificity of the ELISA kit,when SBA was used as the gold criteria,the sensitivity,specificity of ELISA were 96.91%,90.00% respectively.The agreement between SBA and ELISA was 95.83%,no significant difference was found between the two methods by statistics.ConclusionThe anti-MenA PS antibody ELISA kit was suitiable to measure human serum antibody level.Other anti-polysaccharid antibody ELISA kits may be developed according to this technic.