DETECTION OF IgM ANTIBODY WITH RECOMBINANT ANTIGEN rSAG1 FOR TOXOPLASMOSIS DIAGNOSIS / 中国血吸虫病防治杂志

ABSTRACT

Objective To establish rSAG1-IgM-ELISA with purified rSAG1 fusion protein for immunodiagnosis of toxoplasmosis. Methods The rSAG1 fusion protein was purified by Ni 2+ column. The ELISA plate was coated with different concentrations of rSAG1, reacted with pooled positive and negtive human sera. Goat anti-human IgM conjugated to horseradish peroxidase was used as the second antibody. The appropriate detecting condition of the rSAG1-IgM-ELISA assay was determined by orthogonal experiment. The reproducibility, sensitivity and specificity of the assay were assessed. Thirty-five IgM-positive and 57 IgM-negative human sera detected by the imported IgM-ELISA kit were detected with the rSAG1-IgM-ELISA. Results The purity of rSAG1 was above 90%. The appropriate detecting condition was that the coated rSAG1 was 2 5 ?g/ml, the human serum was in 1∶100 dilution, and the second antibody was in 1∶4000 dilution. The coefficient of variation (CV) value of IgM-positive and IgM-negative pooled sera were 13 8% and 7 7% respectively. The inhibition rate of the assay was 62 0% The positive correspondence rate and negative correspondence rate were 82 9% (29/35) and 91 2% (52/57) respectively,the total correspondence rate was 88 0%, compared with the imported IgM-ELISA kit. Conclusions The rSAG1-IgM-ELISA has high sensitivity and specificity, and good correspondence rate with the imported IgM-ELISA kit. It indicates that rSAG1-IgM-ELISA has potential value for early diagnosis of toxoplasmosis.