Abstract:

Obiective To establish the method of preparing the freeze- dried reference substance of indirect hemagglutination assay kit for the diagnosis of schistosomiasis japonica. Methods Schistosoma japonicum antibodies, IgG γ-globulins were purified by 33.3% saturated ammonium sulfate, then filtered through DEAE exchange chromatography, and finally the protein concentration was tested by Lowry method. It was prepared as positive standard reference substance after calibration and validation. The sera from healthy rabbits after processing and calibration were freeze- dried as negative standard reference substance. The stability in laboratory storage conditions of 100 copies of negative and positive of freeze-dried reference substance were detected respectively after 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, and 24 months by ELISA and IHA. Results The titers of freeze-dried reference substance met the requirements after the test by two kinds of method, and its positive coincidence rate and negative coincidence rate were all 100% . Conclusion The negative and positive freeze- dried sera prepared by this method can be utilized as the reference substance of indirect hemagglutination assay kit, and their stabilities meet the requirements of storing for two years.

Key words: Schistosoma japonicum, Negative and positive freeze-dried reference substance, Stability