Evaluation on the applied effect of a recombinant cysteine proteinase of Clonorchis sinensis in serological survey

Objective To evaluate the value of a recombinant cysteine proteinase of Clonorchis sinensis(rCsCP) applied to the serological survey of clonorchiasis,using the antigen in an enzyme linked immunosorbent assay(ELISA) to detect the levels of serum specific antibody in the crowd from an epidemic area and comparing it with C.sinensis adultworm crude antigen(CsCAA).Methods An administrative village in Nanhai district of Foshan city was determined as the survey site,C.sinensis eggs in the villagers' stool were examined by the improved Kato-Katz's thick slide method and sera were taken from some cases.The levels of serum specific antibody were detected by enzyme linked immunosorbent assays with rCsCP and CsCAA as the coated antigens(rCsCP-ELISA and CsCAA-ELISA),respectively,and the results by different methods were statistically analyzed and compared.Results Of 97 persons who received serum examination,the egg positive rate in stool was 60.8%,the positive rate of CsCAA-ELISA 75.3% and that of rCsCP-ELISA 76.3%.The antibody positive rates were higher than the egg positive rate(P0.05),while the difference between the positive rates of ELISAs with two different antigens was not statistically significant(P0.05).The coincidence rates of CsCAA-ELISA and rCsCP-ELISA with the stool examination were 56.7% and 55.7%,respectively,while the coincidence rate of two ELISAs was 82.5%.Of 59 egg-positive cases,the positive rates of CsCAA-ELISA and rCsCP-ELISA were both 76.3%,while,of 38 egg-negative cases,the positive rates of CsCAA-ELISA and rCsCP-ELISA also reached 73.7% and 76.3%,respectively.Conclusion An enzyme linked immunosorbent assay with the recombinant cysteine proteinase of C.sinensis(rCsCP) as the coated antigen,used to detect the specific IgG levels of the crowd in an epidemic area,showed a high coincidence rate with the detection results using the adultworm crude antigen,but similarly difficult to differentiate the current infection and the past infection.