A partially purified specific antigen of Parastrongylus cantonensis for immunodiagnosis of human parastrongyliasis

Abstract

Three distinct protein peaks were obtained when the crude extract of Parastrongylus cantonensis adult worms was passed through a Sephacryl S-200 HR column. The antigenic components of the three isolated peak fractions were studied by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and immunoblot analysis using serum from a patient with parasitologically confirmed parastrongyliasis. The 31-kDa diagnostic antigen of P. cantonensis was demonstrated mainly in the first elution profile. The band of 31-kDa antigenic component reacted strongly with parastrongyliasis serum. A semipurified fraction from the first elution peak was used in the indirect enzyme-linked immunosorbent assay (ELISA) for detecting specific antibody to the 31-kDa antigen of P. cantonensis. A total of 200 serum samples was used in the study. Of these, 25 sera were from patients with parastrongyliasis. Fifteen sera each were from patients with gnathostomiasis, toxocariasis, filariasis, paragonimiasis and cysticercosis. The control group consisted of 100 serum samples from normal healthy individuals. The sensitivity and specificity of the ELISA were 100% and 98.87%, respectively. This Sephacryl S-200 fraction containing an immunodominant antigen of 31 kDa, appears promising as a diagnostic reagent in the ELISA for human parastrongyliasis.