Standardization and application of indirect plate ELISA for immunodiagnosis of paramphistomosis in ruminants

摘要

Indirect plate enzyme-linked immunosorbent assay was standardized and evaluated for its effectiveness in immunodiagnosis of paramphistomosis in experimental and clinical cases in sheep, goat, cattle and buffaloes by using somatic whole adult antigen of Paramphistomum epiclitum and Gastrothylax crumenifer. Plate enzymelinked immunosorbent assay (ELISA) was standardized using 2 μg/ml of antigen concentration with 1:200 and 1:1,000 of sera and conjugate dilution. Indirect Plate ELISA was able to demonstrate the antibody titre at different weeks postinfection in experimental sheep. Immune response at weekly interval varied in all the four experimental sheep. A paired t-test between two types of somatic antigens (P. epiclitum and G. crumenifer) showed that experimental sheep sera showed more affinity for homologous antigen as compared to heterologous antigen. A comparison of plate ELISA on suspected field sera and fecal samples examination by sedimentation method revealed that 77 samples were found to be positive by ELISA but only seven by fecal examination. Sensitivity of plate ELISA was found to be 85.71%, whereas specificity was 23.65% indicating that this test is quite sensitive for clinical cases; an early diagnosis, however, lacks specificity. In comparison to ELISA test the sensitivity and specificity of fecal examination were 7.79 and 88%, respectively.