Detection of circulating parasite antigen in murine fascioliasis by two-site enzyme-linked immunosorbent assays.
A 2-site enzyme immunoassay was developed for the detection of Fasciola hepatica antigen in the serum of fascioliasis infected mice. The assay utilizes high titer rabbit immunoglobulins to parasite excretory/secretory antigens (FhES) as capture antibody, and also as detection antibody when linked to horseradish peroxidase (HRP) or to biotin for reaction with avidin-peroxidase. The assays were compared with a conventional (antibody detection) ELISA to determine diagnostic utility. Using mean rates of detection of fascioliasis, the HRP-based antigen capture assay diagnosed the infection at 1 week postinfection and showed that circulating antigen levels are maximal 3 weeks after infection. The earliest mean diagnosis for the antibody detection and the biotin-based antigen capture ELISAs were 2 and 3 weeks postinfection, respectively. The addition of known quantities of FhES antigens to normal mouse serum gave estimates of lower limits of detectability for the HRP- and biotin-based assays of 25 ng and 0.25 ng, respectively. Routine use of the biotin-avidin system in the antigen capture test resulted in high background activity making this method insensitive.
Langley
R J
RJ
University of Puerto Rico School of Medicine, San Juan.
Hillyer
G V
GV
D000818:Animals; D000909:Antibodies, Helminth / Q000302:isolation & purification; D000947:Antigens, Helminth / Q000302:isolation & purification*; D004797:Enzyme-Linked Immunosorbent Assay; D005210:Fasciola hepatica; D005211:Fascioliasis / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C
D000909:Antibodies, Helminth; D000947:Antigens, Helminth