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An Overview Echinococcus Microwell Serum ELISA
Summary
Echinococcosis (hydatidosis) is the infection caused by cestodes of the genus Echinococcus. Humans are potential intermediate hosts and can become infected by ingesting eggs passed in the feces of an infected animal. The resulting disease is called hydatidosis, or hydatid disease.
Four species are known pathogens of the disease: E. granulosus, E. multilocularis, E. oligarthrus and E. vogeli. The infection caused by E. granulosus is referred to as cystic hydatid disease (CHD) and results in cysts in various organs, especially the liver and lungs. These cysts may become quite large and contain hundreds or thousands of scoleces called hydatid sand. The degree of antibody response to these cysts will vary depending on their location and degree of calcification. Liver cysts typically produce a higher antibody response than lung cysts. Infection due to E. multilocularis is referred to as alveolar hydatid disease (AHD), and also occurs as cysts that may spread throughout the infected tissue. Since Echinococcus eggs are not shed by infected humans, serological determination has been important in the diagnosis of hydatid disease. A number of tests have been used, including latex agglutination (LA), indirect hemagglutination (IHA), complement fixation (CF), agar gel diffusion (AGD) and enzyme linked immunosorbent assay (ELISA).
Cross reactivity between echinococcosis and cysticercosis (Taenia solium infection) will occur to some degree in this assay due to the use of crude antigen. It is recommended that any sample showing a positive result by this test be confirmed by additional testing.
Principle of Procedure
The micro test wells are coated with a crude antigen from an Echinococcus cyst. During the first incubation with the diluted patients’ sera, any antibodies that are reactive with the antigen will bind to the coated wells. After washing to remove the rest of the sample, the Enzyme Conjugate is added. If antibodies have been bound to the wells, the Enzyme Conjugate will then bind to these antibodies. After another series of washes, a chromogen (tetramethlybenzidine or TMB) and a substrate (hydrogen peroxide) are added. If the Enzyme Conjugate is present, the peroxidase will catalyze a reaction that consumes the peroxide and turns the chromogen from clear to blue. Addition of the Stop Solution ends the reaction and turns the blue color to a bright yellow color. The reaction may then be read visually or with an ELISA reader at 450 nm.
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