The Trichinella spiralis IgG ELISA test is a qualitative enzyme immunoassay for the detection of antibodies to Trichinella, in samples of human serum or plasma. This test is intended to be performed by trained medical technologists only. Trichinosis, the infection caused by the nematode Trichinella spiralis, is acquired by ingestion of raw or undercooked meats (primarily pork). Although the nematode may be found in a wide variety of animals worldwide, the domestic pig is the primary source of infection in developed nations. Serology has also been an important tool in the diagnosis of trichinosis for several decades. Various methodologies; such as ELISA, latex agglutination (LA), indirect hemagglutination (IHA) and bentonite flocculation (BFT) have been used.
Although various classes of antibodies have been detected, no single class has shown superior diagnostic ability over the others. BFT has been the method of choice for serology but suffers from nonspecific reactions, some lack of sensitivity (measurable antibodies often do not appear until 3 to 4 weeks after infection) and difficulty in performing the test. Recently, an excretory-secretory (ES) antigen has been purified from the larvae of infected pigs. This antigen has a high degree of specificity for T. spiralis and has been used in several large scale studies. The microwells are coated with Trichinella Excretory/Secretory (ES) antigen. During the first incubation with the diluted patients’ sera, any antibodies which 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 (tetramethylbenzidine or TMB) is 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.