In an immunodiffusion test to diagnose histoplasmosis,a patient's serum is placed in a well in an agar plate.In a positive test,a line forms as the serum diffuses from the well and meets material diffusing from a second well.What type of test is this?
A)an agglutination reaction
B)a precipitation reaction
C)a complement-fixation test
D)an indirect ELISA test
E)a direct ELISA test

Question

Quizplus · Accepted Answer

This is a precipitation reaction where the patient's serum is reacting with material diffusing from a second well, causing the formation of a visible line. In an agglutination reaction, there would be clumping of particles visible to the naked eye. Complement-fixation tests and ELISA tests use different mechanisms to detect the presence of specific antigens or antibodies, and are not applicable in this case.

In an Immunodiffusion Test to Diagnose Histoplasmosis,a Patient's Serum Is