Final answer:
Indirect ELISA detects antibodies in patient serum by attaching antigens to a microtiter plate, while agglutination and precipitin reactions signify the presence of antibodies and antigens in a solution.
Explanation:
Indirect ELISA is a technique used to detect antibodies in patient serum. It involves attaching known antigens to the bottom of a microtiter plate, allowing patient antibodies to bind to them, and then using a secondary enzyme-conjugated antibody to detect the primary antibodies. The color produced from the enzyme-chromogen reaction can quantify the amount of antigen-specific antibodies present.
Agglutination is the process of antibodies clumping together cells or particles, and it can be used as an indicator of the presence of antibodies against bacteria or red blood cells. Precipitin reactions in vitro involve the visible formation of antigen-antibody complexes, indicating the presence of antibodies and antigens in a solution.
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