A 15-year-old male is rushed to the emergency room with a temperature of 103degF, severe headache, and stiff neck. Upon physical examination, a petechial rash is observed all over his body. Suspecting meningitis, the physician orders a lumbar puncture, revealing gram-negative diplococci (Neisseria meningitidis) on Gram stain. The physician wishes to use a more sensitive test to confirm this as the causative agent. Which of the following tests combines features of gel diffusion and immune-electrophoresis and is applicable only to negatively charged antigens?
High-Yield Explanation
Of the many methods available for antigen and antibody detection, LA, ELISA, RIA, CIE, and COA are the most widely used.CIE was originally used for "Australia antigen" (HBsAg) but was soon replaced by RIA. For a decade, CIE was used to detect antigens in body fluids. CIE is not an easy technique. Its success depends on the control of many variables, including solid support, voltage, current, buffer, affinity and avidity of antibodies, charge on the antigen, and time of electrophoresing.