Cholera toxin detection: Which test method(s) are used to assay and detect cholera toxin activity or antigen?

Introduction:
Detecting cholera toxin is important for diagnostics, research, and surveillance. Multiple immunologic and functional assays exist to demonstrate presence or activity of this AB5 enterotoxin.

Given Data / Assumptions:

• Immunoassays can detect toxin antigens with high sensitivity (RIA, ELISA).
• Cell-based assays reveal functional effects on eukaryotic cells (e.g., CHO cell morphology).
• The question asks which of the listed methods are used.

Concept / Approach:
Combine immunologic detection with bioassays that measure biologic activity. Each listed approach is established for cholera toxin detection in different contexts (lab research, reference labs, or historical methods).

Step-by-Step Solution:
Step 1: RIA uses radiolabeled antibodies to quantify antigen; historically very sensitive.Step 2: ELISA uses enzyme-linked antibodies, safer and widely used in routine settings.Step 3: CHO cell assay detects toxin-induced morphological changes reflecting cAMP-mediated effects.Step 4: Integrate: all listed methods assay presence or action of cholera toxin.

Verification / Alternative check:
Reference manuals list ELISA and cell culture assays as standard approaches; RIA appears in historical and research contexts where radioisotopes are permitted.

Why Other Options Are Wrong:

• Single-method options are incomplete since multiple methods are valid.
• None: contradicted by widespread use of these assays.

Common Pitfalls:
Assuming only one “correct” modern test exists; ignoring that activity-based assays complement antigen detection.

Final Answer:
All of the above methods.