Receptor binding assay for paralytic shellfish poisoning toxins: optimization and interlaboratory comparison

Area of Science:

• Marine Biology
• Analytical Chemistry
• Food Safety

Background:

• Paralytic Shellfish Poisoning (PSP) poses a significant public health risk.
• Conventional mouse bioassay (MBA) for PSP toxin detection has limitations in throughput and sensitivity.
• Receptor binding assay (RBA) offers a potential high-throughput alternative.

Purpose of the Study:

• To adapt and validate a receptor binding assay (RBA) for high-throughput detection of PSP toxins using a Packard TopCount scintillation counter.
• To ensure the optimized RBA protocol maintains precision, accuracy, and sensitivity comparable to the original method.
• To demonstrate the robustness and adaptability of the RBA through an interlaboratory study.

Main Methods:

• Transfer of RBA technology to a Packard TopCount scintillation counter.
• Optimization of the RBA protocol for the TopCount instrument.
• Validation through an interlaboratory study comparing results with a Wallac MicroBeta counter and established reference standards.

Main Results:

• The modified RBA protocol demonstrated equivalent precision, accuracy, and sensitivity (limit of detection = 0.2 microg STX equiv/100 g) compared to the original.
• Interlaboratory study confirmed consistency between TopCount and MicroBeta-derived saxitoxin (STX) values.
• No observable differences were found when comparing STX reference standards from different regulatory bodies.

Conclusions:

• The optimized RBA is a robust and adaptable method for high-throughput screening of PSP toxins.
• The RBA serves as a valuable tool for early warning of PSP toxicity, especially at levels below the MBA detection limit.
• This validated RBA protocol enhances food safety by providing rapid and sensitive detection of harmful marine toxins.