Reliable detection of marine biotoxins is a critical requirement for any effective biotoxin monitoring program, requiring any analytical technique to be properly validated. The Neogen rapid test kit for the detection of paralytic shellfish toxin (PSTs) was successfully validated in both single lab and inter-lab validations for use in oysters, offering rapid (within 20 min) on farm results. The test was used in Tasmania to reduce business risk, (i.e. frequent testing of shellfish that can rapidly accumulate PST within a week) and employed in South Australia for regulatory purposes (low frequency of PST detection in this region).
A key factor influencing the suitability of antibody based rapid test kits is the PST profile present in the sample to be analysed. The term PST profile describes the relative concentrations of different PST analogues that might be present in each seafood sample. These profiles differ between toxic algal species, different seafood species and their tissues. Not all PST analogues are equally detected by the antibodies of different test kits (quantified as the % cross-reactivity). These cross-reactivities are critical for ensuring reliable detection across different combinations of PST analogues that might be present in shellfish.
To determine if the AquaBC rapid test kit is suitable replacement for routine monitoring, a full validation for each seafood tissue matrix would normally be conducted to determine the probability of detection curve (probability of detection across a range of PST concentrations) for multiple PST profiles, ideally followed by an inter-laboratory validation (as was conducted for the Neogen test). However, a full validation study requires repeat testing of hundreds of samples and is therefore expensive. From our previous work with the Neogen test kit, we have identified some key performance indicators that would allow for a quick initial assessment of the new AquaBC test kit, using much reduced sample numbers. These small pilot trials would include testing the most commonly encountered PST profiles (i.e. which PST toxin analogues are present) and their relative concentrations (i.e. can we reliably detect the presence of PST at the regulatory level without obtaining too many positive results at PST levels below concern?). Rather than conducting a full validation, this project will provide an initial assessment of these parameters in regard to the PST profiles commonly encountered in TAS, SA and NSW. Should this assessment be positive, a full follow up validation may be recommended.
