212
R. Raine et al.
shellfish monitoring analyses. Alternative methods, cheaper to run and easier to use,
are required by food business operators who are expected to perform end-product
testing. Commercially available to research laboratories and the industry, the DSP
ELISA (Abraxis) immunoassay and the OKATEST PP2A assay are designed for
the detection in shellfish of OA, DTX-1,-2 and DTX-3, with the application of the
important hydrolysis step. Although the immunoassay performed initially well in
2009, serious matrix effects can be seen when the kit was used to analyse hydrolysed
samples. These matrix effects were apparent when mussel flesh samples containing
both high and low levels of DSP toxins were analysed.
The DSP OKATEST performed well in detecting both high and low concentrations of DSP toxins in mussel samples. There were no effects similar to the matrix
effects seen with the immunoassay data, and the data sets agreed with LC-MS on
both fresh and stored samples. The PP2A assay is a functional assay based on
the inhibition of the phosphatase enzyme by the OA-toxin group, which has the
ability to hydrolyse a specific substrate, yielding a product that can be detected
colorimetrically. Samples containing toxins from the okadaic acid group inhibit
the enzyme activity proportionally to the amount of toxin contained in the sample.
Based on the data achieved in this study, the enzymatic based assay (PP2A) would
be recommended in preference to the Abraxis immunoassay for rapid analysis,
screening and end product testing of DSP toxins in shellfish. It is however important
to bear in mind that the DSP OKATEST is a specific assay and therefore will
not detect other regulated lipophilic toxins such as pectenotoxins, azaspiracids and
yessotoxins. This limitation implies that the OKATEST cannot replace the multitoxin LC-MS/MS method, but could confidently be used as an end-product testing
technique by the industry in the case of shellfish solely contaminated with DSP
toxins.
Acknowledgements The authors acknowledge the assistance of Simon Kennedy (Killary Fjord
Shellfish), H. Kleivdal (Biosense Ltd.) and Sarah Cosgrove, Gary McCoy, Evelyn Keady and
Nicolas Touzet. This work could not have been possible without access to the data obtained during
the national biotoxin monitoring programme, carried out by the Marine Institute, for which the
authors are very grateful. This work is a contribution to the project WATER and was part-funded
through the INTERREG IVB Northern Periphery Programme.
References
Botana LM, Rodriguez-Vieytes M, Alfonso A, Louzao MC (1996) Phycotoxins: paralytic shellfish
poisoning and diarrhetic shellfish poisoning. In: Nollet LML (ed) Handbook of food analysis,
vol 2, Residues and other food component analysis. Marcel Dekker, New York, pp 1147–1169
Farrell H, Gentien P, Fernand L, Lunven M, Reguera B, Gonzalez-Gil S, Raine R (2012) Scales
characterising a high density thin layer of Dinophysis acuta Ehrenberg and its transport within
a coastal jet. Harmful Algae 15:36–46
Lindahl O (1986) Report of the ICES Working Group on exceptional algae blooms. ICES, C.M.
1986/L:26, Hirtshals, 17–19 Mar 1986
R. Raine et al.
shellfish monitoring analyses. Alternative methods, cheaper to run and easier to use,
are required by food business operators who are expected to perform end-product
testing. Commercially available to research laboratories and the industry, the DSP
ELISA (Abraxis) immunoassay and the OKATEST PP2A assay are designed for
the detection in shellfish of OA, DTX-1,-2 and DTX-3, with the application of the
important hydrolysis step. Although the immunoassay performed initially well in
2009, serious matrix effects can be seen when the kit was used to analyse hydrolysed
samples. These matrix effects were apparent when mussel flesh samples containing
both high and low levels of DSP toxins were analysed.
The DSP OKATEST performed well in detecting both high and low concentrations of DSP toxins in mussel samples. There were no effects similar to the matrix
effects seen with the immunoassay data, and the data sets agreed with LC-MS on
both fresh and stored samples. The PP2A assay is a functional assay based on
the inhibition of the phosphatase enzyme by the OA-toxin group, which has the
ability to hydrolyse a specific substrate, yielding a product that can be detected
colorimetrically. Samples containing toxins from the okadaic acid group inhibit
the enzyme activity proportionally to the amount of toxin contained in the sample.
Based on the data achieved in this study, the enzymatic based assay (PP2A) would
be recommended in preference to the Abraxis immunoassay for rapid analysis,
screening and end product testing of DSP toxins in shellfish. It is however important
to bear in mind that the DSP OKATEST is a specific assay and therefore will
not detect other regulated lipophilic toxins such as pectenotoxins, azaspiracids and
yessotoxins. This limitation implies that the OKATEST cannot replace the multitoxin LC-MS/MS method, but could confidently be used as an end-product testing
technique by the industry in the case of shellfish solely contaminated with DSP
toxins.
Acknowledgements The authors acknowledge the assistance of Simon Kennedy (Killary Fjord
Shellfish), H. Kleivdal (Biosense Ltd.) and Sarah Cosgrove, Gary McCoy, Evelyn Keady and
Nicolas Touzet. This work could not have been possible without access to the data obtained during
the national biotoxin monitoring programme, carried out by the Marine Institute, for which the
authors are very grateful. This work is a contribution to the project WATER and was part-funded
through the INTERREG IVB Northern Periphery Programme.
References
Botana LM, Rodriguez-Vieytes M, Alfonso A, Louzao MC (1996) Phycotoxins: paralytic shellfish
poisoning and diarrhetic shellfish poisoning. In: Nollet LML (ed) Handbook of food analysis,
vol 2, Residues and other food component analysis. Marcel Dekker, New York, pp 1147–1169
Farrell H, Gentien P, Fernand L, Lunven M, Reguera B, Gonzalez-Gil S, Raine R (2012) Scales
characterising a high density thin layer of Dinophysis acuta Ehrenberg and its transport within
a coastal jet. Harmful Algae 15:36–46
Lindahl O (1986) Report of the ICES Working Group on exceptional algae blooms. ICES, C.M.
1986/L:26, Hirtshals, 17–19 Mar 1986