Interlaboratory evaluation of two enzyme-linked immunosorbent assay kits for the determination of crustacean protein in processed foods.

The labeling of foods containing material derived from crustaceans such as shrimp and crab is to become mandatory in Japan because of increases in the number of allergy patients. To ensure proper labeling, 2 novel sandwich enzyme-linked immunosorbent assay (ELISA) kits for the determination of crustacean protein in processed foods, the N kit (Nissui Pharmaceutical Co., Ltd, Ibaraki, Japan) and the M kit (Maruha Nichiro Holdings, Inc., Ibaraki, Japan), have been developed. Five types of model processed foods containing 10 and/or 11.9 microg/g crustacean soluble protein were prepared for interlaboratory evaluation of the performance of these kits. The N kit displayed a relatively high level of reproducibility relative standard deviation (interlaboratory precision; 4.0-8.4% RSDR) and sufficient recovery (65-86%) for all the model processed foods. The M kit displayed sufficient reproducibility (17.6-20.5% RSDR) and a reasonably high level of recovery (82-103%). The repeatability relative standard deviation (RSDr) values regarding the detection of crustacean proteins in the 5 model foods were mostly < 5.1% RSDr for the N kit and 9.9% RSDr for the M kit. In conclusion, the results of this interlaboratory evaluation suggest that both these ELISA kits would be very useful for detecting crustacean protein in processed foods.

[Simultaneous detection of hepatitis B virus surface antigen (HBsAg) and hepatitis C virus (HCV) related antibodies by an immunochromatographic test method using synthesized oligonucleotide-bound protein probes, OligoFast].

An immunochromatographic test using synthesized oligonucleotide-bound protein probes, OligoFast (Nissui Pharmaceutical Co., Ltd., Tokyo) was developed and evaluated for simultaneous detection of hepatitis B surface antigen (HBsAg) and antibodies related with hepatitis C virus (HCV). The color development of colloidal gold was visually read and easily interpretable for the respective antigen and antibody, positive or negative. When the performance panels of Boston Biomedica Inc. (BBI) for HBsAg and HCV-related antibodies were assayed, the results indicated; first, the most positive specimens with 1.2 IU/ml of HBsAg were correctly determined as positive, and secondly, all the positive specimens for HCV-related antibodies confirmed with Ortho RIBA 3.0 were consistently determined as positive and additional two undetermined specimens were interpreted as positive. However, when the seroconversion panel of BBI for hepatitis B virus (HBV) infection, the seroconversion was delayed 20 to 30 days when compared to HBV DNA detection. When the clinical serum specimens were tested in comparison with the automated AxSYM (Abbott Laboratories, Abbott Park, IL, U.S.A.), both sensitivity and specificity were estimated to be 100% for HBsAg, and 91.3% and 99.0% for HCV-related antibodies, respectively. With these results, we can conclude that this newly developed immunochromatographic test will be applicable to simultaneous detection of HBsAg and HCV-related antibodies in a single device, and will be expected to be widely applied in a clinical setting.