Detection of proteinous toxins using the Bio-Threat Alert system, part 4. Differences in detectability according to manufactural lots and according to toxin subtypes

In a series of experiments, we have tested the usefulness and limitations of the Guardian Bio-Threat Alert (BTA) system for detection of staphylococcal enterotoxin B (SEB), botulinum toxins (BTXs) A and B, and ricin. In this report, the BTA system has been further evaluated for toxin subtypes and the detection ability of manufactural lots of the BTA strips. The SEB strips failed to detect staphylococcal enterotoxin A, C, and D; the BTX strips generally failed to detect BTXs C, D, E, and F, but one lot showed positive results for BTXs C and D with very low sample values. Differences were observed in sample values at 1 μg/ml for all main toxins according to the different manufactural strip lots: 3.9-fold difference for SEB, 6.3-fold difference for BTX A, 10.9-fold difference for BTX B, and 6.4-fold difference for ricin. The ricin strips showed high cross reactivity toward RCA120. The BioWarfare Agent Detection Devices system showed much lower sensitivity than the BTA system for BTX and ricin (detection limit: about 10 μg/ml).