Rapid and selective detection of botulinum neurotoxin serotype-A and -B with a single immunochromatographic test strip.

Botulinum neurotoxins (BoNT) are the most potent toxins known. Produced by Clostridium botulinum, BoNTs are classified into seven, antigenically distinct serotypes, designated A-G. The toxin acts to inhibit acetylcholine release, resulting in paralysis and death. Naturally occurring foodborne disease is most often the result of improper canning of foods, while wound botulism, associated with injection drug users, is on the rise. Because of its potency, BoNTs have also been identified as targets for use by bioterrorists. The 'gold standard' of detection of BoNTs is the mouse bioassay, an expensive and time consuming test that requires specialized equipment and trained personnel. There is a need for a rapid, sensitive diagnostic for BoNTs that could be used by minimally trained personnel in the event of a foodborne outbreak or a bioterrorist threat. Here, we describe the use of a single lateral flow device (LFD) that can detect and distinguish between BoNT/A and B, two of the four serotypes that are known to intoxicate humans and together represent >80% of naturally occurring illness. The device could detect as little as 5 ng/mL of purified BoNT/A and 10 ng/mL of BoNT/B in 2% and 1% milk, respectively. In undiluted apple juice, 25 ng/mL of BoNT/A and 10 ng/mL of BoNT/B could be detected. No cross reactivity between BoNT/A and B antibodies was observed. The LFD described here is easy to use, requires no specialized training or equipment, and can identify and distinguish between BoNT/A and /B serotypes. These attributes make this rapid diagnostic device a potentially valuable tool in the fields of food safety and homeland security.