Avian eyelid assay, a new diagnostic method for detecting botulinum neurotoxin serotypes A, B and E.

Based upon botulinum neurotoxins' (BoNT) mechanism of action, a novel, rapid, and sensitive avian eyelid assay was developed to detect Clostridium botulinum neurotoxin serotypes A, B and E in assay buffer and mimic samples. It showed that chick was the most optimal model of 20-selected laboratory, non-laboratory animals. The eyelid closure of chick was the indicator symptom for positive results. The detection limits achieved range from 5 to 250 mouse LD(50) for toxin types A, B, and E in a buffer system and mimic samples. No cross reactivity occurred when using staphylococcal enterotoxin B, diphtheria toxin and nerve agent sarin, but cross reactivity was obtained in more than 6h for using high dose of tetanus toxin. This cross reactivity can be differentiated by BoNT neutralization tests with a serotype-specific antiserum in parallel. The avian eyelid assay can be performed within as short a time as 0.4-6 h. We report here the development of avian eyelid assay is the second animal bioassay for the detection of toxin types A, B, and E which approaches the sensitivity of the mouse bioassay, and is simple to perform as well as rapid to yield results.