PART 4: EVIDENCE THAT LETHAL TOXIN NEUTRALIZING PEPTIDE LT-10 BINDS TO PROTEINS AND AN EXPLORATION OF ITS POTENTIAL USE IN THE IN VITRO ASSAY OF TOXINS

Abstract

Natural lethal toxin neutralizing factor (N-LTNF), molecular weight 63.0 kDa, was isolated from opossum serum. After trypsin digestion, the active domain of N-LTNF was isolated and sequenced. A synthetic peptide consisting of 10 amino acids from the N-LTNF was designated as LT-10. N-LTNF and LT-10 inhibited the lethality of toxins from animals, plants, and bacteria when tested in mice by a non-immunological mechanism. However, the antibodies against N-LTNF and LT-10 reacted immunologically with toxins only and not with nontoxic substances. Anti-LTNF and anti-LT-10 detected toxins in an ELISA assay that were not detected by a mouse toxicity test, including cholera toxin and digoxin. Furthermore, anti-N-LTNF and anti-LT-10 failed to react immunologically with nontoxic substances, nerve growth factor and collagen. Currently, the mouse bioassay is standard practice for detection and assay of toxins. Binding affinity of anti-LT-10, measured as the ELISA detection limit, showed a linear relationship with the mouse bioassay. In addition, anti-LT-10 detects toxins that are not lethal to mice. Thus, anti-LT-10 may prove useful in assaying toxins as an alternative to mouse bioassay.

Keywords: :

• lethal toxin neutralizing factor
• ELISA
• toxin antidote
• anti-venom
• anti-toxin
• saliva