Neutralization of botulinum neurotoxin by a human monoclonal antibody specific for the catalytic light chain.
BACKGROUND
Botulinum neurotoxins (BoNT) are a family of category A select bioterror agents and the most potent biological toxins known. Cloned antibody therapeutics hold considerable promise as BoNT therapeutics, but the therapeutic utility of antibodies that bind the BoNT light chain domain (LC), a metalloprotease that functions in the cytosol of cholinergic neurons, has not been thoroughly explored.


RESULTS
We used an optimized hybridoma method to clone a fully human antibody specific for the LC of serotype A BoNT (BoNT/A). The 4LCA antibody demonstrated potent in vivo neutralization when administered alone and collaborated with an antibody specific for the HC. In Neuro-2a neuroblastoma cells, the 4LCA antibody prevented the cleavage of the BoNT/A proteolytic target, SNAP-25. Unlike an antibody specific for the HC, the 4LCA antibody did not block entry of BoNT/A into cultured cells. Instead, it was taken up into synaptic vesicles along with BoNT/A. The 4LCA antibody also directly inhibited BoNT/A catalytic activity in vitro.


CONCLUSIONS
An antibody specific for the BoNT/A LC can potently inhibit BoNT/A in vivo and in vitro, using mechanisms not previously associated with BoNT-neutralizing antibodies. Antibodies specific for BoNT LC may be valuable components of an antibody antidote for BoNT exposure.
Adekar
Sharad P
SP
Lankenau Institute for Medical Research, Wynnewood, Pennsylvania, United States of America.
Takahashi
Tsuyoshi
T
Jones
R Mark
RM
Al-Saleem
Fetweh H
FH
Ancharski
Denise M
DM
Root
Michael J
MJ
Kapadnis
B P
BP
Simpson
Lance L
LL
Dessain
Scott K
SK
D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D001904:Botulinum Antitoxin / Q000276:immunology*; D001905:Botulinum Toxins / Q000037:antagonists & inhibitors* / Q000276:immunology*; D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000235:genetics; D007700:Kinetics; D009447:Neuroblastoma; D011994:Recombinant Proteins / Q000276:immunology; D012703:Serotyping
D000911:Antibodies, Monoclonal; D001904:Botulinum Antitoxin; D007147:Immunoglobulin Light Chains; D011994:Recombinant Proteins; D001905:Botulinum Toxins