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- Title
Immunological Characterization and Neutralizing Ability of Monoclonal Antibodies Directed Against Botulinum Neurotoxin Type H.
- Authors
Yongfeng Fan; Barash, Jason R.; Jianlong Lou; Conrad, Fraser; Marks, James D.; Arnon, Stephen S.; Fan, Yongfeng; Lou, Jianlong
- Abstract
<bold>Background: </bold>Only Clostridium botulinum strain IBCA10-7060 produces the recently described novel botulinum neurotoxin type H (BoNT/H). BoNT/H (N-terminal two-thirds most homologous to BoNT/F and C-terminal one-third most homologous to BoNT/A) requires antitoxin to toxin ratios ≥1190:1 for neutralization by existing antitoxins. Hence, more potent and safer antitoxins against BoNT/H are needed.<bold>Methods: </bold>We therefore evaluated our existing monoclonal antibodies (mAbs) to BoNT/A and BoNT/F for BoNT/H binding, created yeast-displayed mutants to select for higher-affinity-binding mAbs by using flow cytometry, and evaluated the mAbs' ability to neutralize BoNT/H in the standard mouse bioassay.<bold>Results: </bold>Anti-BoNT/A HCC-binding mAbs RAZ1 and CR2 bound BoNT/H with high affinity. However, only 1 of 6 BoNT/F mAbs (4E17.2A) bound BoNT/H but with an affinity >800-fold lower (equilibrium dissociation binding constant [KD] = 7.56 × 10(-8)M) than its BoNT/F affinity (KD= 9.1 × 10(-11)M), indicating that the N-terminal two-thirds of BoNT/H is immunologically unique. The affinity of 4E17.2A for BoNT/H was increased >500-fold to KD= 1.48 × 10(-10)M (mAb 4E17.2D). A combination of mAbs RAZ1, CR2, and 4E17.2D completely protected mice challenged with 280 mouse median lethal doses of BoNT/H at a mAb dose as low as 5 µg of total antibody.<bold>Conclusions: </bold>This 3-mAb combination potently neutralized BoNT/H and represents a potential human antitoxin that could be developed for the prevention and treatment of type H botulism.
- Subjects
BOTULINUM A toxins; ANTIDOTES; POISONS; ANTITOXINS; IMMUNOGLOBULINS; ANIMAL experimentation; BIOLOGICAL models; BOTULINUM toxin; BOTULISM; GRAM-positive bacteria; HORSES; MAMMALS; MICE; MONOCLONAL antibodies; RESEARCH funding; PREVENTION
- Publication
Journal of Infectious Diseases, 2016, Vol 213, Issue 10, p1606
- ISSN
0022-1899
- Publication type
journal article
- DOI
10.1093/infdis/jiv770