Plant-Derived Monoclonal Antibody Against Botulinum Neurotoxin: Pharmacokinetic Evaluation in a Mouse Model

Background: Botulism, caused by Clostridium botulinum neurotoxins (BoNT/A and B), is a life-threatening disorder requiring rapid, effective therapeutic intervention. Plant-produced monoclonal antibodies offer a scalable alternative to conventional antibody manufacturing. This study evaluated the pharmacokinetic properties of 1B18 monoclonal antibody (mAb), transiently expressed in and extracted from tobacco (Nicotiana benthamiana), which binds both BoNT/A and BoNT/B with high affinity. Methods: Male ICR mice (n = 12/group) received intravenous or intramuscular doses of plant-produced 1B18 mAb (25–100 µg), with serum samples collected across pre-dose and 13 post-administration timepoints (totaling 14 timepoints). Antibody quantification was performed using ELISA and LC–MS/MS to assess consistency and reliability. Results and Discussion: Following intravenous administration, the mAb exhibited prolonged elimination with half-lives ranging from 40.4 to 56.0 h (at 25 and 50 µg doses). ELISA-derived absolute bioavailability was approximately 99% and 85% at the 50 and 100 µg intramuscular doses, demonstrating efficient systemic absorption comparable to intravenous administration. ELISA was used as the primary quantitative method for pharmacokinetic evaluation, whereas LC-MS/MS provided exploratory, sequence-specific support for the observed concentration–time profiles. Because many LC-MS/MS-derived concentrations were below the mathematically estimated LOQ, cross-platform comparisons were interpreted cautiously and were not considered evidence of analytical equivalence or interchangeability. Conclusions: These findings demonstrate that plant-derived 1B18 mAbs possess favorable pharmacokinetic profiles and high bioavailability, supporting their potential as long-acting therapeutic candidates for botulism treatment and advancing sustainable antibody production strategies.