Figure 3. A point mutation in VAMP-1 renders rats resistant to TeNT peripheral neuroparalysis.

(A) Alignment showing the peptide bond cleaved by TeNT (green) in mouse and human VAMP-1 that is mutated in rats, making the protein resistant to cleavage. (B) Scheme showing the extensions of vibrissae in rats used to evaluate their whisking behavior through video recording after unilateral TeNT injection; top and bottom panels show the maximum extensions proximally and distally from the rat snout; arrows indicate the direction of vibrissa movement. (C) Representative video frames from naive and TeNT-treated rats at the indicated time points after TeNT injection (50 pg in total in a final volume of 10 μL) in the ipsilateral WP; top and bottom panels show that at day 1 ipsilateral whisking is normal with no flaccid paralysis, while vibrissae are stacked around their position at day 3 and day 7, suggestive of WP spastic paralysis. (D) Representative traces of CMAP recordings at the indicated time points after the injection of TeNT in the WP and (E) their quantification. Data are expressed as means ± SD. Black circles indicate the number of animals used in the experiment. (F) Confocal images of the ipsilateral WP musculature 1 day after TeNT injection; the lack of cl-VAMP immunostaining indicates no TeNT activity at the NMJ identified through AChR labeling (green) with fluorescent α-bungarotoxin; insets show a 3× original magnification.