Therapeutic effect of peripheral administration of an anti-prion protein antibody on mice infected with prions.

It is generally thought that effective treatments for prion diseases need to inhibit prion propagation, protect neuronal tissues and promote functional recovery of degenerated nerve tissues. In addition, such treatments should be effective even when given after clinical onset of the disease and administered via a peripheral route. In this study, the effect of peripheral administration of an anti-PrP antibody on disease progression in prion-infected mice was examined. mAb 31C6 was administered via the tail veins of prion-infected mice at the time of clinical onset (120 days post-inoculation with the Chandler prion strain) and the distribution of this mAb in the brain and its effect on mouse survival assessed. The antibody was distributed to the cerebellums and thalami of the infected mice and more than half these mice survived longer than mice that had been given a negative control mAb. The level of PrP(Sc) in the mAb 31C6-treated mice was lower than that in mice treated with the negative control mAb and progression of neuropathological lesions in the cerebellum, where the mAb 31C6 was well distributed, appeared to be mitigated. These results suggest that administration of an anti-PrP mAb through a peripheral route is a candidate for the treatment of prion diseases.