This is a very exciting development for a rapidly fatal disease, for which there is no known therapy. Particularly important is that the passive immunotherapy can be started relatively late in the replication phase of the disease. While not identical, both Alzheimer's and prion disorders result in accumulations of fibrils of conformationally abnormal proteins that cause neurodegeneration. If immunotherapy shows any benefit in human prion disorders, it should encourage further development of immunotherapy for Alzheimer's patients. To my knowledge, this is the only therapy which appears to "cure" scrapie in mice.

View all comments by Dave Morgan

We are pleased that White and colleagues confirm our recent findings that anti-prion antibodies have the potential to be used as prophylaxes following scrapie exposure (Sigurdsson et al., 2002; Sigurdsson et al., 2003). We were surprised that they did not quote our 2003 study that was published before their paper was accepted. In addition, the editors of Nature were well aware of our work, as we submitted it to their journal in June 2002. Together, these in-vivo studies support previous in-vitro findings and results from transgenic mice expressing anti-prion antibodies, as referenced in our articles.

By administering 2 mg of anti-prion antibodies twice a week, White et al. achieved a substantially better therapeutic effect than we did by injecting 50 μg once a week. Although extrapolation of an effective dose in a mouse to a human dose is not an exact science, 2 mg/20 g mouse corresponds to a 6 g/60 kg individual. Hopefully, a clinically...  Read more

We are pleased that White and colleagues confirm our recent findings that anti-prion antibodies have the potential to be used as prophylaxes following scrapie exposure (Sigurdsson et al., 2002; Sigurdsson et al., 2003). We were surprised that they did not quote our 2003 study that was published before their paper was accepted. In addition, the editors of Nature were well aware of our work, as we submitted it to their journal in June 2002. Together, these in-vivo studies support previous in-vitro findings and results from transgenic mice expressing anti-prion antibodies, as referenced in our articles.

By administering 2 mg of anti-prion antibodies twice a week, White et al. achieved a substantially better therapeutic effect than we did by injecting 50 μg once a week. Although extrapolation of an effective dose in a mouse to a human dose is not an exact science, 2 mg/20 g mouse corresponds to a 6 g/60 kg individual. Hopefully, a clinically effective prophylactic dose in humans will be closer to the dose we administered.

To avoid any misunderstanding, we would like to point out that in one of our effective treatment paradigms, we initiated active immunization 24 hours after scrapie infection (Sigurdsson et al., 2002). This would result in detectable anti-prion antibodies probably over a month following exposure. Although this rescue approach had a less dramatic effect than our prophylactic treatment, it cannot be interpreted as a simple neutralization of the inoculum, as stated in the White et al. paper. Rather, it indicates that the antibodies may in some way be interfering with PrP^Sc-mediated conversion of PrP^C to PrP^Sc, and/or increasing clearance of endogenous PrP^Sc.

View all comments by Blas Frangione

Having proof that established prion replication in the living situation can be controlled, there is no reason why these mouse monoclonal antibodies should not be humanized and infused into the brains of patients with human prion diseases.

View all comments by Simon Hawke