Vaccines for conformational disorders.

Neurodegenerative disorders are becoming increasingly common and an ever greater healthcare burden, as the average age in Western populations rises. Many of these are conformational disorders, which are characterized by the accumulation of a host protein that undergoes a structural change increasing its beta-sheet content, rendering it toxic. The most common of these illnesses is Alzheimer's disease. Prion diseases are also conformational disorders, which are currently less common than Alzheimer's disease, however, these illnesses have no treatment and are universally rapidly fatal. The emergence of new variant Creutzfeldt-Jakob disease has raised the possibility of a large population at risk for this illness, as well as causing great concern regarding the safety of blood bank supplies. Recently, immune modulation has emerged as a highly promising therapeutic strategy for both Alzheimer's and prion diseases. We and others have demonstrated in both Alzheimer's and prion disease animal models that vaccination can dramatically improve the course of the illness. A human trial of an Alzheimer's disease vaccine using A beta1-42 was halted due to toxicity in a minority of patients (6%). However, recent data suggests that patients with a humoral response to A beta benefited cognitively from the vaccine. Toxicity in this human trial has been linked to excessive cell-mediated immunity. Novel vaccine strategies are under development for both Alzheimer's disease and prionoses which are predicted to have few or no significant side effects, while being efficacious.