A therapeutic panorama of the spongiform encephalopathies

The spongiform encephalopathies are a group of uniformly fatal, transmissible amyloidoses of humans and animals, for which the causative agents have not yet been precisely defined; in some respects they resemble viruses, but in other respects appear to be replicating host polypeptides. A vast array of anti-infective and other drugs has been studied in animal models, among which a few membrane-active compounds (heteropolyanions and amphotericin B) consistently prolong the course of infection, and occasionally even prevent the illness. However, because no form of therapy has any effect when given after the disease becomes clinically manifest, and because there is no laboratory test to detect preclinical infection, therapeutic efforts in humans have been predictably unsuccessful. If infection and disease turn out to depend upon the pathological accumulation of an amyloidogenic host protein, the prospects for future therapy may include genetic engineering and perhaps even the 'poisoning' of protein crystal growth.