Pharmacological manipulation of early PrPres accumulation in the spleen of scrapie-infected mice.

In most experimental models of scrapie and in some naturally infected species, the lymphoreticular system and the spleen in particular play a major role in the pathogenesis of the disease. Previous studies demonstrated scrapie infectivity in peripheral organs from the day of infection up to the terminal stage. The discovery of the abnormal prion protein, PrPres, as a specific molecular hallmark of scrapie should permit enhanced study of scrapie pathogenesis and has some pharmacological applications. In this study, PrPres accumulation was followed day by day in peripheral organs. Four different phases were identified: the circulation of scrapie inoculum, a clearance phase, the peripheral accumulation of PrPres and a plateau phase. This kinetics was then pharmacologically modified (i) by applying the macrophage "suicide" technique to unveil the cellular types involved in scrapie pathogenesis and (ii) with anti-scrapie drugs such as polyene antibiotics, polyanions and Congo red to investigate their mode and site of action.