Assessment of prion reduction filters in decreasing infectivity of ultracentrifuged 263K scrapie‐infected brain homogenates in “spiked” human blood and red blood cells

Abstract

The use of prion-removing filters may help to reduce the risk of transfusion-transmitted vCJD. To avoid overestimation of prion removal efficiency in validation studies, it may be more appropriate to use supernates from ultracentrifugation of scrapie-infected hamster brain homogenate rather than the current standard brain homogenates.

Detection of water-soluble disease-associated PrP species in blood and brain of scrapie-infected hamster

“…This provides an effective evaluation of the efficiency with which they remove prion infectivity from blood components. Moreover, the infectivity associated with S HS was not removed by leukodepletion from whole blood and red blood cells, further confirming its soluble nature and its presumed biophysical similarity to the endogenous soluble plasma-associated infectivity [10]. This soluble S HS -associated infectivity could represent the same form of prion infectivity previously described by Gregori et al [16,17] as the portion of the TSE infectivity present in a brain spike that could not be removed during validation studies for prion removal from blood.…”

“…This close similarity of S HS to plasma enabled the recent validation of S HS as the best prion spike for validation studies on prion removal from blood-and plasma-derived products [9,10]. In fact, when used to spike manufactured human albumin and human whole blood and red blood cells, S HS was shown to be capable of mimicking the endogenous soluble infectivity of plasma or red blood cells from 263K-infected hamsters with respect to different kinds of filtration devices.…”

“…Lacroux et al [24] recently confirmed this possibility when they found that plasma from scrapie-infected sheep was still efficiently infectious after leukodepletion. Evidence-based studies have revealed that soluble prion infectivity is also present in the central nervous system and that it has a biophysical profile similar to that of the peripheral plasma-associated infectivity [5,9,10]. These studies showed that this neuronal infectivity is associated with an aqueous fraction of scrapie-infected hamster brain homogenate termed S HS .…”

“…The infectivity titer in the 263K-infected S HS , P HS , S LS , and plasma preparations that were used in this study was estimated using an endpoint titration bioassay (9,10). Hamsters used in the bioassay were housed at the animal facility of the Istituto Superiore di Sanità under the supervision of the Service for Biotechnology and Animal Welfare of the institute, which adheres to national and international regulations on animal welfare.…”

Variant CJD

“…71 Although estimates of the infectious titer of blood from patients with vCJD are low 71,72 it has been demonstrated that blood and components from asymptomatic individuals appear capable of transmitting vCJD-infection following blood transfusion. Major efforts have been made toward the development of screening assays and diagnostic tests for vCJD in blood [72][73][74][75] ; the development and implementation of prion reduction filters [76][77][78][79][80] ; understanding the numbers of individuals who may be sub-clinically affected with vCJD 39,[81][82][83][84] and what this really means in terms of further spread of vCJD. There are significant challenges to be faced in each of these areas, which are further confounded by the absence of an available treatment for vCJD.…”