Evaluation of a test for its suitability in the diagnosis of variant Creutzfeldt–Jakob disease
Posted Jun 17 2013 10:48am
Evaluation of a test for its suitability in the diagnosis of variant Creutzfeldt–Jakob disease J. K. Cooper1,*, N. Andrews2, K. Ladhani1, E. Bujaki1, P. D. Minor1Article first published online: 16 JUN 2013
Background and Objectives Evaluation of variant Creutzfeldt–Jakob disease (vCJD) diagnostic/donor screening tests is made complicated by the very limited supply of blood samples from clinically confirmed cases of vCJD. To determine appropriate access for test developers to rare Creutzfeldt–Jakob disease (CJD) blood samples, the oversight committee of the NIBSC CJD Resource Centre has developed a process and protocols detailing minimum requirements for both test sensitivity and specificity. This protocol is broadly similar to that outlined in the common technical specification (European Directive 98/79/EC).
Materials and Methods Tests are subjected to a stepwise evaluation (step 1). vCJD tissue homogenates spiked into pooled human plasma (step 2). Blood samples from animals known to be incubating (Transmissible spongiform encephalopathy) TSE disease (scrapie/Bovine Spongiform encephalopathy (BSE)-infected sheep, BSE-infected primates) and appropriate controls (step 3). Fresh or frozen plasma from normal UK blood donors and (step 4). Plasma samples from individuals with confirmed clinical stage variant CJD (transfusion transmission) or sporadic CJD (no evidence of blood transmission).
Results The assay evaluated performed with good sensitivity with vCJD-spiked tissue homogenates, poor sensitivity for ovine TSE-infected blood samples and failed with plasma from BSE-infected non-human primates and with true vCJD clinical samples.
Conclusions The test evaluated here is currently unsuitable for use in blood donor screening or diagnosis using blood.
FC5.1.1 Transmission Results in Squirrel Monkeys Inoculated with Human sCJD, vCJD, and GSS Blood Specimens: the Baxter Study
Brown, P1; Gibson, S2; Williams, L3; Ironside, J4; Will, R4; Kreil, T5; Abee, C3 1Fondation Alliance BioSecure, France; 2University of South Alabama, USA; 3University of Texas MD Anderson Cancer Center, USA; 4Western General Hospital, UK; 5Baxter BioSience, Austria
Background: Rodent and sheep models of Transmissible Spongiform Encephalopathy (TSE) have documented blood infectivity in both the pre-clinical and clinical phases of disease. Results in a (presumably more appropriate) non-human primate model have not been reported. Objective: To determine if blood components (red cells, white cells, platelets, and plasma) from various forms of human TSE are infectious.
Methods: Blood components were inoculated intra-cerebrally (0.1 ml) and intravenously (0.5 ml) into squirrel monkeys from 2 patients with sporadic Creutzfeldt- Jakob disease (sCJD) and 3 patients with variant Creutzfeldt-Jakob disease (vCJD). Additional monkeys were inoculated with buffy coat or plasma samples from chimpanzees infected with either sCJD or Gerstmann-StrÃ¤ussler-Scheinker disease (GSS). Animals were monitored for a period of 5 years, and all dying or sacrificed animals had post-mortem neuropathological examinations and Western blots to determine the presence or absence of the misfolded prion protein (PrPTSE).
Results: No transmissions occurred in any of the animals inoculated with blood components from patients with sporadic or variant CJD. All donor chimpanzees (sCJD and GSS) became symptomatic within 6 weeks of their pre-clinical phase plasmapheresis, several months earlier than the expected onset of illness. One monkey inoculated with purified leukocytes from a pre-clinical GSS chimpanzee developed disease after 36 months.
Conclusion: No infectivity was found in small volumes of blood components from 4 patients with sporadic CJD and 3 patients with variant CJD. ***However, a single transmission from a chimpanzee-passaged strain of GSS shows that infectivity may be present in leukocytes, and the shock of general anaesthesia and plasmspheresis appears to have triggered the onset of illness in pre-clinical donor chimpanzees.
Saturday, September 5, 2009 TSEAC MEETING FEBRUARY 12, 2004 THE BAXTER STUDY GSS
*** The potential impact of prion diseases on human health was greatly magnified by the recognition that interspecies transfer of BSE to humans by beef ingestion resulted in vCJD. While changes in animal feed constituents and slaughter practices appear to have curtailed vCJD, there is concern that CWD of free-ranging deer and elk in the U.S. might also cross the species barrier. Thus, consuming venison could be a source of human prion disease. Whether BSE and CWD represent interspecies scrapie transfer or are newly arisen prion diseases is unknown. Therefore, the possibility of transmission of prion disease through other food animals cannot be ruled out. There is evidence that vCJD can be transmitted through blood transfusion. There is likely a pool of unknown size of asymptomatic individuals infected with vCJD, and there may be asymptomatic individuals infected with the CWD equivalent. These circumstances represent a potential threat to blood, blood products, and plasma supplies.