title: Evaluation of efficacy of prion reduction filters using blood from an endogenously infected 263K scrapie hamster model.
abstract: BACKGROUND
  The P-Capt prion reduction filter (MacoPharma) removes prion infectivity in model systems. This independent evaluation assesses prion removal from endogenously infected animal blood, using CE-marked P-Capt filters, and replicates the proposed use of the filter within the UK Blood Services.
  
  
  METHODS
  Two units of blood, generated from 263K scrapie-infected hamsters, were processed using leukoreduction filters (LXT-quadruple, MacoPharma). Approximately 100 mL of the removed plasma was added back to the red blood cells (RBCs) and the blood was filtered through a P-Capt filter. Samples of unfiltered whole blood, the prion filter input (RBCs plus plasma and SAGM [RBCPS]), and prion-filtered leukoreduced blood (PFB) were injected intracranially into hamsters. Clinical symptoms were monitored for 500 ± 1 day, and brains were assessed for spongiosis and prion protein deposit.
  
  
  RESULTS
  In Filtration Run 1, none of the 50 challenged animals were diagnosed with scrapie after inoculation with the RBCPS fraction, while two of 190 hamsters injected with PFB were infected. In Filtration Run 2, one of 49 animals injected with RBCPS and two of 193 hamsters injected with PFB were infected. Run 1 reduced the infectious dose (ID) by 1.467 log (>1.187 log and <0.280 log for leukoreduction and prion filtration, respectively). Run 2 reduced prion infectivity by 1.424 log (1.127 and 0.297 log, respectively). Residual infectivity was estimated at 0.212 ± 0.149 IDs/mL (Run 1) and 0.208 ± 0.147 IDs/mL (Run 2).
  
  
  CONCLUSIONS
  Leukoreduction removed the majority of infectivity from 263K scrapie hamster blood. The P-Capt filter removed a proportion of the remaining infectivity, but residual infectivity was observed in two independent processes.
authors.affiliation: Microbiology Services Division, Public Health England, Salisbury, UK.
authors.forename: Neil P
authors.initials: NP
authors.lastname: McLeod
authors.affiliation: Microbiology Services Division, Public Health England, Salisbury, UK.
authors.forename: Philip
authors.initials: P
authors.lastname: Nugent
authors.affiliation: Microbiology Services Division, Public Health England, Salisbury, UK.
authors.forename: Douglas
authors.initials: D
authors.lastname: Dixon
authors.affiliation: Microbiology Services Division, Public Health England, Salisbury, UK.
authors.forename: Mike
authors.initials: M
authors.lastname: Dennis
authors.affiliation: Microbiology Services Division, Public Health England, Salisbury, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Cornwall
authors.affiliation: NHS Blood and Transplant (NHSBT), Filton, UK.
authors.forename: Gary
authors.initials: G
authors.lastname: Mallinson
authors.affiliation: NHS Blood and Transplant (NHSBT), Cambridge, UK.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Watkins
authors.affiliation: NHS Blood and Transplant (NHSBT), Watford, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: Thomas
authors.affiliation: Microbiology Services Division, Public Health England, Salisbury, UK.
authors.forename: J Mark
authors.initials: JM
authors.lastname: Sutton
mesh_terms: D000818:Animals; D058731:Blood Safety / Q000295:instrumentation / Q000379:methods; D006224:Cricetinae; D004195:Disease Models, Animal; D004203:Disinfection / Q000295:instrumentation / Q000379:methods; D007937:Leukapheresis / Q000295:instrumentation / Q000379:methods; D018620:PrPSc Proteins; D012608:Scrapie / Q000097:blood / Q000517:prevention & control*
chemical_list: D018620:PrPSc Proteins