The Generative Brain

Protocole standard prion (PSP), French standard protocol for judging prion inactivation products for reusable medical devices (ANSM, v2011 and v2018)

The protocole standard prion (PSP) is the French laboratory method that a manufacturer must follow to show that a cleaning, disinfection or sterilisation product removes and truly inactivates prions on reusable medical devices such as surgical instruments. It sits under health ministry instruction DGS/RI3/2011/449 of 1 December 2011, which requires a total prion inactivation step on reusable devices depending on the risk of the procedure and of the patient; the ANSM publishes the list of products that pass, and hospitals choose from that list. Two versions exist. PSP v2011 needs one animal study with the hamster strain 263K. PSP v2018, published on 15 May 2018, adds a second animal study with a human type strain and in vitro tests on at least three strains using sensitive amplification methods. The switch to v2018 has been postponed three times; after an HCSP opinion published on 30 October 2023, v2011 stays valid until 31 December 2026. In June 2026 the v2018 list held one product, a washer-disinfector detergent, against nine entries on the v2011 list. Information only, not medical, legal, regulatory or infection control advice.

Key facts

  • The PSP is the standard test protocol manufacturers use to measure how well a product or process removes or inactivates prions (in French, ATNC) on reusable medical devices after invasive procedures, and the ANSM publishes the list of products and processes that meet the version in force.
  • Instruction DGS/RI3/2011/449 of 1 December 2011 updated French rules for reducing prion transmission during invasive procedures, applied from 1 January 2012, replaced the circular of 14 March 2001, and has two annexes: six technical sheets and the 2010 WHO classification of tissues by infectivity.
  • The ministry describes the instruction as requiring a total inactivation step on reusable devices according to the risk level of the procedure and of the patient, and names the PSP as the French reference method for judging any product that claims activity against prions.
  • The instruction lists two reference procedures, each a one hour immersion at room temperature: 1N sodium hydroxide, or bleach (sodium hypochlorite) at 20,000 ppm. The PSP v2018 uses these plus steam at 134 C under 3 bar for 18 minutes as comparators, noting that the instruction treats this steam cycle as giving major but not total inactivation.
  • PSP v2011, dated December 2011 and issued under the health ministry and the medicines agency, requires one in vivo study (strain 263K in Syrian hamsters) and at least two in vitro strains (263K plus a bovine or human strain), without imposing an analytical method.
  • PSP v2018 requires two in vivo studies, strain 263K in hamsters and a human type prion strain chosen to represent a significant public health problem such as sporadic CJD MM1 or variant CJD, each with at least 12 animals per treatment; the hamster study runs 12 to 18 months.
  • In vitro, v2018 requires at least three strains (263K, the human strain used in vivo, and a bovine or human strain), a sensitivity of at least 10^-4 for strains also tested in animals, and an amplification method such as PMCA or RT-QuIC with a sensitivity of at least 10^-6 for strains tested only in vitro. Both the treated wire and the run-off liquid are tested so that simple removal can be told apart from inactivation.
  • Under v2018 a product counts as a total inactivator only if, for both animal strains, its reduction in infectivity is at least equal to that of two comparator treatments and strictly greater than that of a partial efficacy control, and it is inactivating in vitro on every strain tested. Products that act by sequestering, aggregating or fixing proteins on surfaces are not admissible.
  • All tests use the same model: a surgical grade stainless steel wire 0.16 to 0.3 mm thick and 3 to 5 mm long, coated with infected brain homogenate, dried, treated, and then implanted in the animal brain or analysed in vitro.
  • To be listed, a manufacturer sends the ANSM a declaration form, the instructions for use and the full study reports with raw data; under v2018 a standardised synthetic report from the manufacturer is published when a product is listed.
  • PSP v2018 was meant to replace v2011 from 15 May 2021. The deadline moved to 30 June 2023 (test length, development time, COVID-19), then to autumn 2023 pending an HCSP opinion, then to 31 December 2026, after which only v2018-compliant products are due to be listed.
  • In its November 2023 message to regional health agencies the ministry said no product meeting v2018 and hospital needs was on the market, several dossiers were still in testing, and a moratorium had suspended laboratory prion experiments in France for safety reasons.
  • The HCSP opinion behind the 2026 date is dated 7 September 2023 and was put online on 30 October 2023; the ANSM cites it by the later date. It recommends keeping the instruction 449 measures, keeping and strengthening screening of patients and at-risk procedures, and pushing the v2018 deadline back by at least three years to the end of 2026. It also covers exposure accidents in prion laboratories and the risk from propagons.
  • On 10 June 2026 the ANSM announced the first product entered on the v2018 list. The June 2026 list names TFD Premium, also sold as Neodisher MediClean Premium, made by FB Product: a class I detergent used at 1 percent in a washer-disinfector cycle holding 55 C for 10 minutes.
  • The June 2026 v2011 list has nine entries from five makers: three detergents or detergent disinfectants (Ecolab, Sodel, Dr. Weigert), four Steris entries (one detergent and three detergent plus low temperature steriliser combinations, two of them no longer sold) and two STERRAD low temperature sterilisers from Advanced Sterilization Products.
  • A 2020 EFS study funded by the ANSM tested six marketed products described as approved by the French agency on the 263K hamster model and found that some failed against variant CJD prions on steel wires; the authors concluded that 263K is not a reliable guide for validating vCJD decontamination. The paper does not name the products or mention the PSP by name.

Timeline

  1. 1994France starts specific rules on prion risk in reprocessing reusable medical devices.
  2. 1999WHO infection control guidelines for TSEs set out the reference decontamination methods later used as PSP comparators.
  3. 2001Health ministry circular DGS/5C/DHOS/E2/2001/138 on prion precautions in care.
  4. 2011PSP v2011 published under the health ministry and the medicines agency (dated 15 December 2011).
  5. 2011Instruction DGS/RI3/2011/449 issued; it applies from 1 January 2012 and replaces the 2001 circular.
  6. 2016ANSM starts updating the PSP.
  7. 2018ANSM publishes PSP v2018 after hearings, public consultation and an opinion of its benefit-risk committee.
  8. 2020EFS study reports that marketed products approved on the 263K model can fail against vCJD prions.
  9. 2021Transition extended to 30 June 2023.
  10. 2023Transition extended again pending an HCSP opinion; no v2018-compliant product on the French market.
  11. 2023HCSP opinion on prion exposure accidents and invasive care adopted; put online 30 October 2023.
  12. 2023Transition extended to 31 December 2026; regional health agencies told by the DGS and DGOS.
  13. 2026Later HCSP opinion replaces the 2023 opinion; put online 13 August 2026. Its summary covers only exposure accidents and does not mention the PSP or the 2026 date (full text not read).
  14. 2026ANSM announces the first product on the PSP v2018 list.
  15. 2026ANSM PSP reference page last updated.
  16. 2026Planned end of PSP v2011 validity.
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