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Dr Lourens Heres

Framework for a microbiological risk assessment to assess virus safety of blood products for feed. Dr Lourens Heres. Question. How can virus safety of blood plasma be quantified? What are the critical processes to assure virus safety and which steps are insufficiently quantified?.

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Dr Lourens Heres

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  1. Framework for a microbiologicalriskassessmenttoassessvirussafetyofbloodproductsforfeed DrLourensHeres

  2. Question • How can virus safety of blood plasma be quantified? • What are the critical processes to assure virus safety and which steps are insufficiently quantified?

  3. Manyexamples of risk assessments • Milkpowderand Foot-and-Mouth-Disease • No reports of diseaseoutbreaks • pasteurisations • BSE: MBM, Fat, gelatine, waste water, etc… • Different steps – exclusion SRM critical • Severe heat inactivation • Risk of introductionanimaldiseases

  4. Risk assessment elements • Identification and characterization of the hazard • Virus: PEDV / all porcine viruses • Describing the pathways • Exposure assessment • Processes (dilution, inactivation, etc.) • consumption • Dose-respons assessment

  5. Pig viruses posing a risk for porcine products in feed • Endemicvirusses • PRRSV • PCV2 • PPV • Influenza • Hepatitis E • PEDV • Parvo-virus • … • Epidemic Virusses – OIE listed • Classical Swine Fever (CSF) • Foot and Mouth Disease (FMD) • African Swine Fever • Swine Vesicular Disease (SVD) • Aujesky‘s disease

  6. PEDV • Coronavirusses • Non-stable virus • Easily inactivated • Virus in blood through leakage through enterocites in intestine, or faecal contamination during blood collection • Infectivity in blood not (yet) shown • Infectivity of spay dried plasma not shown, and due to spray drying and storage unlikely.

  7. Collection of blood Blood from clinically healthy animals (virus dilution) Anti-coagulants centrifugation Possibilities for chemical / physical treatment filtration Spray - drying Heated to 80°C (thermal inactivation) standardisation Possibilities for chemical / physical treatment storage Inactivation during storage

  8. Risk assessment: critical • Virus control along the chain • killed animal: no more multiplication • Log-reduction steps • One or some infected animals in batch with multiple animals (pooling effect) • Heat and chemical treatments • Drying (heat treatment) • Storage • Other reduction with: splitting plasma and cells,…. • Exposure • Several grams of the product are consumed during different days

  9. Single hit

  10. Infectivity – Infectious Dose Max infectivity level infectedanimals InfectiousDose in susceptibleanimals (allanimalsinfectedwith:) PCV2 ~104-5TCID50 ~103,5 TCID50 FMDV (intranasal, depending on strain) ID50 PRRSV ~105,5 TCID50 Virus load/ml blood: • PCV2 106 DNA • FMDV 105,5 TCID50 • PRRSV 103-4TCID50

  11. Where could a quantitative risk assessment help advantages challenges Unknown parameters Uncertainty Variability Overestimation of risk • Generic approach • Understanding the principles • Structured approach

  12. Limitations for virus QMRA • The outcome will never be a zero risk. • Data from publications • PCR positive or culture infectious dose or animal infectious dose • Power of the experiment: • numbers tested: plates, wells, or animals inoculated • Amount of virus added in inactivation tests • Detection limit of diagnostic tests  uncertainty • Lab-condition versus Field-conditions • Spray driers • Number of animals

  13. Safe: to overcome the non-zero risk outcomes • Risk assessment on animal diseases shows that under the current control measures • The probility of introduction • of CSF in The Netherlands 1 per 16 years • of FMDV in the US 1 per 240 years • Of FMDV in Spain 1 per 40 years

  14. Risk assessments • University of Minnesota • Funded by National Pork Board • Risk assessment ingredients of porcine origin • Started in April • APC • Many studies, see summary next presentation J. Polo • Sonac • With NIZO and Wageningen-UR • Validation of virus safety • Different processes • Different model viruses

  15. Thankyouforyour attention

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