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?

Many examples of risk assessments  Milk powder and Foot-and-Mouth-Disease  No reports of disease outbreaks  pasteurisations  BSE: MBM, Fat, gelatine, waste water, etc…  Different steps – exclusion SRM critical  Severe heat inactivation  Risk of introduction animal diseases

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

Pig viruses posing a risk for porcine products in feed  Endemic virusses  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

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.

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

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

Single hit

Infectivity – Infectious Dose Max infectivity level infected animals Virus load/ml blood:  PCV DNA  FMDV 10 5,5 TCID 50  PRRSV TCID 50 Infectious Dose in susceptible animals (all animals infected with:)  PCV2 ~ TCID 50  ~10 3,5 TCID 50 FMDV (intranasal, depending on strain)  ID 50 PRRSV ~10 5,5 TCID 50

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

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

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

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

Thank you for your attention