Anti b19 screening for safe cellular blood products for at risk patients
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Anti-B19 screening for safe cellular blood products for at–risk patients. Harry Bos on behalf of Project Group Parvo B19 Safe Blood Components (Theo Cuijpers, Marco Koppelman, John Jongerius, Maarten Koot, et al.). SoGAT XVIII, USA, May 24-25th, 2005. Parvovirus B19.

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Anti b19 screening for safe cellular blood products for at risk patients

Anti-B19 screening for safe cellular blood products for at–risk patients

Harry Bos on behalf of Project Group Parvo B19 Safe Blood Components (Theo Cuijpers, Marco Koppelman, John Jongerius, Maarten Koot, et al.)

SoGAT XVIII, USA, May 24-25th, 2005


Parvovirus b19
Parvovirus B19 at–risk patients

  • Small non enveloped virus; 23 nm.

  • Single-stranded DNA genome; approx. 5500 nucl.

  • Encoding 3 proteins:

    • VP1: ± 5% of capsid

    • VP2: ± 95% of capsid

    • NS1: non-structural for viral replication

  • Erythrovirus

    • Highly thropic for erythroid progenitor cells

  • Infected cells undergo lysis caused by expression of NS1

    • Decline in red blood cell count and haemoglobin

SoGAT, May 25th, 2005


Clinical manifestation of infection
Clinical manifestation of infection at–risk patients

  • Epidemiology

    - Seroprevalence in adults world-wide approx. 50-80%

    - Seroconversion rate for adults is about 0.8% per year

  • Healthy individuals

    - Erythema infectiosum (fifth disease)

    - Chills

    - Headache

    - Rash

    - No clinical symptoms

SoGAT, May 25th, 2005


Risk groups for b19 infections
Risk groups for B19 infections at–risk patients

  • Women during second trimester of pregnancy

    - Intra uterine fetal death (10%)

    - Hydrops fetalis (3%)

  • Patients with congenital or acquired haemolytic anaemia

  • Cellular immunodeficient patients

    - Aplastic crisis

    - Prolonged bone marrow damage and aplasia

    - Bone marrow transplantation

SoGAT, May 25th, 2005


Health council of the netherlands
Health Council of the Netherlands* at–risk patients

  • B19 may cause serious complications in risk groups

  • B19 can be transmitted by blood tranfusion

  • B19 infection in healthy individuals:

    - Formation of protective Antibodies

    - Sometimes persistance of B19 virus for some time

  • B19 safe blood components from:

    - Donors with IgG Antibodies

    - Interval at least six months

  • *) Council of the Netherlands Bloodproducts and Parvovirus B19. 2002; publication no. 2002/07

SoGAT, May 25th, 2005


Health council of the netherlands1
Health Council of the Netherlands at–risk patients

  • Plasma products

  • The risk-group approach can not be used for plasma products

  • because of their large-scale production and use.

  • Approach for blood derivatives:

  • - Lowering the load in manufacturing pools by NAT screening and removal of high load units (>5 x 106 IU/ml)

SoGAT, May 25th, 2005


Estimation of demand of parvo safe blood products in the netherlands
Estimation of demand of Parvo safe blood products in the Netherlands

  • Erythrocyte concentrates 54,800 (8%)

  • Plasma 9,950 (8%)

  • Thrombocyte concentrates 11,000 (22%) equivalent to

  • 56,000 donor units

  •  Delivery of thrombocyte concentrates is the determing factor in the number of donors to be screened for B19

  •  Total numbers of donors to be screened: 250,000

  • = 50% of the donorpopulation

SoGAT, May 25th, 2005


B19 igg antibody screening
B19 IgG antibody screening Netherlands

  • Screening Assay:

    - Biotrin Parvovirus B19 Sandwich ELISA

    - α-VP2 IgG

    - FDA cleared B19 ELISA

  • Automation of the screening assay:

    - Automatic pipetting device: Tecan Genesis

    - ELISA back-end processor: Ortho Summit Processor

SoGAT, May 25th, 2005


Od co for reactive parvo b19 result 25 500 donations first time tested
OD/CO for reactive Netherlandsα-Parvo B19 result 25,500 donations first time tested

Reactive OD/CO > 1.0 80.1 %

Reactive OD/CO > 1.5 78.7%

SoGAT, May 25th, 2005


Status anti parvo b19 testing april 1st 2005
Status Anti-parvo B19 Testing April 1st, 2005 Netherlands

  • Reactive OD/CO > 1.5 75.4 %

  • First time tested

    • Realised number 244,572

    • Reactive (OD/CO > 1.5) 184,468

  • Firist and second time tested

    • Reactive (OD/CO > 1.5) 124,932

  • Desired number first and second time reactives 125,000

SoGAT, May 25th, 2005


Status demand of parvo safe cellular blood products in the netherlands april 1th 2005
Status demand of Parvo safe cellular blood products in the Netherlands, April 1th, 2005

Explicit demand of hospitals:

Division Northeast < 10

Division Southeast 15

Division Southwest 16

Division Northwest 10-20 thrombocyte concentrates weekly

) The Parvo status of the product is printed standard on the label of the bloodproduct

SoGAT, May 25th, 2005


Limitations of the b19 screening method
Limitations of the B19 screening method Netherlands, April 1th, 2005

A) False positive reactions

- 1 donor: low pos OD/CO ratio

  • Persistance of B19 virus in infected donors for a period of

  • more than six months

  • - 2 donors: high pos OD/CO ratio, low B19 DNA load

  • Remark: Blood products will probably not be infectious, because the high titer of B19 antibodies will neutralise the virus present in a low concentration.

SoGAT, May 25th, 2005


Persistent b19 infection b
Persistent B19 infection (B) Netherlands, April 1th, 2005

Donor 1

SoGAT, May 25th, 2005


Alternative screening based on natural history of infection
Alternative Screening Based on Natural History of Infection. Netherlands, April 1th, 2005

  • Further R&D on the testing system in place.

  • Follow up of acute infected donors found in plasma-screening

  • Sensitive B19 NAT of 5000 donations 6 month bleeding (2nd IgG anti-Parvo screening). % False positive rate IgG test?

  • Possible Consequences

  • Extension of the 6 month-interval period to the

  • length of the observed viremic period

  • Parvo-NAT screening of donation for safe product

  • IgM and IgG screening of donation for the safe product

  • Or combination of these approaches

SoGAT, May 25th, 2005


Projects under consideration to improve the screening method
Projects under consideration to improve the screening method Netherlands, April 1th, 2005

  • - Determine the false positive rates of the different brands of IgG anti-Parvo assays

  • - Determine the in vitro neutralising effect of B19 antibodies (e.g. α-VP1, α-VP2, α-NS1), using cohort of follow up samples of acute infected individuals.

SoGAT, May 25th, 2005


Conclusions
Conclusions Netherlands, April 1th, 2005

Parvo B19 safe blood components can be derived from donors with IgG Antibodies tested at an interval of at least six months.

Parvo B19 safe cellular blood products can be in case of a transfusion used for risk groups for B19 infection. This approach will reduce serious complications due to transfusion related B19 infection.

Further research is in consideration to improve the screening method.

SoGAT, May 25th, 2005


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