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Transmissibility of B19 by transfusion: evaluation of donor viremia prior to performing a linked donor-recipient study. M Busch, representing REDS-II Parvo B19 protocol team. RADAR Repository. Established from 2000-2003 in seven US cities NHLBI and CDC funded

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M Busch, representing REDS-II Parvo B19 protocol team

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M busch representing reds ii parvo b19 protocol team

Transmissibility of B19 by transfusion: evaluation of donor viremia prior to performing a linked donor-recipient study

M Busch, representing REDS-II

Parvo B19 protocol team


Radar repository

RADAR Repository

  • Established from 2000-2003 in seven US cities

  • NHLBI and CDC funded

  • Full enrollment for recipients included a pre (or peri) tx specimen and a follow-up specimen at 6-12 months

  • RADAR units (mostly RBC) were targeted to surgical patients on specific clinical services at specific hospitals

  • Enrolled recipients got both RADAR and non-RADAR units


Contents of radar repository

Contents of RADAR repository

  • Donation specimens

    • Linked to fully enrolled recipients (n=13,201)

    • Unlinked(n=99.906)

  • Recipients

    • Fully enrolled (n=3575)

    • Initially enrolled but without f/u (n=1402)

  • There are two plasma aliquots (1.8 ml in first, up to 1.8 ml in second) and one 1.5 ml frozen whole blood aliquot for each specimen


Parvovirus b19 study hypotheses

Parvovirus B19 study hypotheses

  • Phase 1:To determine the rate of low, moderate, and high titre viremia and its coexistence with IgM and IgG antibody in blood donors.

    • Assay development

    • Donor viremia study

    • Recipient seroprevalance (for susceptibility)

    • Statistical evaluation

  • Phase 2: To determine the rate of B19 transmission by DNA-positive units and correlate it with donor viral load and antibody status


  • Testing methods

    Testing methods

    • Qualitative PCR: magnetic bead capture kinetic Taqman assay- originally developed by Chiron and adapted by BSRI

    • Quantitative PCR: exact same assay - run in duplicate on an independent aliquot with quantitative standards on same run

    • Commercial EIAs (Biotrin) for IgM and IgG antibody: run in singlicate and repeated for equivocal results


    M busch representing reds ii parvo b19 protocol team

    Sensitivity Panel Testing

    Results of 3 Sensitivity Panels tested before amplification of donor samples

    Cut-off: 40 Cycle Threshold


    M busch representing reds ii parvo b19 protocol team

    Sensitivity Panel Results


    M busch representing reds ii parvo b19 protocol team

    TESTING ALGORITHM

    PARVO B-19 PCR

    CT > 45,

    Undetected

    40 <CT ≤45

    CT≤40

    NEGATIVE

    INDETERMINATE

    REACTIVE

    Internal Control

    CT ≤45

    CT > 45, Undetected

    NEGATIVE

    INVALID

    CONFIRMATORY QUANTITATIVE TESTING , in duplicate

    CT: Cycle Threshold


    M busch representing reds ii parvo b19 protocol team

    Control Chart, 100 IU/mL

    Mean+2SD

    Mean

    Mean-2SD

    Mean+/-2SD = 33.36+/-2.96; data for 56 plates (107 controls)


    Pcr results initial and repeat testing

    PCR results: initial and repeat testing

    • Total tested: 5020

    • Initially reactive: 113 (2.25%)

    • Initially indeterminate: 26 (0.52%)

    • Initially invalid: 56 (1.12%)

    • Total Completed:4982

    • Confirmed positive: 44 (0.88%)

    • Indeterminate: 5 (0.10%)

    • Invalids pending conf: 38

    Low viremia Prevalence= 0.88%; 95% CI, 0.64% - 1.2%


    Pcr and antibody results on confirmed positives

    PCR and antibody results on confirmed positives

    Viral load#CPNo abIgM and IgGIgG only

    <20 21 1(5%) 2 (10%) 18 (86%)

    20-<102 11 1(9%) 2 (18%) 8 (73%)

    102-<103 9 0 5 (56%) 4 (44%)

    103-<104 3 0 3 (100%) 0

    Total 44 2(5%) 12 (27%) 30 (68%)

    • Of 23 donations with >20 IU/ML, median was 105 IU/mL,

      (42-481); highest was 1,869 IU/mL


    M busch representing reds ii parvo b19 protocol team

    • PHASE II

    Exposed Recipients

    Non-exposed Recipients

    Test all (13,201) RADAR donation specimens linked to recipients for B19 DNA

    Random Sample

    Exposed Recipients tested for:

    Enrollment specimens: B19 IgG

    6M+ specimens: B19 DNA, IgM and IgG

    230 non-exposed recipients tested for: enrollment and 6M+ specimens: B19 DNA, IgM and IgG

    Tests Interpretation

    Tests Interpretation

    Newly acquired infection probably associated with transfusion of an infected RADAR donor unit

    =

    [RADAR + baseline] transmission rate

    Newly acquired infection not associated with transfusion of an infected RADAR donor unit

    =

    Baseline transmission rate

    Recipient infected pre-transfusion, not infected, or non-evaluable

    Recipient infected pre-transfusion, not infected, or non-evaluable

    RADAR transmission rate

    =

    {[RADAR + baseline] transmission rate} – {baseline transmission rate}


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