Parvovirus B19 Transmission in Transfusion Recipients as Assessed in a Prospective Study (TRIPS)

1. Parvovirus B19 Transmission in Transfusion Recipients as Assessed in a Prospective Study (TRIPS) Yu MW,1 Virata-Theimer ML,1 Geng Y,1 Schechterly CA,2 Colvin CA,3 Busch MP,4 Alter HJ,2 Luban NLC3 1CBER/FDA; 2CC/NIH; 3CNMC; 4BSRI SoGAT XX, Warsaw, Poland 12-13 June 2007

2. TRIPSTransfusion Related Infections Prospectively Studied • A prospective study to investigate the transfusion risk of HIV, HBV, HCV, CMV, HHV-8, EBV, and parvovirus B19 by using both NAT and serological methods for detection in a cohort of transfusion recipients participating in a linked donor-recipient study

3. Sample Testing for B19 Markers • Plasma or blood samples from 742 transfused patients enrolled between Nov 2001 and Nov 2006 were tested for: • B19 DNA, generally 4 and 8-wk post-transfusion (post-trn) samples by an in-house nested PCR (B19 DNA levels determined by limiting dilution) • Anti-B19 IgG, 12 and 24-wk post-trn samples by EIA (Biotrin) • If B19 DNA positive, • B19 DNA/anti-B19 IgM/anti-B19 IgG, pre-trn, post-trn, and associated donors’ plasma samples • DNA sequencing and phylogenetic analysis for causality assessment

4. Blood and Blood Products Transfused in TRIPS • Cryoprecipitate • Platelets • Red Blood Cells (RBC) • Fresh Frozen Plasma • Frozen Deglycerolized RBC • Liquid Plasma • Stem Cells

5. B19 DNA and Anti-B19 IgG in Recipients Post-Transfusion* Testing # Pos/ # Recipients Tested (%) B19 DNA 14/742 (1.9) Anti-B19 IgG 385/632 (60.9) * B19 DNA testing generally performed on 4 and 8 wk samples and anti-B19 IgG testing on 12 and 24 wk samples

6. 14 B19 DNA Positive Recipients • 11 (78.6%) recipients already pos for B19 DNA @ pre-trn • 6 + for low-level B19 DNA (≤ 63 IU/mL) and IgG • 3 + for DNA (≤ 2 x 107 IU/mL), IgM, and IgG • 1 + for DNA (> 2 x 1010 IU/mL) and IgM • 1 + for DNA only (63 IU/mL) • 1 recipient neg for all B19 markers @ pre- trn but pos for all @ post-trn • 1 recipient neg for all B19 markers @ pre-trn but had not seroconverted @ post-trn [the 4-wk DNA+ sample presumably false +] • 1 recipient with pending pre-trn testing

7. A B19 Infected Recipient After Transfusion Plasma B19 DNA Anti-B19 Testing (IU/mL) IgG IgM Pre-trn Neg* Neg Neg Post-trn: 2 wk 6 x 106 Neg Equiv 4 wk 20 Neg Neg 8 wk 630 Pos Pos 12 wk 140 Pos Pos 24 wk Neg Pos Neg * <20 IU/mL of B19 DNA

8. B19 Marker Testing of Donations Received by the B19 Infected Recipient Donor Trn B19 DNA Anti-B19 No. Date (IU/mL) IgG (IU/mL) IgM 1 Day 0a NTb NT NT 2 0 Neg Neg Neg 3 2 Neg Pos (15) Neg 4 2 5 x 109 Neg Neg 5 4 Neg Pos (79) Neg 6 4 Neg Pos (28) Neg a RBC from 2 donors were transfused every other day starting on Day 0; 6 RBC units were used. b Not tested; sample not available

10. Summary(I) • 1.9% (14/742) of transfusion recipients were parvovirus B19 DNA positive. • Majority (78.6%) of them were already infected with B19 before transfusion. • Only one seronegative recipient (0.1%, 1/742) was infected with B19 via transfusion. • The transmission case was confirmed by causality assessment based upon sequencing and phylogenetic analysis of the linked donor-recipient samples. • Both the donor and the recipient were infected with genotype 1 of B19.

11. Summary(II) • The recipient was infected by receiving 1 unit of RBC having 5 x 109 IUof B19 DNA/mL plasma along with another 1 RBC unit positive for anti-B19 IgG (15 IU/mL plasma) within the same day and 2 other RBC units positive for anti-B19 IgG (79, 28 IU/mL) 2 days afterward. • Total infectious dose: 5 x 1010 IU of B19 DNA in the presence of anti-B19 IgG (150 or 1220 IU; presumably containing some B19 neutralizing antibodies) • Assuming 10 mL of residual plasma per unit of RBC • Assuming the RBC unit with no available sample was negative for all B19 markers

12. Summary(III) • Transfusion transmission of B19 from an acutely infected donor to a susceptible recipient may not be a rare event. • Such a transmission might not have been detected without a prospective study.