Donor screening for parvovirus B19 antibodies:

1
Donor screening for parvovirus B19 antibodies
Reducing or eliminating the risk of
transmission SoGAT 2005 Gordon
Elliott Biotrin 93 The Rise Mount
Merrion Dublin Ireland
2
CE Marked FDA Approved

• Intact Viral particles are essential for 100
  detection of B19.
• VP1/2 antigens expressed in E.Coli do not form
  particles and give 10-20 false negative IgG
  results.

3
(No Transcript)
4

• Vireamic donations - antibody profiles
• 70 Vireamic (10e6 IU / ml) samples collected
  over 12- 18 month period
• Biotrin examined the B19 IgG and IgM levels

5
(No Transcript)
6

• Specificity of the assay
• To evaluate integrity of positive results at the
  low end of the range -
• In a panel of 500 blood donors, 350 (70) were
  IgG positive.
• 18 samples (3.5) were very low pos, index 1.1
  to 2.5
• These 18 samples were tested by confirmatory
  competitive (VP2) assay

7
Specificity of the assay
8

• Effectiveness of IgG donor screening
• Normal donor population (Netherlands) 80 are IgG
  reactive
• Of all vireamic specimens detected by plasma PCR
  screen process (10e6 IU ml), in a 12-18 month
  period, 0 true IgG positives (n70)
• Rate of parvo IgG in normal donors is possibly at
  least 80 times rate in vireamic donors
• Typically 1 in 10,000 fresh blood product units
  donated are vireamic
• (10e5 IU / ml) (greater in epidemic)
• Consider that with a 1 time IgG screen at the
  time of donation, the rate of vireamic donations
  may be better than 1 in 800,000
• (Allowing for 1 false positive in this case,
  1.43 are apparent reactive
• rate of vireamic donations would be of the order
  of 1 in 560,000)

9

• Current Sanquin Approach The two-time testing
  model is clearly successful in reducing, if not
  eliminating, high vireamic donations.
• Main drawback is requirement for time gap in
  two-time testing
• One time screening using combined tests maybe
  possible
• 1) IgG / IgM- donors (zero of 70 viraemics
  tested)
• 2) IgG / Parvo Ag- donors
• 3) IgG / PCR low donors
• Studies ongoing

10

• Use of antigen in Parvovirus IgG ELISAs
• The Biotrin assay is based on G1 (B19) VP2
  Capsid
• Is VP1 and VP2 required for detection of all
  positives?
• Does the Biotrin assay work for Genotype 2 (A6)
  and Genotype 3 (V9)?

Collaboration with Prof. JP Allain, Cambridge
Transfusion Medicine
11
Servant et al, 2002
Test 500 donors from G1 (B19) region (UK) Test
500 donors from G3 (V9) region (Ghana)
12
138 UK Donors tested (to date) using several
capsid antigens
13

• 500 Ghanaian Donors
• 100 tested to date
• Different index value distribution compared to
  European populations
• Lower Index Values overall
• But no difference in results between antigens.
• Testing of Ghanaian Children that G3 Antisera reacts with Biotrins G1 antigen
  as well as with experimental G3 antigen.
• G3 derived antibodies are detected as well as G1
  derived antibodies using the current assay.

14
An Antigen-Capture EIA for the detection of
Parvovirus B19 in human plasma.

• The first EIA for B19 Virus Detection.
• Employs a classic sandwich EIA format.
• Sensitivity of approximately 5 x 107 IU / ml.
• High specificity, no false-positive results in
  over 500 normal human plasmas tested.
• Capability to detect virus in the presence of
  high levels of anti-B19 IgM and / or IgG.
• Detection of variants e.g. V9

15
(No Transcript)
16
Sanquin Theo Cuypers Harry Bos Marco
Koppelman Cambridge JP Allain Daniel
Candotti Armen Parsyan Biotrin Shane
Kerr Amanda Corcoran