High-titer screening PCR: a successful strategy for reducing the parvovirus B19 load in plasma pools for fractionation.
BACKGROUND
Human parvovirus B19 (B19) is regarded as a potential risk factor for certain patient populations receiving plasma components.


METHODS
The prevalence of B19 was determined in a limited plasma donor population. Conditions for high-titer screening PCR were designed to allow the removal of plasma donations in the acute phase of infection with virus loads >or=10(7) genome equivalents per milliliter before manufacturing. Antithrombin III lots originating from screened plasma were compared to lots originating from untested plasma with respect to their B19 DNA load by a sensitive PCR assay.


RESULTS
B19 was shown to have a prevalence of about 1 per 800 plasma donations. Only a minority (1/8000) of occurrences were in the acute phase of infection. Removing plasma units with high virus load as determined by high-titer screening PCR significantly decreased peak virus loads of plasma pools for fractionation. Together with a virus-removal capacity of 10.4 log(10) of the manufacturing process, this screening resulted in a final antithrombin III product that was nonreactive for B19 on PCR.


CONCLUSIONS
Combining the strategy of high-titer screening PCR with the virus reduction capacity of the manufacturing process considerably increased the margin of B19 virus safety of antithrombin III. This strategy should have positive impact on other plasma components as well.
Weimer
T
T
Aventis Behring, and Aventis Bio-Services Europe, Marburg, Germany. Thomas.Weimer@aventis.com
Streichert
S
S
Watson
C
C
Gröner
A
A
D000990:Antithrombin III / Q000302:isolation & purification / Q000592:standards; D016913:Blood Component Transfusion / Q000592:standards*; D001782:Blood Donors; D003257:Consumer Product Safety; D004279:DNA, Viral / Q000097:blood; D006801:Humans; D015994:Incidence; D008403:Mass Screening; D010322:Parvoviridae Infections / Q000635:transmission; D016732:Parvovirus B19, Human / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000592:standards; D011786:Quality Control; D019562:Viral Load / Q000592:standards*
D004279:DNA, Viral; D000990:Antithrombin III