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Background and Objectives Human parvovirus (erythrovirus) B19 is recognized as a major contaminant of blood and blood products. To reduce the risk of contamination, plasma-pool screening and exclusion of highly viraemic donations are recommended. The objectives of this study were to estimate the prevalence of B19 DNA in our blood-donor population, to determine the appropriate pool size to be tested (taking into account parameters such as prevalence, viral load, test sensitivity, and the efficacy of inactivation procedures), and to correlate viral loads with the serological status of donors as regards antibodies against different viral proteins. Materials and Methods Pools of different sizes were tested for B19, using a sensitive nested polymerase chain reaction (PCR) as well as an simple, un-nested, less sensitive PCR. Positive pools were resolved to the level of individual donations, and the viral load and serological markers were determined. Results Of 16 859 donations, 27 (one of 625) were found to be B19 DNA positive, with viral loads ranging from 102 to > 107 IU/ml. Twenty-five of the positive donations were tested for VP-specific anti-B19 antibodies, and eight (32%) were negative for both immunoglobulin (Ig)M and IgG. They were probably collected in the preseroconversion window period or from chronic carriers without detectable antibodies. We regarded the seven (28%) IgM-positive donors as being in the early phase of infection. The remaining 10 (40%) IgM-negative, IgG-positive donors were probably carriers of persistent infection (i.e. PCR positive despite the presence of IgG antibodies), as suggested by their low viral loads (< 104 IU/ml). Fifteen out of 36 major pools contained one or more contaminated donations. Among these, 12 tested positive by nested PCR and only three by un-nested PCR, this reflecting a viral load of > 104 IU/ml. Conclusions By testing all donations as pools of 480 by un-nested PCR, and resolving positive pools to identify the responsible donations, it is possible to ensure that the viral load in fractionation pools (5000 donations) remains < 103 IU/ml, compatible with the efficacy of inactivation procedures and complying with Food and Drug Administration (FDA) recommendations. [ABSTRACT FROM AUTHOR]

Background and Objectives: To determine the prevalence of HCV-RNA-positive plasma pools in Belgium, to validate our PCR method and to increase the safety of the released blood products., Materials and Methods: Plasma pools consisting each of about 5,000 donations from Belgian unpaid volunteer blood donors were analysed by PCR for the presence of HCV RNA. Two different extraction methods were compared and validated., Results: Two out of 367 plasma pools were found to be HCV RNA positive and were discarded. For one of these two pools, the look-back procedure identified an anti-HCV-negative contaminated donation. The HCV genotype of both the contaminated pool and the donation was 5a, a genotype rare in Europe. The viral load of the preseroconverted donation was 2.9 x 10(7) gEq/ml according to the bDNA method., Conclusion: In the case of plasma derivatives, various important steps are already included to increase safety. Nucleic acid testing of manufacturing plasma pools ensures that viral load in the starting material is as low as possible.