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Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay
Published on: September 9, 2012
Human parvovirus PARV4 in clotting factor VIII concentrates
J F Fryer1, A R Hubbard, S A Baylis
1Division of Virology, National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK.
Background And Objectives:
Parvoviruses are small non-enveloped DNA viruses, relatively resistant to virus inactivation procedures. The recently identified human parvovirus PARV4, including a related genotype 2 virus (also termed PARV5), has been found to be a contaminant of pooled plasma used in the manufacture of plasma-derived products. This report describes an investigation to determine whether PARV4 is present in clotting factor concentrates.
Materials And Methods:
Factor VIII concentrates manufactured in the past 30-35 years were screened for PARV4 and human parvovirus B19 (B19V) sequences. Viral loads in products testing positive for PARV4 were quantified using a consensus TaqMan assay designed to a highly conserved region. DNA sequence analysis was performed to confirm the genotypes present.
Results:
From a total of 175 lots of factor VIII concentrate, 28 of these contained PARV4 sequences, and in two lots both genotypes 1 and 2 were found to be present. The highest viral loads observed exceeded 10(5) copies per ml. The majority of factor VIII concentrates testing positive for PARV4 were manufactured in the 1970s and 1980s. Human B19V was also a frequent contaminant of these products.
Conclusions:
PARV4 was detected in 16% of factor VIII concentrates, particularly in older batches from the 1970s and 1980s. The significance in terms of the viral safety and potential transmission to recipients of these products is not yet known.
Insights
Human parvovirus PARV4 was found in 16% of factor VIII concentrates, especially older batches. Further research is needed to understand the viral safety implications for recipients.
Area of Science:
- Virology
- Molecular Biology
- Public Health
Background:
- Parvoviruses are resilient non-enveloped DNA viruses.
- Human parvovirus PARV4 (and genotype 2, PARV5) contaminates pooled plasma for plasma-derived products.
- The presence of PARV4 in clotting factor concentrates requires investigation.
Purpose of the Study:
- To investigate the presence of human parvovirus PARV4 in factor VIII concentrates.
- To quantify PARV4 viral loads and identify genotypes within these products.
Main Methods:
- Screening of 175 factor VIII concentrate lots manufactured over 30-35 years for PARV4 and human parvovirus B19 (B19V) DNA.
- Quantification of PARV4 viral loads using a consensus TaqMan assay.
- DNA sequence analysis for genotype confirmation.
Main Results:
- PARV4 sequences were detected in 28 out of 175 (16%) factor VIII concentrate lots.
- Two lots contained both PARV4 genotypes 1 and 2.
- Highest viral loads exceeded 10(5) copies/mL; most positive lots were from the 1970s and 1980s.
- Human parvovirus B19V was also frequently detected.
Conclusions:
- PARV4 is a contaminant in a significant proportion of older factor VIII concentrates.
- The viral safety implications for recipients of these products remain unknown.
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