Journal of Medical Virology 67:259–266 (2002) Parvovirus B19 Infection in Pregnancy: Quantitative Viral DNA Analysis Using a Kinetic Fluorescence Detection System (TaqMan PCR) Antje Kno ¨ ll, 1 * Frank Louwen, 2 Bernd Kochanowski, 1,3 Annelie Plentz, 1 Julia Stu ¨ ssel, 2 Karin Beckenlehner, 1 Wolfgang Jilg, 1 and Susanne Modrow 1 1 Institute of Medical Microbiology and Hygiene, University of Regensburg, Germany 2 Department of Obstetrics and Gynecology, University of Mu ¨ nster, Germany 3 Microbiological Laboratory Dr. Mattes Dr. Kochanowski, Neuo¨tting, Germany Human parvovirus B19 infections are common in the general population, and infection during pregnancy may cause hydrops fetalis and fetal death. To initiate adequate treatment, accurate laboratory diagnosis is essential. The most sen- sitive tests are nested PCR systems, but these assays provide semiquantitative results at best. A parvovirus B19 DNA assay was developed based on the real time TaqMan PCR. This method was calibrated on the basis of serial plasmid dilu- tions and tested with an international parvovirus B19 standard. The assay was capable of quantify- ing parvovirus B19 DNA from one to about 5  10 7 genome equivalents per reaction (corresponding to 100 to 5  10 9 genome equivalents per ml serum). Samples from 51 pregnant women with suspected acute parvovirus B19 infection were tested, and positive PCR results were obtained in at least one of the materials investigated in 41 cases. The median viral DNA load in maternal blood samples was 1.3  10 4 copies/ml (range 7.2  10 2 –2.6  10 7 ). Maternal virus DNA concen- tration was not associated with the presence of maternal symptoms and/or fetal complications. As the stage of infection was not known in the majority of cases, our data do not exclude an association between peak levels of parvovirus B19 DNA and the development of complications. Maternal sera and corresponding fetal mate- rial were available for concurrent testing from 15 DNA-positive cases: in most fetal samples, viral DNA concentrations were several orders of magnitude higher (up to 2.1  10 12 copies/ml) compared to the corresponding maternal blood samples. J. Med. Virol. 67:259 – 266, 2002. ß 2002 Wiley-Liss, Inc. KEY WORDS: hydrops; fetus; viral load; real time PCR; diagnosis INTRODUCTION Parvovirus B19, the only known human pathogenic parvovirus, was first discovered in 1975 in England in serum of a healthy blood donor [Cossart et al., 1975]. The virus infects lytically human erythroid precursor cells, interrupting normal red cell production [Young et al., 1984]. Parvovirus B19 is the causative agent of the usually harmless childhood disease erythema infectiosum or fifth disease [Anderson et al., 1983, 1984]. Parvovirus B19 infection shows a wide variety of disease manifestations, depending on the immunologic and hematologic state of the host. In immunocompetent individuals, especially adults, it may lead to an acute arthropathy [Reid et al., 1985; White et al., 1985]. In patients with underlying hemolytic disorders, the virus can cause an aplastic crisis [Pattison et al., 1981], and in the immunocompromised host, infection becomes persistent leading to chronic anemia [Van Horn et al., 1986; Kurtzman et al., 1987]. Parvovirus B19 has also been associated with myocarditis and hepatitis [Yoto et al., 1996; Enders et al., 1998]. In 1984, the first reports about adverse outcomes of parvovirus B19 infection in pregnancy were published [Brown et al., 1984; Knott et al., 1984]. It is now known that in the fetus, where red cell volume is expanding rapidly and red cell survival is short, infection can lead to severe anemia, resulting in generalized edema, con- gestive heart failure, and fetal death. Myocarditis may also contribute to fetal damage: the cellular receptor for parvovirus B19, blood group P antigen or globoside, is present on fetal cardiac myocytes and signs of *Correspondence to: Antje Kno ¨ll, M.D., Institute of Medical Microbiology and Hygiene, University of Regensburg, Franz- Josef-Strauß-Allee 11, 93053 Regensburg, Germany. E-mail: antje.knoell@klinik.uni-regensburg.de Accepted 5 December 2001 DOI 10.1002/jmv.2216 Published online in Wiley InterScience (www.interscience.wiley.com) ß 2002 WILEY-LISS, INC.