Detection of parvovirus B19 infection in formalin-fixed and paraffin-embedded placenta and fetal tissues

Abstract

Parvovirus B19 infection was first discovered in 1975 and it is implicated in fetal death from hydrops fetalis the world over. Diagnosis is usually made through histological identification of the intranuclear inclusion in placenta and fetal organs. However, these cells may be scarce or uncharacteristic, making definitive diagnosis difficult. We analyzed histologically placentas and fetal organs from 34 cases of non-immune hydrops fetalis, stained with Hematoxylin and Eosin (HE) and submitted to immunohistochemistry and polymerase chain reaction (PCR). Of 34 tissue samples, two (5.9%) presented typical intranuclear inclusion in circulating normoblasts seen in Hematoxylin and Eosin stained sections, confirmed by immunohistochemistry and PCR. However, PCR of fetal organs was negative in one case in which the placenta PCR was positive. We concluded that parvovirus B19 infection frequency is similar to the literature and that immunohistochemistry was the best detection method. It is highly specific and sensitive, preserves the morphology and reveals a larger number of positive cells than does HE with the advantage of showing cytoplasmic and nuclear positivity, making it more reliable. Although PCR is more specific and sensitive in fresh or ideally fixed material it is not so in formalin-fixed paraffin-embedded tissues, frequently the only one available in such cases.

Parvovirus Infection: An Immunohistochemical Study Using Fetal and Placental Tissue

“…There is a vast amount of literature on parvovirus infection during pregnancy; however, relatively few studies have had a sufficient number of parvovirus cases to evaluate the use of IHC [2][3][4]6,7,[11][12][13][14][15] (Table 3). Several studies [3,4,11,12] had very large sample sizes and aimed to investigate the frequency of parvovirus infection in first, second, or third trimester fetal losses.…”

Parvovirus B19 infection in human pregnancy

“…98,[155][156][157][158][159][160][161][162][163] Histopathology 4,21,67,95,164 and immunohistochemistry have also been employed, but have little use in routine practice. 8,96,156,[165][166][167][168] hPV B19 IgM is usually detectable 10-12 days after infection and can persist in the circulation for 3-4 months or longer, 23,169 and circulating IgG persists lifelong with slowly decreasing titres unless boosted by subsequent viral exposure. In pregnant women and the immunosupressed, serological responses are less characteristic.…”

Placental endothelial cells can be productively infected by Parvovirus B19

“…12 Reports on the distribution of viral nucleic acids or capsid proteins in placental tissue sections indicate the presence of infected erythroid precursors within foetal capillaries in placental villi. 12,13 The presence of lymphocyte infiltrates 14 and of apoptotic processes 15 correlated to B19V infection have also been described.…”