Fetal pathology in human parvovirus B19 infection

Isolated hypoplasia of the abdominal wall associated with fetal parvovirus B19 infection

We report a rare case of a preterm infant with a diagnosis of hydrops fetalis, associated with parvovirus B19 infection. At birth, the infant had severe ascites. She recovered and was discharged in later good condition. In follow-up at 10 years of age, she still had severe isolated hypoplasia of the abdominal muscles. Isolated hypoplasia of the abdominal muscles after parvovirus B19 infection appears to be a separate entity, which should be differentiated from other abdominal wall anomalies.

Parvovirus B19 infection during pregnancy and risks to the fetus

Parvovirus B19 infects 1 to 5% of pregnant women, generally with normal pregnancy outcomes. During epidemics, the rate of infection is higher. Major congenital anomalies among offspring of infected mothers are rare, as the virus does not appear to be a significant teratogen. However, parvovirus B19 infection may cause significant fetal damage, and in rare cases, brain anomalies and neurodevelopmental insults, especially if infection occurs in the first 20 weeks of pregnancy. Parvovirus B19 is also an important cause of fetal loss, especially in the second half of pregnancy when spontaneous fetal loss from other causes is relatively rare. Parvovirus B19 infection may affect many fetal organs and can cause severe anemia, following fetal erythroid progenitor cells infection and apoptosis, especially in fetuses, that have shortened half-life of erythrocytes. Severe anemia may cause high output cardiac failure and nonimmune hydrops fetalis. In addition, parvovirus B19 may directly infect myocardial cells and produce myocarditis that further aggravates the cardiac failure. Intrauterine fetal transfusion is commonly used for the treatment of severe fetal anemia with survival rates of 75 to 90% and significant reduction of fetal morbidity. Only 66 cases were evaluated neurodevelopmentally, of which 10 (16%) had slight or severe neurodevelopmental problems. Because parvovirus B19 infection can cause severe fetal morbidity and mortality, it should be part of the routine work-up of pregnant women who have been exposed to the virus or of pregnancies with suspected fetal hydrops. Assessment for maternal infection during pregnancy is especially important during epidemics, when sero-conversion rates are high. Birth Defects Research 109:311-323, 2017. © 2017 Wiley Periodicals, Inc.

Persistence of Villous Immaturity in Term Deliveries Following Intrauterine Transfusion for Parvovirus B19 Infection and RhD-associated Hemolytic Disease of the Fetus and Newborn

Common causes of fetal anemia and hydrops include parvovirus B19 infection during the first 2 trimesters of pregnancy, as well as maternal alloimmunization to RhD with subsequent hemolytic disease of the fetus and newborn (HDFN) in an RhD positive fetus. Although both of these conditions have historically caused significant fetal morbidity and mortality, the advent of intrauterine transfusion (IUT) over the last few decades has dramatically improved outcomes. Prior literature has extensively documented placental changes associated with untreated parvovirus infection and RhD HDFN in intrauterine fetal demises and preterm births; however, histopathologic changes in term placentas from term infants treated with IUT have not been reported. We present placental findings in 2 cases of parvovirus B19-associated hydrops and 2 cases of RhD HDFN-associated hydrops in term infants after IUT, highlighting unique aspects that may be diagnostically useful for the examining pathologist.

Isolated hypoplasia of abdominal wall muscles associated with fetal ascites

We report the case of an infant born after parvovirus B19-induced fetal hydrops, who presented at birth with bilateral abdominal wall laxity, which was more evident on the flanks. Imaging exams revealed congenital hypoplasia of oblique abdominal muscles not associated with other anatomical abnormalities except for small liver calcifications. We review the medical literature and identify similar cases associated with fetal ascites. We propose that isolated hypoplasia of abdominal wall muscles can be associated with fetal ascites from various causes, and represents a separate condition from prune belly syndrome.

Diagnosis of in utero Parvovirus B19 infection and maternal immune response - the relevance of linear epitopes and advanced serologic testing

IMPORTANCE OF THE FIELD

Parvovirus B19 (B19V) infection in utero causing fetal anemia and non-immune hydrops fetalis (NIHF) is a potentially life-threatening event for the fetus. Postexpositional non-invasive diagnosis is based on maternal IgG/IgM response and detection of viral genome in maternal blood. Serologic testing directs prenatal follow-up. Fetal infection is confirmed by polymerase chain reaction or in situ hybridization in fetal blood and/or amniotic fluid cells. The performance of serologic tests is significant in order to direct pre- and perinatal care at rational use of resources. Timing of diagnostic procedures and knowledge of the time course of infection in pregnant, asymptomatic women are critical. IgM negative testing in the presence of prolonged viremia may complicate individual risk analysis in pregnancy. Recently, advanced IgG avidity assays and epitope-type specific assays (IgG ETS EIA) have been re-evaluated.

AREAS COVERED IN THIS REVIEW

Epidemiology, clinical relevance and management of B19V infection in pregnancy. A review of the current literature (November 1984 - May 2009) and evaluation of current information on performance and predictive value of molecular and VP1/VP2 antigen-based IgG tests directed at the diagnosis of materno-fetal B19V infection and detection of past immunity. New aspects of B19V-associated fetal disease other than anemia/NIHF are also covered.

WHAT THE READER WILL GAIN

An overview of immunology and clinical relevance of B19V infection in pregnancy, of the potential value of advanced serologic testing and fields of future research.

TAKE HOME MESSAGE

In the absence of a commercially available vaccine, serologic tests remain important tools in individual risk analysis of pregnant women exposed to B19V. Sequential application of IgG avidity and IgG ETS EIAs may improve risk stratification and timing of invasive testing in B19V-exposed pregnancies, in particular with IgM-negativity and/or persistent DNAemia. Prospective evaluation of these test systems correlated to fetal outcome in order to reduce fetal morbidity and mortality as well as the overall burden of disease of B19V with regard to fetal malformation may be subject to future research.

Parvovirus B-19 infection during pregnancy

The development of an acute parvovirus B-19 infection during pregnancy can cause pregnancy complications ranging from early pregnancy loss to nonimmune hydrops. There is no treatment, but preventive measures can be used to decrease perinatal mortality. The diagnosis is made on the basis of clinical suspicion and serology. If the fetus exhibits hydrops in the latter part of pregnancy, the main treatment options include either correcting the associated anemia with intrauterine blood transfusion or birth with extrauterine management. Although the serious problems associated with this virus during pregnancy are uncommon, they can be fatal. In view of this, a pregnant woman who is antibody negative should try to avoid contact with large groups of young children in order to decrease contact with potential vectors.

Quantitative direct probe method for the detection of parvovirus B19

Parvovirus B19 infection is associated with anemia and spontaneous abortions. While many qualitative assays are available, a few molecular-based quantitative methods have been described. This study reports the development and optimization of a quantitative direct-probe method for the detection of Parvovirus B19 DNA. Different concentrations of RNA probes were used to identify the optimal conditions for hybridizing to the target DNA. Detection of DNA was linear between concentrations of 2 ng/ml to 200 pg/ml. Because this method requires no enzymatic amplification, it is not susceptible to amplifier contamination or enzymatic inhibitors, and it can be applied to serum samples or paraffin-embedded tissue.

Fetal brain infection with human parvovirus B19

Intrauterine parvovirus B19 infection is known to be one of the causes of hydrops fetalis. However, there are few reports of the pathologic changes in the central nervous system. Postmortem examination of a fetus revealed multinucleated giant cells of macrophage/microglia lineage and many small calcifications around the vessels, predominantly in the cerebral white matter. Parvovirus B19 genome DNA was detected in the nucleus of the multinucleated giant cells and solitary endothelial cells by polymerase chain reaction amplification and in situ polymerase chain reaction methods. Capsid antigen was also demonstrated in the cytoplasm of the endothelial cells by immunofluorescent assay. Thus, intrauterine B19 parvovirus infection could be associated with marked neuropathologic changes in the fetal brain at the midembryonal period. Neurologic follow-up of complications may be necessary for children who survive the intrauterine infection.

The incidence of, and factors leading to, parvovirus B19-related hydrops fetalis following maternal infection; report of 10 cases and meta-analysis

OBJECTIVES

to clarify the approximation of the frequency of B19-related nonimmune hydrops fetalis (NIHF), and to know the critical period during which maternal infection led to NIHF.

METHODS

we investigated the characteristics of 10 cases of antenatal B19 infection diagnosed over the past 10 years in Miyagi prefecture, Japan, and performed a meta-analysis of these cases and those previously reported in the literature.

RESULTS

NIHF caused by intrauterine B19 infection was diagnosed between 11 and 23 weeks of gestation in 10 women over the past 10 years in Miyagi prefecture, Japan. The source of infection was the mother's older child in six out of 10 cases, and children at a kindergarten where the mothers worked in two cases. The interval between the onset of infection and the diagnosis of NIHF ranged from 2 to 6 weeks. B19 infection was responsible for 10 (15.2%) in 66 cases of aetiology unknown NIHF in this study, and for 57 (19.1%) of 299 cases of non-malformed or aetiology-unknown NIHF by meta-analysis of the literature. Meta-analysis of the 165 reported cases of antenatal B19 infection, including the 10 cases described above, showed that there was a 10.2% excess risk of fetal death in women infected with B19 during pregnancy and a 12.40% excess risk in women infected during the first 20 weeks of pregnancy. Transplacental transmission was confirmed in 69 (24.1%) of 286 cases. The mean gestational age at diagnosis of NIHF was 22.8 +/- 5.1 weeks. The mean interval between the onset of maternal infection and diagnosis of NIHF was 6.2 +/- 3.7 weeks.

CONCLUSIONS

these approximations will be useful for counselling and management for pregnant women. The critical period during which maternal infection led to NIHF correlated with the hepatic period of hematopoietic activity. These findings suggest that parvovirus B19 may have an affinity for erythroid lineage cells at the hepatic stage of hematopoiesis, which may strongly influence the clinical features of feto-maternal B19 infection.

Feto-placentary pathology in human parvovirus B19 infection

In view of the scarce references concerning the histological data in congenital parvovirus human B19 infection, we intend to provide a description of the pathological features observed in six autopsies. The virus was detected by DNA hybridization (ISH-DBH), PCR and electronmicroscopy (EM) in paraffin-embedded feto-placentary tissues. These cases constitute a subset from 86 Non Immunologic Hydrops Fetalis (NIHF) cases, in which a systemic complex of inflammatory/degenerative lesions of unknown etiology was visualized by optical microscopy. In one case a syphilitic process was detected, typefying a double infection. All fetuses showed a similar pathology--hydrops, hepato-splenomegaly, lung hypoplasia and erythroblastemia, the specific histological feature being the presence of intranuclear inclusions in the erythroid progenitors, in the erythropoietic visceral tissue and in blood marrow. Complex cardiopathy allied to abnormal lung lobulation and polisplenia were observed once; in 2 cases endocardial fibroelastosis was diagnosed. The pulmonary lesions were represented by dysmaturity allied to interstitial mononuclear infiltration. The hepatic consisted of cholestasis, portal fibrosis, canalicular proliferation, hemossiderosis, focal necroses and giant cell transformation. The central nervous system lesions were predominantly anoxic although the autolysis impaired a correct diagnosis.

Infectious causes of hydrops fetalis

A variety of infectious agents have been associated with nonimmune hydrops fetalis, most notably parvovirus B19, cytomegalovirus, herpes simplex virus, Toxoplasma gondii, and Treponema pallidum. These agents produce hydrops through effects on fetal bone marrow, myocardium, or vascular endothelium. Knowledge of the epidemiology and clinical characteristics of maternal and fetal infection can be used to select a diagnostic approach. Etiologic diagnosis will guide prognosis and the selection of specific chemotherapy.

A study by means of a new assay of the relationship between an outbreak of erythema infectiosum and non-immune hydrops fetalis caused by human parvovirus B19

An enzyme-linked immunosorbent assay (ELISA), used to detect IgG and IgM antibody specific for human parvovirus B19, was established by use of human parvovirus B19 capsid protein VP-1 expressed in Escherichia coli. Paired samples of serum derived from 44 mothers and single samples derived from 24 babies having unexplained non-immune hydrops fetalis (NIHF), were tested by means of the assay. Five cases (11%) of NIHF were suspected of having been induced by intrauterine human parvovirus B19 infection because the samples of maternal serum were positive for parvovirus B19 IgM antibody. Four of the five cases arose during an outbreak of erythema infectiosum. According to our study and previous reports over 90% of NIHF caused by parvovirus B19 intrauterine infection have become clinically overt in the second trimester of pregnancy during a period ranging from 15 to 27 weeks of gestation.

Immunohistochemical distribution of surfactant apoproteins in hypoplastic lungs of nonimmunologic hydrops fetalis

Forty-three patients with nonimmunologic hydrops fetalis (NIHF), including 32 patients (74%) with hypoplastic lung, were immunohistochemically examined for the expression of surfactant apolipoproteins (SPs), using anti-gamma G immunoglobulins against human SP-A with a molecular weight (MW) of 35 K and SP-B with a MW of 5 K compared with that in 59 patients in a control group and 45 patients with hypoplastic lung induced by causes other than NIHF. In the control group, SP-A was expressed in the lungs from 23 gestational weeks and became more numerous and intense in alveolar type II cells after 31 gestational weeks, whereas SP-B began to be expressed from 20 gestational weeks, and almost all patients showed a diffuse positivity after 26 gestational weeks. In the NIHF group, SP-A expression was generally weak, even after 31 gestation weeks. Moreover, most of the patients showing a weak expression of SP-A were also associated with hypoplastic lung and had a clinical history of persistent intrauterine pleural effusion of more than 2 weeks. Conversely, the immunoreactivity of SP-B was well preserved in NIHF cases either with or without hypoplastic lung. These results suggest that in the NIHF lung, there is a possible delay in the functional maturation or development of SP-A synthesis by alveolar type II cells, and this retardation of the functional maturation in type II cells also participates in the postnatal respiratory insufficiency in NIHF.

Human parvovirus B19 infection and unbalanced translocation in a case of hydrops fetalis

In a case of hydrops fetalis, serological examination showed a recent maternal human parvovirus B19 infection. Amniocentesis revealed a unique unbalanced translocation between chromosomes 3 and 11 of the fetus. The mother proved to have a balanced reciprocal translocation between chromosomes 3 and 11. A grossly macerated hydropic male fetus was delivered with a flat nose and low implanted deformed ears. Histopathological examination revealed nuclear inclusion bodies in fetal erythroid cells, confirming human parvovirus B19 infection. Parvovirus B19 DNA was demonstrated by in situ hybridization in the nuclei of heart muscle cells. Our finding of two different disorders in one case illustrates the importance of a complete evaluation of every case of hydrops fetalis, especially concerning counselling on the outcome of future pregnancies. The human parvovirus B19 infection will not recur due to the acquired immunity of the mother, whereas the balanced reciprocal translocation will endanger future pregnancies.

A fetus with a parvovirus B19 infection and congenital anomalies

A fetus with multiple structural defects was seen at prenatal ultrasound examination. After termination of the pregnancy a bilateral cleft lip, alveolus, and palate; micrognathia; and webbed joints were seen. Fetal tissues showed indications of infection, intranuclear inclusion bodies, chronic stress, haemolysis, arterial wall damage, and profuse haemorrhage. Parvovirus B19 DNA was detected in fetal tissues by dot hybridization after polymerase chain reaction. The possibility of parvovirus B19 infection leading to congenital malformations is discussed.

Fetal damage caused by parvoviral infections

The single-stranded DNA parvoviruses occur in humans and many species of animals. In general, they are species-specific and capable of producing disease at any stage of life. Parvoviruses have a requirement to replicate in cells in a permissive S-phase of DNA mitosis. The infections may be cytolytic to select cell groups resulting in specific developmental defects or may produce more generalized effects such as anemia, pancytopenia, or hemorrhage. The fetus is at particular risk for damage because of the vast number of cells in active mitosis. The teratogenic effects may be severe, often resulting in fetal death. Infections in childhood and adulthood are more frequently mild to subclinical. Some of the teratogenic effects recognized in animal species have been identified in humans. With increased knowledge of parvovirus effects in animals, more pathogenic effects may be related to human parvoviral disease. The need for vaccination, currently used annually in many domestic animal species, continues to be evaluated for humans.

Viral infections in the dental setting: potential effects on pregnant HCWs

Occupational exposure of pregnant health care workers to infectious diseases may cause a variety of effects. This article reviews potential effects of viral infections in pregnant health care workers by pathogens transmittable in a dental setting.

Diagnosis and incidence of fetal parvovirus infection in an autopsy series: II. DNA amplification

This study evaluates the practical utility of the polymerase chain reaction (PCR) as a diagnostic method for intrauterine fetal parvovirus infection in cases of hydrops fetalis. Paraffin-embedded, formalin-fixed fetal tissues from cases of hydrops fetalis were assessed for parvovirus B19 by histology and PCR in conjunction with 32P hybridization. Of 673 fetal and neonatal autopsies performed at Women and Infants' Hospital for the years 1985 through 1990, 32 cases were determined to have hydrops fetalis, of which five were positive for parvovirus infection by both histology and the PCR. PCR was not used in seven (22%) of the 32 hydrops cases because 1 microgram of DNA was not available for study. Histology was as sensitive as PCR in detecting parvovirus B19 in fetal autopsy tissues from cases of hydrops fetalis, and could be used reliably in each case to diagnose parvovirus infection. In our hands, histology is as sensitive as PCR and less labor-intensive. We would reserve PCR for cases without inclusions and with a strong suspicion of parvovirus infection, or for fluids in which histological analysis is not available.

Localization of an immunodominant domain on baculovirus-produced parvovirus B19 capsids: correlation to a major surface region on the native virus particle

An immunodominant region on baculovirus-produced parvovirus B19 VP2 capsids was localized between amino acids 259 and 426 by mapping the binding sites of a panel of monoclonal antibodies which recognize determinants on the particles. The binding sites of three monoclonal antibodies were fine-mapped within this antigenic domain. Six VP2-specific monoclonal antibodies recognized determinants common to both the empty capsids and native parvovirus. The defined antigenic region is most probably exposed on the native B19 virion and corresponds to part of the threefold spike on the surface of canine parvovirus particles.

Long-term outcome in fetal hydrops from parvovirus B19 infection

Parvovirus B19 infection in the fetus is associated with anemia and hydrops and can result in fetal death. Fetal transfusion has been used in an attempt to improve outcome; however, it is associated with its own perinatal morbidity. We report two cases of fetal parvovirus B19 infection that were confirmed by polymerase chain reaction for parvovirus B19 deoxyribonucleic acid in umbilical cord blood. Ultrasonographic signs of compromise were observed at 30 and 24 weeks of gestation. Both fetuses were hydropic and one fetus was also anemic. Serial sonograms demonstrated that the hydrops resolved spontaneously over 3 to 5 weeks after diagnosis. One infant was delivered at 32 weeks of gestation as a result of idiopathic preterm labor. The other infant was delivered at term. Both infants appeared relatively normal at birth and have developed normally in the first year of life. Thus fetal hydrops in association with parvovirus B19 infection does not always lead to poor long-term outcome. A conservative approach without in utero therapy may be appropriate for the management of some of these fetuses.

Clinical and histopathological features of parvovirus B19 infection in the human fetus

OBJECTIVE

To provide a comprehensive description of the clinical and histopathological features associated with parvovirus B19 infection of the human fetus.

SUBJECTS

All cases of parvovirus B19-related fetal death presenting to the John Radcliffe Hospital, Oxford, over a 16 year period. Diagnosis was confirmed retrospectively by non-isotopic in situ hybridization for parvovirus B19 DNA.

RESULTS

The ten cases occurred in two clusters (1979-80 and 1988-89) and presented between 15 and 29 weeks gestation. In at least three cases maternal infection was asymptomatic. Nine fetuses were grossly hydropic at necropsy. Histological features common to all cases included the presence of typical intranuclear inclusions in erythroid precursor cells and evidence of vasculitis within placental villi. Inflammatory changes were also present in the myocardium of four cases, with evidence of subendocardial fibroelastosis in three.

CONCLUSIONS

Histological features of fetal parvovirus B19 infection are similar across a range of gestational ages. The heart failure and hydropic state associated with fetal parvovirus infection may be of multifactorial aetiology, and not due to fetal anaemia alone.

Preliminary X-ray crystallographic investigation of human parvovirus B19

Crystals that diffract X rays to at least 8 A resolution have been grown from human B19 parvovirus empty capsids. These particles consist of VP-2 derived from a baculovirus expression system. This is possibly the first time that a self-assembled empty viral capsid, grown in other than normal host cells, has been crystallized. Partial X-ray diffraction data have been collected using synchrotron radiation. The space group is P2(1)3 with a = 362 A. The particle position in the crystal cell is given, at least roughly, from packing considerations.

Evaluation of a synthetic-peptide enzyme-linked immunosorbent assay for immunoglobulin M to human parvovirus B19

A synthetic peptide corresponding to a part of the virus protein 1-virus protein 2 overlapping region of human parvovirus B19 was used in an indirect enzyme-linked immunosorbent assay. Antibodies of the immunoglobulin (Ig) M class were measured in serum samples from patients with erythema infectiosum and controls. In comparison with an IgM assay using native B19 viral antigen, the peptide antigen assay was 92% sensitive and 87% specific. B19 IgM reactivities were seen in a limited number of children with other viral diseases. Specific IgM reactivities to short synthetic viral peptides have previously been reported only with Epstein-Barr virus. Since other sources of viral antigen are limited, the peptide antigen assay may be a useful alternative for the diagnosis of B19-associated disease in human beings.

An immunofluorescence assay for the detection of parvovirus B19 IgG and IgM antibodies based on recombinant viral antigen

An indirect immunofluorescence assay for serum IgG and IgM antibodies to human parvovirus B19 was established using recombinant B19 viral antigen, the capsid protein VP1, which had been produced in a baculovirus expression system. This protein gives a strong and characteristic signal in the immunofluorescence assay, making it a suitable candidate for this test system. The test results showed a good correlation with results obtained with a solid-phase capture radioimmunoassay (Cohen et al., 1983). 76% of sera from a random selection of blood donors were positive for B19 IgG which agrees with previous findings. The course of the IgM and IgG antibody response to B19 infection could be followed with the immunofluorescence assay by determining the titers of series of sera taken after a recent B19 infection. Investigation of 24 sera containing rubella-specific IgM showed no cross-reactivity with the recombinant B19 VP1 used in this test system. The test described here has the advantage of being based on a renewable source of antigen and will be further evaluated for routine diagnostic use in comparison with radioimmunoassay.

Antigenic parvovirus B19 coat proteins VP1 and VP2 produced in large quantities in a baculovirus expression system

Two baculovirus expression vectors derived from Autographica californica nuclear polyhedrosis virus (AcNPV) were prepared containing the complete 2.5 kb coding region for parvovirus B19 coat protein VP1 (AcB19VP1L) and the 1.8 kb coding region for VP2 (AcB19VP2L), placed under the control of the polyhedrin promoter. The recombinant viruses were used to infect Spodoptera frugiperda cells and the proteins expressed were analysed using appropriate antibodies. AcB19VP1L-infected cells produced B19 VP1 as shown by its reaction with 13 human sera containing B19-specific antibodies in Western blot analysis and indirect immunofluorescence. The signal seen with VP1 in immunofluorescence makes it suitable for the development of a diagnostic assay based on this technique. VP1 also reacted with two monoclonal antibodies (mAbs) specific for the B19 protein part of a 196 kDa beta-galactosidase B19 fusion protein expressed in E. coli. Cells infected with AcB19VP2L produced B19 VP2 which reacted with the same human sera in indirect immunofluorescence and with five of the 13 sera in Western blots. VP2 did not react with the fusion protein-specific mAbs. The large amounts of viral antigen produced in this system means the development of widely available diagnostic tests for B19 infection and the further characterization of the B19 structural proteins are within reach.