Antibody responses in parvovirus B19 infected patients

[Parvovirus B19 infections in adults]

Acute Parvovirus B19 (PVB19) infection is responsible for erythema infectiosum in children and non-specific polyarthralgias in immunocompetent adults associated with skin lesions and rarer manifestations (hepatic, neurological, cardiac or nephrological). In immunocompromised patients, cytopenias are more frequent and in some cases, viremia persists and is responsible for PVB19 chronic infection. PVB19 is responsible for pure red cell aplasia during chronic hemolytic diseases. Acute PVB19 infection is a differential diagnosis of some autoimmune diseases and has been suspected to be a trigger for some autoimmune diseases because of its ability to promote the emergence of autoimmune markers. Mechanisms of molecular mimicry, induction of apoptosis and activation of enzymes have been demonstrated, explaining in part the production of autoantibodies during infection. However, the demonstration of a causal relationship in the triggering of autoimmune disease remains to be done. This review provides a synthesis of the PVB19 infection clinical data in adults with a particular focus on these links with autoimmunity.

Proliferative glomerulonephritis with monoclonal immunoglobulin deposits associated with parvovirus B19

Proliferative glomerulonephritis with monoclonal immunoglobulin deposits (PGNMID) is included in the group of dysproteinaemias causing renal disease. Only a minority of cases are associated with a haematological malignancy. Two cases have been linked to acute parvovirus B19 infections. We report a 36-year-old African-American woman who presented with renal dysfunction, proteinuria, haematuria and a kidney biopsy reported as PGNMID with IgG3-kappa deposits. Her evaluation for a haematological malignancy was unrevealing. Her parvovirus IgM and IgG levels were positive. The patient was initially treated with an ACE inhibitor and spontaneously remitted with minimal proteinuria after 1 month. Repeat parvovirus B19 serologies 6 months later showed persistent IgG and DNA by PCR positivity but IgM negativity. Given the clinical scenario, we believe that her PGNMID was induced by acute parvovirus B19 infection, which appeared to resolve once her acute infection abated. In this report, we describe our latest understanding of PGNMID.

A Parsonage-Turner Syndrome secondary to Parvovirus B19 infection

Parvovirus B19 (PVB19) is a small DNA virus that causes the fifth disease in children; however it can also affect adults. The infection can be asymptomatic in about a quarter of healthy subjects. Typical clinical manifestations are: short lived fever accompanied by asthenia, myalgias and pharyngodynia; symmetrical acute polyarthritis; megalo-erytema in child; maculopulotic rash and/or fleeting purpuric at the extremities in adult; adenopathies in the cervical area. Atypical manifestions can affect neurological system (both central and peripheral), hearth and kidney. We describe a 37-year-old man with neuralgic amyotrophy (Parsonage-Turner syndrome) caused by Parvovirus B19 infection.

The VP1u of Human Parvovirus B19: A Multifunctional Capsid Protein with Biotechnological Applications

The viral protein 1 unique region (VP1u) of human parvovirus B19 (B19V) is a multifunctional capsid protein with essential roles in virus tropism, uptake, and subcellular trafficking. These functions reside on hidden protein domains, which become accessible upon interaction with cell membrane receptors. A receptor-binding domain (RBD) in VP1u is responsible for the specific targeting and uptake of the virus exclusively into cells of the erythroid lineage in the bone marrow. A phospholipase A₂ domain promotes the endosomal escape of the incoming virus. The VP1u is also the immunodominant region of the capsid as it is the target of neutralizing antibodies. For all these reasons, the VP1u has raised great interest in antiviral research and vaccinology. Besides the essential functions in B19V infection, the remarkable erythroid specificity of the VP1u makes it a unique erythroid cell surface biomarker. Moreover, the demonstrated capacity of the VP1u to deliver diverse cargo specifically to cells around the proerythroblast differentiation stage, including erythroleukemic cells, offers novel therapeutic opportunities for erythroid-specific drug delivery. In this review, we focus on the multifunctional role of the VP1u in B19V infection and explore its potential in diagnostics and erythroid-specific therapeutics.

Fetal Dilated Cardiomyopathy Associated With Variants of Uncertain Significance in MYH7 and DSG2 Genes: A Case Report and Review of the Literature

BACKGROUND

Fetal dilated cardiomyopathy (DCM) is an uncommon prenatal diagnosis associated with significant morbidity and mortality.

CASE

This report describes a patient with a diagnosis of fetal DCM at 31⁰ weeks gestation, several weeks after a maternal flu-like illness. Spontaneous improvement was noted on serial echocardiograms. Maternal Coxsackievirus B titers were significantly elevated at 1:80, although post-natal cord blood test results were negative. Genetic panel testing for DCM demonstrated two heterozygous variants of uncertain significance in the MYH7 and DSG2 genes. Although an early post-natal echocardiogram demonstrated a normal left ventricular ejection fraction, right ventricular dysfunction was noted with subsequent cardiac decompensation requiring temporary inotropic support. An echocardiogram at the age of 2 years confirmed normal biventricular function.

CONCLUSION

The finding of fetal DCM should trigger a broad evaluation. In the setting of limited fetal cardiac reserve, the significant hemodynamic changes that occur post-natally may trigger additional decompensation. Clinicians should be aware of the prognostic value of right ventricular function, as measured by fractional area change, in addition to the limitations of serologic and genetic testing.

Optimized nested PCR enhances biological diagnosis and phylogenetic analysis of human parvovirus B19 infections

Diagnosis and epidemiological analysis of human parvovirus B19 (hB19V) infections are essential for disease management in severely ill patients. This study aimed to evaluate the performance of an optimized NS1-VP1u nested PCR for detection and sequencing of viruses in clinical samples using 224 clinical and five reference samples. PCR sensitivity, specificity, and positive and negative predictive values were perfect (100%). While phylogenetic analysis of a 615 bp-long fragment demonstrated that the viruses in all of the samples belonged to genotype 1, this study confirmed that this optimized PCR could detect all known hB19V with high performance.

Validation of monoplex assays detecting antibodies against Corynebacterium diphtheriae and Clostridium tetani toxins, rubella virus and parvovirus B19 for incorporation into Multiplex Serology

Serological assays detecting antibodies in serum or plasma samples are useful and versatile instruments to investigate an individual's infection and vaccination history, e.g. for clinical diagnosis, personal risk evaluation, and seroepidemiological studies. Multiplex Serology is a suspension bead array-based high-throughput methodology for simultaneous measurement of antibodies against multiple pathogens in a single reaction vessel, thus economizing sample volume, measurement time, and costs. We developed and validated bead-based pathogen-specific Monoplex Serology assays, i.e. assays including only antigens for the respective pathogen, to detect antibodies against Corynebacterium diphtheriae and Clostridium tetani toxins, rubella virus and parvovirus B19. The developed assays expand the portfolio of existing pathogen-specific bead-based serology assays and can be efficiently incorporated into larger Multiplex Serology panels. The newly developed Monoplex Serology assays consist of only one antigen per infectious agent, expressed as Glutathione S-transferase-fusion proteins in E. coli. Specificity, sensitivity and Cohen's kappa statistics in comparison with routine clinical diagnostic assays were calculated for serum dilutions 1:100 and 1:1000. All pathogen-specific assays were successfully validated at both serum dilutions with the exception of rubella Monoplex Serology which showed impaired sensitivity (57.6%) at dilution 1:1000. Specificities of successfully validated Monoplex Serology assays ranged from 85.6% to 100.0% (median: 91.7%), and sensitivities from 81.3% to 95.8% (median: 90.9%); agreement with the reference assays ranged from substantial to almost perfect (kappa: 0.66-0.86, median: 0.78). Statistical performance and slim assay design enable efficient incorporation of the developed assays into Multiplex Serology.

Parvovirus B19-associated Hemophagocytic Lymphohistiocytosis in a Patient With Glucose-6-phosphate Dehydrogenase Deficiency

We report a case of a 12-year-old male with glucose-6-phosphate dehydrogenase deficiency presenting with clinical signs of sepsis and pancytopenia. Investigations revealed parvovirus B19 (PVB19)-associated hemophagocytic lymphohistiocytosis (HLH). The patient recovered fully and quickly with symptomatic treatment. Current evidence suggests that PVB19-associated HLH has a favorable prognosis. Mild undiagnosed cases of HLH may be the cause of pancytopenia in PVB19 infections.

Serological and molecular analysis of parvovirus B19 infection in Mayan women with systemic lupus erythematosus in Mexico

Background:

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease that mainly affects women, characterized by the production of autoantibodies. Its causal agent is unknown, but the combination of environmental, hormonal and genetic factors may favor the development of the disease. Parvovirus B19 has been associated with the development of SLE, since it induces the production of anti-single stranded DNA antibodies. It is unknown whether PV-B19 infection is an environmental factor that trigger or reactivate SLE in the Mexican Mayan population.

Aim:

A preliminary serological and molecular study of PV-B19 infection in Mayan women with established SLE was done.

Methods:

IgG and IgM anti PV-B19 were evaluated in 66 SLE patients and 66 control subjects, all women of Mayan origin. Viral DNA and viral load were analyzed by qPCR.

Results:

Insignificant levels of IgM were observed in 14.3% (4/28) of the patients and 11.4% (4/35) of control subjects. IgG was detected in 82.1% (23/28) of the patients and 82.9% (29/35) of control subjects, but were significantly higher in patients. Viral DNA was found in 86.0% (57/66) of the patients and 81.0% (54/66) of control subjects. Viral load, quantified in 28/66 patients and 31/66 controls which were positive for IgM and IgG, was significantly higher in controls.

Conclusion:

The high prevalence of PV-B19 in Yucatan, and the presence of IgM, IgG, and viral load in Mayan women with established SLE suggest that PV-B19 infection could be an environmental factor to trigger or reactivate SLE.

Genotype 1 of human parvovirus B19 in clinical cases

Summary Introduction: Virus surveillance strategies and genetic characterization of human parvovirus B19 (B19V) are important tools for regional and global control of viral outbreak. In São Paulo, Brazil, we performed a study of B19V by monitoring the spread of this virus, which is an infectious agent and could be mistakenly reported as a rash and other types of infection. Method: Serum samples were subjected to enzyme immunoassay, real time polymerase chain reaction, and sequencing. Results: From the 462 patients with suspected cases of exanthematic infections, the results of the 164 serum samples were positive for B19V immunoglobulin M. Among these cases, there were 38 patients with erythema infections and B19-associated with other infections such as encephalitis, hydrops fetalis, chronic anemia, hematological malignancies. These samples were sequenced and identified as genotype 1. Conclusion: This study showed patients with infections caused by B19V and sequencing genotype 1. Continuous monitoring is necessary to detect all known genotypes, and the emergence of new genotypes of these viruses for case management in public health control activities.

Substitution rate and natural selection in parvovirus B19

The aim of this study was to estimate substitution rate and imprints of natural selection on parvovirus B19 genotype 1. Studied datasets included 137 near complete coding B19 genomes (positions 665 to 4851) for phylogenetic and substitution rate analysis and 146 and 214 partial genomes for selection analyses in open reading frames ORF1 and ORF2, respectively, collected 1973–2012 and including 9 newly sequenced isolates from Serbia. Phylogenetic clustering assigned majority of studied isolates to G1A. Nucleotide substitution rate for total coding DNA was 1.03 (0.6–1.27) x 10⁻⁴ substitutions/site/year, with higher values for analyzed genome partitions. In spite of the highest evolutionary rate, VP2 codons were found to be under purifying selection with rare episodic positive selection, whereas codons under diversifying selection were found in the unique part of VP1, known to contain B19 immune epitopes important in persistent infection. Analyses of overlapping gene regions identified nucleotide positions under opposite selective pressure in different ORFs, suggesting complex evolutionary mechanisms of nucleotide changes in B19 viral genomes.

Evaluation of the diagnostic work-up in children with myocarditis and idiopathic dilated cardiomyopathy

The underlying etiology of dilated cardiomyopathy (DCM) in children varies, 14-22% is secondary to myocarditis, and the majority remains idiopathic. Etiology has prognostic value; however, 'a clinical diagnosis of myocarditis' has been frequently used because the gold standard [endomyocardial biopsy (EMB)] is often not performed. Therefore, a consistent diagnostic approach and interpretation is needed. In this multicenter study, we evaluated the diagnostic approach and interpretation of the viral results in children with myocarditis and idiopathic DCM. We included 150 children with DCM, of whom 103 were assigned the diagnosis myocarditis (n = 21) or idiopathic DCM (n = 82) by the attending physician. Viral tests were performed in 97/103 patients, in only 34% (n = 35) some of the tests were positive. Of those patients, we evaluated the probability of the assigned diagnosis using the viral test results. We classified viral test results as reflecting definite or probable myocarditis in 14 children and possible or unlikely myocarditis in 21 children. Based on this classification, 23% of patients were misclassified. We found that in children with DCM, the diagnostic approach varied and the interpretation was mainly based on viral results. Since a 'clinical diagnosis of myocarditis' has been frequently used in daily practice because of the lack of EMB results, a uniform protocol is needed. We propose to use viral test results in several steps (blood PCR, serology, PCR and/or cultures of the gastro-intestinal and respiratory tract, and EMB results) to estimate the probability of myocarditis.

Persistence of human parvovirus B19 in tissues from adult individuals: a comparison with serostatus and its clinical utility

Human parvovirus B19 (PVB19) is linked to variety of diseases, including erythema infectiosum, transient aplastic crisis, fetal hydrops, cardiomyopathy and, recently, hepatitis and arthritis. Persistence of PVB19 in asymptomatic individuals has been reported in skin, synovium, myocardium and bone marrow. A higher level of PVB19 DNA has been observed in various tissues from cases of disease than in controls. Simultaneously, equal detection of PVB19 DNA has been shown in both cases and controls. Thus, it has become fundamental to study PVB19 DNA persistence in tissues that are unaffected by disease. This will help to better understand PVB19 DNA persistence in symptomatic and asymptomatic individuals and its possible pathogenic role in various diseases. A total of 70 adult autopsies were included and divided into seropositive (SP) and seronegative (SN) groups based on PVB19 IgG. Nested PCR for PVB19 DNA was carried out in myocardium, liver, kidney, and bone marrow. Of the 70 patients, 60% belonged to the SP group and 40% to the SN group. Seropositivity ranged from 50% in the 12 to 20 year old group to 66.7% in the 61 to 80 year old group. The viral genome was detected in 34.3% of myocardium, 20% of bone marrow, 10% of kidney and 8.6% of liver samples. There was no significant difference in the persistence rates between the SP and SN groups. The persistence of PVB19 DNA in various tissues ranged from 8.3% to 36% in the SP group and 10% to 30% in the SN group. The persistence of PVB19 DNA in all the tissues was low, and PVB19 serostatus had no influence on the persistence of PVB19 DNA.

The presence of enterovirus, adenovirus, and parvovirus B19 in myocardial tissue samples from autopsies: an evaluation of their frequencies in deceased individuals with myocarditis and in non-inflamed control hearts

PURPOSE

Multiple viruses have been detected in cardiac tissue, but their role in causing myocarditis remains controversial. Viral diagnostics are increasingly used in forensic medicine, but the interpretation of the results can sometimes be challenging. In this study, we examined the prevalence of adenovirus, enterovirus, and parvovirus B19 (PVB) in myocardial autopsy samples from myocarditis related deaths and in non-inflamed control hearts in an effort to clarify their significance as the causes of myocarditis in a forensic material.

METHODS

We collected all autopsy cases diagnosed with myocarditis from 1992 to 2010. Eighty-four suicidal deaths with morphologically normal hearts served as controls. Polymerase chain reaction was used for the detection of the viral genomes (adenovirus, enterovirus, and PVB) in myocardial tissue specimens. The distinction between acute and persistent PVB infection was made by the serological determination of PVB-specific immunoglobulins M and G.

RESULTS

PVB was detected in 33 of 112 (29 %) myocarditis cases and 37 of 84 (44 %) control cases. All of the samples were negative for the presence of adenovirus and enterovirus. Serological evidence of an acute PVB infection, determined by the presence of immunoglobulin M, was only present in one case. In the remaining cases, PVB was considered to be a bystander with no or limited association to myocardial inflammation.

CONCLUSION

In this study, adenovirus, enterovirus, and PVB were found to be rare causes of myocarditis. The detection of PVB in myocardial autopsy samples most likely represents a persistent infection with no or limited association with myocardial inflammation. The forensic investigation of myocardial inflammation demands a thorough examination, including special attention to non-viral causes and requires a multidisciplinary approach.

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.

Molecular and phylogenetic analyses of human Parvovirus B19 isolated from Brazilian patients with sickle cell disease and β-thalassemia major and healthy blood donors

Human Parvovirus B19 (B19V) is a recognized cause of life-threatening conditions among patients with hemoglobinopathies. This study investigates B19V infection in patients with sickle cell disease and β-thalassemia using different experimental approaches. A total of 183 individuals (144 with sickle cell disease and 39 with β-thalassemia major) and 100 healthy blood donors were examined for B19V using anti-B19V IgG enzyme immunoassay, quantitative PCR, DNA sequencing, and phylogenetic analysis. Viremia was documented in 18.6% of patients and 1% of donors, and was generally characterized by low viral load (VL); however, acute infections were also observed. Anti-B19V IgG was detected in 65.9% of patients with sickle cell disease and in 60% of donors, whereas the patients with thalassemia exhibited relatively low seroreactivity. The seroprevalence varied among the different age groups. In patients, it progressively increased with age, whereas in donors it reached a plateau. Based on partial NS1 fragments, all isolates detected were classified as subgenotype 1A with a tendency to elicit genetically complex infections. Interestingly, quasispecies occurred in the plasma of not only patients but also donors with even higher heterogeneity. The partial NS1 sequence examined did not exhibit positive selection. Quantitation of B19V with a conservative probe is a technically and practically useful approach. The extensive spread of B19V subgenotype 1A in patients and donors and its recent introduction into the countryside of the São Paulo State, Brazil were demonstrated; however, it is difficult to establish a relationship between viral sequences and the clinical outcomes of the infection.

Republished: pathogenesis and diagnosis of myocarditis

Acute myocarditis is an inflammatory disease of the heart muscle that may progress to dilated cardiomyopathy and chronic heart failure. A number of factors including the sex hormone testosterone, components of innate immunity, and profibrotic cytokines have been identified in animal models as important pathogenic mechanisms that increase inflammation and susceptibility to chronic dilated cardiomyopathy. The clinical presentation of acute myocarditis is non-specific and mimics more common causes of heart failure and arrhythmias. Suspected myocarditis is currently confirmed using advanced non-invasive imaging and histopathologic examination of heart tissue. However, the diverse presentations of myocarditis and the lack of widely available, safe, and accurate non-invasive diagnostic tests remain major obstacles to early diagnosis and population based research. Recent advances in the understanding of disease pathogenesis described in this review should lead to more accurate diagnostic algorithms and non-invasive tests.

Immunohistochemical detection of parvovirus B19 in "gloves and socks" papular purpuric syndrome: direct evidence for viral endothelial involvement. Report of three cases and review of the literature

Papular-purpuric "gloves and socks" syndrome is a distinctive dermatosis featuring acral pruritus, edema, and petechiae. It has been attributed in most--but not all--reported cases to Parvovirus B19 infection, on the grounds of serological proof of recent infection or detection of viral DNA by polymerase chain reaction in patient serum or biopsies. We report the immunohistochemical detection of Parvovirus B19 VP2 structural protein in the endothelial lining of dermal blood vessels in 3 examples of Papular-purpuric "gloves and socks" syndrome and review previously described immunohistochemical investigations in cutaneous involvement by this infection.

Inactivation and neutralization of parvovirus B19 Genotype 3

BACKGROUND

Parvovirus B19 (B19V) is a common contaminant of human plasma donations. Three B19V genotypes have been defined based on their DNA sequence. Reliable detection of Genotype 3 DNA has proved problematic because of unexpected sequence variability. B19V Genotype 3 is found primarily in West Africa, but was recently detected in plasma from a North American donor. The safety of plasma-derived medicinal products, with respect to B19V, relies on exclusion of high-titer donations, combined with virus clearance at specific manufacturing steps. Studies on inactivation of B19V are difficult to perform and inactivation of Genotype 3 has not yet been investigated.

STUDY DESIGN AND METHODS

Inactivation of B19V Genotypes 3 and 1 by pasteurization of human serum albumin and incubation at low pH was studied using a cell culture assay for infectious virus particles. Infected cells were detected by reverse transcription-polymerase chain reaction analysis of virus capsid mRNA. Neutralization of B19V Genotype 3 was investigated using human immunoglobulin preparations.

RESULTS

Genotypes 1 and 3 displayed comparable inactivation kinetics during pasteurization of albumin at 56°C, as well as by incubation at various low-pH conditions (pH 4.2 at 37°C and pH 4.5 at 23°C, respectively) used in immunoglobulin manufacturing. Both Genotypes were readily neutralized by pooled immunoglobulin preparations of North American or European origin.

CONCLUSION

Pasteurization and low-pH treatment were equally effective in inactivating B19V Genotypes 1 and 3. Neutralization experiments indicated that pooled immunoglobulin of North American or European origin is likely to be equally effective in treatment of disease induced by both genotypes.

Diagnosis, management and possibilities to prevent parvovirus B19 infection in pregnancy

Human parvovirus B19 (B19V) infection in pregnancy can cause severe fetal anemia and nonimmune hydrops fetalis, which may be associated with spontaneous abortion and fetal death. Approximately 30–40% of women of child-bearing age are not immune to B19V infection. The risk to fetal life is particularly high if maternal infection occurs during the first 20 weeks of gestation. In this article we intend to give an overview on the molecular biology, epidemiology and management of B19V infection during pregnancy. These data will be combined with an assessment of the clinical situation of the infected fetus and the possibilities for avoiding and/or preventing B19V infection in pregnant women. Currently B19V infection is the causative agent of one of the most frequently occurring infectious complications in pregnancy that endangers fetal life, and so the necessity to develop a preventive vaccine is discussed.

High frequency, sustained T cell responses to PARV4 suggest viral persistence in vivo

BACKGROUND

Parvovirus 4 (PARV4) is a recently identified human virus that has been found in livers of patients infected with hepatitis C virus (HCV) and in bone marrow of individuals infected with human immunodeficiency virus (HIV). T cells are important in controlling viruses but may also contribute to disease pathogenesis. The interaction of PARV4 with the cellular immune system has not been described. Consequently, we investigated whether T cell responses to PARV4 could be detected in individuals exposed to blood-borne viruses.

METHODS

Interferon γ (IFN-γ) enzyme-linked immunospot assay, intracellular cytokine staining, and a tetrameric HLA-A*0201-peptide complex were used to define the lymphocyte populations responding to PARV4 NS peptides in 88 HCV-positive and 13 HIV-positive individuals. Antibody responses were tested using a recently developed PARV4 enzyme-linked immunosorbent assay.

RESULTS

High-frequency T cell responses against multiple PARV4 NS peptides and antibodies were observed in 26% of individuals. Typical responses to the NS pools were >1000 spot-forming units per million peripheral blood mononuclear cells.

CONCLUSIONS

PARV4 infection is common in individuals exposed to blood-borne viruses and elicits strong T cell responses, a feature typically associated with persistent, contained infections such as cytomegalovirus. Persistence of PARV4 viral antigen in tissue in HCV-positive and HIV-positive individuals and/or the associated activated antiviral T cell response may contribute to disease pathogenesis.

False-negative serology in patients with acute parvovirus B19 infection

BACKGROUND

Acute parvovirus B19 (B19V) infection is characterized by high-level viremia. Antibodies against the capsid proteins VP1 and VP2 may complex with B19V-particles thereby becoming undetectable in diagnostic tests.

OBJECTIVES

We intended to obtain data on the frequency of false-negative serology in acute B19V-infection.

STUDY DESIGN

129 plasma or serum samples of healthy blood donors and of patients with suspected B19V-infection were analyzed for B19V-DNA by qPCR and VP1/VP2-specific IgG and IgM by ELISA. Eleven of these samples were derived from four pregnant women with previous contact to B19V-infected individuals. Using acidic conditions virus/antibody-complexes were disrupted and detected by WesternLine and ELISA.

RESULTS

83/118 samples were derived from acutely infected individuals displaying viremia (10(3)-10(12)geq/mL). In 24/83 viremic samples (28.9%) VP1/VP2-specific IgM and IgG were undetectable in ELISA, but could be demonstrated to be complexed with B19V-particles. Each 7/83 (8.4%) was IgM-positive/IgG-negative and IgM-negative/IgG-positive, in 45/83 samples (54.2%) IgG and IgM could be detected. 35 samples did not contain B19V-DNA; five of these were from seronegative persons. Analyzing consecutive sera derived from four pregnant women, B19V-DNA was demonstrated in 10/11 samples, B19V-specific IgG- and IgM-antibodies were detectable in 10/11 and 4/11 samples, respectively. In 2/4 women seroconversion was observed, but IgM was not detected in 50% of the samples. B19V-specific IgG but not IgM was detectable in 2/4 women.

CONCLUSION

Acute B19V-infection cannot be diagnosed by exclusive analysis of B19V-specific antibodies. Only the combination of assays for detection of B19V-DNA and antibodies enables correct serodiagnosis.

Virus serology in patients with suspected myocarditis: utility or futility?

AIMS

Serological analyses of viral infection in suspected myocarditis are still widely used, although convincing evidence for their value is lacking. We determined prospectively the diagnostic value of virus serology in comparison with endomyocardial biopsy (EMB) including viral genome detection and immunohistochemistry in patients with clinically suspected myocarditis.

METHODS AND RESULTS

Virus serology and state-of-the-art evaluation of EMB were performed in 124 patients (age 40 ± 15 years) with suspected myocarditis. Endomyocardial biopsy was studied for inflammation with histological and immunohistological criteria. The viral genome was detected in the myocardium by polymerase chain reaction. Acute viral infection with enterovirus, adenovirus, parvovirus B19, cytomegalovirus, human herpesvirus, and Epstein-Barr virus was diagnosed by IgM or IgA in the initial sample or IgG seroconversion in the follow-up sample. Immunohistological signs of inflammation were present in 54 patients. The viral genome was detected in the myocardium of 58 patients (47%). In 20 patients (16%), acute viral infection was diagnosed by serology. Only in 5 out of 124 patients (4%), there was serological evidence of an infection with the same virus that was detected by EMB. Sensitivity and specificity of virus serology were 9 and 77%, respectively. The positive predictive value was 25% and the negative predictive value was 49%. The lack of correlation between serology and EMB remained also for patients with biopsy-proven myocarditis and patients with time from initial symptoms to EMB procedure of ≤1 month.

CONCLUSIONS

For patients with suspected myocarditis, virus serology has no relevance for the diagnosis of myocardial infection. Endomyocardial biopsy remains the gold standard in the diagnostic of viral myocarditis.

Parvovirus B19 genotype specific amino acid substitution in NS1 reduces the protein's cytotoxicity in culture

A clinical association between idiopathic liver disease and parvovirus B19 infection has been observed. Fulminant liver failure, not associated with other liver-tropic viruses, has been attributed to B19 in numerous reports, suggesting a possible role for B19 components in the extensive hepatocyte cytotoxicity observed in this condition. A recent report by Abe and colleagues (Int J Med Sci. 2007;4:105-9) demonstrated a link between persistent parvovirus B19 genotype I and III infection and fulminant liver failure. The genetic analysis of isolates obtained from these patients demonstrated a conservation of key amino acids in the nonstructural protein 1 (NS1) of the disease-associated genotypes. In this report we examine a conserved residue identified by Abe and colleagues and show that substitution of isoleucine 181 for methionine, as occurs in B19 genotype II, results in the reduction of B19 NS1-induced cytotoxicity of liver cells. Our results support the hypothesis that in the setting of persistent B19 infection, direct B19 NS1-induced cytotoxicity may play a role in idiopathic fulminant liver failure.

Analysis of nucleotide sequences of human parvovirus B19 genome reveals two different modes of evolution, a gradual alteration and a sudden replacement: a retrospective study in Sapporo, Japan, from 1980 to 2008

There have been no long-term systematic analyses of the molecular epidemiology of human parvovirus B19 (B19V). We investigated the variations of nucleotide sequences of B19V strains collected in Sapporo, Japan, from 1980 to 2008. In that period, six outbreaks of erythema infectiosum occurred regularly at 5-year intervals. The B19V strains collected successively, regardless of the outbreak, were analyzed for nucleotide variation in the subgenomic NS1-VP1u junction. The isolated strains can be classified into 10 subgroups. Two patterns of change of endemic strains were observed. One was a dynamic replacement of strains that occurred almost every 10 years, and the other was a gradual change consisting of an accumulation of point mutations.

Prevalence and clinical aspects of human bocavirus infection in children

Human bocavirus (HBoV) was recently described as a new member of the Parvoviridae. In order to investigate the suggested association of HBoV with respiratory and gastric disease in infants and young children, sera of 357 paediatric patients hospitalized with infectious and non-infectious diseases were retrospectively analyzed for the presence of HBoV DNA and virus-specific antibodies using quantitative PCR and ELISA, respectively. HBoV seroprevalence was determined to range from 25% in infants younger than 1 year of age to 93% in children aged more than 3 years. Viral loads between 1 x 10(2) and 1.2 x 10(6) geq/mL were observed in 6.7% (20/297) of sera obtained preferentially from young children suffering from infectious diseases. HBoV genomes were furthermore detected in 5% (3/60) of sera collected from individuals with non-infectious illnesses. HBoV DNA was present most frequently in patients with respiratory disease (9.6%). Whereas only 5.2% of patients with upper respiratory tract disease were viraemic, HBoV DNA was found in 14.6% and 10.0% of patients with lower respiratory tract illness and pneumonia, respectively. Acute HBoV infections were also observed in 7.5% of patients with gastroenteritis and in one child with inflammatory bowel disease. None of 77 patients hospitalized for various other infectious diseases (e.g. rash, urinary tract infection, meningitis) displayed viraemia. In 60.9% and 47.8% of DNA-positive children, HBoV-specific IgM and IgG was observed, respectively. The present prospective study provides comprehensive data on the clinical association of acute HBoV infection with respiratory illness and on the seroprevalence of virus-specific antibodies in children.

Anti-human parvovirus B19 nonstructural protein antibodies in patients with rheumatoid arthritis

BACKGROUND

Previous studies have reported the association between the development of NS1-specific IgG and arthropathy after the infection of human parvovirus B19 (B19). However, the role of anti-B19-NS1 IgG in RA is still unclear. This study investigated the role of anti-B19-NS1 antibody in patients with rheumatoid arthritis (RA).

METHODS

B19-VP IgM and IgG antibodies, nested PCR, B19-NS1 IgM and IgG antibodies, and anti-cyclic citrullinated peptide (CCP) antibodies were assessed by ELISA and Western blot in this study.

RESULTS

Significantly higher prevalence of B19-NS1 IgM and IgG antibodies in patients with recent B19 infection was observed as well as the higher prevalence of B19-NS1 IgM and IgG antibodies in RA patients with seronegative diagnostic patterns. However, no significant variation of both B19-NS1 IgM and IgG was detected in RA patients with different B19 diagnostic patterns. Additionally, significantly higher presence of anti-CCP IgG was observed in RA patients with B19-NS1 IgM.

CONCLUSIONS

This study suggests the possibility of anti-B19-NS1 IgM as an indicator for RA diagnosis and indicates the suspense of the higher prevalence of anti-B19-NS1 antibody in RA patients with seronegative B19 diagnostic patterns. However, these results provide clues in understanding the association of anti-B19-NS1 antibody in RA patients.

Prevalence of Agonistic Autoantibodies Against the Angiotensin II Type 1 Receptor and Soluble fms-Like Tyrosine Kinase 1 in a Gestational Age–Matched Case Study

We showed earlier that activating autoantibodies against the angiotensin II type 1 (AT 1 ) receptor (AT1-AA) circulate in preeclamptic women. They may be involved in the pathogenesis of preeclampsia. Protein alignment suggests that the binding site for AT1-AAs is highly homologous to the capsid protein VP2 of parvovirus B19. We performed a prospective, nested, case-control study of 30 gestational age–matched women with preeclampsia and 30 normotensive pregnant women. We measured AT1-AA, soluble fms-like tyrosine kinase 1 (sFlt-1), and serum immunoglobulin G against parvovirus B19 proteins. AT1-AAs were present in 70% of preeclamptic patients and absent in 80% of controls. Prediction by AT1-AA was improved in late-onset preeclampsia. The discrimination for sFlt-1 was 96%. We did not find an interaction between sFlt-1 and AT1-AA. A human monoclonal immunoglobulin G antibody against parvovirus B19 VP2-protein showed a positive reaction in the AT1-AA bioassay, which could be blocked by an AT 1 receptor blocker, as well as by the epitope amino acid sequence. Immunoglobulin G against parvovirus B19 proteins was similarly distributed between preeclamptic patients and controls and had no significant importance. We detected significantly more AT1-AA in women with an immune response corresponding with parvovirus B19 infection corresponding with a distant viral infection associated with virus elimination. We concluded that AT1-AAs were common in patients with preeclampsia in a prospective case-control study, although sFlt-1 was a superior biomarker. AT1-AA may represent a better marker for late disease, whereas sFlt1 is a better marker for early onset disease.

Effects of human parvovirus B19 VP1 unique region protein on macrophage responses

Background

Activity of secreted phospholipase A (sPLA2) has been implicated in a wide range of cellular responses. However, little is known about the function of human parvovirus B19-VP1 unique region (VP1u) with sPLA2 activity on macrophage.

Methods

To investigate the roles of B19-VP1u in response to macrophage, phospholipase A2 activity, cell migration assay, phagocytosis activity, metalloproteinase assay, RT-PCR and immunoblotting were performed.

Results

In the present study, we report that migration, phagocytosis, IL-6, IL-1β mRNA, and MMP9 activity are significantly increased in RAW264.7 cells by B19-VP1u protein with sPLA2 activity, but not by B19-VP1uD175A protein that is mutated and lacks sPLA2 activity. Additionally, significant increases of phosphorylated ERK1/2 and JNK proteins were detected in macrophages that were treated with B19-VP1u protein, but not when they were treated with B19-VP1uD175A protein.

Conclusion

Taken together, our experimental results suggest that B19-VP1u with sPLA2 activity affects production of IL-6, IL-1β mRNA, and MMP9 activity, possibly through the involvement of ERK1/2 and JNK signaling pathways. These findings could provide clues in understanding the role of B19-VP1u and its sPLA2 enzymatic activity in B19 infection and B19-related diseases.

Molecular diagnosis of the viral component in cardiomyopathies: pathophysiological, clinical and therapeutic implications

BACKGROUND

Myocarditis is defined as the inflammation of myocardium associated with cardiac dysfunction. Despite this clear-cut definition, diagnosis and etiologic treatment continue to create considerable debate. Viral infections are frequent causes of myocarditis and there is evidence that persistent viral infection is associated with poor prognosis in different subtypes of cardiomyopathy.

OBJECTIVE

To review methods for diagnosis of viral myocarditis and present the use of polymerase chain reaction (PCR)-based protocols for evaluating viral infection in myocarditis/cardiomyopathies.

METHODS

A review of published literature.

RESULTS/CONCLUSION

There is increasing evidence that PCR-based protocols can provide reliable molecular evidence for the presence of viral infection in myocardium. Thus application of molecular techniques will allow collection and analysis of more information on the epidemiology of viral cardiomyopathies, patient risk stratification and appropriate medical treatment.

NS1 specific CD8+ T-cells with effector function and TRBV11 dominance in a patient with parvovirus B19 associated inflammatory cardiomyopathy

Background

Parvovirus B19 (B19V) is the most commonly detected virus in endomyocardial biopsies (EMBs) from patients with inflammatory cardiomyopathy (DCMi). Despite the importance of T-cells in antiviral defense, little is known about the role of B19V specific T-cells in this entity.

Methodology and Principal Findings

An exceptionally high B19V viral load in EMBs (115,091 viral copies/μg nucleic acids), peripheral blood mononuclear cells (PBMCs) and serum was measured in a DCMi patient at initial presentation, suggesting B19V viremia. The B19V viral load in EMBs had decreased substantially 6 and 12 months afterwards, and was not traceable in PBMCs and the serum at these times. Using pools of overlapping peptides spanning the whole B19V proteome, strong CD8⁺ T-cell responses were elicited to the 10-amico-acid peptides SALKLAIYKA (19.7% of all CD8⁺ cells) and QSALKLAIYK (10%) and additional weaker responses to GLCPHCINVG (0.71%) and LLHTDFEQVM (0.06%). Real-time RT-PCR of IFNγ secretion-assay-enriched T-cells responding to the peptides, SALKLAIYKA and GLCPHCINVG, revealed a disproportionately high T-cell receptor Vbeta (TRBV) 11 expression in this population. Furthermore, dominant expression of type-1 (IFNγ, IL2, IL27 and T-bet) and of cytotoxic T-cell markers (Perforin and Granzyme B) was found, whereas gene expression indicating type-2 (IL4, GATA3) and regulatory T-cells (FoxP3) was low.

Conclusions

Our results indicate that B19V Ag-specific CD8⁺ T-cells with effector function are involved in B19V associated DCMi. In particular, a dominant role of TRBV11 and type-1/CTL effector cells in the T-cell mediated antiviral immune response is suggested. The persistence of B19V in the endomyocardium is a likely antigen source for the maintenance of CD8⁺ T-cell responses to the identified epitopes.

Relevance of specific immunoglobulin M and immunoglobulin G for parvovirus B19 diagnosis in patients with acute lymphoblastic leukemia receiving chemotherapy: prospective study

CONTEXT

Immunocompromised patients suffer from prolonged viral infections often without detectable immune response. However, even if the immune response occurs, can it clear the virus completely?

OBJECTIVE

To detect parvovirus B19 DNA and its antibodies in bone marrow cells and in serum by polymerase chain reaction (PCR) in children with acute lymphoblastic leukemia receiving chemotherapy to highlight the relation of humoral immune response to the presence of viremia. Also, to evaluate the optimal diagnostic test(s) for a correct diagnosis of parvovirus B19 disease in immunocompromised patients.

DESIGN

Forty-eight children with acute lymphoblastic leukemia receiving maintenance chemotherapy were included in the study in addition to 20 healthy children with matched age and sex. Study for parvovirus B19 was performed by serologic determination of specific immunoglobulin (Ig) M and IgG, and viral DNA was determined by PCR in both serum and bone marrow aspiration.

RESULTS

Parvovirus B19 DNA was detected in both serum and bone marrow in 20% of patients. Specific IgG was found in 40% and IgM in 26.7%. Two cases (10%) in the control group were positive for IgG. The agreement between IgG and positive results of PCR in the bone marrow was 33.3%, and the agreement for IgM and PCR in the serum was 33.3%.

CONCLUSIONS

Parvovirus B19 is considered a common viral infection in children with acute lymphoblastic leukemia receiving chemotherapy. We must use our full potential to exclude such infection, which can mimic the side effects of chemotherapy in these patients. In immunocompromised patients, there are immunologic discrepancies in humoral immune responses for both IgM and IgG between individuals with parvovirus B19 persistence and healthy individuals, findings that may reflect both failed immunity and antigenic exhaustion. The contemporaneous determination of parvovirus B19 DNA by PCR in both bone marrow and peripheral blood and specific serologic markers appears to be the most appropriate diagnostic protocol for the correct laboratory diagnosis of parvovirus B19 infection in these patients.

Parvovirus-B19-associated complications in renal transplant recipients

Parvovirus B19 is a common human pathogen, causing erythema infectiosum in children, hydrops fetalis in pregnant women, and transient aplastic crisis in patients with chronic hemolytic anemia. Immunosuppressed patients can fail to mount an effective immune response to B19, resulting in prolonged or persistent viremia. Renal transplant recipients can develop symptomatic B19 infections as a result of primary infection acquired via the usual respiratory route or via the transplanted organ, or because of reactivation of latent or persistent viral infection. The most common manifestations of B19 infection in immunosuppressed patients are pure red cell aplasia and other cytopenias. Thus, this diagnosis should be considered in transplant recipients with unexplained anemia and reticulocytopenia or pancytopenia. Collapsing glomerulopathy and thrombotic microangiopathy have been reported in association with B19 infection in renal transplant recipients, but a causal relationship has not been definitively established. Prompt diagnosis of B19 infection in the renal transplant recipient requires a high index of suspicion and careful selection of diagnostic tests, which include serologies and polymerase chain reaction. Most patients benefit from intravenous immunoglobulin therapy and/or alteration or reduction of immunosuppressive therapy. Conservative therapy might be sufficient in some cases.

Parvovirus B19 and the kidney

Infection with parvovirus B19 causes several clinical syndromes (fifth disease, transient aplastic crisis, pure red cell aplasia, and hydrops fetalis) and may contribute to other illnesses. B19 has been linked to renal disease in three settings: As a cause of acute glomerulopathy and as a cause of anemia in ESRD and kidney transplantation. Case reports implicate parvovirus in the pathogenesis of proliferative glomerulonephritis and collapsing glomerulopathy, but a causal relationship has not been established. A proposed role for B19 infection is based on the temporal association of renal findings with viral infection, positive serology, and identification of the viral genome in the glomerulus. Mechanisms may include cytopathic effects on glomerular epithelial cells and/or endothelial cells and glomerular deposition of immune complexes. Patients who require dialysis may have increased susceptibility to acute and chronic anemia after parvoviral infection. Factors that predispose this population to complications of B19 infection include impaired immune response, deficient erythropoietin production, and possibly decreased erythrocyte survival. The clinical burden of parvovirus B19 infection in renal transplant recipients may be underestimated; these individuals may develop persistent viremia as a result of a dysfunctional immune response. Chronic anemia and pure red blood cell aplasia are the most common complications of parvovirus infection in this population; the diagnosis should be considered in transplant recipients with unexplained anemia or pancytopenia. Allograft rejection and dysfunction have been reported in association with infection, but a cause-effect relationship has not been proved. Further investigation of the relationship between B19 and kidney disease is warranted.

Induction of antiphospholipid antibodies and antiphospholipid syndrome-like autoimmunity in naive mice with antibody against human parvovirus B19 VP1 unique region protein

BACKGROUND

Previous studies have postulated a connection between human parvovirus B19 (B19) infection and anti-phospholipid antibodies (APhL). B19 infection and anti-phospholipid syndrome (APS) exhibit congruent symptoms. Recently, phospholipase A2 (PLA2)-like activity has been linked to the VP1 unique region (VP1u) of B19. However, the precise role of B19-VP1u in pathogenesis of autoimmunity is still obscure.

METHODS

To elucidate the roles of VP1u in B19 infection and autoimmunity, the reactivity of B19-VP1u proteins with various autoantibodies were evaluated by ELISA and immunoblotting. Rabbits were immunized with purified recombinant B19-VP1u protein to generate anti-sera. Absorption experiments were conducted to determine the binding specificity of rabbit anti-sera against B19-VP1u, cardiolipin (CL) and beta-2-glycoprotein I (beta2GPI). Moreover, the effects of passive transfer of polyclonal rabbit anti-B19-VP1u IgG antibodies on platelets, activated partial thromboplastin time (aPTT), and autoantibodies were assessed.

RESULTS

Autoantibodies against CL, beta2GPI, and phospholipid (PhL) in sera from patients with B19 infection, were cross-reactive with B19-VP1u. Consistently, sera from rabbits immunized with recombinant B19-VP1u protein displayed raised detectable immunoglobulins against B19-VP1u, CL, beta2GPI and PhL. Additionally, the mice immunized with anti-B19-VP1u IgG developed thrombocytopenia, prolongation of aPTT, and autoantibody against beta2GPI and PhL.

CONCLUSIONS

These experimental results suggested the association between B19-VP1u and production of anti-beta2GPI antibodies, APhL, and APS-like autoimmunity. Altogether, it may provide a clue in understanding the role of B19-VP1u in inducing autoantibodies and B19-associated APS manifestations.

Parvovirus B19 and immune disorders

Parvovirus B19 (PVB19) is the causative agent of erythema infectiosum and sometimes the infection is correlated with severe haematological complications, or in pregnancy to fetalis hydrops. Moreover some authors suggest an infection involvement in some autoimmune diseases. To this purpose we evaluated seroprevalence for PVB19 in following the autoimmune or dysreactive pathologies: systemic lupus erythematosus (SLE), cryoglobulinemia, idiopathic systemic--ANCA associated vasculitis, rheumatoid arthritis (RA). In the case of LES, 31/42 patients were positive for PVB19 versus 21/42 of blood donors, as controls subjects (73.8% vs. 50%; significant difference for p < 0.05), moreover a significant difference for p < 0.001 was detected comparing mean titre values of IgGs against PVB19 of two groups (UI 1.94 +/- 0.90 vs. 1.24 +/- 0.80). In contrast no significant differences were found in the case of percent seropositivity of cryoglobulinemic subjects (37/57 = 64.9%, the majority of whom were HCV+) in comparison with the control group (50%). However mean units index (UI) was 1.63 +/- 0.81; p = 0.019 versus the control group. Similar result, with regard to the percentage of seropositivity, was found for vasculitis (9/17 = 52.9%). The data reported here can confirm a possible correlation between PVB19 prior infection and LES and also suggest possible implications in the case of cryoglobulinemia. In fact, most of our patients were affected by a nephropathic or systemic form of HCV+ cryoglobulinemia and the presence of other infective cofactors could be suggestive in the evolution of this clinical situation.

The association of VP1 unique region protein in acute parvovirus B19 infection and anti-phospholipid antibody production

BACKGROUND

Previous studies have postulated a connection between human parvovirus B19 (B19) infection and anti-phospholipid antibodies (aPL). Recently, the phospholipase domain of B19 has been linked to B19-VP1 unique region (VP1u). To elucidate the roles of VP1u in B19 infection and aPL production, the major reactivity of anti-B19-VP1u, anti-cardiolipin antibody (aCL), and anti-beta2-glycoprotein I (beta2GPI) antibody was evaluated.

METHODS

Sera from 102 clinically suspected cases of B19 infection were analyzed by nested PCR and ELISA. Humoral responses of anti-B19-VP1u and anti-B19-VP1uD175A IgM/IgG antibodies, aCL and the anti-beta2GPI antibody were assessed by Western blot and ELISA. Absorption experiments were also performed to determine the binding specificity of immunoglobulins to B19-VP1u, CL and beta2GPI.

RESULTS

Sera from patients with the diagnostic pattern DNA+/IgM+/IgG+ had a high frequency (57%) for recognition of CL and beta2GPI. Furthermore, adsorption experiments were performed by adding purified B19-VP1u, which partially suppressed the reactivity of anti-B19VP1u to CL and beta2GPI.

CONCLUSIONS

Serum from patients with acute B19 infection has a high frequency in recognition of CL and beta2GPI, and the phospholipase domain observed in the B19-VP1u may have contributed to the production of aPL. These findings may provide a clue for understanding the roles of B19-VP1u in B19 infection and aPL production.

[Safety of blood products and B19 parvovirus]

More than 25 years after the discovery of the parvovirus B19 (B19), the issue of the safety of blood components and the screening of this virus in blood donations is still debated. Although more often transmitted by respiratory route, B19 may also be transmitted by transfusion of blood components. This risk of exposure has been estimated to a frequency ranging from 1/625 to 1/50,000, according to the sensitivity of the detection methods and to seasonal epidemiologic circumstances. Usually, B19 is responsible for benign pathologies. However, such an infection can have a serious clinical outcome in three categories of susceptible recipients: (i) patients with shortened red cell survival (thalassemia major, sickle cell disease, other hemolytic diseases); (ii) immunocompromised patients (previously exposed to B19 or not) (iii) and pregnant women (not previously exposed the B19), with a risk of hydrops fetalis or of intrauterine death. Selected blood components, not collected during the short but highly viremic pre-seroconversion phase, could be reserved for these three groups of at-risk recipients. The screening of such viremic donations could be performed with nucleic acid testing (NAT), but an alternate strategy could be the selection of B19 immunised donors far from the primo-infection (positive for B19 IgG and negative for B19 IgM, or only positive for IgG at two controls distant of several months). However, the existence of persistently B19-infected individuals carrying B19 DNA despite the presence of specific IgG (estimated at 1% of blood donors) could constitute a potential threat for transfused immunocompromised recipients. The screening of such donors, which could be performed through a very highly sensitive NAT, would be justified only if the infectivity of such blood donations is demonstrated. If not, a screening of blood donors positive for B19 IgG would be a sufficient preventive measure.

Phylogenetic evidence for the rapid evolution of human B19 erythrovirus

Human B19 erythrovirus is a ubiquitous viral pathogen, commonly infecting individuals before adulthood. As with all autonomous parvoviruses, its small single-stranded DNA genome is replicated with host cell machinery. While the mechanism of parvovirus genome replication has been studied in detail, the rate at which B19 virus evolves is unknown. By inferring the phylogenetic history and evolutionary dynamics of temporally sampled B19 sequences, we observed a surprisingly high rate of evolutionary change, at approximately 10(-4) nucleotide substitutions per site per year. This rate is more typical of RNA viruses and suggests that high mutation rates are characteristic of the Parvoviridae.

[Acute serous meningitis in a patient with erythema infectiosum]

BACKGROUND

Clinical manifestations caused by parvovirus B19 (PVB19) are various and depend on the age and immunity of an infected person. In children, the most frequent clinical manifestation of parvovirus B19 primary infection is erythema infectiosum (EI).

CASE REPORT

In this case report we presented a 12-year-old patient with 2 clinical syndromes: erythema infectiosum and serous meningitis. Erythema infectiosum was manifested as fever, typical skin lesions ("slapped cheeks"), erythematous macules and papules confluent with reticular appearance on the extremities and the trunk. Serous meningitis had a mild course with an increased number of lymphocytes (120/ mm3) and the mildly increased level of proteins (0.75 g/l). The serological examination showed the presence of IgM and IgG antibodies against parvovirus B19 in serum, as well as in cerebrospinal fluid (CSF). The reduction of serum/CSF ratio of IgG antibodies was present. The symptomatic therapy was used in the treatment. The course and the prognosis were benign.

CONCLUSION

Human PVB19, although non-specifically associated with CNS diseases could be an etiological factor that might cause serous meningitis. So, it should be considered in different diagnosis in patients with aseptic meningitis, especially during the outbreaks of erythema infectiosum.

Parvovirus B19 VP2-proteins produced in Saccharomyces cerevisiae: comparison with VP2-particles produced by baculovirus-derived vectors

The capsids of human parvovirus B19 consist of two structural proteins, the minor-capsid protein VP1 and the major-capsid protein VP2. The latter which constitutes for 95% of the capsid are able to form virus-like particles (VLPs) in yeast without the presence of VP1-proteins. VP2-proteins produced in Saccharomyces cerevisiae have the capacity to form VLPs in the absence of VP1-proteins. These yeast-derived VLPs resemble native virus or recombinant VP2-VLPs produced by baculovirus systems in respect of size, molecular weight and of antigenicity as shown by antigen-capture ELISA and T-cell proliferation tests. Regarding costs, yield and ease of handling particle production in yeast represents an alternative to the recombinant baculovirus expression system which is so far the source for VP2-VLPs of human parvovirus B19.

Sustained CD8+ T-cell responses induced after acute parvovirus B19 infection in humans

Murine models have suggested that CD8+ T-cell responses peak early in acute viral infections and are not sustained, but no evidence for humans has been available. To address this, we longitudinally analyzed the CD8+ T-cell response to human parvovirus B19 in acutely infected individuals. We observed striking CD8+ T-cell responses, which were sustained or even increased over many months after the resolution of acute disease, indicating that CD8+ T cells may play a prominent role in the control of parvovirus B19 and other acute viral infections of humans, including potentially those generated by live vaccines.

Human Parvovirus B19 Serology and Avidity Using a Combination of Recombinant Antigens Enables a Differentiated Picture of the Current State of Infection

In order to improve serodiagnostic methods for the determination of the state of human parovirus B19 infection, a new test system, recomLine Parvovirus, based on the use of recombinant antigens, has been developed and evaluated. The test system combines the advantages of enzyme-linked immunosorbent assay (ELISA) methods with those of the Western blot technique. For the recombinant line assay, five antigens of human parvovirus B19 that were recombinantly produced in Escherichia coli were applied directly on nitrocellulose membranes: VP2, the aminoterminal and the carboxyterminal domain of VP1 (VP-N and VP-C), VP-1S another fragment of VP-N and NS1. In addition, empty virus particles isolated from eukaryotic cell cultures were also applied. The recombinant-line assay was used to detect human IgG and IgM antibodies directed against human parvovirus B19. In addition, the avidity of the IgG antibodies was investigated. The recombinant line assay was evaluated using 87 human serum samples of patients recently infected with human parvovirus B19 including 10 samples of three infection time courses and 100 serum samples of healthy blood donors. All results were compared with commercially available ELISAs. In the case of discrepancies, Western blot analysis was performed. The data revealed the recombinant line assay to be highly sensitive and specific. The individual determination of the human immune response against several recombinant antigens covering the structural proteins of human parvovirus B19 gives a deeper insight into the actual status of infection. In addition, the determination of IgG avidity against these individual recombinant antigens enables a more precise and differentiated picture of the infection event.