Human parvovirus B19 infection in infancy associated with acute and chronic lymphocytic myocarditis and high cytokine levels: report of 3 cases and review

The knowns and unknowns of cardiac autoimmunity in viral myocarditis

Myocarditis can result from various infectious and non-infectious causes that can lead to dilated cardiomyopathy (DCM) and heart failure. Among the infectious causes, viruses are commonly suspected. But the challenge is our inability to demonstrate infectious viral particles during clinical presentations, partly because by that point, the viruses would have damaged the tissues and be cleared by the immune system. Therefore, viral signatures such as viral nucleic acids and virus-reactive antibodies may be the only readouts pointing to viruses as potential primary triggers of DCM. Thus, it becomes hard to explain persistent inflammatory infiltrates that might occur in individuals affected with chronic myocarditis/DCM manifesting myocardial dysfunctions. In these circumstances, autoimmunity is suspected, and antibodies to various autoantigens have been demonstrated, suggesting that immune therapies to suppress the autoimmune responses may be necessary. From this perspective, we endeavoured to determine whether or not the known viral causes are associated with development of autoimmune responses to cardiac antigens that include both cardiotropic and non-cardiotropic viruses. If so, what their nature and significance are in developing chronic myocarditis resulting from viruses as primary triggers.

Effect of Astragalus injection on inflammatory mediators in patients with viral myocarditis: A systematic review and meta-analysis

BACKGROUND

To explore the therapeutic effect and mechanism of Astragalus injection on viral myocarditis, we conducted a systematic review and meta-analysis to identify the influence of Astragalus injection on inflammatory mediators and overall efficiency in patients undergoing viral myocarditis.

METHODS

EMBASE, Cochrane Library, PubMed, Chinese Biomedical Literature, Chinese National Knowledge Infrastructure (CNKI), and Wanfang databases were searched to screen randomized controlled trials (RCTs) published before July 3, 2022. The quality of participating studies was assessed by the Cochrane Collaboration Risk of Bias tool. The calculation of qualitative data used a risk ratio (RR) with a 95% confidence interval (95% CI), and quantitative data had standardized mean differences (SMDs) with a 95% CI. The heterogeneity among trials was quantified with Cochran's Q test and the I² statistic. Confounding factors were estimated by sensitivity analysis, meta-regression, and subgroup analysis. The publication bias of participating articles was evaluated by funnel plot and Egger's test. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) system was recommended for assessing the strength of evidence.

RESULTS

Nineteen available studies were included in our present meta-analysis, all of which were conducted in China. The outcomes expose that Astragalus injection dramatically decreased the levels of pro-inflammatory TNF-α (SMD=-2.271, 95% CI=-2.802 to -1.739, p<0.001, I²=90.6%), IL-6 (SMD=-1.501, 95% CI=-1.872 to -1.130, p<0.001, I²=83.2%), IL-17 (SMD=-3.194, 95% CI=-4.569 to -1.818, p<0.001, I²=88.9%), 1L-8 (SMD=-6.133, 95% CI=-9.938 to -2.328, p = 0.002, I²=97%), 1L-1 (SMD=-1.814, 95% CI=-2.557 to -1.070, p<0.001, I²=92.1%), CRP (SMD=-2.020, 95% CI=-3.107 to -0.932, p<0.001, I²=92.7%), and IFN-γ (SMD=-1.512, 95% CI=-2.771 to -0.253, p = 0.019, I²=92%) and increased the total effective rate of treatment (RR=1.225, 95% CI=1.17 to 1.29, p<0.001, I²=0.0%) in patients with viral myocarditis.

CONCLUSION

Astragalus injection can play a therapeutic role in patients with viral myocarditis through immunomodulatory effects. Outcomes were treated with caution due to significant heterogeneity among studies. Large-scale RCTs should be performed to support these conclusions.

Recombinant Muscovy Duck Parvovirus Led to Ileac Damage in Muscovy Ducklings

Waterfowl parvovirus (WPFs) has multiple effects on the intestinal tract, but the effects of recombinant Muscovy duck parvovirus (rMDPV) have not been elucidated. In this study, 48 one-day-old Muscovy ducklings were divided into an infected group and a control group. Plasma and ileal samples were collected from both groups at 2, 4, 6, and 8 days post-infection (dpi), both six ducklings at a time. Next, we analyzed the genomic sequence of the rMDPV strain. Results showed that the ileal villus structure was destroyed seriously at 4, 6, 8 dpi, and the expression of ZO-1, Occludin, and Claudin-1 decreased at 4, 6 dpi; 4, 6, 8 dpi; and 2, 6 dpi, respectively. Intestinal cytokines IFN-α, IL-1β and IL-6 increased at 6 dpi; 8 dpi; and 6, 8 dpi, respectively, whereas IL-2 decreased at 6, 8 dpi. The diversity of ileal flora increased significantly at 4 dpi and decreased at 8 dpi. The bacteria Ochrobactrum and Enterococcus increased and decreased at 4, 8 dpi; 2, 4 dpi, respectively. Plasma MDA increased at 2 dpi, SOD, CAT, and T-AOC decreased at 2, 4, 8 dpi; 4, 8 dpi; and 4, 6, 8 dpi, respectively. These results suggest that rMDPV infection led to early intestinal barrier dysfunction, inflammation, ileac microbiota disruption, and oxidative stress.

Parvovirus B19-Associated Myocarditis: A Literature Review of Pediatric Cases

Parvovirus B19 (B19V) infection may lead to myocarditis, a life-threatening condition in pediatric patients. In this review, we aim to present published pediatric cases of B19V-associated myocarditis in order to understand the deep complex connections and draw useful conclusions. We performed a comprehensive search of MEDLINE, Science Direct, and Google Scholar electronic databases. A total of 32 cases were included in our study. The most common presenting symptom was tachycardia in 22/32 patients (68.7%), followed by tachypnoea (21/32, 65.6%), fever, and rash (12/32, 37.5% for both of them). Cardiac arrest, loss of consciousness, and systemic infection were associated with the worst prognosis, with statistically significant differences (p-value 0.001, 0.02, 0.001. respectively). A percentage as high as 90.4% of patients with left ventricular (LV) dysfunction and reduced ejection fraction (EF) were discharged. Twelve patients required ventilatory support, five required extracorporeal membrane oxygenation (ECMO), and three underwent heart surgery. Treatment with immunosuppressive agents and immunoglobulin was found to be beneficial for patients (p-value 0.006 and 0.004, respectively). In conclusion, B19V myocarditis has high mortality rates in children. There is no specific antiviral treatment for B19V infection and therapeutic strategies for myocarditis aim to delay the worsening of heart failure and to preserve the LV function. Inotropic drugs, diuresis, ventilatory support, Intravenous immunoglobulin (IVIG), and immunosuppressive therapy seem to help the recovery of the myocardium in children with LV dilation, dysfunction, and reduced EF. Children with cardiac arrest, arrhythmias, and loss of consciousness have the worst prognosis.

Myocardial Damage by SARS-CoV-2: Emerging Mechanisms and Therapies

Evidence is emerging that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can infect various organs of the body, including cardiomyocytes and cardiac endothelial cells in the heart. This review focuses on the effects of SARS-CoV-2 in the heart after direct infection that can lead to myocarditis and an outline of potential treatment options. The main points are: (1) Viral entry: SARS-CoV-2 uses specific receptors and proteases for docking and priming in cardiac cells. Thus, different receptors or protease inhibitors might be effective in SARS-CoV-2-infected cardiac cells. (2) Viral replication: SARS-CoV-2 uses RNA-dependent RNA polymerase for replication. Drugs acting against ssRNA(+) viral replication for cardiac cells can be effective. (3) Autophagy and double-membrane vesicles: SARS-CoV-2 manipulates autophagy to inhibit viral clearance and promote SARS-CoV-2 replication by creating double-membrane vesicles as replication sites. (4) Immune response: Host immune response is manipulated to evade host cell attacks against SARS-CoV-2 and increased inflammation by dysregulating immune cells. Efficiency of immunosuppressive therapy must be elucidated. (5) Programmed cell death: SARS-CoV-2 inhibits programmed cell death in early stages and induces apoptosis, necroptosis, and pyroptosis in later stages. (6) Energy metabolism: SARS-CoV-2 infection leads to disturbed energy metabolism that in turn leads to a decrease in ATP production and ROS production. (7) Viroporins: SARS-CoV-2 creates viroporins that lead to an imbalance of ion homeostasis. This causes apoptosis, altered action potential, and arrhythmia.

Answered and Unanswered Questions in Early-Stage Viral Vector Transduction Biology and Innate Primary Cell Toxicity for Ex-Vivo Gene Editing

Adeno-associated virus is a highly efficient DNA delivery vehicle for genome editing strategies that employ CRISPR/Cas9 and a DNA donor for homology-directed repair. Many groups have used this strategy in development of therapies for blood and immune disorders such as sickle-cell anemia and severe-combined immunodeficiency. However, recent events have called into question the immunogenicity of AAV as a gene therapy vector and the safety profile dictated by the immune response to this vector. The target cells dictating this response and the molecular mechanisms dictating cellular response to AAV are poorly understood. Here, we will investigate the current known AAV capsid and genome interactions with cellular proteins during early stage vector transduction and how these interactions may influence innate cellular responses. We will discuss the current understanding of innate immune activation and DNA damage response to AAV, and the limitations of what is currently known. In particular, we will focus on pathway differences in cell line verses primary cells, with a focus on hematopoietic stem and progenitor cells (HSPCs) in the context of ex-vivo gene editing, and what we can learn from HSPC infection by other parvoviruses. Finally, we will discuss how innate immune and DNA damage response pathway activation in these highly sensitive stem cell populations may impact long-term engraftment and clinical outcomes as these gene-editing strategies move towards the clinic, with the aim to propose pathways relevant for improved hematopoietic stem cell survival and long-term engraftment after AAV-mediated genome editing.

Tale of two viruses: parvovirus B19 and HIV

We present a HIV-infected patient who developed severe anaemia due to chronic parvovirus B19 infection and subsequently had an unplanned pregnancy. This is in the context of poor adherence to antiretroviral therapy and significant immunosuppression; there was a delay in diagnosis of chronic parvovirus infection due to attribution of anaemia to HIV. She received immunoglobulin therapy and effective antiretroviral therapy, with reduction in parvovirus load and improvement in anaemia. She was counselled regarding the need for monitoring in pregnancy due to risk of intrauterine infection. We review the literature of management of chronic parvovirus infection in the immunosuppressed and the consequences of intrauterine infection.

Intravenous immunoglobulin for presumed viral myocarditis in children and adults

BACKGROUND

This is an update of a previous review. Case reports and case series have described dramatic responses to intravenous immunoglobulin (IVIG) in people with presumed viral myocarditis, and its administration has become commonplace.

OBJECTIVES

The primary objective of this review was to compare event-free (death, requirement for a cardiac transplant, or placement of a left ventricular assist device) or overall (death) survival of adults and children with presumed viral myocarditis treated with IVIG versus those who did not receive IVIG. A secondary objective was to determine if a group of patients with presumed viral myocarditis could be identified (on the basis of age, duration of symptoms, acuity of onset of symptoms, cardiac function at presentation, virological results, or the presence or absence of histological evidence of acute myocarditis on cardiac biopsy in patients in whom a biopsy was performed) who would be the most likely to benefit from IVIG.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, DARE, CINAHL, Web of Science Core Collection, and LILACS in July 2019, and two trial registries in November 2019. We contacted authors of trials and checked reference lists of relevant papers. We applied no language restrictions.

SELECTION CRITERIA

We included studies if (1) participants had a clinical diagnosis of acute myocarditis with a left ventricular ejection fraction (LVEF) ≤ 0.45, left ventricular end-diastolic diameter (LVEDD) > 2 standard deviations (SDs) above the norm, or a left ventricular shortening fraction (LVSF) > 2 SDs below the mean, with duration of cardiac symptoms < 6 months; (2) participants had no evidence of non-infectious or bacterial cardiac disease; and (3) participants were randomly assigned to receive at least 1 g/kg of IVIG versus no IVIG or placebo. We excluded studies if (1) participants had received immunosuppression before outcome assessment; or (2) onset of myocarditis was reported to have occurred < 6 months postpartum.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the search results and extracted data. We assessed risk of bias with the Cochrane 'Risk of bias' tool. We conducted meta-analysis for two outcomes (overall survival and improvement in LVEF) with two adult trials. Other meta-analyses were not possible because only three relevant trials were included, and researchers analysed markedly different populations and used different outcome measures.

MAIN RESULTS

In this update we added two trials to the two previously included trials. A quasi-randomised trial was previously included due to a paucity of evidence from randomised trials; however, with the addition of two new randomised trials, it was removed from this update. For two adult trials, the overall risk of bias was unclear with very low-certainty evidence for all outcomes. The first trial studied 62 adults with recent-onset dilated cardiomyopathy randomly assigned to receive IVIG or an equivalent volume of 0.1% albumin in a blinded fashion. The effect on event-free survival between groups was uncertain (risk ratio (RR) of any event 1.76, 95% confidence interval (CI) 0.48 to 6.40). The second trial studied 41 adults with acute myocarditis randomised to either high-dose IVIG (1 to 2 g/kg over two days) or no treatment. The IVIG group reported greater survival time after 60 days (no raw data, P < 0.01), but the evidence is uncertain. We pooled the reported number of deaths in both trials, with no evidence of a difference between groups (RR 0.91, 95% CI 0.23 to 3.62, I² = 31%, very low-certainty evidence). The evidence on the effect of IVIG treatment on LVEF (pooled mean difference (MD) -0.01, 95% CI -0.06 to 0.05) after 12 months and an unknown time frame is uncertain. The results for functional capacity, assessed by peak oxygen consumption at 12 months, were uncertain (MD -0.80, 95% CI -4.57 to 2.97). The results for infusion-related side effects were also uncertain due to a very large CI (RR 20.29, 95% CI 1.25 to 329.93). Lastly, there was uncertain evidence addressing failure to attain complete recovery (RR 0.46, 95% CI 0.19 to 1.14).  Evidence for improvement in LVEDD, left ventricular shortening fraction, and hospitalisation status in adults was not reported.  In the single included paediatric trial, the overall risk of bias was low with very low-certainty evidence for all outcomes. The trial included 86 children in Egypt presenting with acute myocarditis. Children were randomly assigned to 1 g/kg IVIG daily for two consecutive days or placebo followed by echocardiography one and six months post randomisation for recording of LVEDD and LVSF. The evidence for overall survival after six months was uncertain (risk of death RR 0.48, 95% CI 0.20 to 1.15). The evidence was also uncertain for improvement in LVEDD and LVSF after six months (LVEDD MD -4.00, 95% CI -9.52 to 1.52; LVSF no raw data).  Evidence for improvement in LVEF, functional capacity, side effects, complete recovery, and hospitalisation status in children was not reported.  AUTHORS' CONCLUSIONS: Evidence from two trials of very low certainty and with unclear risk of bias provides contradictory evidence on the use of IVIG in the treatment of adults with presumed viral myocarditis. One trial reported that use of IVIG results in longer survival time after 60 days, whilst the other trial found that IVIG does not provide an appreciable benefit. The evidence of a difference in event-free or overall survival, LVEDD, or LVSF is of very low certainty in a single paediatric trial with a low risk of bias. Until higher-quality studies with low risk of bias and larger sample sizes have demonstrated benefit in a particular group of patients, the evidence for treatment with IVIG for presumed viral myocarditis is uncertain. Further studies of the pathophysiology of myocarditis would lead to improved diagnostic criteria, which would facilitate future research.

Cardio-Immunology of Myocarditis: Focus on Immune Mechanisms and Treatment Options

Myocarditis and inflammatory cardiomyopathy are syndromes, not aetiological disease entities. From animal models of cardiac inflammation we have detailed insight of the strain specific immune reactions based on the genetic background of the animal and the infectiosity of the virus. Innate and adaptive immunity also react in man. An aetiological diagnosis of a viral vs. a non-viral cause is possible by endomyocardial biopsy with histology, immunohistology and PCR for microbial agents. This review deals with the different etiologies of myocarditis and inflammatory cardiomyopathy on the basis of the genetic background and the predisposition for inflammation. It analyses the epidemiologic shift in cardiotropic viral agents in the last 30 years. Based on the understanding of the interaction between infection and the players of the innate and adaptive immune system it summarizes pathogenetic phases and clinical faces of myocarditis. It gives an up-to-date information on specific treatment options beyond symptomatic heart failure and antiarrhythmic therapy. Although inflammation can resolve spontaneously, specific treatment directed to the causative etiology is often required. For fulminant, acute, and chronic autoreactive myocarditis without viral persistence immunosuppressive treatment can be life-saving, for viral inflammatory cardiomyopathy ivIg treatment can resolve inflammation and often eradicate the virus.

Parvovirus B19: A Cause of Sepsislike Syndrome in an Infant

Parvovirus B19 (PB19) is an important human pathogen that results in a wide spectrum of clinical outcomes, from mild, self-limiting erythema infectiosum in immunocompetent children and arthralgia in adults to lethal cytopenia in immunocompromised patients and intrauterine fetal death. However, there have been few reports of PB19 infection in neonates or young infants (aged 28-90 days), and no previous reports contained descriptions of PB19 infection as a cause of sepsislike syndrome in this age group. We report a case of sepsislike syndrome caused by PB19 infection in a 56-day-old infant whose mother had polyarthralgia at the time of his admission. PB19 infection was diagnosed on the basis of positive polymerase chain reaction results for PB19 DNA in the serum and cerebrospinal fluid. Positive immunoglobulin M and negative immunoglobulin G for PB19 suggested acute infection. He was admitted to the ICU because of poor peripheral circulation, but fully recovered without antibiotic administration. After excluding other possible pathogens, PB19 should be suspected as a cause of sepsislike syndrome in young infants, especially those who have close contact with PB19-infected individuals.

Human Parvoviruses

Parvovirus B19 (B19V) and human bocavirus 1 (HBoV1), members of the large Parvoviridae family, are human pathogens responsible for a variety of diseases. For B19V in particular, host features determine disease manifestations. These viruses are prevalent worldwide and are culturable in vitro, and serological and molecular assays are available but require careful interpretation of results. Additional human parvoviruses, including HBoV2 to -4, human parvovirus 4 (PARV4), and human bufavirus (BuV) are also reviewed. The full spectrum of parvovirus disease in humans has yet to be established. Candidate recombinant B19V vaccines have been developed but may not be commercially feasible. We review relevant features of the molecular and cellular biology of these viruses, and the human immune response that they elicit, which have allowed a deep understanding of pathophysiology.

Myocarditis in Paediatric Patients: Unveiling the Progression to Dilated Cardiomyopathy and Heart Failure

Myocarditis is a challenging and potentially life-threatening disease associated with high morbidity in some paediatric patients, due to its ability to present as an acute and fulminant disease and to ultimately progress to dilated cardiomyopathy. It has been described as an inflammatory disease of the myocardium caused by diverse aetiologies. Viral infection is the most frequent cause of myocarditis in developed countries, but bacterial and protozoal infections or drug hypersensitivity may also be causative agents. The prompt diagnosis in paediatric patients is difficult, as the spectrum of clinical manifestation can range from no myocardial dysfunction to sudden cardiac death. Recent studies on myocarditis pathogenesis have revealed a triphasic nature of this disease, which influences the diagnostic and therapeutic strategies to adopt in each patient. Endomyocardial biopsy remains the gold standard for diagnosing myocarditis, and several non-invasive diagnostic tools can be used to support the diagnosis. Intravenous immunoglobulin has become part of routine practice in the treatment of myocarditis in paediatric patients at many centres, but its true effect on the cardiac function has been the target of many studies. The aim of this review is to approach the recently discovered facets of paediatric myocarditis regarding its progression to dilated cardiomyopathy.

The Receptor-Binding Domain in the VP1u Region of Parvovirus B19

Parvovirus B19 (B19V) is known as the human pathogen causing the mild childhood disease erythema infectiosum. B19V shows an extraordinary narrow tissue tropism for erythroid progenitor cells in the bone marrow, which is determined by a highly restricted uptake. We have previously shown that the specific internalization is mediated by the interaction of the viral protein 1 unique region (VP1u) with a yet unknown cellular receptor. To locate the receptor-binding domain (RBD) within the VP1u, we analyzed the effect of truncations and mutations on the internalization capacity of the recombinant protein into UT7/Epo cells. Here we report that the N-terminal amino acids 5-80 of the VP1u are necessary and sufficient for cellular binding and internalization; thus, this N-terminal region represents the RBD required for B19V uptake. Using site-directed mutagenesis, we further identified a cluster of important amino acids playing a critical role in VP1u internalization. In silico predictions and experimental results suggest that the RBD is structured as a rigid fold of three α-helices. Finally, we found that dimerization of the VP1u leads to a considerably enhanced cellular binding and internalization. Taken together, we identified the RBD that mediates B19V uptake and mapped functional and structural motifs within this sequence. The findings reveal insights into the uptake process of B19V, which contribute to understand the pathogenesis of the infection and the neutralization of the virus by the immune system.

Parvovirus B19 myocarditis in children: an observational study

BACKGROUND

The advent of PCR testing for the presence of viral genomes has led to the identification of parvovirus B19 (PVB19) as a causative agent of myocarditis.

METHODS

The clinical presentation, course and outcome of children with PVB19 myocarditis was ascertained through a retrospective review. The PVB19 viral genome was detected by PCR from whole blood or endomyocardial biopsy specimens in patients presenting with new onset heart failure.

RESULTS

Seventeen patients presented at a median age of 1.3 years (range: 0.4-15.4 years) in cardiac failure with a mean fractional shortening of 15±3%. Eleven patients required mechanical ventilation and intravenous inotropes and seven required extra-corporeal mechanical oxygenation. Four of the five deaths occurred in patients who had a short prodromal illness of less than 48 hours. All patients with ST segment elevation died (n=4). All non-fulminant cases survived. Event-free survival occurred in 11/17 (65%) patients. Five (29%) patients died and one patient underwent heart transplantation. Complete recovery of cardiac function occurred within a median of 12 months (range: 1-48) in five patients. There was incomplete recovery in five patients and one patient had persistent dilated cardiomyopathy.

CONCLUSIONS

PVB19 can cause a devastating myocarditis in children. Children with fulminant myocarditis, ST segment changes or a short prodrome have the worst outcome. Transplantation may be considered, but is rarely required in the acute period if mechanical circulatory support is utilised. If the initial presentation is survived, recovery of the myocardium can occur even in those who had fulminant myocarditis.

Intravenous immunoglobulin for presumed viral myocarditis in children and adults

BACKGROUND

This is an update of a previous review. Case reports and case series have described dramatic responses to intravenous immunoglobulin (IVIG) in people with presumed viral myocarditis, and its administration has become commonplace.

OBJECTIVES

The primary objective of this review was to compare transplant-free survival of adults and children with presumed viral myocarditis treated with IVIG versus those who did not receive IVIG. A secondary objective was to determine if a group of patients with presumed viral myocarditis could be identified (on the basis of age, duration of symptoms, acuity of onset of symptoms, cardiac function at presentation, virological results or the presence or absence of histological evidence of acute myocarditis on cardiac biopsy in patients in whom a biopsy was performed) who would be the most likely to benefit from IVIG.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2013, Issue 12 of 12), the Database of Abstracts of Reviews of Effects (DARE) (2013, Issue 4 of 4), MEDLINE (Ovid, 1946 to January Week 3 2014), EMBASE (Ovid, 1980 to Week 4 2014), the Cumulative Index to Nursing and Allied Health Literature (CINAHL) EBSCO, Web of Science (Thomson Reuters, 1970 to 24 January 2014), the Latin American and Caribbean Health Science Information Database (LILACS) (1982 to 30 January 2014), trials registries and conference proceedings. We contacted authors of trials and checked reference lists of relevant papers. We applied no language restrictions.

SELECTION CRITERIA

We included studies if (1) participants had a clinical diagnosis of acute myocarditis with a left ventricular ejection fraction (LVEF) ≤ 0.45, left ventricular end-diastolic diameter (LVEDD) > 2 standard deviations (SDs) above the norm or a shortening fraction (SF) > 2 SDs below the mean with duration of cardiac symptoms < 6 months; (2) participants had no evidence of non-infectious or bacterial cardiac disease; and (3) participants were randomly assigned to receive at least 1 g/kg of IVIG versus no IVIG or placebo. We excluded studies if (1) participants had received immunosuppression before outcome assessment; or (2) onset of myocarditis was reported to occur < 6 months post partum.

DATA COLLECTION AND ANALYSIS

Two review authors screened searches and extracted data independently. We assessed quality using the 'Risk of bias' tool. Meta-analysis was not possible because only two relevant studies were found, and researchers analysed markedly different populations.

MAIN RESULTS

In this update, review authors added one study to the study from the original review. The first relevant study involved 62 adults with recent-onset dilated cardiomyopathy randomly assigned to receive IVIG or an equivalent volume of 0.1% albumin in a blinded fashion. The overall risk of bias was unclear. The incidence of death or the requirement for cardiac transplant or placement of a left ventricular assist device was low in both groups (odds ratio (OR) for event-free survival 0.52, 95% confidence interval (CI) 0.12 to 2.30). Follow-up at six months and at 12 months showed equivalent improvement in LVEF (mean difference (MD) 0.00, 95% CI -0.07 to 0.07 at six months; MD 0.01, 95% CI -0.06 to 0.08 at 12 months). Functional capacity as assessed by peak oxygen consumption was equivalent in the two groups at 12 months (MD -0.80, 95% CI -4.57 to 2.97). Infusion-related side effects were more common in the treated group, but all were reported to be mild (OR 30.16, 95% CI 1.69 to 539.42).The second study added at this update included 83 children in India with suspected viral encephalitis and myocarditis. The overall risk of bias was high. The odds ratio for event-free survival was 7.39 (95% CI 0.91 to 59.86). Follow-up occurred only until hospital discharge, and LVEF was 49.5% in the treated group versus 35.9% in the placebo group (risk difference 13.6%, 95% CI 5.1 to 22.1%; P value = 0.001).

AUTHORS' CONCLUSIONS

Evidence from one trial does not support the use of IVIG for the treatment of adults with presumed viral myocarditis. The only paediatric trial had high risk of bias but suggested that benefit may be seen in the select group of children beyond the neonatal period who have viral encephalitis with myocarditis. Until higher-quality studies have demonstrated benefit in a particular group of patients, IVIG for presumed viral myocarditis should not be provided as routine practice in any situation. Further studies of the pathophysiology of myocarditis would lead to improved diagnostic criteria, which would facilitate future research.

Use of intravenous immunoglobulin in critically ill patients

Intravenous immunoglobulin (IVIG) has been suggested for the treatment of many ailments due to its ability to modulate the immune system and to provide passive immunity to commonly circulating pathogens. Its use as primary and adjunctive therapy for the treatment of conditions affecting critically ill patients is an attractive option, especially when alternative therapy does not exist. The body of literature on the use of IVIG for the treatment of several serious conditions, including sepsis, toxic shock syndrome, acute myocarditis, Stevens-Johnson syndrome, toxic epidermal necrolysis, and H1N1 influenza, were reviewed. Despite advances in treatment of these conditions since they were first described, there remains a paucity of well-designed studies on the use of IVIG for their treatment. Therefore, the use of IVIG for treatment of these conditions remains controversial.

Antibody-mediated enhancement of parvovirus B19 uptake into endothelial cells mediated by a receptor for complement factor C1q

Despite its strong host tropism for erythroid progenitor cells, human parvovirus B19 (B19V) can also infect a variety of additional cell types. Acute and chronic inflammatory cardiomyopathies have been associated with a high prevalence of B19V DNA in endothelial cells of the myocardium. To elucidate the mechanisms of B19V uptake into endothelium, we first analyzed the surface expression of the well-characterized primary B19V receptor P antigen and the putative coreceptors α5β1 integrins and Ku80 antigen on primary and permanent endothelial cells. The receptor expression pattern and also the primary attachment levels were similar to those in the UT7/Epo-S1 cell line regarded as functional for B19V entry, but internalization of the virus was strongly reduced. As an alternative B19V uptake mechanism in endothelial cells, we demonstrated antibody-dependent enhancement (ADE), with up to a 4,000-fold increase in B19V uptake in the presence of B19V-specific human antibodies. ADE was mediated almost exclusively at the level of virus internalization, with efficient B19V translocation to the nucleus. In contrast to monocytes, where ADE of B19V has been described previously, enhancement does not rely on interaction of the virus-antibody complexes with Fc receptors (FcRs), but rather, involves an alternative mechanism mediated by the heat-sensitive complement factor C1q and its receptor, CD93. Our results suggest that ADE represents the predominant mechanism of endothelial B19V infection, and it is tempting to speculate that it may play a role in the pathogenicity of cardiac B19V infection. Importance: Both efficient entry and productive infection of human parvovirus B19 (B19V) seem to be limited to erythroid progenitor cells. However, in vivo, the viral DNA can also be detected in additional cell types, such as endothelial cells of the myocardium, where its presence has been associated with acute and chronic inflammatory cardiomyopathies. In this study, we demonstrated that uptake of B19V into endothelial cells most probably does not rely on the classical receptor-mediated route via the primary B19V receptor P antigen and coreceptors, such as α5β1 integrins, but rather on antibody-dependent mechanisms. Since the strong antibody-dependent enhancement (ADE) of B19V entry requires the CD93 surface protein, it very likely involves bridging of the B19V-antibody complexes to this receptor by the complement factor C1q, leading to enhanced endocytosis of the virus.

Intravenous immunoglobulin in the therapy of adult acute fulminant myocarditis: A retrospective study

Acute fulminant myocarditis (AFM) is a serious heart disease with limited treatment. This observational retrospective study aimed to investigate whether intravenous immunoglobulin (IVIG) was able to improve left ventricular function and reduce the episodes of arrhythmia in adult patients with AFM. The medical records of all patients with AFM who were admitted to the Critical Care Unit of Guangdong General Hospital (Guangzhou, China) between January 2001 and December 2010 were reviewed. A cohort of 58 patients was included in the study. Of these 58, 32 patients were treated with IVIG (400 mg/kg per day) for five days, while the remaining patients did not receive IVIG therapy. The patients who received IVIG therapy had a higher left ventricular ejection fraction (LVEF) and a reduced left ventricular end-diastolic diameter (LVDD) compared with the non-IVIG therapy patients four weeks subsequent to the treatment (P_LVEF=0.011 and P_LVDD=0.048). The post-treatment incidence of ventricular tachycardia/ventricular fibrillation (VT/VF) and atrioventricular block (AVB) was reduced in the patients who received IVIG therapy compared with the baseline values (P_VT/VF=0.025, P_AVB=0.003); however, no significant differences were observed in the non-IVIG therapy patients (P_VT/VF=0.564, P_AVB=0.083) following treatment. There were two mortalities in the IVIG therapy group and seven in the non-IVIG therapy group (P=0.072). This retrospective study suggested that the use of IVIG for the treatment of AFM may be associated with improved left ventricular function and reduced episodes of fulminant arrhythmias.

Current treatment options in (peri)myocarditis and inflammatory cardiomyopathy

In inflammatory dilated cardiomyopathy and myocarditis there is--apart from heart failure and antiarrhythmic therapies--no alternative to an aetiologically driven specific treatment. Prerequisite are noninvasive and invasive biomarkers including endomyocardial biopsy and PCR on cardiotropic agents. This review deals with the different etiologies of myocarditis and inflammatory cardiomyopathy including the genetic background, the predisposition for heart failure and inflammation. It analyses the epidemiologic shift in pathogenetic agents in the last 20 years, the role of innate and aquired immunity including the T- and B-cell driven immune responses. The phases and clinical faces of myocarditis are summarized. Up-to-date information on current treatment options starting with heart failure and antiarrhythmic therapy are provided. Although inflammation can resolve spontaneously, specific treatment directed to the causative aetiology is often required. For fulminant, acute and chronic autoreactive myocarditis immunosuppressive treatment is beneficial, while for viral cardiomyopathy and myocarditis ivIg can resolve inflammation and is as successful as interferon therapy in enteroviral and adenoviral myocarditis. For Parvo B19 and HHV6 myocarditis eradication of the virus is still a problem by any of these treatment options. Finally, the potential of stem cell therapy has to be tested in future trials. In virus-negative, autoreactive perimyocardial disease a locoregional approach with intrapericardial instillation of high local doses of triamcinolone acetate has been shown to be highly efficient and with few systemic side-effects.

Parvovirus B19 myocarditis causes significant morbidity and mortality in children

Although parvovirus B19 (PVB19) currently is the most common cause of viral myocarditis, limited pediatric data exist. Whereas other viruses infect cardiomyocytes, PVB19 targets coronary endothelium, leading to myocardial ischemia and dysfunction. A retrospective review investigated patients with polymerase chain reaction (PCR)-verified PVB19 myocarditis at Texas Children's Hospital and Arkansas Children's Hospital (January 2005 to August 2008). The primary end points of the study were transplant-free survival and circulatory collapse (death, mechanical support, or transplantation). For the 19 patients identified (age, 6 months to 15 years), the most common presenting symptoms were respiratory and gastrointestinal. At admission, all the patients demonstrated ventricular dysfunction requiring inotropic support (median ejection fraction, 24 %; median left ventricle end-diastolic diameter [LVEDD] z-score, 4.6). Whereas T-wave abnormalities were common, ST elevation was evident in five patients (two died and three required transplantation). Serum B-type natrietic peptide was elevated in all 12 patients tested (range, 348-8,058 pg/ml), and troponin I was high in 7 of 9 patients (range, 0.04-14.5 ng/ml). Of the 15 patients with circulatory collapse, nine received mechanical support, eight underwent successful transplantation, and five died. Only six patients (32 %) experienced transplant-free survival, and five patients had full recovery of function at discharge. In the transplant-free survival group, ST changes on presenting electrocardiography were less likely (p = 0.03), and the admission LVEDD z-score tended to be lower (3.3 vs 5.6; p = 0.08). In children, PVB19 myocarditis causes significant mortality and morbidity. Although mechanical intervention can support patients in the initial stage of decompensated heart failure, patients with PVB19 myocarditis often demonstrate persistent dysfunction requiring medical therapy and transplantation.

Profile of circulating levels of IL-1Ra, CXCL10/IP-10, CCL4/MIP-1β and CCL2/MCP-1 in dengue fever and parvovirosis

Dengue virus (DENV) and parvovirus B19 (B19V) infections are acute exanthematic febrile illnesses that are not easily differentiated on clinical grounds and affect the paediatric population. Patients with these acute exanthematic diseases were studied. Fever was more frequent in DENV than in B19V-infected patients. Arthritis/arthralgias with DENV infection were shown to be significantly more frequent in adults than in children. The circulating levels of interleukin (IL)-1 receptor antagonist (Ra), CXCL10/inducible protein-10 (IP-10), CCL4/macrophage inflammatory protein-1 beta and CCL2/monocyte chemotactic protein-1 (MCP-1) were determined by multiplex immunoassay in serum samples obtained from B19V (37) and DENV-infected (36) patients and from healthy individuals (7). Forward stepwise logistic regression analysis revealed that circulating CXCL10/IP-10 tends to be associated with DENV infection and that IL-1Ra was significantly associated with DENV infection. Similar analysis showed that circulating CCL2/MCP-1 tends to be associated with B19V infection. In dengue fever, increased circulating IL-1Ra may exert antipyretic actions in an effort to counteract the already increased concentrations of IL-1β, while CXCL10/IP-10 was confirmed as a strong pro-inflammatory marker. Recruitment of monocytes/macrophages and upregulation of the humoral immune response by CCL2/MCP-1 by B19V may be involved in the persistence of the infection. Children with B19V or DENV infections had levels of these cytokines similar to those of adult patients.

Comparison of the clinical presentation, treatment, and outcome of fulminant and acute myocarditis in children

BACKGROUND

Myocarditis (MC) is an important cause of cardiac dysfunction in children. Fulminant MC is sometimes fatal, and sequelae may develop during follow-up. We conducted a nationwide survey to determine the clinico-epidemiological features of MC in Japanese children and adolescents.

METHODS AND RESULTS

Survey questionnaires were mailed to 627 hospitals, which were asked if they had treated MC patients aged between 1 month and 17 years during the period from January 1997 through December 2002. Responses were collected until December 2005, and data were collected and analyzed until January 2008. A total of 169 patients were reported: 64 fulminant cases, 89 acute cases, and 8 chronic cases. Incidence was 43.5 cases/year and 0.26 cases/100,000. Pathogens were identified in 37 patients; coxsackie virus accounted for 60%. Major cardiovascular manifestations at onset were congestive heart failure, refractory arrhythmia, and syncope in 70, 37, and 17 patients, respectively. Intravenous immunoglobulin was administered to 73 patients. Mechanical support seemed to be effective and life-saving. Among the 169 patients, 123 survived. Cardiovascular sequelae were reported in 49 patients.

CONCLUSIONS

The survival rate for children with fulminant MC was disappointing. Overall, two-thirds of survivors had no sequelae. Mechanical support may reduce the mortality and the risk of clinical worsening.

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.

The evolving approach to paediatric myocarditis: a review of the current literature

Paediatric myocarditis remains challenging from the perspectives of diagnosis and management. Multiple aetiologies exist and the majority of cases appear to be related to viral illnesses. Enteroviruses are believed to be the most common cause, although cases related to adenovirus may be more frequent than suspected. The clinical presentation is extremely varied, ranging from asymptomatic to sudden unexpected death. A high index of suspicion is crucial. There is emerging evidence to support investigations such as serum N-terminal B-type natriuretic peptide levels, as well as cardiac magnetic resonance imaging as adjuncts to the clinical diagnosis. In the future, these may reduce the necessity for invasive methods, such as endomyocardial biopsy, which remain the gold standard. Management generally includes supportive care, consisting of cardiac failure medical management, with the potential for mechanical support and cardiac transplantation. Treatments aimed at immunosuppression remain controversial. The paediatric literature is extremely limited with no conclusive evidence to support or refute these strategies. This article summarises the current literature regarding aetiology, clinical presentation, diagnosis, and management of myocarditis in paediatric patients.

Increased cardiac injury in NZB/W F1 mice received antibody against human parvovirus B19 VP1 unique region protein

Human parvovirus B19 (B19) infection has been postulated to both myocardial injury and development of systemic lupus erythematosus (SLE). However, the influence of anti-B19-VP1u antibodies on cardiac disorders in SLE is still obscure. To elucidate the effects of anti-B19-VP1u IgG in SLE, passive transfer of PBS, normal rabbit IgG or rabbit anti-B19-VP1u IgG was injected intravenously into NZB/W F1 mice, respectively. Significant expression of IL-1β, IL-6 and TNF-α were detected in NZB/W F1 mice receiving rabbit anti-B19-VP1u IgG. Markedly cardiomyocyte disarray and lymphocyte infiltration were observed in left ventricle of hearts from NZB/W F1 mice receiving rabbit anti-B19-VP1u IgG. Additionally, significant increases of matrix metalloproteinase-9 (MMP9) activity and protein expression were detected in left ventricle of hearts from NZB/W F1 mice receiving B19-VP1u IgG. Accordingly, significant increase of phosphorylated p-38 and NF-κB proteins were observed in left ventricle of hearts from NZB/W F1 mice receiving B19-VP1u IgG. However, no significant variation of cardiac atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), heart-type fatty acid-binding protein (h-FABP) and creatine kinase MB (CK-MB) were detected among all experimental groups. These findings firstly demonstrated the aggravated effects of anti-B19 VP1u IgG on cardiac injury by induction of inflammatory but not myocardial infarction-associated proteins through activation of phosphorylated p-38 and NF-κB signaling.

Parvovirus-mediated fetal cardiomyopathy with atrioventricular nodal disease

Acute parvovirus B19 infection (API) in pregnancy has been associated with fetal anemia and hydrops fetalis. Direct myocardial damage from API in a fetus and an infant has been described. This report presents a case of fetal second-degree heart block and cardiomyopathy secondary to API. A 19-year-old G4P1112 (gravida 4 para 2 with 1 term delivery, 1 preterm delivery, 1 termination, and 2 living children) was referred at 20 weeks gestation for fetal bradycardia. A 2:1 atrioventricular block was identified by fetal echocardiography at 23 weeks. Hydrops developed at 25 weeks. Amniocentesis and percutaneous umbilical blood sampling demonstrated API. At 31 weeks, the patient presented with preterm labor and delivered a viable female infant, who died of poor cardiac function and arrhythmia on the first day of life. In addition to fetal anemia and hydrops fetalis, API in pregnancy may cause direct fetal myocardial damage and conduction system disease.

Pericarditis and pleuritis associated with human parvovirus B19 infection in a systemic lupus erythematosus patient

Human parvovirus B19 (PVB19) infection sometimes shows systemic lupus erythematosus (SLE)-like symptoms. We present an SLE patient showing pericarditis and pleuritis with a fever and an acute swelling of extremities 2 months after the fist consultation. Initially, a diagnosis of SLE exacerbation was made. Additional laboratory examination showed positive results for immunoglobulin M (IgM) antibody to PVB19 and PVB19 DNA in serum and pleural effusion at that time. After 1 month, PVB19 DNA in serum and IgM antibody to PVB19 was negative. Based on these findings, a final diagnosis of PVB19 infection in an SLE patient was made. PVB19 infection should be taken into consideration for SLE with acute swelling of the extremities and fever, as these symptoms are often observed in adult cases of PVB19 infection. Steroid pulse therapy rapidly improved these symptoms, and later the dose of steroid was reduced to 5 mg/day of prednisolone. Thus, steroids may be one of the choices for severe and/or rapidly progressive symptoms of pericarditis and pleuritis due to PVB19 infection.

Viral myocarditis: diagnosis, aetiology and management

Myocarditis is an inflammatory disease of the cardiac muscle caused by myocardial infiltration of immunocompetent cells following any kind of cardiac injury. Classic myocarditis mainly occurs as a result of the host's immune response against organisms that cause common infectious illnesses, as a manifestation of hypersensitivity or as a toxic reaction to drug therapy. Chronic inflammatory events may survive successful clearance of initial cardiotoxic agents, be triggered or amplified by autoimmunological processes, or develop in the context of systemic diseases. If the underlying infectious or immune-mediated causes of the disease are carefully defined by clinical and biopsy-based tools, specific immunosuppressive and antiviral treatment options may improve the prognosis of patients with acute and chronic disease.

Human parvovirus B19 NS1 protein modulates inflammatory signaling by activation of STAT3/PIAS3 in human endothelial cells

The pathogenic mechanism by which parvovirus B19 may induce inflammatory cardiomyopathy (iCMP) is complex but is known to involve inflammatory processes, possibly including activation of JAK/STAT signaling. The nonstructural B19 protein NS1 acts as a transactivator triggering signaling cascades that eventually lead to activation of interleukin 6 (IL-6). We examined the impact of NS1 on modulation of STAT signaling in human endothelial cells (HMEC-1). The NS1 sequences were identified from B19 DNA isolated from the myocardia of patients with fatal iCMP. B19 infection as well as NS1 overexpression in HMEC-1 cells produced a significant upregulation in the phosphorylation of both tyrosine(705) and serine(727) STAT3 (P < 0.05). The increased STAT3 phosphorylation was accompanied by dimerization, nuclear translocation, and DNA binding of pSTAT3. In contrast, NS1 expression did not result in increased STAT1 activation. Notably, the expression levels of the negative regulators of STAT activation, SOCS1 and SOCS3, were not altered by NS1. However, the level of PIAS3 was upregulated in NS1-expressing HMEC-1 cells. Analysis of the transcriptional activation of target genes revealed that NS1-induced STAT3 signaling was associated with upregulation of genes involved in immune response (e.g., the IFNAR1 and IL-2 genes) and downregulation of genes associated with viral defense (e.g., the OAS1 and TYK2 genes). Our results demonstrate that B19 NS1 modulates the STAT/PIAS pathway. The NS1-induced upregulation of STAT3/PIAS3 in the absence of STAT1 phosphorylation and the lack of SOCS1/SOCS3 activation may contribute to the mechanisms by which B19 evades the immune response and establishes persistent infection in human endothelial cells. Thus, NS1 may play a critical role in the mechanism of viral pathogenesis in B19-associated iCMP.

Parvovirus B19 infection associated with dilated cardiomyopathy in patients with previous anthracycline exposure

We describe two children with previous anthracycline exposure for cancer who presented with acute decompensated left ventricular dysfunction. Both patients had evidence of dilated cardiomyopathy and required mechanical ventilation and inotropic support. Parvovirus B19 was detected by polymerase chain reaction of the blood. After several weeks of ventilation and inotropic support, both patients were weaned from ventilation and managed with oral carvedilol, ACE inhibition, and diuretics. Acute left ventricular decompensation in patients following anthracycline exposure may not be solely attributed to drug exposure, and viral etiologies should be considered.

Association of hypospadias and cardiac defect in a Parvovirus B19-infected stillborn: A causality relation?

Parvovirus B19 intrauterine infection is a known cause of hydrops fetalis and fetal death. It is also associated with congenital malformations, although the teratogenic potential seems to be low. Postmortem examination of a male stillborn of 29 gestational weeks revealed mild subcutaneous edema, malformed micropenis, perineoscrotal hypospadias and atrial septal defect, along with fetal erythroblastosis and villitis. Polymerase chain reaction detected Parvovirus B19 DNA genome in tissues from the fetus and the placenta, confirming the hypothesis of an intrauterine infection.

Unscrambling the role of human parvovirus B19 signaling in systemic autoimmunity

Despite enormous progress in understanding how the immune system works, the pathogenesis of autoimmune diseases still remains unclear. Growing evidence indicates that infectious agents can be potent initial triggers, subverting and exploiting host cell signaling pathways. This role is exemplified by the association of parvovirus B19 (B19) with human autoimmune disease. Infection with this common virus exhibits striking similarities with systemic autoimmune diseases, and can be associated with elevated serum autoantibody titers. The B19 virus produces proline-rich, 11-kDa proteins that have been implicated in modulation of host signaling cascades involved in virulence and pathogenesis. Additionally, B19 produces a non-structural protein (NS1) that functions as a transcription regulator by directly binding the p6 promoter and the Sp1/Sp3 transcription factors. The protein is also involved in DNA replication, cell cycle arrest and initiation of apoptotic damage, particularly in erythroid cells. When transfected to non-permissive cells, NS1 recruits the mitochondria cell death pathway. It is even more remarkable that NS1 functions as a trans-acting transcription activator for the IL6 promoter, up-regulating IL6 expression in host cells. Hence, B19 infection may play a pivotal role in triggering inflammatory disorders. By promoting apoptotic damage and trans-activating pro-inflammatory cytokine promoters, B19 may break the delicate balance between cell survival and apoptosis, and may contribute to immune deregulation. Understanding the mechanisms used by B19 to alter the cell signaling machinery may provide further insight into the mechanism by which autoimmune diseases develop.

Phospholipase A2 activity-dependent stimulation of Ca2+ entry by human parvovirus B19 capsid protein VP1

Recent reports demonstrated an association of human parvovirus B19 with inflammatory cardiomyopathy (iCMP), which is accompanied by endothelial dysfunction. As intracellular Ca(2+) activity is a key regulator of cell function and participates in mechanisms leading to endothelial dysfunction, the present experiments explored the effects of the B19 capsid proteins VP1 and VP2. A secreted phospholipase A2 (PLA2)-like activity has been located in the VP1 unique region of the B19 minor capsid protein. As PLA2 has recently been shown to activate the store-operated or capacitative Ca(2+) channel I(CRAC), we analyzed the impact of the viral PLA2 motif on Ca(2+) entry. We cloned the VP1 and VP2 genes isolated from a patient suffering from fatal B19 iCMP into eukaryotic expression vectors. We also generated a B19 replication-competent plasmid to demonstrate PLA2 activity under the control of the complete B19 genome. After the transfection of human endothelial cells (HMEC-1), cytosolic Ca(2+) activity was determined by utilizing Fura-2 fluorescence. VP1 and VP2 expression did not significantly modify basal cytosolic Ca(2+) activity or the decline of cytosolic Ca(2+) activity following the removal of extracellular Ca(2+). However, expression of VP1 and of the full-length B19 clone, but not of VP2, significantly accelerated the increase of cytosolic Ca(2+) activity following the readdition of extracellular Ca(2+) in the presence of thapsigargin, indicating an activation of I(CRAC.) The effect of VP1 was mimicked by the PLA2 product lysophosphatidylcholine and abolished by an inactivating mutation of the PLA2-encoding region of the VP1 gene. Our observations point to the activation of Ca(2+) entry by VP1 PLA2 activity, an effect likely participating in the pathophysiology of B19 infection.

Parvovirus B19: a new emerging pathogenic agent of inflammatory cardiomyopathy

The human parvovirus B19 (PVB19), an erythrovirus causing diverse clinical manifestations ranging from asymptomatic or mild to more severe outcomes such as hydrops fetalis, is the only currently known human pathogenic parvovirus. Recently, PVB19 has been identified as a causative agent of pediatric and adult inflammatory cardiac diseases. The first hints for a possible etiopathogenetic role of the PVB19 infection and the development of cardiac dysfunction were demonstrated by molecular biology methods such as in situ hybridization (ISH) and polymerase chain reaction (PCR). In this regard, PVB19-associated inflammatory cardiomyopathy is characterized by infection of endothelial cells of small intracardiac arterioles and venules, which may be associated with endothelial dysfunction, impairment of myocardial microcirculation, and penetration of inflammatory cells in the myocardium.

Increased expression and secretion of interleukin-6 in human parvovirus B19 non-structural protein (NS1) transfected COS-7 epithelial cells

Human parvovirus B19 (B19) has been associated with a variety of autoimmune diseases, including rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). We have demonstrated previously that B19 non-structural protein (NS1) induced apoptosis through the mitochondria cell death pathway in COS-7 epithelial cells and that B19 NS1 may play a role in the pathogenesis of autoimmune diseases. In order to examine the expression profiles of cytokines and chemokines in B19 NS1 transfected COS-7 cells, we constructed the NS1 gene in the pEGFP-C1 vector named enhanced green fluorescence protein gene (EGFP)-NS1. COS-7 cells were transfected with EGFP or EGFP-NS1 plasmid. The expression profiles of cytokines and chemokines, including interleukin (IL)-1beta, IL-5, IL-6, IL-8, IL-10, tumour necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta, granulocyte-macrophage colony-stimulating factor (GM-CSF), growth-related oncogene alpha (GROalpha), interferon gamma-inducible protein (IP)-10, stromal cell derived factor (SDF)-1, macrophage inflammatory protein (MIP)-1beta, monocyte chemoattractant protein (MCP)-1, regulated upon activation normal T cell expressed and secreted (RANTES), Fractalkine, CX3CR1, CCR2, CCR5 and CCR11 were examined in COS-7 cells, EGFP and EGFP-NS1 transfected cells using enzyme-linked immunosorbent assay (ELISA) or reverse transcription-polymerase chain reaction (RT-PCR). Increased expression and levels of IL-6 were found in EGFP-NS1 transfected cells using RT-PCR and ELISA. There were no significant increases in the expression of IL-1beta, IL-8, IP-10, SDF-1, RANTES, Fractalkine, CX3CR-1, CCR2, CCR5, CCR11, TNF-alpha, GM-CSF and TGF-beta using RT-PCR. There were no significantly increased levels of IL-5, IL-10, TNF-alpha, TGF-beta, GROalpha, MIP-1beta and MCP-1 found by ELISA in this study. Our results show that increased expression and secretion of IL-6 in B19 NS1 transfected epithelial cells may play a role in the pathogenesis of autoimmune diseases.

Human parvovirus B19: a new emerging pathogen of inflammatory cardiomyopathy

The human parvovirus B19 (PVB19), an erythrovirus causing diverse clinical manifestations ranging from asymptomatic or mild to more severe outcomes such as hydrops fetalis, is the only known human pathogenic parvovirus so far. Although enteroviruses have long been considered the most common cause of inflammatory cardiomyopathy, PVB19 is emerging as a important candidate. Recent studies have indicated an association of PVB19 with paediatric and adult inflammatory cardiac disease. However, whether or not PVB19 has an impact on inflammatory cardiomyopathy in adult patients is still unclear. The first hints for a possible aetiopathogenetic role of the PVB19-infection and the development of cardiac dysfunction were demonstrated by molecular biology utilizing in situ hybridization (ISH) and polymerase chain reaction (PCR). According to available evidence, PVB19-associated inflammatory cardiomyopathy is characterized by infection of endothelial cells of small intracardiac arterioles and venules, which may be associated with endothelial dysfunction, impairment of myocardial microcirculation, and penetration of inflammatory cells into the myocardium.

T helper cell-mediated interferon-gamma expression after human parvovirus B19 infection: persisting VP2-specific and transient VP1u-specific activity

Human parvovirus B19 is a small non-enveloped DNA virus with an icosahedral capsid consisting of proteins of only two species, the major protein VP2 and the minor protein VP1. VP2 is contained within VP1, which has an additional unique portion (VP1u) of 227 amino acids. We determined the ability of eukaryotically expressed parvovirus B19 virus-like particles consisting of VP1 and VP2 in the ratio recommended for vaccine use, or of VP2 alone, to stimulate, in an HLA class II restricted manner, peripheral blood mononuclear cells (PBMC) to proliferate and to secrete interferon gamma (IFN-gamma) and interleukin (IL)-10 cytokines among recently and remotely B19 infected subjects. PBMC reactivity with VP1u was determined specifically with a prokaryotically expressed VP1u antigen. In general, B19-specific IFN-gamma responses were stronger than IL-10 responses in both recent and remote infection; however, IL-10 responses were readily detectable among both groups, with the exception of patients with relapsed or persisting symptoms who showed strikingly low IL-10 responses. Whereas VP1u-specific IFN-gamma responses were very strong among the recently infected subjects, the VP1u-specific IFN-gamma and IL-10 responses were virtually absent among the remotely infected subjects. The disappearance of VP1u-specific IFN-gamma expression is surprising, as B-cell immunity against VP1u is well maintained.