C.-Thomas Bock

Presentation, Patterns of Myocardial Damage, and Clinical Course of Viral Myocarditis

Background— Enteroviruses and adenoviruses have been considered the most common causes of viral myocarditis, but parvovirus B19 (PVB19) and human herpesvirus 6 (HHV6) are increasingly found in endomyocardial biopsy samples. Methods and Results— Consequently, our aim was to evaluate the prevalence and clinical presentation of cardiac PVB19 and/or HHV6 infection in a cohort of myocarditis patients and to follow its clinical course. In addition, we sought to demonstrate patterns of myocardial damage and to determine predictors for chronic heart failure. Our study design consisted of a cardiovascular magnetic resonance protocol as well as endomyocardial biopsies in the myocardial region affected as indicated by cardiovascular magnetic resonance. One hundred twenty-eight patients were enrolled by clinical criteria. In the group of myocarditis patients (n=87), PVB19 (n=49), HHV6 (n=16), and combined PVB19/HHV6 infections (n=15) were detected most frequently. The remaining patients were diagnosed with healing myocarditis (n=15) or did not have myocarditis (n=26). Patients with PVB19 presented in a manner similar to that of myocardial infarction; most had typical subepicardial late gadolinium enhancement in the lateral wall and recovered within months. Conversely, patients with HHV6 and especially with HHV6/PVB19 myocarditis presented with new onset of heart failure, had septal late gadolinium enhancement, and frequently progressed toward chronic heart failure. Conclusions— Our data indicate that PVB19 and HHV6 are the most important causes for viral myocarditis in Germany and that the clinical presentation is related to the type of virus. Furthermore, clinical presentation, type of virus, and pattern of myocardial damage are related to the clinical course.

Hepatitis B surface antigen (HBsAg) levels in the natural history of hepatitis B virus (HBV)-infection: a European perspective.

BACKGROUND & AIMS The quantifiable level of HBsAg has been suggested as a predictor of treatment response in chronic hepatitis B. However, there is limited information on HBsAg levels considering the dynamic natural course of HBV-infection. This study aimed to determine HBsAg levels in the different phases of HBV-infection in European HBsAg-positive patients. METHODS 226 HBV-monoinfected patients, not undergoing antiviral therapy, were analyzed in a cross-sectional study. Patients were categorized according to the phase of HBV-infection: HBeAg(+) immune tolerance phase (IT, n=30), immune clearance phase (IC, n=48), HBeAg(-) low-replicative phase (LR, n=68), HBeAg(-) hepatitis (ENH, n=68), and acute hepatitis B (n=12). HBsAg was quantified and correlated with HBV-DNA, HBV-genotypes and clinical parameters. In addition, 30 LR-patients were followed longitudinally. RESULTS HBsAg levels were higher in IT-patients and IC-patients compared to LR-patients and ENH-patients (4.96/4.37/3.09/3.87-log(10)IU/ml, p<0.001). HBsAg showed a strong correlation with HBV-DNA during acute hepatitis B (R=0.79, p<0.01). Correlation of HBsAg and HBV-DNA was weak or missing when analyzing different phases of persistent HBV-infection separately. However, associations between HBsAg and HBV-DNA were observed in patients infected with HBV-genotype D but not with HBV-genotype A. LR-patients with HBV-reactivation during follow-up (increase of HBV-DNA >2000IU/ml) showed >3-fold higher baseline HBsAg levels with a NPV of 95% for an HBsAg cut-off of 3500IU/ml. CONCLUSIONS HBsAg levels show significant differences during the natural course of HBV-infection and between HBV-genotypes. These findings may have important implications for understanding the natural history of HBV-infection and for using quantitative HBsAg as a diagnostic tool, i.e. as a marker for predicting HBV-reactivation.

Molecular pathology of inflammatory cardiomyopathy

Endomyocardial biopsy (EMB) is often performed in patients presenting with sudden onset of heart failure to identify myocarditis. The introduction of immunohistochemical techniques for the detection and differentiation of infiltrating immune cells, specific adhesion molecules and MHC class I and II molecules increased the prognostic value of EMB in the diagnosis of myocarditis considerably. A major breakthrough in the understanding of pathogenetic mechanisms in myocarditis was achieved by diagnostic use of molecular biological methods. By application of in situ hybridization and PCR, enteroviruses, and more recently, parvovirus B19 (PVB19) have been identified as relevant agents of myocarditis. The different cell tropism of these viruses implicates distinct pathogenic principles, which, at present, are not completely understood. Whereas enteroviruses damage the heart primarily via direct lysis of infected myocytes, PVB19 does not infect myocytes, but endothelial cells of small intracardiac arterioles and venules, resulting in impairment of myocardial microcirculation with secondary myocyte necrosis during acute infection. Histological and immunohistological stainings combined with molecular biological approaches in EMB will help us to resolve the question of whether patients with myocarditis should be treated by specific antiviral agents or by immunosuppressive therapies.

Impact of the hepatitis B virus genotype and genotype mixtures on the course of liver disease in Vietnam

Eight genotypes (A‐H) of hepatitis B virus (HBV) have been identified. However, the impact of different genotypes on the clinical course of hepatitis B infection remains controversial. We investigated the frequency and clinical outcome of HBV genotypes and genotype mixtures in HBV‐infected patients from Vietnam, Europe, and Africa. In addition, we analyzed the effects of genotype mixtures on alterations in in vitro viral replication. In Asian patients, seven genotypes (A‐G) were detected, with A, C, and D predominating. In European and African patients, only genotypes A, C, D, and G were identified. Genotype mixtures were more frequently encountered in African than in Asian (P = .01) and European patients (P = .06). In Asian patients, the predominant genotype mixtures included A/C and C/D, compared to C/D in European and A/D in African patients. Genotype A was more frequent in asymptomatic compared with symptomatic patients (P < .0001). Genotype C was more frequent in patients with hepatocellular carcinoma (HCC; P = .02). Genotype mixtures were more frequently encountered in patients with chronic hepatitis in comparison to patients with acute hepatitis B (P = .015), liver cirrhosis (P = .013), and HCC (P = .002). Viral loads in patients infected with genotype mixtures were significantly higher in comparison to patients with a single genotype (P = .019). Genotype mixtures were also associated with increased in vitro HBV replication. In conclusion, infection with mixtures of HBV genotypes is frequent in Asia, Africa, and Europe. Differences in the replication‐phenotype of single genotypes compared to genotype‐mixtures suggest that co‐infection with different HBV‐genotypes is associated with altered pathogenesis and clinical outcome. (HEPATOLOGY 2006;43:1375–1384.)

Cross-Resistance Testing of Antihepadnaviral Compounds Using Novel Recombinant Baculoviruses Which Encode Drug-Resistant Strains of Hepatitis B Virus

ABSTRACT Long-term nucleoside analog therapy for hepatitis B virus (HBV)-related disease frequently results in the selection of mutant HBV strains that are resistant to therapy. Molecular studies of such drug-resistant variants are clearly warranted but have been difficult to do because of the lack of convenient and reliable in vitro culture systems for HBV. We previously developed a novel in vitro system for studying HBV replication that relies on the use of recombinant baculoviruses to deliver greater than unit length copies of the HBV genome to HepG2 cells. High levels of HBV replication can be achieved in this system, which has recently been used to assess the effects of lamivudine on HBV replication and covalently closed circular DNA accumulation. The further development of this novel system and its application to determine the cross-resistance profiles of drug-resistant HBV strains are described here. For these studies, novel recombinant HBV baculoviruses which encoded the L526M, M550I, and L526M M550V drug resistance mutations were generated and used to examine the effects of these substitutions on viral sensitivity to lamivudine, penciclovir (the active form of famciclovir), and adefovir, three compounds of clinical importance. The following observations were made: (i) the L526M mutation confers resistance to penciclovir and partial resistance to lamivudine, (ii) the YMDD mutations M550I and L526M M550V confer high levels of resistance to lamivudine and penciclovir, and (iii) adefovir is active against each of these mutants. These findings are supported by the limited amount of clinical data currently available and confirm the utility of the HBV-baculovirus system as an in vitro tool for the molecular characterization of clinically significant HBV strains.

Late HDV RNA relapse after peginterferon alpha-based therapy of chronic hepatitis delta

Interferon alpha is the only treatment option for hepatitis delta virus (HDV). Trials investigating the efficacy of pegylated interferon alpha (PEG‐IFNa) showed HDV RNA negativity rates of 25‐30% 24 weeks after therapy. However, the clinical and virological long‐term outcome of HDV‐infected patients treated with PEG‐IFNa is unknown. We performed a retrospective‐prospective follow‐up of 77 patients treated for 48 weeks with either PEG‐alfa‐2a and adefovir (ADV) or either drug alone in the Hep‐Net‐International‐Delta‐Hepatitis‐Intervention‐Study 1 (HIDIT‐1) trial. Long‐term follow‐up data were available for 58 out of 77 patients (75%) with a median time of follow‐up of 4.5 (0.5‐5.5) years and a median 3 visits per patient. Patients treated with ADV alone received retreatment with PEG‐IFNa (48% versus 19%; P = 0.02) more often. Hepatitis B virus surface antigen (HBsAg) became negative in six PEG‐IFNa‐treated patients until the end of long‐term follow‐up (10%). Sixteen patients tested HDV RNA‐negative 6 months after PEG‐IFNa treatment who were entered in the long‐term follow‐up study. Out of these, nine individuals tested HDV RNA‐positive at least once during further long‐term follow‐up, with seven patients being HDV RNA‐positive at the most recent visit. Clinical endpoints (liver‐related death, liver transplantation, hepatic decompensation, hepatocellular carcinoma) were observed in three PEG‐IFNa‐treated (8%) and three ADV‐treated (14%) patients during posttreatment long‐term follow‐up with an overall annual event rate of 2.5% (4.9% in cirrhosis). Sequencing confirmed the reappearance of pretreatment virus strains in all cases. Conclusion: Late HDV RNA relapses may occur after PEG‐IFNa therapy of hepatitis delta and thus the term sustained virological response should be avoided in HDV infection. The annual posttreatment rate of clinical events in hepatitis delta patients eligible for PEG‐IFNa therapy is about 2.5% and 4.9% in patients with cirrhosis. (Hepatology 2014;60:87‐97)

Parvovirus B19: a pathogen responsible for more than hematologic disorders

Abstract. The clinical and pathomorphological patterns of parvovirus B19 (PVB19)-associated diseases is the result of a balance between virus, host target cells and immune response. It is a characteristic feature of PVB19 that in patients with various other preexisting diseases, e.g., many hemolytic anemias, immune complex-mediated vasculitic disorders, and primary or secondary immunodeficiencies, the underlying diseases can be triggered, aggravated or complicated by severe organ manifestations. Identification of PVB19 by means of routine histology and immunohistology is only given in lytic infections occurring in transient aplastic anemia or nonimmune hydrops fetalis by the detection of viral inclusion bodies in erythroid precursor cells. In all other PVB19-associated diseases, molecular pathological methods must be applied. In this report, quantitative real-time polymerase chain reaction was used to determine the viral load in formalin-fixed and paraffin-embedded tissues derived from various organs. Using in situ hybridization it was demonstrated that endothelial cells of the microcirculatory periphery of the heart and hepatobiliar system in lytic infections are PVB19-specific target cells in children and adults. Because treatment of lytic PVB19 infection has been successfully applied, the pathologist should be alerted to include PVB19 into the diagnostic spectrum of viral disease, especially in immunocompromised patients.

Phospholipase A2 Activity-Dependent Stimulation of Ca2+ Entry by Human Parvovirus B19 Capsid Protein VP1

ABSTRACT Recent reports demonstrated an association of human parvovirus B19 with inflammatory cardiomyopathy (iCMP), which is accompanied by endothelial dysfunction. As intracellular Ca2+ 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 Ca2+ channel ICRAC, we analyzed the impact of the viral PLA2 motif on Ca2+ 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 Ca2+ activity was determined by utilizing Fura-2 fluorescence. VP1 and VP2 expression did not significantly modify basal cytosolic Ca2+ activity or the decline of cytosolic Ca2+ activity following the removal of extracellular Ca2+. However, expression of VP1 and of the full-length B19 clone, but not of VP2, significantly accelerated the increase of cytosolic Ca2+ activity following the readdition of extracellular Ca2+ in the presence of thapsigargin, indicating an activation of ICRAC. 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 Ca2+ entry by VP1 PLA2 activity, an effect likely participating in the pathophysiology of B19 infection.

Human Parvovirus B19 NS1 Protein Modulates Inflammatory Signaling by Activation of STAT3/PIAS3 in Human Endothelial Cells

ABSTRACT 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 tyrosine705 and serine727 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.

In vivo evidence for ribavirin-induced mutagenesis of the hepatitis E virus genome

Objective Hepatitis E virus (HEV) infection can take chronic courses in immunocompromised patients potentially leading to liver cirrhosis and liver failure. Ribavirin (RBV) is currently the only treatment option for many patients, but treatment failure can occur which has been associated with the appearance of a distinct HEV polymerase mutant (G1634R). Here, we performed a detailed analysis of HEV viral intrahost evolution during chronic hepatitis E infections. Design Illumina deep sequencing was performed for the detection of intrahost variation in the HEV genome of chronically infected patients. Novel polymerase mutants were investigated in vitro using state-of-the-art HEV cell culture models. Results Together, these data revealed that (1) viral diversity differed markedly between patients but did not show major intraindividual short-term variations in untreated patients with chronic hepatitis E, (2) RBV therapy was associated with an increase in viral heterogeneity which was reversible when treatment was stopped, (3) the G1634R mutant was detectable as a minor population prior to therapy in patients who subsequently failed to achieve a sustained virological response to RBV therapy and (4) in addition to G1634R further dominant variants in the polymerase region emerged, impacting HEV replication efficiency in vitro. Conclusions In summary, this first investigation of intrahost HEV population evolution indicates that RBV causes HEV mutagenesis in treated patients and that an emergence of distinct mutants within the viral population occurs during RBV therapy. We also suggest that next-generation sequencing could be useful to guide personalised antiviral strategies.