Detection of enteroviral RNA in idiopathic dilated cardiomyopathy and other human cardiac tissues

Role of coxsackievirus and adenovirus receptor (CAR) expression and viral load of adenovirus and enterovirus in patients with dilated cardiomyopathy

Enteroviruses (EVs) and adenoviruses (AdVs) are two important etiological agents of viral myocarditis and dilated cardiomyopathy (DCM). Both these viruses share a common receptor, the coxsackievirus and adenovirus receptor (CAR), for their infection. However, the role of viral load and CAR expression in disease severity has not yet been completely elucidated. The present study aimed to determine viral load of EV and AdV in DCM patients and correlate them with the level of CAR expression in these patients. Sixty-three DCM cases and 30 controls, each of whom died of heart disease other than DCM and non-cardiac disease respectively, were included. Viral load was determined by TaqMan real-time PCR using primers and probes specific for the AdV hexon gene and the 5'UTR region of EV. The CAR mRNA level was semi-quantitated by RT-PCR, and antigen expression was studied by immunohistochemistry. A significantly high AdV load (p < 0.05) and CAR expression (p < 0.05) were observed in DCM cases versus controls, whereas the EV load showed no significant difference. The data suggests a clinical threshold of 128 AdV copies/500 ng of DNA for DCM, with 66.7 % sensitivity and 65 % specificity. A positive correlation between AdV load and CAR expression (p < 0.001) was also observed in DCM cases. The high adenoviral load and increased CAR expression in DCM and their association with adverse disease outcome indicates role of both virus and receptor in disease pathogenesis. Thus, the need for targeting both the virus and the receptor for treatment of viral myocarditis and early DCM requires further confirmation with larger studies.

Analysis of formalin-fixed and frozen myocardial autopsy samples for viral genome in childhood myocarditis and dilated cardiomyopathy with endocardial fibroelastosis using polymerase chain reaction (PCR)

Viral infection of the myocardium is implicated in the pathogenesis of myocarditis and dilated cardiomyopathy (DCM). Enteroviruses have been considered the most common viral etiologic agents, based on peripheral culture and serologic methods. Recently, polymerase chain reaction (PCR) has been shown to be useful in the detection of viral genomes from various infected organs and body fluids. In this study, myocardial samples from autopsy specimens (formalin fixed and fresh frozen) were examined for enteroviral and DNA viral (adenovirus, herpes simplex virus [HSV], and cytomegalovirus (CMV]) genome by PCR. The specimens studied were from 58 patients with myocarditis, 28 patients with DCM and endocardial fibroelastosis [EFE], and 22 controls. Viral genome was detectable in 34 of the 58 (59%) autopsy-proven myocarditis samples (18 adenovirus, 12 enterovirus, 2 CMV, 2 HSV) and 6 of the 28 samples from patients with DCM and EFE (6 adenovirus). We conclude that PCR is effective in the rapid amplification of virus from frozen and formalin-fixed myocardial samples and that adenovirus is an important etiologic agent in viral myocarditis as well as DCM with EFE.

The role of viral infections in the development of dilated cardiomyopathy

Enteroviruses (EVs) are the most frequent pathogens in myocarditis and in the subsequently developing dilated cardiomyopathy as well. Furthermore, persistence of other viruses might play a pathogenic role in the evolution from myocarditis to dilated cardiomyopathy. Explanted heart of 28 patients, who underwent heart transplantation were screened for EV, AdV3 and HHV6 sequences in order to assess the incidence of cardiac viral infection that may be implicated in the pathogenesis of cardiomyopathy, and estimate viral distribution in the myocardium. Viral sequences were extracted from five different regions of the hearts. Nested PCR was used to amplify conservative regions of AdV3, HHV6 and EVs. Histological examination was performed on routinely processed myocardial samples. AdV3 was verified in one fourth of the patients. ADV3 and HHV6 sequences coexisted in one case with inflammatory cardiomyopathy. Some patients had more than one positive area of their heart. AdV3 positive right ventricular samples were double in amount compared to the left ones. None of the patients had positive result for EV. This is the first occasion to identify AdV3 (a mainly respiratory infective virus) sequence in explanted hearts of cardiomyopathy patients. Though the clinical importance of our results is still unclear, AdV3 could be a new member of the viral group with possible pathogenic effect on the myocardium. Regional distribution of viral sequence location confirmed that the right ventricular wall as a biopsy sampling site might be adequate for endomyocardial biopsy pro diagnostic purposes.

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.

Molecular evaluation of enteroviruses in the pathogenesis of idiopathic dilated cardiomyopathy

BACKGROUND

There is great disparity in the literature as to the presence and relevance of enterovirus in heart tissue from patients with dilated cardiomyopathy (DCM). Published estimates of enteroviral positive tissue in DCM range from 0 to 50%. Very little sequence information is so far available on those samples which are positive.

HYPOTHESIS

Re-examination of fresh biopsy material from patients previously tested, plus 13 new cases of DCM, and sequencing the products would yield information on the validity of the technique and on the type of virus being detected.

METHODS

RNA from biopsy or explant tissue was tested for the presence of enterovirus using reverse transcriptase polymerase chain reaction (PCR). The nucleotide sequences of all positive PCR products were determined by direct sequencing.

RESULTS

Positive PCR signals were found in 10% of samples from patients with DCM and in 16% of control tissues. Two DCM and 12 control samples gave the same nucleotide sequence, which was different from the CB3 used as a positive control. The other 4 DCM samples all produced multiple bands on sequencing.

CONCLUSION

The results do not support a major role for enterovirus in DCM. There is need for some caution, however, as a review of the literature shows that studies using single biopsies, such as this one, produce consistently lower estimates for enterovirus than do those wherein multiple biopsies are examined.

Myocarditis and inflammatory cardiomyopathy: histomorphological diagnosis

Myocarditis is a non-ischemic inflammatory disease of the myocardium associated with cardiac dysfunction. It most often results from infectious agents, hypersensitivity responses, or immune-related injury. In spite of the development of various diagnostic modalities, early and definite diagnosis of myocarditis still depends on the detection of inflammatory infiltrates in endomyocardial biopsy specimens according to Dallas criteria. Routine application of immunohistochemistry (for characterization of inflammatory cell infiltration) and Polymerase Chain Reaction PCR analysis (for identification of infective agents) has become an essential part of the diagnostic armamentarium for a more precise biopsy report. A new morphological classification is advanced to overcome the limits of Dallas criteria. A semiquantitative assessment of myocyte damage/inflammation (grading) as well as of fibrosis (staging) is indicated, thus providing histopathological diagnosis useful to the clinician for more appropriate patient risk stratification and for the application of new therapies. Consequently, the final diagnosis of myocarditis should be mainly based on three features: etiology, grade, and stage of the disease.

Cardiotropic viruses in the myocardium of children with end-stage heart disease

BACKGROUND

Transplantation has become a lifesaving procedure for children with end-stage heart failure. The long-term outcome for children who undergo transplantation has been of considerable interest, but the causes of graft failure and death are largely unknown, and the role of pre-transplant viral infection is unclear.

METHODS

Myocardial samples from 80 explanted hearts from children with end-stage heart disease caused by congenital heart disease (CHD), cardiomyopathy, or chronic rejection were analyzed using polymerase chain reaction and reverse-transcriptase polymerase chain reaction for cardiotropic viruses using virus-specific primers. We used immunohistochemical analysis of cytoskeletal proteins to evaluate myocyte architecture.

RESULTS

We identified parvoviral genomes in 6 patients (3 with CHD and 3 with cardiomyopathy). We detected no other viruses. Immunohistochemistry showed normal staining for key components of the cytoskeleton/sarcolemma, sarcomere, and nuclear membrane in the 6 virus-positive samples. The clinical outcome of these children was worse (4 long-term survivors, but 2 deaths) than for individuals without the genome.

CONCLUSIONS

Detecting viruses within the myocardium at the point of end-stage heart failure is not common, regardless of the primary pathology. However, the presence of viruses may result in poor outcome for the patient.

Frequent detection of parvovirus B19 genome in the myocardium of adult patients with idiopathic dilated cardiomyopathy

Aside from enteroviruses and other viruses, e.g., adenoviruses, which are known to be associated with idiopathic dilated cardiomyopathy (IDC), a cardiac tropism is also attributed to parvovirus B19 (PVB19). The purpose of the present study was to determine the prevalence of enterovirus, adenovirus and PVB19 genomes in the myocardium of adult patients with IDC and to analyze the significance of PVB19 with regard to the course of the disease, as compared to the other cardiotropic viruses. In 52 adult patients with IDC and 10 control patients with normal left ventricular ejection fraction (> or =55%) undergoing coronary artery bypass surgery, myocardial tissue samples were investigated for enteroviral RNA using polymerase chain reaction (PCR) and Southern blot hybridization of the PCR product. Specific nested PCR was used to assess the prevalence of adenovirus and PVB19 DNA, in addition to sequencing of the latter. The clinical and echocardiographic course of the disease was followed for a mean (+/- SD) period of 21.1+/-9.5 months. Fourteen of the 52 patients (27%) were enterovirus-positive, 2/52 (4%) patients were adenovirus-positive, 14/52 (27%) patients were PVB19-positive, 8/52 (15%) patients were enterovirus plus PVB19-positive, and in 14/52 (27%) patients no viral genomes were found. Six patients died during the follow-up period, without any significant difference between the patient groups: 1/14 (7%) in the enterovirus-positive, 0/2 (0%) in the adenovirus-positive, 2/14 (14%) in the PVB19-positive, 1/8 (12.5%) in the enterovirus plus PVB19-positive, and 2/14 (14%) in the virus-negative group. PVB19 genome was found in 4 of the 10 (40%) control patients, but no enterovirus or adenovirus genomes were detected in these patients. In conclusion, in the myocardium of patients with IDC, PVB19 is detectable as frequently as enteroviral genome. PVB19-positive patients with IDC have a rather favorable prognosis and do not differ significantly from the other virus-positive or virus-negative patient groups with respect to survival. Finally, the pathogenetic and prognostic significance of PVB19 in IDC still remains unclear.

Detection of viruses in myocardial tissues by polymerase chain reaction. evidence of adenovirus as a common cause of myocarditis in children and adults

OBJECTIVES

The purpose of this study was to analyze cardiac tissue and blood for viral genomes using polymerase chain reaction (PCR) to define the common viral etiologies of myocarditis by age group.

BACKGROUND

Enteroviruses are considered the most common cause of myocarditis at all ages. Diagnosis relies on viral cultures, serology, and cardiac histology, which lack sensitivity, as well as PCR. However, in many cases enteroviruses are not detected.

METHODS

Cardiac samples were obtained for PCR analysis from patients with myocarditis (n = 624) and dilated cardiomyopathy (DCM) (n = 149). Patients were analyzed by age group, including neonates (n = 116), infants (n = 191), toddlers (n = 87), children (n = 110), adolescents (n = 92), and adults (n = 177). After nucleic acids had been extracted from an endomyocardial biopsy, an explant, or autopsy samples, PCR and reverse transcription PCR were performed to detect the genomic sequences of enterovirus, adenovirus, cytomegalovirus (CMV), herpes simplex virus (HSV), Epstein-Barr virus (EBV), parvovirus, respiratory syncytial virus (RSV), and influenza A virus.

RESULTS

Viral genome was amplified (adenovirus = 142, enterovirus = 85, CMV = 18, parvovirus = 6, influenza A = 5, HSV = 5, EBV = 3, RSV = 1) from 239 (38%) of the 624 samples from myocarditis patients, including 26 patient samples in which dual infection was found. Virus was detected in 30 (20%) of 149 DCM patient samples; only adenovirus (n = 18) and enterovirus (n = 12) were detected.

CONCLUSIONS

Polymerase chain reaction identified adenovirus as the most common virus in the myocardium of children and adults with myocarditis and DCM. Although enteroviruses are also found in these patients, they appear to be a less common cause of myocarditis than adenovirus.

Viral causes of cardiac inflammation

Over the past year there have been few significant breakthroughs in the understanding of the etiologies of viral myocarditis or dilated cardiomyopathy (DCM). One interesting trend has been the increasing number of reports of myocarditis associated with parvovirus B19 infection. Whether this is simply a result of improved diagnostics, or reflects an underlying change in the etiology is unclear. However, studies of the underlying mechanisms of these disorders have resulted in several reports linking the acquired and viral forms. Over the past few years the cytoarchitecture has been a focus of study for familial DCM. During the last year, one key molecule, dystrophin, has been shown to be disrupted in patients with end-stage cardiomyopathy, irrespective or etiology, mutated in patients with sporadic forms of disease and identified as a potential susceptibility gene for viral infection of the myocardium. The shared cellular receptor, the Coxsackievirus B-Adenovirus receptor (CAR), for the two most common viral agents associated with acquired myocarditis and DCM, was shown to be up-regulated in patients with DCM, potentially making the expression of this protein a marker of susceptibility to virus infection. However, a study of the CAR gene in patients with DCM or myocarditis did not identify any genetic mutations in these patients. Finally a receptor for viral double stranded RNA (TLR-3) was identified. The role of this receptor in the innate immune response against cardiotropic viruses has yet to be elucidated.

Coxsackie B virus infection in idiopathic dilated cardiomyopathy: clinical and pharmacological implications

Idiopathic dilated cardiomyopathy (IDC) is a myocardial disease characterised by ventricular dilatation, impaired contractility, and the symptoms of congestive heart failure. Although the causes of IDC remain uncertain, much interest has been focused on the enteroviral infection in the myocardium in the pathogenesis of this disease. Enteroviral RNA has been demonstrated in the myocardium at all stages of IDC. Recent studies using sequence analysis of enteroviral polymerase chain reaction (PCR) products have shown that the viruses detected in hearts of patients with IDC are coxsackie B. In addition, active coxsackieviral RNA replication in the myocardium has been demonstrated by strand-specific detection of viral RNA. Viral antigen has also been found in hearts with IDC by immunohistochemical techniques. In tissue culture experiments and transgenic mice, it has been shown that restricted coxsackieviral RNA replication, and not infectious virus progeny, in the myocardium can impair cardiac contractile function and lead to dilated cardiomyopathy. Coxsackieviral RNA in the myocardium can be a marker of a poor clinical outcome after partial left ventriculectomy, and might influence prognosis after heart transplantation. Therefore, there is a therapeutic need to detect replicating coxsackieviral RNA in the myocardium, and a specific therapy for coxsackie B viruses is indicated in the management of patients with virus-positive IDC.

Damaged myocytes as detected by the colocalization of DNA fragmentation and tissue transglutaminase and their prognostic significance in enterovirus-associated dilated cardiomyopathy

BACKGROUND

Apoptotic cardiac myocytes have been described in chronic heart failure, but no data exist on the relationship between these 'damaged' myocytes and myocardial detection of enterovirus RNA often associated with dilated cardiomyopathy (DCM).

DESIGN

In patients with idiopathic DCM, endomyocardial biopsy samples were studied for enteroviral RNA by one step reverse transcription-polymerase chain reaction (PCR) and a subsequent hybridization of the PCR product using a Southern blot technique. The endomyocardial biopsies were further investigated for markers of cell damage and apoptosis: DNA fragmentation and expression of tissue-transglutaminase (TTG) in the myocytes using the in-situ endlabelling method or an anti-TTG-staining, respectively. To assess the prognostic significance of these two markers the correlation between the percentage of myocytes positive both for DNA fragmentation and TTG (the index of damaged myocytes) and the hemodynamic course of the patients during a mean follow-up period of 15.9 +/- 6.2 months was investigated prospectively by echocardiography.

RESULTS

In 14 (45%) of the 31 patients with idiopathic DCM, enteroviral RNA was found in the endomyocardial biopsy samples, while 17 patients (55%) were enterovirus-negative. In enterovirus-positive patients, the index of 'damaged' myocytes was significantly lower (10.7 +/- 4.9% vs. 19.2 +/- 8.8%, P = 0.002) and the left ventricular ejection fraction (LVEF) improved significantly (P = 0.00017 vs. P = 0.13) during long-term follow-up. In addition, a weak negative correlation was seen between the index of damaged myocytes and the changes in LVEF in all patients during long-term follow-up (r = - 0.48, P = 0.004).

CONCLUSION

Our results favour the view that enterovirus-positive patients with DCM have less damaged myocytes and a better haemodynamic course than enterovirus-negative patients.

Persistent expression of cytokines in the chronic stage of CVB3-induced myocarditis in NMRI mice

Coxsackievirus B3 (CVB3)-induced myocarditis in NMRI mice represents a model for studying the pathogenesis of this chronic heart disease. Previously, we reported on specific cytokine patterns during the acute stage of myocarditis since cytokines are thought to play the important role in this cardiomyopathy. In this study, the expression of various cytokine mRNAs and CVB3-RNA kinetics was examined with particular emphasis on the late phase of myocarditis, by using reverse transcriptase-polymerase chain reaction (RT-PCR), in situ hybridization (ISH) and immunohistochemistry (IHC). In addition, replicating and persisting CVB3-RNAs were semiquantified by PCR-ELISA. Distinct histopathological changes responsible for ongoing heart disease were found and characterized by increased fibrosis, persistent cellular infiltration and degenerated necrotic myocytes. One of the most important findings of this study was that the mRNA-expression of TNF- alpha, IL-1 alpha, interferon- gamma, IL-10, IL-18, macrophage inflammatory protein-1 alpha (MIP-1 alpha), transforming growth factor- beta (TGF- beta) and inducible nitric oxide synthase (iNOS) persisted as long as 98 days after the virus infection. The induction of IL-10 as well as IFN- gamma mRNAs was also verified by ISH and IHC at days 28 and 98 p.i. The clearly apparent persistence of the viral genomes in the myocardium of infected mice was confirmed by seminested PCR, ISH, and PCR-enzyme linked immunoabsorbent assay (ELISA), showing the highest amount of viral RNA in myocardial cells at day 7 after infection. These data indicate that the persistence of viral RNA is associated with persistently high levels of cytokine mRNAs which, when translated, could severely contribute to pathological changes and injury of connective tissue in the chronic stage of myocarditis.

Association of viral genome with graft loss in children after cardiac transplantation

BACKGROUND

The survival of recipients of cardiac allografts is limited by rejection, lymphoproliferative disease, and coronary vasculopathy. The purpose of this study in children who had received heart transplants was to evaluate the cardiac allografts for myocardial viral infections and to determine whether the presence of viral genome in the myocardium correlates with rejection, coronary vasculopathy, or graft loss.

METHODS

We enrolled heart-transplant recipients 1 day to 18 years old who were undergoing evaluation for possible rejection and coronary vasculopathy. Endomyocardial-biopsy specimens were evaluated for evidence of rejection with the use of standard criteria and were analyzed for the presence of virus by the polymerase chain reaction (PCR).

RESULTS

PCR analyses were performed on 553 consecutive biopsy samples from 149 transplant recipients. Viral genome was amplified from 48 samples (8.7 percent) from 34 patients (23 percent); adenovirus was found in 30 samples, enterovirus in 9 samples, parvovirus in 5 samples, cytomegalovirus in 2 samples, herpes simplex virus in 1 sample, and Epstein-Barr virus in 1 sample. In 29 of the 34 patients with positive results on PCR (85 percent), an adverse cardiac event occurred within three months after the positive biopsy, and 9 of the 34 patients had graft loss due to coronary vasculopathy, chronic graft failure, or acute rejection. In 39 of the 115 patients with negative results on PCR (34 percent), an adverse cardiac event occurred within three months of the negative PCR finding; graft loss did not occur in any of the patients in this group. The odds of graft loss were 6.5 times as great among those with positive results on PCR (P=0.006). The detection of adenovirus was associated with considerably reduced graft survival (P=0.002).

CONCLUSIONS

Identification of viral genome, particularly adenovirus, in the myocardium of pediatric transplant recipients is predictive of adverse clinical events, including coronary vasculopathy and graft loss.

Evaluation of viral infection in the myocardium of patients with idiopathic dilated cardiomyopathy

OBJECTIVES

The aim of this study was to evaluate the viral etiology of idiopathic dilated cardiomyopathy (DCM).

BACKGROUND

The demonstration of enteroviral genome in hearts with DCM has reinforced the importance of enteroviruses in the pathogenesis of DCM. However, there is uncertainty about the character and activity of enteroviruses detected in the myocardium. Recently, the association of hepatitis C virus or adenovirus with DCM has been reported.

METHODS

Myocardial specimens from 26 patients with idiopathic DCM, which were obtained at partial left ventriculectomy (PLV), were examined virologically. Strand-specific detection of enteroviral RNA was performed to differentiate active viral replication from latent persistence. Polymerase chain reaction was used to detect genomic sequences of hepatitis C virus, adenovirus, cytomegalovirus, influenza viruses, mumps virus, herpes simplex viruses, varicella-zoster virus and Epstein-Barr virus.

RESULTS

Plus-strand enteroviral RNA was detected in 9 (35%) of the 26 patients. Minus-strand enteroviral RNA was determined in seven (78%) of these nine plus-strand RNA-positive patients. Sequence analysis revealed that the enteroviruses detected were coxsackie B viruses, such as coxsackievirus B3 and B4. However, genetic material from other viruses was not detected. Six (86%) of seven minus-strand enteroviral RNA-positive patients died of cardiac insufficiency within the first six months after PLV.

CONCLUSIONS

Coxsackie B viruses were seen in hearts with idiopathic DCM. Active viral RNA replication appeared to be present in a significant proportion of these cases. Minus-strand coxsackieviral RNA in the myocardium can be a marker for poor clinical outcome after PLV. There was no evidence of persistent infection by other viruses in hearts with DCM.

Cardiomyopathy in childhood, mitochondrial dysfunction, and the role of L-carnitine

Cardiomyopathy in childhood is associated with high morbidity and mortality rates. Many metabolic causes have been identified, including genetic or acquired defects in mitochondrial energy production affecting beta-oxidation, carnitine transport, and the electron transport chain. Combining conventional inotropic and antiarrhythmic therapy with metabolic interventions has improved overall outcome. L-carnitine, a natural substance involved in mitochondrial transport of fatty acids, is one such therapy and plays a central role in the regulation of the inner mitochondrial supply of free coenzyme A. Carnitine deficiency can be caused by both genetic and environmental causes with resultant signs and symptoms of metabolic disease, including cardiomyopathy. Administration of L-carnitine can result in improvement or resolution of the cardiomyopathy.

Detection of enteroviral RNA in end-stage dilated cardiomyopathy in children and adolescents

Medical records and archival myocardial specimens of 33 children and adolescents with end-stage idiopathic dilated cardiomyopathy (IDCM) were collected to evaluate retrospectively the potential role of enteroviral persistence in the pathogenesis of IDCM. The clinical history and laboratory assessment of each patient were reviewed carefully in order to obtain information on the nature and etiology of infections in the past and at the time of diagnosis of cardiomyopathy. Sixty-four formaldehyde-fixed, paraffin-embedded myocardial specimens, obtained from endomyocardial biopsies (n = 5), explanted hearts (n = 10), or autopsies (n = 49), were studied by the polymerase chain reaction (PCR) and by in situ hybridization to detect enteroviral RNA in the specimens. Control specimens included 34 formaldehyde-fixed, paraffin-embedded myocardial specimens from children with other cardiomyopathies, metabolic diseases, structural heart defects, or various noncardiac malignancies. The presence of cellular RNA in the specimens was confirmed by amplification of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA or beta-actin mRNA as positive controls. Only one specimen from the 32 IDCM patients with appropriate myocardial specimens was positive for enteroviral RNA by PCR. Sequence analysis of the amplified viral segment showed a significant degree of homology between the viral sequence and echovirus 1. One specimen from the control patients also appeared positive by PCR, but sequence analysis of the amplified viral segment revealed it as rhinovirus 16. The results do not indicate any significant role for enteroviral persistence in end-stage childhood IDCM, although they need to be confirmed using a prospective study with fresh frozen specimens. However, mechanisms other than viral persistence may be more important in the progression of IDCM to end-stage heart failure in this age group.

Advances in molecular genetics of dilated cardiomyopathy. The Heart Muscle Disease Study Group

In clinical surveys, familial dilated cardiomyopathy (FDC) has been demonstrated in 20% to 30% of patients. In these patients, the cause of the disease lies at the DNA level. Molecular genetic studies represent the tools for the understanding of the etiology of FDC and are currently producing relevant advances: 6 different loci have been mapped so far. The only known disease gene is the dystrophin gene causing X-linked dilated cardiomyopathy, but other cytoskeletal proteins, such as adhalin, could be involved. In familial right ventricular cardiomyopathy (or arrhythmogenic right ventricular dysplasia) characterized by isolated or prevalent right ventricular involvement, three further disease loci have been identified.

[Enteroviral myocarditis and dilated cardiomyopathy]

In situ hybridization and PCR studies have demonstrated that enteroviruses of the human picornavividae, and in particular coxsackieviruses of group B (CVB), are detectable in endomyocardial biopsies of patients with acute and chronic myocarditis, indicating the possibility of enterovirus persistence in the human heart. As well, such infections are observed in patients with end-stage dilated cardiomyopathy, suggesting an etiologic link between myocarditis and dilated cardiomyopathy. The molecular diagnosis of persistent heart muscle infection allows to differentiate myocarditis and dilated cardiomyopathy, sustained by virus persistence, from postviral immune-mediated cardiac disease. Apart from providing an etiologic diagnosis, there are therapeutic implications from in situ demonstration of myocardial enterovirus infection. As to whether antiviral therapy with interferon is capable of providing protection against enterovirus myocarditis must be determined by controlled prospective clinical studies. Immunosuppressive therapy of myocarditis appears to be justified only after exclusion of persistent heart muscle infection. Experimental studies indicate that altered viral replication strategies, the incompetence of effector mediators of local immunity to eliminate persistently infected myocardial cells as well as infection of cellular constituents of the immune system itself, are major pathogenic determinants for development and maintenance of chronic myocarditis and cardiomyopathy.

Detection of intrauterine viral infection using the polymerase chain reaction

Intrauterine viral infection commonly presents as nonimmune hydrops fetalis or intrauterine growth restriction. Cytomegalovirus (CMV) and parvovirus are commonly recognized causes of fetal infection using serology and cultures. We used the polymerase chain reaction (PCR) to evaluate the frequency of fetal viral infection and the associated clinical course and outcome. Specimens (amniotic fluid, fetal blood, pleural fluid, tissue) from 303 abnormal pregnancies at risk for viral infection and 154 controls were analyzed using primers for CMV, herpes simplex virus, parvovirus B19, adenovirus, enterovirus, Epstein-Barr virus, and respiratory syncytial virus. Viral genome was detected in 144/371 samples (39%) or 124/303 patients (41%), with adenovirus (n = 74 patients; 24%), CMV (n = 30 patients; 10%), and enterovirus (n = 22 patients; 7%) most common. Only 4/154 (2.6%), unaffected control patients' samples were PCR positive. We conclude that diagnosis of fetal viral infection by PCR is common in abnormal pregnancies. Adenovirus and enterovirus may cause fetal infection that have been previously unrecognized.

Association of parvovirus B19 genome in children with myocarditis and cardiac allograft rejection: diagnosis using the polymerase chain reaction

BACKGROUND

Inflammatory diseases of the heart, including myocarditis and cardiac transplant rejection, are important causes of morbidity and mortality in children. Although viral infection may be suspected in either of these clinical conditions, the definitive etiology is often difficult to ascertain. Furthermore, the histology is identical for both disorders. Coxsackievirus has long been considered the most common cause of viral myocarditis; however, we previously demonstrated by polymerase chain reaction (PCR) analysis that many different, and sometimes unexpected, viruses may be responsible for myocarditis and cardiac rejection. In this study, we describe the association of parvovirus genome identified through PCR analysis of cardiac tissue in the clinical setting of myocarditis and cardiac allograft rejection.

METHODS AND RESULTS

Myocardial tissue from endomyocardial biopsy, explant, or autopsy was analyzed for parvovirus B19 using primers designed to amplify a 699-base pair PCR product from the VP1 gene region. Samples tested included those obtained from patients with suspected myocarditis (n=360) or transplant rejection (n=200) or control subjects (n=250). Parvoviral genome was identified through PCR in 9 patients (3 myocarditis; 6 transplant) and no control patients. Of the 3 patients with myocarditis, 1 presented with cardiac arrest leading to death, 1 developed dilated cardiomyopathy, and the other gradually improved. Four of the 6 transplant patients had evidence of significant rejection on the basis of endomyocardial biopsy histology. All transplant patients survived the infection.

CONCLUSIONS

Parvovirus is associated with myocarditis in a small percentage of children and may be a potential contributor to cardiac transplant rejection. PCR may provide a rapid and sensitive method of diagnosis.

Inflammatory myocardial diseases and cardiomyopathies

Inflammatory myocardial disease has been associated with a variety of infectious and noninfectious etiologies. It is associated with the development of dilated cardiomyopathy in some patients. Given its imprecise diagnosis, varied clinical presentation and undefined natural history, it is quite difficult to make broad generalizations regarding its evaluation and treatment. It is hoped continued application of new molecular biological and other techniques will shed further light on the pathophysiologic mechanisms of myocarditis in humans, thus pointing to therapeutic interventions.

The elusive search for fetal infection. Changing the gold standards

Two percent to four percent of all newborns have a major structural malformation of which only a small percentage can be explained by either aneuploidy or a single-gene disorder. No other mammal has a similar reproductive problem. It is the suggestion that previously unrecognized viral infection accounts for a large percentage of these abnormalities by interfering with appropriate embryonic cell migration, reducing hyperplasia, or damaging the precursor structure by means of an inflammatory mechanism.

Long-term follow up of patients with dilated heart muscle disease treated with human leucocytic interferon alpha or thymic hormones initial results

OBJECTIVE

To determine whether giving interferon-alpha or thymomodulin in addition to conventional treatment improves cardiac function in patients with idiopathic myocarditis and idiopathic dilated cardiomyopathy.

DESIGN

Single-centre, randomised, open label, parallel group comparison of conventional treatment plus interferon-alpha, conventional treatment plus thymomodulin, and conventional treatment alone.

PATIENTS

38 patients aged 19-54 years (23 men) with biopsy-proven myocarditis or dilated cardiomyopathy. 12 were treated with conventional treatment alone, 13 were treated with interferon-alpha and conventional treatment, and 13 with thymomodulin and conventional treatment.

SETTING

Tertiary cardiac referral centre.

MAIN OUTCOME MEASURES

Clinical evaluation, echocardiography, and Holter monitoring at baseline, 6 months, and 1 and 2 years. Radionuclide ventriculography at rest and during exercise after 2 years. Endomyocardial biopsy at baseline and after a year if the initial diagnosis was myocarditis.

RESULTS

Left ventricular ejection fraction was improved in 21 (81%) of 26 patients after interferon-alpha or thymomodulin administration and in 8 (66%) of 12 conventionally treated patients (P < 0.05) at 2 year follow up. The maximum exercise time was significantly longer at 2-year follow up in patients treated with immunomodulators (mean (SEM) 5.1 (0.6) minutes for interferon-alpha and 5.0 (0.4) minutes for thymomodulin) than in conventionally treated patients (3.3 (0.4) minutes). Left ventricular ejection fraction during exercise (assessed by radionuclide ventriculography) improved in 9 of 12 patients treated with interferon-alpha, 10 of 12 patients treated with thymomodulin, and 3 of 9 conventionally treated patients at 2 year follow up. The electrocardiogram was normal in 21 (88%) of 24 patients after interferon-alpha or thymomodulin treatment and 2 (22%) of 9 conventionally treated patients. At 2 year follow up, 19 (73%) of 26 patients treated with immunomodulators and 4 (25%) of 12 conventionally treated patients had improved their functional class.

CONCLUSIONS

The results suggest that treatment of idiopathic myocarditis and/or idiopathic dilated cardiomyopathy with interferon-alpha or thymomodulin induces an earlier and significantly superior clinical improvement than conventional treatment alone.

Molecular detection and differentiation of enteroviruses in endomyocardial biopsies and pericardial effusions from dilated cardiomyopathy and myocarditis

Enteroviruses (EVs), especially group B coxsackieviruses, have been implicated in the pathogenesis of myocarditis and dilated cardiomyopathy (DCM). To determine whether a specific type of EV is present in DCM hearts, we examined the genotypes of EVs detected in endomyocardial biopsies and pericardial effusions by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) analysis. Positive PCR results were obtained from biopsies in 6 (19 percent) of 31 patients with DCM, 5 (18 percent) of 28 with myocarditis, 5 (22 percent) of 23 with other cardiac diseases, and from pericardial effusions in 4 (57 percent) of 7 patients with pericarditis. SSCP profiles of most of the clinical samples were different and were not identical to any of the standard group B coxsackie viruses. Our findings suggest that EV genomes are involved in the myocardium of patients with various cardiac conditions and that a particular type of EV is not present in DCM hearts.

Reverse transcription PCR to detect enteroviruses in surface water

We have developed a simple, fast, and efficient procedure to detect enteroviruses in water samples. Aliquots of water are subjected to two-step filtration, with the second filter containing a positively charged nylon membrane that holds back virus particles. Viruses thus adsorbed are directly lysed, and RNA is isolated by hybridization to specific oligonucleotides bound to magnetic beads. The solution used contains guanidine thiocyanate, which lyses virus particles, inactivates enzymes, e.g., RNases, allows mild hybridization conditions, and does not influence biotin-streptavidin interaction on magnetic beads. Detection and specific identification are accomplished by reverse transcription PCR of the highly conserved noncoding region at the 5' end of virus RNA combined with Southern hybridization. The system was tested with tap water artificially spiked with poliovirus vaccine and yielded a detection limit of 20 50% tissue culture infective doses per liter. We used the same procedure to investigate the water quality of surface water at public beaches by rivers and lakes. Of 40 samples tested, 7 were positive for enteroviruses. A comparison with enterobacterial contamination determined by PCR and classical microbiological methods in parallel showed that enteroviruses were found only in samples also positive for Escherichia coli. In conclusion, this procedure can easily be adapted to test large water samples and is simple enough to be used for routine determinations of water quality in terms of virus contamination.

Familial dilated cardiomyopathy

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Long-term follow-up of patients with myocarditis and idiopathic dilated cardiomyopathy after immunomodulatory therapy

The randomized clinical trial with interferon-alpha (IFN) or thymic hormones versus conventional therapy was conducted in patients with myocarditis and idiopathic dilated cardiomyopathy (IDC). We enrolled 180 patients to receive IFN (3-5 million units per day) for 3 months, thymomodulin (10 mg three times per week) for 2 months, or conventional therapy alone. Patients were followed-up for 7 years after the end of treatment. Left ventricular function, exercise tolerance and survival rate were significantly better at long-term follow-up in patients treated with IFN or thymomodulin, than in conventionally treated patients. These results implicate that immune modulating therapy might represent important contribution in the treatment of myocarditis and IDC.

Absence of linkage between idiopathic dilated cardiomyopathy and candidate genes involved in the immune function in a large Italian pedigree

Idiopathic dilated cardiomyopathy (IDC) is a heart disease of unknown aetiology characterised by impaired ventricular function usually associated with dilatation of the cardiac chambers. In order to test the hypothesis of an immunological cause for the disease at the genetic level, we performed linkage analysis between the putative disease locus and some of the potential candidate genes involved in the immune response or coding for the targets for autoantibodies in a large multigeneration family (63 members) from southern Italy with autosomal dominant transmission of the disease. Twenty-nine polymorphic markers on 18 different chromosomal locations were investigated, including markers linked to the genes coding for the HLA antigens, the immunoglobulin heavy and light chains, the receptors for the immunoglobulin Fc fragments, the subunits of the T cell receptor and the associated CD3, CD4, CD8, and CD45 antigens, interleukins 1, 3, 4, 5, 6, 9, and 11, the interleukin 1 and 2 receptors, and the genes coding for the beta 1 adrenoreceptor, the adenine nucleotide translocator-1, and the cardiac alpha and beta myosin heavy chains. No evidence for genetic linkage to IDC was found at any of these candidate loci. These results indicate that the still unidentified IDC gene maps outside several loci involved in the regulation of immune reactivity.

Acute myocarditis. Rapid diagnosis by PCR in children

BACKGROUND

The diagnosis of viral myocarditis remains difficult and generally depends on clinical and histological criteria. Viral cultures and serology are often unrewarding, with low yields. The purpose of this study was to analyze the usefulness of polymerase chain reaction (PCR) in the rapid diagnosis of acute myocarditis in children.

METHODS AND RESULTS

PCR was used to analyze 38 myocardial tissue samples from 34 patients with suspected acute viral myocarditis and 17 control patients with congenital heart disease (14) or hypertrophic cardiomyopathy (3). Myocardial samples were obtained at the time of right ventricular biopsy (13 samples), from explanted hearts (18 samples) at transplantation, and from cardiac autopsy specimens (24 samples) and were evaluated for the presence of enterovirus, cytomegalovirus (CMV), adenovirus, and herpes simplex virus (HSV) using PCR primers designed to consensus and unique sequences of these viral genomes. Blood also was obtained at the time of biopsy (11) or transplant (18). In 26 of 38 myocardial samples (68%), viral genome was detected by PCR (15 adenoviral, 8 enteroviral, 2 HSV, 1 CMV), whereas all control myocardial samples and blood samples were negative. Four patients had positive viral cultures, and these matched the PCR findings. Disagreement with histopathology occurred in 13 of 26 PCR-positive specimens, usually associated with adenovirus.

CONCLUSIONS

PCR offers a rapid, sensitive diagnostic method for myocardial viral infection. While enterovirus is an important etiological agent, adenovirus was more prevalent in this series and should be evaluated when etiology is sought. PCR used in conjunction with standard endomyocardial biopsy appears to enhance the likelihood of detecting viral genome in the myocardium of patients with clinical evidence of myocarditis.

Viral infection and the pathogenesis of dilated cardiomyopathy

Long-term follow-up studies of patients with suspected viral myocarditis reveal progression to dilated cardiomyopathy (DCM) in a significant number of cases. Thus, an underlying viral etiology has been hypothesized in the pathogenesis of ongoing heart disease that leads to DCM. Recent application of molecular biology in clinical diagnosis has strengthened this hypothesis. By use of probe hybridization and polymerase chain reaction, enteroviral RNA has been detected in the myocardium of patients at all stages of the disease process: myocarditis, chronic heart disease, and DCM. Experimental murine models of enterovirus-induced heart disease provide a framework for examining the pathogenic mechanisms. Viral cytotoxicity, immunological responses, viral RNA persistence, and spasm of the coronary microvasculature are all implicated in the ongoing disease process. Abnormal cardiac function and heart failure are attributed to the pathological changes that occur.

PCR for the diagnosis of enteroviral meningitis

A 2-step 'semi-nested' enterovirus PCR was developed and applied to CSF and serum specimens from 27 consecutive patients with aseptic meningitis. CSF and sera from 8 patients with non-enteroviral diagnoses were included as negative clinical controls. Enterovirus RNA was detected in CSF by PCR in 15 of the patients with aseptic meningitis, compared with 6 by virus culture. Acute-phase sera proved positive for enterovirus RNA in 11 patients, thus increasing the number of PCR-positive patients to 18. Convalescent-phase sera were all negative by PCR. The correlation of a positive or negative PCR result in CSF and/or serum versus combined conventional virology (serology and isolation from 1-3 sites, i.e. CSF, stool and throat) was 78%. All negative controls were negative by PCR. PCR is a reliable and sensitive diagnostic tool for the detection of enteroviral infections. Both CSF and acute-phase serum should be considered for testing.

Use of the polymerase chain reaction with a murine model of picornavirus-induced myocarditis

Enteroviruses are common pathogens responsible for a wide spectrum of systemic infections. Conventional diagnosis of these infections relies on the isolation of viruses in cell culture and their identification by seroneutralization with polyclonal or monoclonal antibodies. Among enteroviruses, coxsackieviruses B have been involved as causative agents for viral myocarditis. Most of the time, in the case of cardiac pathologies, viral isolation is negative. Molecular biology techniques appear to be an alternative to conventional diagnosis and could supply evidence for the direct implication of enteroviruses in these severe pathologies. In this paper, we describe a murine experimental model of infection with the presumed highly cardiopathogenic coxsackie-virus B type 3. A kinetics of infection was observed for a period of 31 days, and the classical virological markers (viral isolation from feces and heart biopsies, seroconversion) were monitored and compared by means of molecular techniques (molecular hybridization, polymerase chain reaction [PCR]). In this 31-day period, the detection of coxsackievirus B type 3 RNA in the heart was possible only by using two successive seminested PCRs. After 9 to 11 days of active viral replication, when all other virological markers were negative, positive PCR signals were obtained, which supports the hypothesis of a shift to persistent enteroviral infection.

Detection of enteroviral ribonucleic acid in myocardial biopsies from patients with idiopathic dilated cardiomyopathy by polymerase chain reaction

Infection by enteroviruses, especially by Coxsackie B viruses, has been incriminated in pathogenesis of dilated cardiomyopathy. We developed polymerase chain reaction tests for the detection of enteroviral and Coxsackie B3 genomes, respectively, in myocardial biopsies obtained from a homogeneous group of 19 patients with idiopathic dilated cardiomyopathy. To determine unambiguously the incidence of enteroviruses and Coxsackie B3 viruses in these patients, we used two primer pairs, one common to all enteroviruses and the other specific for Coxsackie B3 viruses. In six patients of the dilated cardiomyopathy group, enteroviral ribonucleic acid (RNA) could be detected; only one was subspecified as Coxsackie B3 RNA. In contrast, no enteroviral RNA could be detected in a contrast group of 21 patients with other cardiac disorders. These results suggest that enteroviruses other than Coxsackie B3 are causally linked to the pathogenesis of dilated cardiomyopathy.