Detection of enterovirus-specific RNA sequences in explanted myocardium biopsy specimens from patients with dilated or ischemic cardiomyopathy

Enterovirus Persistence in Cardiac Cells of Patients With Idiopathic Dilated Cardiomyopathy Is Linked to 5' Terminal Genomic RNA-Deleted Viral Populations With Viral-Encoded Proteinase Activities

BACKGROUND

Group B enteroviruses are common causes of acute myocarditis, which can be a precursor of chronic myocarditis and dilated cardiomyopathy, leading causes of heart transplantation. To date, the specific viral functions involved in the development of dilated cardiomyopathy remain unclear.

METHODS

Total RNA from cardiac tissue of patients with dilated cardiomyopathy was extracted, and sequences corresponding to the 5' termini of enterovirus RNAs were identified. After next-generation RNA sequencing, viral cDNA clones mimicking the enterovirus RNA sequences found in patient tissues were generated in vitro, and their replication and impact on host cell functions were assessed on primary human cardiac cells in culture.

RESULTS

Major enterovirus B populations characterized by 5' terminal genomic RNA deletions ranging from 17 to 50 nucleotides were identified either alone or associated with low proportions of intact 5' genomic termini. In situ hybridization and immunohistological assays detected these persistent genomes in clusters of cardiomyocytes. Transfection of viral RNA into primary human cardiomyocytes demonstrated that deleted forms of genomic RNAs displayed early replication activities in the absence of detectable viral plaque formation, whereas mixed deleted and complete forms generated particles capable of inducing cytopathic effects at levels distinct from those observed with full-length forms alone. Moreover, deleted or full-length and mixed forms of viral RNA were capable of directing translation and production of proteolytically active viral proteinase 2A in human cardiomyocytes.

CONCLUSIONS

We demonstrate that persistent viral forms are composed of B-type enteroviruses harboring a 5' terminal deletion in their genomic RNAs and that these viruses alone or associated with full-length populations of helper RNAs could impair cardiomyocyte functions by the proteolytic activity of viral proteinase 2A in cases of unexplained dilated cardiomyopathy. These results provide a better understanding of the molecular mechanisms that underlie the persistence of EV forms in human cardiac tissues and should stimulate the development of new therapeutic strategies based on specific inhibitors of the coxsackievirus B proteinase 2A activity for acute and chronic cardiac infections.

Functional Consequences of RNA 5'-Terminal Deletions on Coxsackievirus B3 RNA Replication and Ribonucleoprotein Complex Formation

Group B coxsackieviruses are responsible for chronic cardiac infections. However, the molecular mechanisms by which the virus can persist in the human heart long after the signs of acute myocarditis have abated are still not completely understood. Recently, coxsackievirus B3 strains with 5'-terminal deletions in genomic RNAs were isolated from a patient suffering from idiopathic dilated cardiomyopathy, suggesting that such mutant viruses may be the forms responsible for persistent infection. These deletions lacked portions of 5' stem-loop I, which is an RNA secondary structure required for viral RNA replication. In this study, we assessed the consequences of the genomic deletions observed in vivo for coxsackievirus B3 biology. Using cell extracts from HeLa cells, as well as transfection of luciferase replicons in two types of cardiomyocytes, we demonstrated that coxsackievirus RNAs harboring 5' deletions ranging from 7 to 49 nucleotides in length can be translated nearly as efficiently as those of wild-type virus. However, these 5' deletions greatly reduced the synthesis of viral RNA in vitro, which was detected only for the 7- and 21-nucleotide deletions. Since 5' stem-loop I RNA forms a ribonucleoprotein complex with cellular and viral proteins involved in viral RNA replication, we investigated the binding of the host cell protein PCBP2, as well as viral protein 3CD^pro, to deleted positive-strand RNAs corresponding to the 5' end. We found that binding of these proteins was conserved but that ribonucleoprotein complex formation required higher PCBP2 and 3CD^pro concentrations, depending on the size of the deletion. Overall, this study confirmed the characteristics of persistent CVB3 infection observed in heart tissues and provided a possible explanation for the low level of RNA replication observed for the 5'-deleted viral genomes-a less stable ribonucleoprotein complex formed with proteins involved in viral RNA replication.IMPORTANCE Dilated cardiomyopathy is the most common indication for heart transplantation worldwide, and coxsackie B viruses are detected in about one-third of idiopathic dilated cardiomyopathies. Terminal deletions at the 5' end of the viral genome involving an RNA secondary structure required for RNA replication have been recently reported as a possible mechanism of virus persistence in the human heart. These mutations are likely to disrupt the correct folding of an RNA secondary structure required for viral RNA replication. In this report, we demonstrate that transfected RNAs harboring 5'-terminal sequence deletions are able to direct the synthesis of viral proteins, but not genomic RNAs, in human and murine cardiomyocytes. Moreover, we show that the binding of cellular and viral replication factors to viral RNA is conserved despite genomic deletions but that the impaired RNA synthesis associated with terminally deleted viruses could be due to destabilization of the ribonucleoprotein complexes formed.

Persistent viral infection in primary Sjogren's syndrome: review and perspectives

Exocrine gland pathology in primary Sjogren's syndrome is characterized by destruction of acinar epithelial cells and chronic lymphocytic infiltrates surrounding ductal epithelial cells. These cells seem to be activated, as it is inferred by their immunophenotype. The cause of this activation and the chronic inflammatory response that targets epithelial cells remain unknown. Here, we will review the evidence pointing to a persistent viral infection as a probable cause of primary Sjogren's syndrome and discuss potential directions for future research.

Autoimmunity and Coxsackievirus Infection in Primary Sjögren's Syndrome

Exocrine gland epithelial cells are the target of autoimmune pathology in primary Sjögren's syndrome (pSS). Their activated phenotype has incited the notion that they are infected by a virus. We recently presented evidence that coxsackieviruses may persistently infect the salivary glands of pSS patients. We hypothesize that coxsackieviruses may play a permissive role for the perpetuation and possibly the induction of autoimmune disease in pSS.

Enterovirus infections: a review of clinical presentation, diagnosis, and treatment

The enteroviruses, RNA viruses of the Picornaviridae family, are ubiquitous pathogens which include more than 70 different serotypes that infect people of all ages and tend to occur seasonally in the summer and fall. Clinical manifestations may vary diversely with one serotype, while multiple serotypes can present with identical symptoms and may mimic bacterial infections. Most enterovirus infections cause benign, self-limiting disease; however, they can also produce severe and sometimes fatal illnesses such as meningitis, encephalitis, myocarditis, neonatal sepsis, and polio. Severe enterovirus infections are being diagnosed and treated earlier with better prognostic outcomes due to the advances of polymerase chain reaction technology in accurately detecting virus in patient fluids as well as the recent development of new antiviral therapies.

Enterovirus infections: diagnosis and treatment

Enteroviruses cause infections that present in diverse ways and affect people of all ages. Infections peak during summer and fall epidemics and cause 10 to 15 million symptomatic infections annually in the United States. The 70 enteroviral serotypes cause illness that ranges from nonspecific fevers and rashes to life-threatening myocarditis or central nervous system disease. These common infections create a significant burden on our society and healthcare system. New developments in rapid diagnosis of enterovirus infections using polymerase chain reaction (PCR) positively affect patient management and have the potential to reduce the healthcare impact of enterovirus infection. The future holds promise for effective antiviral drugs that can treat enterovirus infections and decrease their significant morbidity and mortality.

Multicenter study on hepatitis C virus infection in patients with dilated cardiomyopathy. North Italy Transplant Program (NITP)

Preliminary epidemiological and histological studies from Japan suggested that hepatitis C virus (HCV) infection has a role in the development of dilated cardiomyopathy (DCM). This multicenter study was conducted to verify this hypothesis on a large cohort of Italian patients with end-stage heart failure. Antibodies to HCV were determined in the 752 consecutive patients (608 males and 144 females; age, 53 +/- 13 years) who entered the waiting list for cardiac transplantation from 1995 to 1997 at the six cardiac surgery centers participating in the North Italy Transplant program. Three hundred and nine patients (41%) had dilated, 9 (1%) restrictive, and 4 (0.5%) hypertrophic cardiomyopathy; 284 patients (38%) had ischemic, 65 (9%) valvular, and 22 (3%) congenital heart disease; 5 patients (0.5%) had primary pulmonary hypertension; 54 patients (7%) had other or nonspecified heart disease. Overall, 41 of 752 patients (5.4%) resulted anti-HCV-reactive. Serological evidence of HCV infection was found in 12 of 309 patients with DCM (3.9%; 95% CI, 1.7-6.0), and in 29 of 443 without DCM (6.5%; 95% CI, 4.2-8.8), without statistical difference (difference of prevalence rate: 2.6%; 95% CI, -4.9 to 5.8). In conclusion, HCV does not seem to have a primary role in the pathogenesis of DCM. However, since our findings are in disagreement with those obtained in smaller series of patients of other ethnicity, large studies from different countries should be conducted.

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.

Meta-analysis of the association of enteroviruses with human heart disease

The role of viruses in the genesis of both dilated cardiomyopathy (DCM) and acute myocarditis remains uncertain. Modern molecular techniques such as polymerase chain reaction (PCR) and in situ hybridisation are sensitive means of detecting viral genomic material in human myocardial tissue and may help to resolve the quest. Meta-analysis of the papers in the literature records studies of both acute myocarditis and DCM where molecular techniques were used to demonstrate enteroviruses. This review studies information from the published literature as well as statistical analysis of the cumulative molecular data relating enteroviruses to DCM, and to compare these findings with the information available on the role of enteroviruses in acute myocarditis. Twelve papers reported studies in acute myocarditis, of which 11 found higher percentages of enteroviral RNA positivity in the diseased population, giving an overall odds ratio of 4.4. Seventeen papers reported studies in DCM, with 11 recording higher positivity rates in these patients. Cumulative analysis of these data suggests an overall odds ratio of 3.8. The causative role of enteroviruses in acute myocarditis, particularly in children, is supported by meta-analysis of the available literature. The data on DCM is suggestive of an association but a proportion of the studies are negative.