Virus detection and semiquantitation in explanted heart tissues of idiopathic dilated cardiomyopathy adult patients by use of PCR coupled with mass spectrometry analysis

Enterovirus-Cardiomyocyte Interactions: Impact of Terminally Deleted Genomic RNAs on Viral and Host Functions

Group B enteroviruses, including coxsackievirus B3 (CVB3), can persistently infect cardiac tissue and cause dilated cardiomyopathy. Persistence is linked to 5' terminal deletions of viral genomic RNAs that have been detected together with minor populations of full-length genomes in human infections. In this study, we explored the functions and interactions of the different viral RNA forms found in persistently infected patients and their putative role(s) in pathogenesis. Since enterovirus cardiac pathogenesis is linked to the viral proteinase 2A, we investigated the effect of different terminal genomic RNA deletions on 2A activity. We discovered that 5' terminal deletions in CVB3 genomic RNAs decreased the levels of 2A proteinase activity but could not abrogate it. Using newly generated viral reporters encoding nano-luciferase, we found that 5' terminal deletions resulted in decreased levels of viral protein and RNA synthesis in singly transfected cardiomyocyte cultures. Unexpectedly, when full-length and terminally deleted forms were cotransfected into cardiomyocytes, a cooperative interaction was observed, leading to increased viral RNA and protein production. However, when viral infections were carried out in cells harboring 5' terminally deleted CVB3 RNAs, a decrease in infectious particle production was observed. Our results provide a possible explanation for the necessity of full-length viral genomes during persistent infection, as they would stimulate efficient viral replication compared to that of the deleted genomes alone. To avoid high levels of viral particle production that would trigger cellular immune activation and host cell death, the terminally deleted RNA forms act to limit the production of viral particles, possibly as trans-dominant inhibitors. IMPORTANCE Enteroviruses like coxsackievirus B3 are able to initiate acute infections of cardiac tissue and, in some cases, to establish a long-term persistent infection that can lead to serious disease sequelae, including dilated cardiomyopathy. Previous studies have demonstrated the presence of 5' terminally deleted forms of enterovirus RNAs in heart tissues derived from patients with dilated cardiomyopathy. These deleted RNAs are found in association with very low levels of full-length enterovirus genomic RNAs, an interaction that may facilitate continued persistence while limiting virus particle production. Even in the absence of detectable infectious virus particle production, these deleted viral RNA forms express viral proteinases at levels capable of causing viral pathology. Our studies provide mechanistic insights into how full-length and deleted forms of enterovirus RNA cooperate to stimulate viral protein and RNA synthesis without stimulating infectious viral particle production. They also highlight the importance of targeting enteroviral proteinases to inhibit viral replication while at the same time limiting the long-term pathologies they trigger.

Enteroviruses and Type 1 Diabetes: Multiple Mechanisms and Factors?

Type 1 diabetes (T1D) is a chronic autoimmune disease characterized by insulin deficiency and resultant hyperglycemia. Complex interactions of genetic and environmental factors trigger the onset of autoimmune mechanisms responsible for development of autoimmunity to β cell antigens and subsequent development of T1D. A potential role of virus infections has long been hypothesized, and growing evidence continues to implicate enteroviruses as the most probable triggering viruses. Recent studies have strengthened the association between enteroviruses and development of autoimmunity in T1D patients, potentially through persistent infections. Enterovirus infections may contribute to different stages of disease development. We review data from both human cohort studies and experimental research exploring the potential roles and molecular mechanisms by which enterovirus infections can impact disease outcome.

Enteroviruses and Type 1 Diabetes: Multiple Mechanisms and Factors?

Type 1 diabetes (T1D) is a chronic autoimmune disease characterized by insulin deficiency and resultant hyperglycemia. Complex interactions of genetic and environmental factors trigger the onset of autoimmune mechanisms responsible for development of autoimmunity to β cell antigens and subsequent development of T1D. A potential role of virus infections has long been hypothesized, and growing evidence continues to implicate enteroviruses as the most probable triggering viruses. Recent studies have strengthened the association between enteroviruses and development of autoimmunity in T1D patients, potentially through persistent infections. Enterovirus infections may contribute to different stages of disease development. We review data from both human cohort studies and experimental research exploring the potential roles and molecular mechanisms by which enterovirus infections can impact disease outcome.

Myocarditis Presenting as Sudden Death in Infants and Children: A Single Centre Analysis by ESGFOR Study Group

BACKGROUND

Acute myocarditis is an inflammatory disease of the heart mostly diagnosed in young people, which can present as sudden death. The etiology includes infectious agents (mostly viruses), systemic diseases and toxins. We aim to characterize infants and children with myocarditis at post-mortem presenting as sudden deaths.

METHODS

Retrospective evaluation of 813 post-mortems in infants and children dying suddenly and unexpectedly between 2009-2019. Data retrieved included histological features, microbiology and clinical history.

RESULTS

23 of 813 post-mortems reviewed corresponded to acute myocarditis and 1 to dilated cardiomyopathy related to remote Parvovirus infection. PCR identified enterovirus (7), parvovirus (7 cases, 2 also with HHV6 and 1 case with EVB), Influenza A (1), Parainfluenza type 3 (1). Two cases corresponded to hypersensitivity myocarditis, 1 was Group A Streptococcus and 5 idiopathic myocarditis. Enterovirus was frequent in infants (7/10), and in newborns was associated with meningoencephalitis or congenital myocarditis. More than 50% were less than 2 years of age and all remained clinically unsuspected.

CONCLUSION

Myocarditis represents almost 3% of all sudden pediatric deaths. Enterovirus and parvovirus were the most common viruses. This retrospective analysis showed that patients experienced viral symptoms but remained unsuspected, highlighting the need for more clinical awareness of myocarditis.

Detection of parvovirus B19 and human herpesvirus 6 in pediatric dilated cardiomyopathy: Impact after heart transplantation

Objectives:

The aim of this study is to evaluate HHV-6 and PVB19 infection using polymerase chain reaction (PCR) and immunofluorescent assay (IFA) in the myocardium of pediatric patients with dilated cardiomyopathy (DCM) and the impact of viral persistence in the cardiac allograft after heart transplantation (HT).

Methods:

Multiplex droplet digital PCR was used to analyze the prevalence of viral sequences in myocardial samples from 48 pediatric DCM patients and 10 control subjects. Of the 48 DCM patients, 44 underwent HT. After HT, consecutive endomyocardial biopsy (EMB) samples were analyzed for the presence of PVB19 and HHV-6 antigens using IFA and the patients were evaluated for rejections, coronary vasculopathy, and graft loss.

Results:

Of the 48 DCM patients, 14 had positive viral PCR results in explanted/autopsy hearts. Among them, PVB19 was found in 8/48, HHV6 in 4/48, both PVB19 and HHV6 in 1/48, and enterovirus in one, but no adenovirus was found. The EMB samples obtained after HT were positive for PVB19 and HHV-6 in 7/44 and 3/44 cases, respectively. Viral presence in both the explanted heart and the cardiac allograft was demonstrated in 4 patients, 3 of whom were positive for PVB19, and one of whom was positive for HHV-6 pretransplant. Coronary vasculopathy and graft loss were more common in patients with PVB19-positive myocardial tissues versus those who were PVB19-negative.

Conclusions:

There is an association between PVB19 and HHV-6 infection and DCM in children. The study suggests the persistence of PVB19 and HHV-6 in the host can lead to subsequent viral reactivation in the transplanted heart, even in those recipients who do not have active myocarditis. PVB19 in the cardiac allograft tended toward higher adverse post-HT events.

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.

Revealing enterovirus infection in chronic human disorders: An integrated diagnostic approach

Enteroviruses (EVs) causing persisting infection are characterized by minimal replication and genetic changes. Typing of these agents may complement disease assessment and shed light on pathogenesis. Here we report an integrated approach for EV detection in human samples that is based on pre-enrichment of virus in cell culture before search for the viral genome and viral antigens. Cases of post-polio syndrome, type 1 diabetes, and chronic cardiomyopathy were investigated. As tissue-based approaches require invasive procedures, information was mainly gleaned from virus in blood. Molecular assays targeting conserved genome regions of all EV types (5'UTR, 2 C, 3Dpol) were employed. As compared to direct assays of plasma or leukocytes, the EV detection rate was significantly enhanced by co-culture of leukocytes with cell lines prior to molecular and immunologic tests. Results of RT-PCR and sequencing were confirmed by staining cell cultures with a panel of EV-specific antibodies. Sequence and phylogenetic analysis showed that EVs of the C species (polioviruses) were associated with the post-polio syndrome, while members of the B species were found in type 1 diabetes and cardiomyopathy. The procedure may be used for investigating the possible association of different EVs with a variety of chronic neurologic, endocrine, and cardiac disorders.

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.

Enterovirus but not Parvovirus B19 is associated with idiopathic dilated cardiomyopathy and endomyocardial CD3, CD68, or HLA-DR expression

We assessed Enterovirus (EV) &Parvovirus B19 (PVB19) genomes and CD3, CD68&HLA-DR detection in dilated cardiomyopathies (DCM). EV&PVB19 genomes and CD3, CD68&HLA-DR were detected by PCR and immunohistochemistry assays in 115 endomyocardial biopsies obtained in 13 idiopathic DCM (iDCM) and 10 explained DCM (eDCM) patients. Results were compared with those of 47 atrial surgical samples (47 surgery controls) and 22 autoptic cardiac samples (11 healthy heart controls) (2008-2014, Reims, France). EV was detected in 23.1% of iDCM patients but not in eDCM and controls (P = 0.003) (viral load 803 copies/μg). PVB19 was detected in 76.9%, 80.0%, 63.6% and 78.2% of iDCM, eDCM, healthy heart and surgery controls (P = 0.99) with a mean viral load of 413, 346, 1,428, and 71 copies/μg. CD3, CD68 or HLA-DR were detected in 100 and 50% of EV and PVB19 "mono-infected" iDCM patients. EV was exclusively detected in iDCM cases in association with CD3, CD68, or HLA-DR indicating that EV could be an etiological cause in a subset of iDCM cases. By contrast the equal frequent detection of PVB19 in iDCM cases and controls without association with CD3, CD68, or HLA-DR suggested that PVB19 could be a bystander in many DCM cases. J. Med. Virol. 89:55-63, 2017. © 2016 Wiley Periodicals, Inc.

Construction of a subgenomic CV-B3 replicon expressing emerald green fluorescent protein to assess viral replication of a cardiotropic enterovirus strain in cultured human cells

Coxsackieviruses B (CV-B) (Picornaviridae) are a common infectious cause of acute myocarditis in children and young adults, a disease, which is a precursor to 10-20% of chronic myocarditis and dilated cardiomyopathy (DCM) cases. The mechanisms involved in the disease progression from acute to chronic myocarditis phase and toward the DCM clinical stage are not fully understood but are influenced by both viral and host factors. Subgenomic replicons of CV-B can be used to assess viral replication mechanisms in human cardiac cells and evaluate the effects of potential antiviral drugs on viral replication activities. Our objectives were to generate a reporter replicon from a cardiotropic prototype CV-B3/28 strain and to characterize its replication properties into human cardiac primary cells. To obtain this replicon, a cDNA plasmid containing the full CV-B3/28 genome flanked by a hammerhead ribozyme sequence and an MluI restriction site was generated and used as a platform for the insertion of sequences encoding emerald green fluorescent protein (EmGFP) in place of those encoding VP3. In vitro transcribed RNA from this plasmid was transfected into HeLa cells and human primary cardiac cells and was able to produce EmGFP and VP1-containing polypeptides. Moreover, non-structural protein biological activity was assessed by the specific cleavage of eIF4G1 by viral 2A(pro). Viral RNA replication was indirectly demonstrated by inhibition assays, fluoxetine was added to cell culture and prevented the EmGFP synthesis. Our results indicated that the EmGFP CV-B3 replicon was able to replicate and translate as well as the CV-B3/28 prototype strain. Our EmGFP CV-B3 replicon will be a valuable tool to readily investigate CV-B3 replication activities in human target cell models.

Virological diagnosis of central nervous system infections by use of PCR coupled with mass spectrometry analysis of cerebrospinal fluid samples

Viruses are the leading cause of central nervous system (CNS) infections, ahead of bacteria, parasites, and fungal agents. A rapid and comprehensive virologic diagnostic testing method is needed to improve the therapeutic management of hospitalized pediatric or adult patients. In this study, we assessed the clinical performance of PCR amplification coupled with electrospray ionization-time of flight mass spectrometry analysis (PCR-MS) for the diagnosis of viral CNS infections. Three hundred twenty-seven cerebrospinal fluid (CSF) samples prospectively tested by routine PCR assays between 2004 and 2012 in two university hospital centers (Toulouse and Reims, France) were retrospectively analyzed by PCR-MS analysis using primers targeted to adenovirus, human herpesviruses 1 to 8 (HHV-1 to -8), polyomaviruses BK and JC, parvovirus B19, and enteroviruses (EV). PCR-MS detected single or multiple virus infections in 190 (83%) of the 229 samples that tested positive by routine PCR analysis and in 10 (10.2%) of the 98 samples that tested negative. The PCR-MS results correlated well with herpes simplex virus 1 (HSV-1), varicella-zoster virus (VZV), and EV detection by routine PCR assays (kappa values [95% confidence intervals], 0.80 [0.69 to 0.92], 0.85 [0.71 to 0.98], and 0.84 [0.78 to 0.90], respectively), whereas a weak correlation was observed with Epstein-Barr virus (EBV) (0.34 [0.10 to 0.58]). Twenty-six coinfections and 16 instances of uncommon neurotropic viruses (HHV-7 [n = 13], parvovirus B19 [n = 2], and adenovirus [n = 1]) were identified by the PCR-MS analysis, whereas only 4 coinfections had been prospectively evidenced using routine PCR assays (P < 0.01). In conclusion, our results demonstrated that PCR-MS analysis is a valuable tool to identify common neurotropic viruses in CSF (with, however, limitations that were identified regarding EBV and EV detection) and may be of major interest in better understanding the clinical impact of multiple or neglected viral neurological infections.