Quantitative genomic and antigenomic enterovirus RNA detection in explanted heart tissue samples from patients with end-stage idiopathic dilated cardiomyopathy

Major Group-B Enterovirus populations deleted in the noncoding 5' region of genomic RNA modulate activation of the type I interferon pathway in cardiomyocytes and induce myocarditis

Major 5'-terminally deleted (5'TD) RNA forms of group-B coxsackievirus (CVB-5'TD) has been associated with myocarditis in both mice and humans. Although it is known that interferon-β (IFN-β) signaling is critical for an efficient innate immune response against CVB-induced myocarditis, the link between CVB-5'TD RNA forms and type I IFN signaling in cardiomyocytes remains to be explored. In a mouse model of CVB3/28-induced myocarditis, major early-emerging forms of CVB-5'TD RNA have been characterized as replicative viral populations that impair IFN-β production in the heart. Synthetic CVB3/28 RNA forms mimicking each of these major 5'TD virus populations were transfected in mice and have been shown to modulate innate immune responses in the heart and to induce myocarditis in mice. Remarkably, transfection of synthetic viral RNA with deletions in the secondary structures of the 5'-terminal CVB3 RNA domain I, modifying stem-loops "b", "c" or "d", were found to impair IFN-β production in human cardiomyocytes. In addition, the activation of innate immune response by Poly(I:C), was found to restore IFN-β production and to reduce the burden of CVB-5'TD RNA-forms in cardiac tissues, thereby reducing the mortality rate of infected mice. Overall, our results indicate that major early-emerging CVB3 populations deleted in the domain I of genomic RNA, in the 5' noncoding region, modulate the activation of the type I IFN pathway in cardiomyocytes and induce myocarditis in mice. These findings shed new light on the role of replicative CVB-5'TD RNA forms as key pathophysiological factors in CVB-induced human myocarditis.

Replication Activities of Major 5' Terminally Deleted Group-B Coxsackievirus RNA Forms Decrease PCSK2 mRNA Expression Impairing Insulin Maturation in Pancreatic Beta Cells

Emergence of 5' terminally deleted coxsackievirus-B RNA forms (CVB-TD) have been associated with the development of human diseases. These CVB-TD RNA forms have been detected in mouse pancreas during acute or persistent experimental infections. To date, the impact of the replication activities of CVB-TD RNA forms on insulin metabolism remains unexplored. Using an immunocompetent mouse model of CVB3/28 infection, acute and persistent infections of major CVB-TD populations were evidenced in the pancreas. The inoculation of mice with homogenized pancreases containing major CVB-TD populations induced acute and chronic pancreatic infections with pancreatitis. In the mouse pancreas, viral capsid protein 1 (VP1) expression colocalized with a decrease in beta cells insulin content. Moreover, in infected mouse pancreases, we showed a decrease in pro-hormone convertase 2 (PCSK2) mRNA, associated with a decrease in insulin plasmatic concentration. Finally, transfection of synthetic CVB-TD50 RNA forms into cultured rodent pancreatic beta cells demonstrated that viral replication with protein synthesis activities decreased the PCSK2 mRNA expression levels, impairing insulin secretion. In conclusion, our results show that the emergence and maintenance of major CVB-TD RNA replicative forms in pancreatic beta cells can play a direct, key role in the pathophysiological mechanisms leading to the development of type 1 diabetes.

Early Emergence of 5' Terminally Deleted Coxsackievirus-B3 RNA Forms Is Associated with Acute and Persistent Infections in Mouse Target Tissues

Major EV-B populations characterized by 5′ terminal deletions (5′TD) have been shown to be associated with the development of myocarditis and type 1 diabetes in mice or humans. To date, the dynamics of EV-B 5′TD-RNA forms’ emergence during the course of infection and their impact on cellular functions remain unclear. Using a RACE-PCR approach in CVB3/28-infected mouse organs, we showed an early (3 days post infection, DPI) emergence of major 5′TD populations associated with minor full-length RNA forms. Viral replication activities with infectious particle production were associated with heart, liver, and pancreas acute inflammatory lesions, whereas clearance of viral RNA without organ lesions was observed in the brain, lung, intestines, and muscles from 3 to 7 DPI. At 28 DPI, low viral RNA levels, +/-RNA ratios < 5 associated with viral protein 1 expression revealed a persistent infection in the heart and pancreas. This persistent infection was characterized by molecular detection of only 5′TD RNA forms that were associated with dystrophin cleavage in the heart and insulin production impairment in beta-pancreatic cells. These results demonstrated that major EV-B 5′TD RNA forms can be early selected during systemic infection and that their maintenance may drive EV-induced acute and persistent infections with target cell dysfunctions.

Persistent Enterovirus Infection: Little Deletions, Long Infections

Enteroviruses have now been shown to persist in cell cultures and in vivo by a novel mechanism involving the deletion of varying amounts of the 5′ terminal genomic region termed domain I (also known as the cloverleaf). Molecular clones of coxsackievirus B3 (CVB3) genomes with 5′ terminal deletions (TD) of varying length allow the study of these mutant populations, which are able to replicate in the complete absence of wildtype virus genomes. The study of TD enteroviruses has revealed numerous significant differences from canonical enteroviral biology. The deletions appear and become the dominant population when an enterovirus replicates in quiescent cell populations, but can also occur if one of the cis-acting replication elements of the genome (CRE-2C) is artificially mutated in the element’s stem and loop structures. This review discusses how the TD genomes arise, how they interact with the host, and their effects on host biology.

Picornavirus May Be Linked to Parkinson’s Disease through Viral Antigen in Dopamine-Containing Neurons of Substantia Nigra

Parkinson’s disease (PD) is a neurodegenerative disease linked with the loss of dopaminergic neurons in the brain region called substantia nigra and caused by unknown pathogenic mechanisms. Two currently recognized prominent features of PD are an inflammatory response manifested by glial reaction and T-cell infiltration, as well as the presence of various toxic mediators derived from activated glial cells. PD or parkinsonism has been described after infection with several different viruses and it has therefore been hypothesized that a viral infection might play a role in the pathogenesis of the disease. We investigated formalin-fixed post-mortem brain tissue from 9 patients with Parkinson’s disease and 11 controls for the presence of Ljungan virus (LV) antigen using a polyclonal antibody against the capsid protein of this recently identified picornavirus with neurotropic properties, suspected of being both a human and an animal pathogen. Evidence of viral antigen was found in 7 out of 9 Parkinson’s disease cases and in only 1 out of 11 controls (p = 0.005). The picornavirus antigen was present in dopamine-containing neurons of the substantia nigra. We propose that LV or an LV-related virus initiates the pathological process underlying sporadic PD. LV-related picornavirus antigen has also been reported in patients with Alzheimer’s disease. Potentially successful antiviral treatment in Alzheimer’s disease suggests a similar treatment for Parkinson's disease. Amantadine, originally developed as an antiviral drug against influenza infection, has also been used for symptomatic treatment of patients with PD for more than 50 years and is still commonly used by neurologists today. The fact that amantadine also has an antiviral effect on picornaviruses opens the question of this drug being re-evaluated as potential PD therapy in combination with other antiviral compounds directed against picornaviruses.

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.

The Enterovirus Theory of Disease Etiology in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Critical Review

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a complex, multi-system disease whose etiological basis has not been established. Enteroviruses (EVs) as a cause of ME/CFS have sometimes been proposed, as they are known agents of acute respiratory and gastrointestinal infections that may persist in secondary infection sites, including the central nervous system, muscle, and heart. To date, the body of research that has investigated enterovirus infections in relation to ME/CFS supports an increased prevalence of chronic or persistent enteroviral infections in ME/CFS patient cohorts than in healthy individuals. Nevertheless, inconsistent results have fueled a decline in related studies over the past two decades. This review covers the aspects of ME/CFS pathophysiology that are consistent with a chronic enterovirus infection and critically reviews methodologies and approaches used in past EV-related ME/CFS studies. We describe the prior sample types that were interrogated, the methods used and the limitations to the approaches that were chosen. We conclude that there is considerable evidence that prior outbreaks of ME/CFS were caused by one or more enterovirus groups. Furthermore, we find that the methods used in prior studies were inadequate to rule out the presence of chronic enteroviral infections in individuals with ME/CFS. Given the possibility that such infections could be contributing to morbidity and preventing recovery, further studies of appropriate biological samples with the latest molecular methods are urgently needed.

Modeling the complete kinetics of coxsackievirus B3 reveals human determinants of host-cell feedback

Complete kinetic models are pervasive in chemistry but lacking in biological systems. We encoded the complete kinetics of infection for coxsackievirus B3 (CVB3), a compact and fast-acting RNA virus. The model consists of separable, detailed modules describing viral binding-delivery, translation-replication, and encapsidation. Specific module activities are dampened by the type I interferon response to viral double-stranded RNAs (dsRNAs), which is itself disrupted by viral proteinases. The experimentally validated kinetics uncovered that cleavability of the dsRNA transducer mitochondrial antiviral signaling protein (MAVS) becomes a stronger determinant of viral outcomes when cells receive supplemental interferon after infection. Cleavability is naturally altered in humans by a common MAVS polymorphism, which removes a proteinase-targeted site but paradoxically elevates CVB3 infectivity. These observations are reconciled with a simple nonlinear model of MAVS regulation. Modeling complete kinetics is an attainable goal for small, rapidly infecting viruses and perhaps viral pathogens more broadly. A record of this paper's transparent peer review process is included in the Supplemental information.

Structures and Functions of Viral 5' Non-Coding Genomic RNA Domain-I in Group-B Enterovirus Infections

Group-B enteroviruses (EV-B) are ubiquitous naked single-stranded positive RNA viral pathogens that are responsible for common acute or persistent human infections. Their genome is composed in the 5′ end by a non-coding region, which is crucial for the initiation of the viral replication and translation processes. RNA domain-I secondary structures can interact with viral or cellular proteins to form viral ribonucleoprotein (RNP) complexes regulating viral genomic replication, whereas RNA domains-II to -VII (internal ribosome entry site, IRES) are known to interact with cellular ribosomal subunits to initiate the viral translation process. Natural 5′ terminally deleted viral forms lacking some genomic RNA domain-I secondary structures have been described in EV-B induced murine or human infections. Recent in vitro studies have evidenced that the loss of some viral RNP complexes in the RNA domain-I can modulate the viral replication and infectivity levels in EV-B infections. Moreover, the disruption of secondary structures of RNA domain-I could impair viral RNA sensing by RIG-I (Retinoic acid inducible gene I) or MDA5 (melanoma differentiation-associated protein 5) receptors, a way to overcome antiviral innate immune response. Overall, natural 5′ terminally deleted viral genomes resulting in the loss of various structures in the RNA domain-I could be major key players of host–cell interactions driving the development of acute or persistent EV-B infections.

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.

Post-mortem microbiology in sudden death: sampling protocols proposed in different clinical settings

BACKGROUND

Autopsies, including minimally invasive autopsies, are a powerful tool for determination of the cause of death. When a patient dies from an infection, microbiology is crucial to identify the causative organism. Post-mortem microbiology (PMM) aims to detect unexpected infections causing sudden deaths; confirm clinically suspected but unproven infection; evaluate the efficacy of antimicrobial therapy; identify emergent pathogens; and recognize medical errors. Additionally, the analysis of the thanatomicrobiome may help to estimate the post-mortem interval.

AIMS

The aim was to provide advice in the collection of PMM samples and to propose sampling guidelines for microbiologists advising autopsy pathologists facing different sudden death scenarios.

SOURCES

A multidisciplinary team with experts in various fields of microbiology and autopsies on behalf of the ESGFOR (ESCMID - European Society of Clinical Microbiology and Infectious Diseases - study group of forensic and post-mortem microbiology and in collaboration with the European Society of Pathology) developed this narrative review based on a literature search using MedLine and Scopus electronic databases supplemented with their own expertise.

CONTENT

These guidelines address measures to prevent sample contamination in autopsy microbiology; general PMM sampling technique; protocols for PMM sampling in different scenarios and using minimally invasive autopsy; and potential use of the evolving post-mortem microbiome to estimate the post-mortem interval.

IMPLICATIONS

Adequate sampling is paramount to identify the causative organism. Meaningful interpretation of PMM results requires careful evaluation in the context of clinical history, macroscopic and histological findings. Networking and closer collaboration among microbiologists and autopsy pathologists is vital to maximize the yield of PMM.

Major Persistent 5' Terminally Deleted Coxsackievirus B3 Populations in Human Endomyocardial Tissues

We performed deep sequencing analysis of the enterovirus 5′ noncoding region in cardiac biopsies from a patient with dilated cardiomyopathy. Results displayed a mix of deleted and full-length coxsackievirus B3, characterized by a low viral RNA load (8.10² copies/μg of nucleic acids) and a low viral RNA positive-sense to RNA negative-sense ratio of 4.8.

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.

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.

Reversion to wildtype of a mutated and nonfunctional coxsackievirus B3CRE(2C)

The cis-acting replication element (CRE) in the 2C protein coding region [CRE(2C)] of enteroviruses (EV) facilitates the addition of two uridine residues (uridylylation) onto the virus-encoded protein VPg in order for it to serve as the RNA replication primer. We demonstrated that coxsackievirus B3 (CVB3) is replication competent in the absence of a native (uridylylating) CRE(2C) and also demonstrated that lack of a functional CRE(2C) led to generation of 5' terminal genomic deletions in the CVB3 CRE-knock-out (CVB3-CKO) population. We asked whether reversion of the mutated CRE(2C) occurred, thus permitting sustained replication, and when were 5' terminal deletions generated during replication. Virions were isolated from HeLa cells previously electroporated with infectious CVB3-CKO T7 transcribed RNA or from hearts and spleens of mice after transfection with CVB3-CKO RNA. Viral RNA was isolated in order to amplify the CRE(2C) coding region and the genomic 5' terminal sequences. Sequence analysis revealed reversion of the CVB3-CKO sequence to wildtype occurs by 8 days post-electroporation of HeLa cells and by 20days post-transfection in mice. However, 5' terminal deletions evolve prior to these times. Reversion of the CRE(2C) mutations to wildtype despite loss of the genomic 5' termini is consistent with the hypothesis that an intact CRE(2C) is inherently vital to EV replication even when it is not enabling efficient positive strand initiation.

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.

Mutational Disruption of cis-Acting Replication Element 2C in Coxsackievirus B3 Leads to 5'-Terminal Genomic Deletions

Following natural human or experimental murine infections and in cell culture, coxsackievirus B (CVB) RNA can persist for weeks in the absence of a cytopathic effect, yet viral RNA remains detectable. Our earlier studies demonstrated that this persistence produced viral RNA with up to 49 nucleotide deletions at the genomic 5' terminus which partially degraded the cloverleaf (or domain I), an RNA structure required for efficient viral replication. A cis-acting replication element (CRE) in the 2C protein-coding region [CRE(2C)] templates the addition of two uridine residues to the virus genome-encoded RNA replication primer VPg prior to positive-strand synthesis. Because our previous work also demonstrated that the genomes of CVB with a 5'-terminal deletion (CVB-TD) have VPg covalently linked, even though they rarely terminate in the canonical UU donated by CRE(2C)-mediated uridylylation of VPg, we hypothesized that a functional (uridylylating) CRE(2C) would be unnecessary for CVB-TD replication. Using the same 16 mutations in the CVB3 CRE(2C) structure that were considered lethal for this virus by others, we demonstrate here both in infected cell cultures and in mice that wild-type (wt) and CVB3-TD strains carrying these mutations with a nonuridylylating CRE(2C) are viable. While the wt genome with the mutated CRE(2C) displays suppressed replication levels similar to those observed in a CVB3-TD strain, mutation of the CRE(2C) function in a CVB3-TD strain does not further decrease replication. Finally, we show that replication of the parental CVB3 strain containing the mutated CRE(2C) drives the de novo generation of genomic deletions at the 5' terminus.

IMPORTANCE

In this report, we demonstrate that while CVB can replicate without a uridylylating CRE(2C), the replication rate suffers significantly. Further, deletions at the 5' terminus of the genome are generated in this virus population, with this virus population supplanting the wild-type population. This demonstrates that VPg can prime without being specifically uridylylated and that this priming is error prone, resulting in the loss of sequence information from the 5' terminus. These findings have significance when considering the replication of human enteroviruses, and we believe that these data are unattainable in a cell-free system due to the poor replication of these CRE-deficient viruses.

Coxsackievirus can persist in murine pancreas by deletion of 5' terminal genomic sequences

Enterovirus infections are generally acute and rapidly cleared by the host immune response. Enteroviruses can at times persist in immunologically intact individuals after the rise of the type-specific neutralizing immune response. The mechanism of enterovirus persistence was shown in group B coxsackieviruses (CVB) to be due to naturally-occurring deletions at the 5' terminus of the genome which variably impact the stem-loop secondary structure called domain I. These deletions result in much slower viral replication and a loss of measurable cytopathic effect when such 5' terminally deleted (TD) viruses are assayed in cell culture. The existence and persistence of CVB-TD long after the acute phase of infection has been documented in hearts of experimentally inoculated mice and naturally infected humans but to date, the existence of TD enteroviral populations have not been documented in any other organ. Enteroviral infections have been shown to impact type 1 diabetes (T1D) onset in humans as well as in the non-obese diabetic mouse model of T1D. The first step to studying the potential impact of CVB-TD on T1D etiology is to determine whether CVB-TD populations can arise in the pancreas. After inoculation of NOD diabetic mice with CVB, viral RNA persists in the absence of cytopathic virus in pancreas weeks past the acute infectious period. Analysis of viral genomic 5' termini by RT-PCR showed CVB-TD populations displace the parental population during persistent replication in murine pancreata.

Role of viruses and other microbes in the pathogenesis of type 1 diabetes

Type 1 diabetes is caused by an immune-mediated destruction of insulin producing beta-cells in the pancreas. The risk of the disease is determined by interactions between more than 40 different susceptibility genes and yet unidentified environmental factors. The rapidly increasing incidence indicates that these environmental agents have a significant role in the pathogenesis. Microbes have associated with both increased and decreased risk reflecting their possible role as risk or protective factors. Two main hypotheses have been proposed to explain these effects: the hygiene hypothesis suggests that microbial exposures in early childhood stimulate immunoregulatory mechanisms which control autoimmune reactions (analogy with allergy), while the triggering hypothesis suggests that specific microbes damage insulin producing cells. Certain viruses, particularly enteroviruses, are currently the main candidates for such risk microbes. Enteroviruses cause diabetes in animals and have associated with increased risk of type 1 diabetes in epidemiological studies. They have also been detected in the pancreas of diabetic patients. Possible protective effect of microbes has been studied in animal models and in epidemiological studies, where certain enteral microbes (e.g. hepatitis A virus and Helicobacter pylori) and patterns of gut microbiome have associated with low risk of type 1 diabetes. In conclusion, these microbial effects offer attractive possibilities for the development of preventive interventions for type 1 diabetes based on the elimination of triggering agents (e.g. enterovirus vaccines) or use of protective microbes as probiotics.

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.

Intrafamilial spread of enterovirus infections at the clinical onset of type 1 diabetes

BACKGROUND

At the clinical onset of type 1 diabetes mellitus (T1D), enterovirus (EV) infections are suspected to play a role. EVs in blood are seen as a possible biomarker of T1D. EV infections may occur in temporal and geographic clusters and may spread within families.

OBJECTIVE

We checked whether EVs were present in the blood of newly diagnosed diabetic probands and of their consenting siblings and parents. We aimed at evaluating the frequency of EV infection, whether infections were spreading within families, and which EV species were involved.

SUBJECTS AND METHODS

Blood was drawn from 24 newly diagnosed diabetic children/adolescents and their family members (20 siblings and 41 parents). Blood donors and non-diabetic children/adolescents diagnosed with overweight/short stature were used as controls. RNA was extracted from plasma/leukocytes. Reverse-transcription polymerase chain reaction assays capable of detecting virtually all EV types and of giving preliminary species identification were used.

RESULTS AND CONCLUSIONS

EV genomes were found in the blood of 19 of 24 (79%) diabetics, 12 of 20 (60%) non-diabetic siblings, 26 of 41 (63%) parents, and 1 of 29 (3%) pediatric controls. EVs of the A, B, C, and D species were detected, with the B and C species more prevalent. Probands and virus-positive members of each family consistently shared the same EV species. During follow-up, 4 of 20 (20%) siblings of diabetic probands developed T1D with a latency of 3-25 months. In conclusion, infection by different EV species is highly prevalent at the clinical onset and extends to family members. EV may represent a precipitating factor of T1D. However, the disease only develops in a subset of infected individuals.

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

Viral detection in heart tissues has become a central issue for the diagnosis and exploration of the pathogenesis of idiopathic dilated cardiomyopathy (IDCM). In the present study, common cardiotropic viruses in 67 explanted heart samples of 31 IDCM adult patients were detected and semiquantified by using for the first time a new technology based on PCR assay coupled to electrospray ionization-time of flight mass spectrometry analysis (PCR-MS), with comparison to reference quantitative real-time PCR (RT-qPCR) assay. PCR-MS identified single or mixed enterovirus (EV) and parvovirus B19 (PVB19) infections in 27 (40.2%) of 67 samples, corresponding to 15 (48.3%) of the 31 patients, whereas RT-qPCR identified viral infections in 26 (38.8%) samples, corresponding to 16 (51.6%) of the patients. The PCR-MS results correlated well with EV and PVB19 detection by RT-qPCR (kappa = 0.85 [95% confidence interval {CI}, 0.72 to 1.00] and kappa = 0.82 [95% CI, 0.66 to 0.99], respectively). The levels of EV RNA (median, 550 [range, 178 to 3,200] copies/μg of total extracted nucleic acids) and of PVB19 DNA (median, 486 [range, 80 to 1,157] copies/μg of total extracted nucleic acids) were measured using PCR-MS and correlated with those obtained by RT-qPCR (r(2) = 0.57, P = 0.002 and r(2) = 0.64, P < 0.001 for EV and PVB19, respectively). No viruses other than EV and PVB19 strains were detected using the new PCR-MS technology, which is capable of simultaneously identifying 84 known human viruses in one assay. In conclusion, we identified single or mixed EV and PVB19 cardiac infections as potential causes of IDCM. The PCR-MS analysis appeared to be a valuable tool to rapidly detect and semiquantify common viruses in cardiac tissues and may be of major interest to better understand the role of viruses in unexplained cardiomyopathies.

Enterovirus 68 in pediatric patients hospitalized for acute airway diseases

Enterovirus 68 was detected in 10 respiratory specimens from pediatric patients hospitalized for acute wheezing or bronchitis during 2009 in the northeast of France. Viral loads ranged from 2 × 10(5) to 7.2 × 10(7) copies/ml. Alignment of 5' nontranslated regions and phylogenetic analysis of partial VP1 gene sequences show that these viruses clustered and belonged to clade C.