Coxsackievirus B4 can infect human pancreas ductal cells and persist in ductal-like cell cultures which results in inhibition of Pdx1 expression and disturbed formation of islet-like cell aggregates

Vemurafenib Inhibits Acute and Chronic Enterovirus Infection by Affecting Cellular Kinase Phosphatidylinositol 4-Kinase Type IIIβ

Enteroviruses are one of the most abundant viruses causing mild to serious acute infections in humans and also contributing to chronic diseases like type 1 diabetes. Presently, there are no approved antiviral drugs against enteroviruses. Here, we studied the potency of vemurafenib, an FDA-approved RAF kinase inhibitor for treating BRAFV600E mutant-related melanoma, as an antiviral against enteroviruses. We showed that vemurafenib prevented enterovirus translation and replication at low micromolar dosage in an RAF/MEK/ERK-independent manner. Vemurafenib was effective against group A, B, and C enteroviruses, as well as rhinovirus, but not parechovirus or more remote viruses such as Semliki Forest virus, adenovirus, and respiratory syncytial virus. The inhibitory effect was related to a cellular phosphatidylinositol 4-kinase type IIIβ (PI4KB), which has been shown to be important in the formation of enteroviral replication organelles. Vemurafenib prevented infection efficiently in acute cell models, eradicated infection in a chronic cell model, and lowered virus amounts in pancreas and heart in an acute mouse model. Altogether, instead of acting through the RAF/MEK/ERK pathway, vemurafenib affects the cellular PI4KB and, hence, enterovirus replication, opening new possibilities to evaluate further the potential of vemurafenib as a repurposed drug in clinical care. IMPORTANCE Despite the prevalence and medical threat of enteroviruses, presently, there are no antivirals against them. Here, we show that vemurafenib, an FDA-approved RAF kinase inhibitor for treating BRAFV600E mutant-related melanoma, prevents enterovirus translation and replication. Vemurafenib shows efficacy against group A, B, and C enteroviruses, as well as rhinovirus, but not parechovirus or more remote viruses such as Semliki Forest virus, adenovirus, and respiratory syncytial virus. The inhibitory effect acts through cellular phosphatidylinositol 4-kinase type IIIβ (PI4KB), which has been shown to be important in the formation of enteroviral replication organelles. Vemurafenib prevents infection efficiently in acute cell models, eradicates infection in a chronic cell model, and lowers virus amounts in pancreas and heart in an acute mouse model. Our findings open new possibilities to develop drugs against enteroviruses and give hope for repurposing vemurafenib as an antiviral drug against enteroviruses.

Persistent Coxsackievirus B3 Infection in Pancreatic Ductal Cells In Vitro Downregulates Cellular Polyamine Metabolism

Picornaviruses infect a wide variety of cell types in vitro, with rapid replication kinetics and pronounced cytopathic effect. Coxsackievirus B3 (CVB3) can also establish a persistent infection in vivo that can lead to pathology, including dilated cardiomyopathy and myocarditis. One model system to study persistent infection is the pancreatic ductal cell line PANC-1, which CVB3 infects and is maintained indefinitely. We have characterized this model for CVB3 infection to study persistent infection for over 6 months. We find that CVB3 rapidly replicates within PANC-1 cells without robust cytopathic effect, and after 1 month in culture, titers stabilize. We find that infection does not significantly affect cellular viability. Persistent virus reverts to lytic infection when transferred to Huh7 or Vero cells. We find that persistent CVB3 adapts to PANC-1 cells via mutation of its capsid proteins and, curiously, the viral polymerase (3Dpol) to generate a high-fidelity polymerase. Persistent infection is associated with reduced cleavage of eIF4G, reduced plaque size, and decreasing particle infectivity. We further find that polyamine metabolism is altered in persistently infected cells, with the rate-limiting enzyme ornithine decarboxylase (ODC1) reduced in translation. We further find that targeting polyamine synthesis reduces persistent infection without affecting the viability of the PANC-1 cells. Finally, we find that viral fidelity is essential to maintaining CVB3 infection, and targeting viral fidelity reduces persistent virus infection. Together, these data highlight a novel role for polyamines and fidelity in persistent CVB3 infection and suggest avenues for therapeutic development to target persistent infection. IMPORTANCE Enteroviruses are significant human pathogens that can cause severe disease, including cardiomyopathies. Viruses like coxsackievirus B3 (CVB3) can cause tissue damage by lytically infecting cells; however, CVB3 can also persistently infect, which has been associated with several pathologies. Studying persistent infection in vitro is challenging, as CVB3 lytically infects most cellular model systems. Here, we show that CVB3 establishes persistent infection in pancreatic ductal cells in vitro, similar to prior studies on other coxsackieviruses. We also show that this infection results in adaptation of the virus to these cells, as well as changes to cellular metabolism of polyamines.

The Role of Viral Infections in the Onset of Autoimmune Diseases

Autoimmune diseases (AIDs) are the consequence of a breach in immune tolerance, leading to the inability to sufficiently differentiate between self and non-self. Immune reactions that are targeted towards self-antigens can ultimately lead to the destruction of the host's cells and the development of autoimmune diseases. Although autoimmune disorders are comparatively rare, the worldwide incidence and prevalence is increasing, and they have major adverse implications for mortality and morbidity. Genetic and environmental factors are thought to be the major factors contributing to the development of autoimmunity. Viral infections are one of the environmental triggers that can lead to autoimmunity. Current research suggests that several mechanisms, such as molecular mimicry, epitope spreading, and bystander activation, can cause viral-induced autoimmunity. Here we describe the latest insights into the pathomechanisms of viral-induced autoimmune diseases and discuss recent findings on COVID-19 infections and the development of AIDs.

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.

Persistent coxsackievirus B infection and pathogenesis of type 1 diabetes mellitus

Enteroviruses are believed to trigger or accelerate islet autoimmunity in genetically susceptible individuals, thereby resulting in loss of functional insulin-producing β-cells and type 1 diabetes mellitus (T1DM). Although enteroviruses are primarily involved in acute and lytic infections in vitro and in vivo, they can also establish a persistent infection. Prospective epidemiological studies have strongly associated the persistence of enteroviruses, especially coxsackievirus B (CVB), with the appearance of islet autoantibodies and an increased risk of T1DM. CVB can persist in pancreatic ductal and β-cells, which leads to structural or functional alterations of these cells, and to a chronic inflammatory response that promotes recruitment and activation of pre-existing autoreactive T cells and β-cell autoimmune destruction. CVB persistence in other sites, such as the intestine, blood cells and thymus, has been described; these sites could serve as a reservoir for infection or reinfection of the pancreas, and this persistence could have a role in the disturbance of tolerance to β-cells. This Review addresses the involvement of persistent enterovirus infection in triggering islet autoimmunity and T1DM, as well as current strategies to control enterovirus infections for preventing or reducing the risk of T1DM onset.

Persistent coxsackievirus B1 infection triggers extensive changes in the transcriptome of human pancreatic ductal cells

Enteroviruses, particularly the group B coxsackieviruses (CVBs), have been associated with the development of type 1 diabetes. Several CVB serotypes establish chronic infections in human cells in vivo and in vitro. However, the mechanisms leading to enterovirus persistency and, possibly, beta cell autoimmunity are not fully understood. We established a carrier-state-type persistent infection model in human pancreatic cell line PANC-1 using two distinct CVB1 strains and profiled the infection-induced changes in cellular transcriptome. In the current study, we observed clear changes in the gene expression of factors associated with the pancreatic microenvironment, the secretory pathway, and lysosomal biogenesis during persistent CVB1 infections. Moreover, we found that the antiviral response pathways were activated differently by the two CVB1 strains. Overall, our study reveals extensive transcriptional responses in persistently CVB1-infected pancreatic cells with strong opposite but also common changes between the two strains.

Characterisation of enterovirus RNA detected in the pancreas and other specimens of live patients with newly diagnosed type 1 diabetes in the DiViD study

AIMS/HYPOTHESIS

The Diabetes Virus Detection (DiViD) study is the first study to laparoscopically collect pancreatic tissue and purified pancreatic islets together with duodenal mucosa, serum, peripheral blood mononuclear cells (PBMCs) and stools from six live adult patients (age 24-35 years) with newly diagnosed type 1 diabetes. The presence of enterovirus (EV) in the pancreatic islets of these patients has previously been reported.

METHODS

In the present study we used reverse transcription quantitative real-time PCR (RT-qPCR) and sequencing to characterise EV genomes present in different tissues to understand the nature of infection in these individuals.

RESULTS

All six patients were found to be EV-positive by RT-qPCR in at least one of the tested sample types. Four patients were EV-positive in purified islet culture medium, three in PBMCs, one in duodenal biopsy and two in stool, while serum was EV-negative in all individuals. Sequencing the 5' untranslated region of these EVs suggested that all but one belonged to enterovirus B species. One patient was EV-positive in all these sample types except for serum. Sequence analysis revealed that the virus strain present in the isolated islets of this patient was different from the strain found in other sample types. None of the islet-resident viruses could be isolated using EV-permissive cell lines.

CONCLUSIONS/INTERPRETATION

EV RNA can be frequently detected in various tissues of patients with type 1 diabetes. At least in some patients, the EV strain in the pancreatic islets may represent a slowly replicating persisting virus.

Investigation of the utility of the 1.1B4 cell as a model human beta cell line for study of persistent enteroviral infection

The generation of a human pancreatic beta cell line which reproduces the responses seen in primary beta cells, but is amenable to propagation in culture, has long been an important goal in diabetes research. This is particularly true for studies focussing on the role of enteroviral infection as a potential cause of beta-cell autoimmunity in type 1 diabetes. In the present work we made use of a clonal beta cell line (1.1B4) available from the European Collection of Authenticated Cell Cultures, which had been generated by the fusion of primary human beta-cells with a pancreatic ductal carcinoma cell, PANC-1. Our goal was to study the factors allowing the development and persistence of a chronic enteroviral infection in human beta-cells. Since PANC-1 cells have been reported to support persistent enteroviral infection, the hybrid 1.1B4 cells appeared to offer an ideal vehicle for our studies. In support of this, infection of the cells with a Coxsackie virus isolated originally from the pancreas of a child with type 1 diabetes, CVB4.E2, at a low multiplicity of infection, resulted in the development of a state of persistent infection. Investigation of the molecular mechanisms suggested that this response was facilitated by a number of unexpected outcomes including an apparent failure of the cells to up-regulate certain anti-viral response gene products in response to interferons. However, more detailed exploration revealed that this lack of response was restricted to molecular targets that were either activated by, or detected with, human-selective reagents. By contrast, and to our surprise, the cells were much more responsive to rodent-selective reagents. Using multiple approaches, we then established that populations of 1.1B4 cells are not homogeneous but that they contain a mixture of rodent and human cells. This was true both of our own cell stocks and those held by the European Collection of Authenticated Cell Cultures. In view of this unexpected finding, we developed a strategy to harvest, isolate and expand single cell clones from the heterogeneous population, which allowed us to establish colonies of 1.1B4 cells that were uniquely human (h1.1.B4). However, extensive analysis of the gene expression profiles, immunoreactive insulin content, regulated secretory pathways and the electrophysiological properties of these cells demonstrated that they did not retain the principal characteristics expected of human beta cells. Our data suggest that stocks of 1.1B4 cells should be evaluated carefully prior to their use as a model human beta-cell since they may not retain the phenotype expected of human beta-cells.

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.

Effect of Coxsackievirus B4 Infection on the Thymus: Elucidating Its Role in the Pathogenesis of Type 1 Diabetes

The thymus gland is a primary lymphoid organ for T-cell development. Various viral infections can result in disturbance of thymic functions. Medullary thymic epithelial cells (mTECs) are important for the negative selection of self-reactive T-cells to ensure central tolerance. Insulin-like growth factor 2 (IGF2) is the dominant self-peptide of the insulin family expressed in mTECs and plays a crucial role in the intra-thymic programing of central tolerance to insulin-secreting islet β-cells. Coxsackievirus B4 (CVB4) can infect and persist in the thymus of humans and mice, thus hampering the T-cell maturation and differentiation process. The modulation of IGF2 expression and protein synthesis during a CVB4 infection has been observed in vitro and in vivo in mouse models. The effect of CVB4 infections on human and mouse fetal thymus has been studied in vitro. Moreover, following the inoculation of CVB4 in pregnant mice, the thymic function in the fetus and offspring was disturbed. A defect in the intra-thymic expression of self-peptides by mTECs may be triggered by CVB4. The effects of viral infections, especially CVB4 infection, on thymic cells and functions and their possible role in the pathogenesis of type 1 diabetes (T1D) are presented.

Persistence of Coxsackievirus B4 in Pancreatic β Cells Disturbs Insulin Maturation, Pattern of Cellular Proteins, and DNA Methylation

Coxsackievirus-B4 (CV-B4) can persist in pancreatic cell lines and impair the phenoytpe and/or gene expressions in these cells; however, the models used to study this phenomenon did not produce insulin. Therefore, we investigated CV-B4 persistence and its consequences in insulin-producing pancreatic β cells. The insulin-secreting rat β cell line, INS-1, was infected with CV-B4. After lysis of a large part of the cell layer, the culture was still maintained and no additional cytopathic effect was observed. The amount of insulin in supernatants of cell cultures persistently infected with CV-B4 was not affected by the infection; in fact, a larger quantity of proinsulin was found. The mRNA expression of pro-hormone convertase 2, an enzyme involved in the maturation of proinsulin into insulin and studied using real-time reverse transcription-polymerase chain reaction, was inhibited in infected cultures. Further, the pattern of 47 cell proteins analyzed using Shotgun mass spectrometry was significantly modified. The DNA of persistently infected cell cultures was hypermethylated unlike that of controls. The persistent infection of INS-1 cells with CV-B4 had a deep impact on these cells, especially on insulin metabolism. Cellular changes caused by persistent CV-B4 infection of β cells can play a role in type 1 diabetes pathogenesis.

Genetic Adaptation of Coxsackievirus B1 during Persistent Infection in Pancreatic Cells

Coxsackie B (CVB) viruses have been associated with type 1 diabetes. We have recently observed that CVB1 was linked to the initiation of the autoimmune process leading to type 1 diabetes in Finnish children. Viral persistency in the pancreas is currently considered as one possible mechanism. In the current study persistent infection was established in pancreatic ductal and beta cell lines (PANC-1 and 1.1B4) using four different CVB1 strains, including the prototype strain and three clinical isolates. We sequenced 5′ untranslated region (UTR) and regions coding for structural and non-structural proteins and the second single open reading frame (ORF) protein of all persisting CVB1 strains using next generation sequencing to identify mutations that are common for all of these strains. One mutation, K257R in VP1, was found from all persisting CVB1 strains. The mutations were mainly accumulated in viral structural proteins, especially at BC, DE, EF loops and C-terminus of viral capsid protein 1 (VP1), the puff region of VP2, the knob region of VP3 and infection-enhancing epitope of VP4. This showed that the capsid region of the viruses sustains various changes during persistency some of which could be hallmark(s) of persistency.

Coxsackievirus B Type 4 Infection in β Cells Downregulates the Chaperone Prefoldin URI to Induce a MODY4-like Diabetes via Pdx1 Silencing

Enteroviruses are suspected to contribute to insulin-producing β cell loss and hyperglycemia-induced diabetes. However, mechanisms are not fully defined. Here, we show that coxsackievirus B type 4 (CVB4) infection in human islet-engrafted mice and in rat insulinoma cells displays loss of unconventional prefoldin RPB5 interactor (URI) and PDX1, affecting β cell function and identity. Genetic URI ablation in the mouse pancreas causes PDX1 depletion in β cells. Importantly, diabetic PDX1 heterozygous mice overexpressing URI in β cells are more glucose tolerant. Mechanistically, URI loss triggers estrogen receptor nuclear translocation leading to DNA methyltransferase 1 (DNMT1) expression, which induces Pdx1 promoter hypermethylation and silencing. Consequently, demethylating agent procainamide-mediated DNMT1 inhibition reinstates PDX1 expression and protects against diabetes in pancreatic URI-depleted mice . Finally, the β cells of human diabetes patients show correlations between viral protein 1 and URI, PDX1, and DNMT1 levels. URI and DNMT1 expression and PDX1 silencing provide a causal link between enterovirus infection and diabetes.

Coxsackievirus B type 4 infection downregulates URI and affects β cell function

Genetic URI ablation in mouse pancreas recapitulates diabetes

URI controls Pdx1 methylation via ERα-activating DNMT1

Coxsackievirus B type 4, URI, PDX1, and DNMT1 expression correlate in human pancreata

Coxsackievirus-B4 Infection Can Induce the Expression of Human Endogenous Retrovirus W in Primary Cells

Human Endogenous Retrovirus W Envelope (HERV-W ENV) mRNA or protein can be found in peripheral blood mononuclear cells (PBMCs) and exocrine pancreas of patients with type 1 diabetes (T1D). Further, previous observations have shown an association between enteroviral infection and development of T1D; specifically, coxsackievirus-B (CV-B) has been detected in the blood and pancreas of patients with T1D. Notably, viruses can activate HERV-W expression. Hence, we evaluated the effect of CV-B4 infection on HERV-W ENV mRNA expression. Primary human pancreatic ductal cells were obtained from five brain-dead donors. In the pancreatic cells of three donors, the HERV-W ENV mRNA level measured using RT-qPCR was upregulated upon CV-B4 infection. The HERV-W ENV protein was detected in the infected cells using the immunoblot assay. In human PBMCs inoculated with CV-B4 or when CV-B4 was incubated with an enhancing serum, the HERV-W ENV mRNA level was higher than the background RNA level. In monocyte-derived macrophages obtained from 5 of 13 donors, the HERV-W ENV mRNA level was higher in cultures inoculated with CV-B4 than in the control. Therefore, CV-B4 can upregulate or induce the transcription of a certain HERV-W ENV copy (or copies) in primary cell cultures, such as monocytes, macrophages, and pancreatic cells.

Enteroviruses and T1D: Is It the Virus, the Genes or Both which Cause T1D

Type 1 diabetes (T1D) is a chronic autoimmune disorder that results from the selective destruction of insulin-producing β-cells in the pancreas. Up to now, the mechanisms triggering the initiation and progression of the disease are, in their complexity, not fully understood and imply the disruption of several tolerance networks. Viral infection is one of the environmental factors triggering diabetes, which is initially based on the observation that the disease’s incidence follows a periodic pattern within the population. Moreover, the strong correlation of genetic susceptibility is a prerequisite for enteroviral infection associated islet autoimmunity. Epidemiological data and clinical findings indicate enteroviral infections, mainly of the coxsackie B virus family, as potential pathogenic mechanisms to trigger the autoimmune reaction towards β-cells, resulting in the boost of inflammation following β-cell destruction and the onset of T1D. This review discusses previously identified virus-associated genetics and pathways of β-cell destruction. Is it the virus itself which leads to β-cell destruction and T1D progression? Or is it genetic, so that the virus may activate auto-immunity and β-cell destruction only in genetically predisposed individuals?

Eradication of persistent coxsackievirus B infection from a pancreatic cell line with clinically used antiviral drugs

BACKGROUND

Persistent enterovirus infections create a difficult therapeutic challenge in immunocompromised patients and may also contribute to the development of chronic diseases including type 1 diabetes, cardiomyopathies, post-polio syndrome and chronic fatigue syndrome.

OBJECTIVES

To study the ability of antiviral drugs to eradicate such infection in vitro to evalaute their potential in the treatments of these patients.

STUDY DESIGN

We set out to evaluate several licensed or clinically tested drugs which have shown some anti-enterovirus activity in previous studies for their ability to cure persistent infection established by two different coxsackievirus B1 strains in a pancreatic cell line (PANC-1 cells).

RESULTS

Among all tested drugs Enviroxime, Fluoxetine, concentrated human IgG product (Hizentra) and Pleconaril were able to eradicate persistent Coxsackievirus B1 infection. The effect Enviroxime, Hizentra and Pleconaril varied between the two virus strains.

CONCLUSIONS

The identified drugs are feasible candidates for clinical trials among patients with persistent coxsackievirus B infections or chronic enterovirus-associated diseases.

Pancreatic beta cells persistently infected with coxsackievirus B4 are targets of NK cell-mediated cytolytic activity

It has been suggested that the persistence of coxsackieviruses-B (CV-B) in pancreatic beta cells plays a role in the pathogenesis of type 1 diabetes (T1D). Yet, immunological effectors, especially natural killer (NK) cells, are supposed to clear virus-infected cells. Therefore, an evaluation of the response of NK cells to pancreatic beta cells persistently infected with CV-B4 was conducted. A persistent CV-B4 infection was established in 1.1B4 pancreatic beta cells. Infectious particles were found in supernatants throughout the culture period. The proportion of cells containing viral protein VP1 was low (< 5%), although a large proportion of cells harbored viral RNA (around 50%), whilst cell viability was preserved. HLA class I cell surface expression was downregulated in persistently infected cultures, but HLA class I mRNA levels were unchanged in comparison with mock-infected cells. The cytolytic activities of IL-2-activated non-adherent peripheral blood mononuclear cells (PBMCs) and of NK cells were higher towards persistently infected cells than towards mock-infected cells, as assessed by an LDH release assay. Impaired cytolytic activity of IL-2-activated non-adherent PBMCs from patients with T1D towards infected beta cells was observed. In conclusion, pancreatic beta cells persistently infected with CV-B4 can be lysed by NK cells, implying that impaired cytolytic activity of these effector cells may play a role in the persistence of CV-B in the host and thus in the viral pathogenesis of T1D.

Coxsackievirus B Persistence Modifies the Proteome and the Secretome of Pancreatic Ductal Cells

The group B Coxsackieviruses (CVB), belonging to the Enterovirus genus, can establish persistent infections in human cells. These persistent infections have been linked to chronic diseases including type 1 diabetes. Still, the outcomes of persistent CVB infections in human pancreas are largely unknown. We established persistent CVB infections in a human pancreatic ductal-like cell line PANC-1 using two distinct CVB1 strains and profiled infection-induced changes in cellular protein expression and secretion using mass spectrometry-based proteomics. Persistent infections, showing characteristics of carrier-state persistence, were associated with a broad spectrum of changes, including changes in mitochondrial network morphology and energy metabolism and in the regulated secretory pathway. Interestingly, the expression of antiviral immune response proteins, and also several other proteins, differed clearly between the two persistent infections. Our results provide extensive information about the protein-level changes induced by persistent CVB infection and the potential virus-associated variability in the outcomes of these infections.

Coxsackievirus-B4 Infection of Human Primary Pancreatic Ductal Cell Cultures Results in Impairment of Differentiation into Insulin-Producing Cells

Coxsackievirus-B4 (CV-B4) E2 can persist in the pancreatic ductal-like cells (Panc-1 cell line), which results in an impaired differentiation of these cells into islet-like cell aggregates (ICA). In this study, primary pancreatic ductal cells obtained as a by-product of islet isolation from the pancreas of seven brain-dead adults were inoculated with CV-B4 E2, followed-up for 29 days, and the impact was investigated. Viral titers in culture supernatants were analyzed throughout the culture. Intracellular viral RNA was detected by RT-PCR. Levels of ductal cell marker CK19 mRNA and of insulin mRNA were evaluated by qRT-PCR. The concentration of c-peptide in supernatants was determined by ELISA. Ductal cells exposed to trypsin and serum-free medium formed ICA and resulted in an increased insulin secretion. Ductal cells from five brain-dead donors were severely damaged by CV-B4 E2, whereas the virus persisted in cultures of cells obtained from the other two. The ICAs whose formation was induced on day 14 post-inoculation were scarce and appeared tiny in infected cultures. Also, insulin mRNA expression and c-peptide levels were strongly reduced compared to the controls. In conclusion, CV-B4 E2 lysed human primary pancreatic ductal cells or persisted in these cells, which resulted in the impairment of differentiation into insulin-producing cells.

Emergence of Fluoxetine-Resistant Variants during Treatment of Human Pancreatic Cell Cultures Persistently Infected with Coxsackievirus B4

This study reports the antiviral activity of the drug fluoxetine against some enteroviruses (EV). We had previously established a model of persistent coxsackievirus B4 (CVB4) infection in pancreatic cell cultures and demonstrated that fluoxetine could clear the virus from these cultures. We further report the emergence of resistant variants during the treatment with fluoxetine in this model. Four independent persistent CVB4 infections in Panc-1 cells were treated with fluoxetine. The resistance to fluoxetine was investigated in an acute infection model. The 2C region, the putative target of fluoxetine antiviral activity, was sequenced. However, Fluoxetine treatment failed to clear CVB4 in two persistent infections. The resistance to fluoxetine was later confirmed in HEp-2 cells. The decrease in viral titer was significantly lower when cells were inoculated with the virus obtained from persistently infected cultures treated with fluoxetine than those from susceptible mock-treated cultures (0.6 log TCID50/mL versus 4.2 log TCID50/mL, p < 0.0001). Some previously described mutations and additional ones within the 2C protein were found in the fluoxetine-resistant isolates. The model of persistent infection is an interesting tool for assessing the emergence of variants resistant to anti-EV molecules. The resistance of EV strains to fluoxetine and its mechanisms require further investigation.

In vivo imaging of insulin-secreting human pancreatic ductal cells using MRI reporter gene technique: A feasibility study

PURPOSE

The purpose of this study was to investigate the feasibility of in vivo imaging of human pancreatic ductal cells by OATP1B3 reporter gene under MRI.

METHODS

A human cell line (PANC-1) derived from the pancreatic ductal epithelium was used in this study. After transduction of OATP1B3, the cellular physiological functions and the ability of intracellular uptake of the MRI contrast medium (Gd-EOB-DTPA) were examined. Induced differentiation of the PANC-1 cells into hormone-secreting cells were performed to simulate pancreatic β-like cells. The hormone-secreting cells were implanted into rats and in vivo MRI was evaluated.

RESULTS

The mRNA and proteins of OATP1B3 were highly expressed. No significant change of cellular physiological functions was found after the expression. After induced differentiation, the hormone secretion capacities of the OATP1B3-expressing PANC-1 cells were confirmed. Intra-cellular uptake of Gd-EOB-DTPA was determined in vitro by inductively coupled plasma mass spectrometry and MRI. In vivo MRI of the OATP1B3-expressing xenograft revealed an increased signal intensity after contrast enhancement.

CONCLUSION

OATP1B3 can be used as a safe and feasible in vivo MRI gene reporter for human pancreatic ductal cells.

Aqueous extracts of Syzygium brazzavillense can inhibit the infection with coxsackievirus B4 in vitro

Traditional practitioners commonly use plant crude extracts to treat various diseases in patients with symptoms that can be seen during enterovirus infections. In this study, the antienteroviral activity of medicinal plants from the Republic of Congo has been evaluated in vitro. Through an ethnopharmacological approach, seven plants grouped into six families were identified. Aqueous and organic extracts of various organs from these plants were prepared. The organic extracts at subcytotoxic concentrations did not inhibit the cytopathic effect (CPE) induced by coxsackievirus (CV)B1-5, CVA6, poliovirus type 1, and enterovirus 71. The aqueous extract of Syzygium brazzavillense, but not those of other plants, inhibited the CPE induced by CVB3 and CVB4 at 30 µg/mL (CC₅₀ ; 2800 µg/mL, IC₅₀ ; 0.8 µg/mL) and by CVB2 and poliovirus type 1 at higher concentrations. When aqueous extract of this plant was mixed with CVB4, the replication of the virus was inhibited. In conclusion, aqueous extracts of Syzygium brazzavillense can inhibit the infection with CVB4 and other enteroviruses in vitro. The present ethnopharmacological investigation helped to identify a plant with potential properties useful to combat enterovirus infections.

Developing a vaccine for type 1 diabetes by targeting coxsackievirus B

INTRODUCTION

Virus infections have long been considered as a possible cause of type 1 diabetes (T1D). One virus group, enteroviruses (EVs), has been studied extensively, and clinical development of a vaccine against T1D-associated EV types has started.

AREAS COVERED

Epidemiological studies have indicated an association between EVs and T1D. These viruses have a strong tropism for insulin-producing β-cells; the destruction of these cells leads to T1D. The exact mechanisms by which EVs could cause T1D are not known, but direct infection of β-cells and virus-induced inflammation may play a role. Recent studies have narrowed down the epidemiological association to a subset of EVs: group B coxsackieviruses (CVBs). These findings have prompted efforts to develop vaccines against CVBs. Prototype CVB vaccines have prevented both infection and CVB-induced diabetes in mice. This review summarizes recent progress in the field and the specifics of what could constitute the first human vaccine developed for a chronic autoimmune disease.

EXPERT COMMENTARY

Manufacturing of a clinical CVB vaccine as well as preclinical studies are currently in progress in order to enable clinical testing of the first CVB vaccine. Ongoing scientific research projects can significantly facilitate this effort by providing insights into the mechanisms of the CVB-T1D association.

Understanding of type 1 diabetes mellitus: what we know and where we go

The incidence of type 1 diabetes mellitus (T1DM) in children and adolescents is increasing worldwide. Combined effects of genetic and environmental factors cause T1DM, which make it difficult to predict whether an individual will inherit the disease. Due to the level of self-care necessary in T1DM maintenance, it is crucial for pediatric settings to support achieving optimal glucose control, especially when adolescents are beginning to take more responsibility for their own health. Innovative insulin delivery systems, such as continuous subcutaneous insulin infusion (CSII), and noninvasive glucose monitoring systems, such as continuous glucose monitoring (CGM), allow patients with T1DM to achieve a normal and flexible lifestyle. However, there are still challenges in achieving optimal glucose control despite advanced technology in T1DM administration. In this article, disease prediction and current management of T1DM are reviewed with special emphasis on biomarkers of pancreatic β-cell stress, CSII, glucose monitoring, and several other adjunctive therapies.

Bioinformatics Assembling and Assessment of Novel Coxsackievirus B1 Genome

The human microbiome project via application of metagenomic next-generation sequencing techniques has found surprising large and diverse amounts of microbial sequences across different body sites. There is a wave of investigators studying autoimmune related diseases designing from birth case and control studies to elucidate microbial associations and potential direct triggers. Sequencing analysis, considered big data as it typically includes millions of reads, is challenging but particularly demanding and complex is virome profiling due to its lack of pan-viral genomic signature. Impressively thousands of virus complete genomes have been deposited and these high-quality references are core components of virus profiling pipelines and databases. Still it is commonly known that most viral sequences do not map to known viruses. Moreover human viruses, particularly RNA groups, are notoriously heterogeneous due to high mutation rates. Here, we present the related assembling challenges and a series of bioinformatics steps that were applied in the construction of the complete consensus genome of a novel clinical isolate of Coxsackievirus B1. We further demonstrate our effort in calling mutations between prototype Coxsackievirus B1 sequence from GenBank and serial clinical isolate genome grown in cell culture.

miRNAs in enterovirus infection

During the last years, it has become evident that miRNAs are important players in almost all physiological and pathological processes, including viral infections. Enterovirus infections range from mild to severe acute infections concerning several organ systems and are also associated with chronic diseases. In this review, we summarize the findings on the impact of acute and persistent enterovirus infection on the expression of cellular miRNAs. Furthermore, the currently available data on the regulation of cellular or viral targets by the dysregulated miRNAs are reviewed. Finally, a translational perspective, namely the use of miRNAs as biomarkers of enterovirus infection and as antiviral strategy is discussed.

Salivary anti-coxsackievirus-B4 neutralizing activity and pattern of immune parameters in patients with type 1 diabetes: a pilot study

AIMS

Enteroviruses, especially coxsackieviruses B (CV-B), have been associated with the pathogenesis of type 1 diabetes (T1D). An anti-CV-B4 neutralizing activity in saliva of T1D patients was previously reported. Our aim was to study the association between the saliva anti-CV-B4 neutralizing activity and immune parameters in T1D patients in comparison with non-diabetic individuals.

METHODS

Saliva and blood samples were collected from 15 T1D patients and 8 controls. The anti-CV-B4 and anti-poliovirus type 1 (PV-1) activities of saliva and serum samples were determined by a plaque neutralization assay. Quantification of serum cytokines was performed by ELISA and the frequencies of lymphocyte subsets were evaluated using flow cytometry.

RESULTS

The levels of salivary anti-CV-B4 neutralizing activity were higher in T1D patients than in controls (p = 0.02), whereas the serum levels of anti-CV-B4 neutralizing activity and the saliva and serum levels of anti-PV-1 neutralizing activity were not different. The proportions of effector CD4⁺ T cells and CD19⁺ B cells, but not those of CD4⁺ T cells, CD8⁺ T cells and Foxp3⁺ regulatory T cells, were higher in T1D patients than in controls (p = 0.02 and p = 0.01 respectively). Moreover, serum IFN-γ levels were lower in T1D patients compared to controls (p = 0.03) while IL-4 and IL-10 were not different. There was an association between saliva anti-CV-B4 activity, down-regulation of IFN-γ and B cell expansion in peripheral blood of T1D patients.

CONCLUSION

The association between saliva anti-CV-B4 activity and disturbance of immune system in T1D patients deserves further investigation.

A novel rat CVB1-VP1 monoclonal antibody 3A6 detects a broad range of enteroviruses

Enteroviruses (EVs) are common RNA viruses that cause diseases ranging from rash to paralytic poliomyelitis. For example, EV-A and EV-C viruses cause hand-foot and mouth disease and EV-B viruses cause encephalitis and myocarditis, which can result in severe morbidity and mortality. While new vaccines and treatments for EVs are under development, methods for studying and diagnosing EV infections are still limited and therefore new diagnostic tools are required. Our aim was to produce and characterize new antibodies that work in multiple applications and detect EVs in tissues and in vitro. Rats were immunized with Coxsackievirus B1 capsid protein VP1 and hybridomas were produced. Hybridoma clones were selected based on their reactivity in different immunoassays. The most promising clone, 3A6, was characterized and it performed well in multiple techniques including ELISA, immunoelectron microscopy, immunocyto- and histochemistry and in Western blotting, detecting EVs in infected cells and tissues. It recognized several EV-Bs and also the EV-C representative Poliovirus 3, making it a broad-spectrum EV specific antibody. The 3A6 rat monoclonal antibody can help to overcome some of the challenges faced with commonly used EV antibodies: it enables simultaneous use of mouse-derived antibodies in double staining and it is useful in murine models.

Persistent coxsackievirus B4 infection induces microRNA dysregulation in human pancreatic cells

Enterovirus infections are implicated in the development of type 1 diabetes (T1D). MicroRNAs as regulators of gene expression are involved in many physiological and pathological processes. Given that viral infections dysregulate cellular microRNAs, we investigated the impact of persistent coxsackievirus B4 infection on microRNA expression of human pancreatic cells. Next-generation sequencing was used to determine microRNA expression in PANC-1 cells persistently infected (for several weeks) with coxsackievirus B4 and uninfected control cells. Target prediction restricted to T1D risk genes was performed with miRWalk2.0. Functional annotation analysis was performed with DAVID6.7. Expression of selected microRNAs and T1D risk genes was measured by quantitative reverse-transcription polymerase chain reaction. Eighty-one microRNAs were dysregulated in persistently infected PANC-1 cells. Forty-nine of the known fifty-five T1D risk genes were predicted as putative targets of at least one of the dysregulated microRNAs. Most functional annotation terms that were enriched in these 49 putative target genes were related to the immune response or autoimmunity. mRNA levels of AFF3, BACH2, and IL7R differed significantly between persistently infected cells and uninfected cells. This is the first characterization of the microRNA expression profile changes induced by persistent coxsackievirus B4 infection in pancreatic cells. The predicted targeting of genes involved in the immune response and autoimmunity by the dysregulated microRNAs as well as the dysregulated expression of diabetes risk genes shows that persistent coxsackievirus B4 infection profoundly impacts the host cell. These data support the hypothesis of a possible link between persistent coxsackievirus B4 infection and the development of T1D.

Detection and localization of viral infection in the pancreas of patients with type 1 diabetes using short fluorescently-labelled oligonucleotide probes

Enteroviruses, specifically of the Coxsackie B virus family, have been implicated in triggering islet autoimmunity and type 1 diabetes, but their presence in pancreata of patients with diabetes has not been fully confirmed.

To detect the presence of very low copies of the virus genome in tissue samples from T1D patients, we designed a panel of fluorescently labeled oligonucleotide probes, each of 17-22 nucleotides in length with a unique sequence to specifically bind to the enteroviral genome of the picornaviridae family.

With these probes enteroviral RNA was detected with high sensitivity and specificity in infected cells and tissues, including in FFPE pancreas sections from patients with T1D. Detection was not impeded by variations in sample processing and storage thereby overcoming the potential limitations of fragmented RNA. Co-staining of small RNA probes in parallel with classical immunstaining enabled virus detection in a cell-specific manner and more sensitively than by viral protein.

Echovirus 6 Infects Human Exocrine and Endocrine Pancreatic Cells and Induces Pro-Inflammatory Innate Immune Response

Human enteroviruses (HEV), especially coxsackievirus serotype B (CVB) and echovirus (E), have been associated with diseases of both the exocrine and endocrine pancreas, but so far evidence on HEV infection in human pancreas has been reported only in islets and ductal cells. This study aimed to investigate the capability of echovirus strains to infect human exocrine and endocrine pancreatic cells. Infection of explanted human islets and exocrine cells with seven field strains of E6 caused cytopathic effect, virus titer increase and production of HEV protein VP1 in both cell types. Virus particles were found in islets and acinar cells infected with E6. No cytopathic effect or infectious progeny production was observed in exocrine cells exposed to the beta cell-tropic strains of E16 and E30. Endocrine cells responded to E6, E16 and E30 by upregulating the transcription of interferon-induced with helicase C domain 1 (IF1H1), 2′-5′-oligoadenylate synthetase 1 (OAS1), interferon-β (IFN-β), chemokine (C–X–C motif) ligand 10 (CXCL10) and chemokine (C–C motif) ligand 5 (CCL5). Echovirus 6, but not E16 or E30, led to increased transcription of these genes in exocrine cells. These data demonstrate for the first time that human exocrine cells represent a target for E6 infection and suggest that certain HEV serotypes can replicate in human pancreatic exocrine cells, while the pancreatic endocrine cells are permissive to a wider range of HEV.

Persistence of Coxsackievirus B4 in pancreatic ductal-like cells results in cellular and viral changes

INTRODUCTION

Although known as cytolytic viruses, group B coxackieviruses (CVB) are able to establish a persistent infection in vitro and in vivo. Viral persistence has been reported as a key mechanism in the pathogenesis of CVB-associated chronic diseases such as type 1 diabetes (T1D). The impact of CVB4 persistence on human pancreas ductal-like cells was investigated.

METHODS

A persistent CVB4 infection was established in ductal-like cells. PDX-1 expression, resistance to CVB4-induced lysis and CAR expression were evaluated. The profile of cellular microRNAs (miRNAs) was investigated through miRNA-sequencing. Viral phenotypic changes were examined, and genomic modifications were assessed by sequencing of the viral genome.

RESULTS

The CVB4 persistence in ductal-like cells was productive, with continuous release of infectious particles. Persistently infected cells displayed a resistance to CVB4-induced lysis upon superinfection and expression of PDX-1 and CAR was decreased. These changes were maintained even after virus clearance. The patterns of cellular miRNA expression in mock-infected and in CVB4-persistently infected ductal-like cells were clearly different. The persistent infection-derived virus (PIDV) was still able to induce cytopathic effect but its plaques were smaller than the parental virus. Several mutations appeared in various PIDV genome regions, but amino acid substitutions did not affect the predicted site of interaction with CAR.

CONCLUSION

Cellular and viral changes occur during persistent infection of human pancreas ductal-like cells with CVB4. The persistence of cellular changes even after virus clearance supports the hypothesis of a long-lasting impact of persistent CVB infection on the cells.

Environmental risk factors for type 1 diabetes

The incidence of type 1 diabetes has risen considerably in the past 30 years due to changes in the environment that have been only partially identified. In this Series paper, we critically discuss candidate triggers of islet autoimmunity and factors thought to promote progression from autoimmunity to overt type 1 diabetes. We revisit previously proposed hypotheses to explain the growth in the incidence of type 1 diabetes in light of current data. Finally, we suggest a unified model in which immune tolerance to β cells can be broken by several environmental exposures that induce generation of hybrid peptides acting as neoautoantigens.

Differential effects of three echovirus strains on cell lysis and insulin secretion in beta cell derived lines

In an earlier study, infection of human pancreatic islets with epidemic strains of echovirus (E4, E16, E30), with proven but differently ability to induce islet autoimmunity, resulted either in a severe damage (i.e., E16 and E30) or proceeded without visible changes in infected islets (i.e., E4). In this study, the ability of these strains to replicate in beta cells and the consequence of such an infection for beta cell lysis and beta cell function was studied in the pancreatic beta cell lines INS-1, MIN6, and NIT-1. The strains of E16 and E30 did replicate in INS1, MIN6, and NIT1 cells and resulted in a pronounced cytopathic effect within 3 days following infection. By contrast, E4 replicated in all examined insulinoma cells with no apparent cell destruction. The insulin release in response to high glucose stimulation was hampered in all infected cells (P < 0.05) when no evidence of cytolysis was present; however, the adverse effect of E16 and E30 on insulin secretion appeared to be higher than that of the E4 strain. The differential effects of echovirus infection on cell lysis, and beta cell function in the rodent insulinoma INS1, MIN6, and NIT 1 cells reflect those previously obtained in primary human islets and support the notion that the insulin-producing beta cells can harbor a non-cytopathic viral infection.

Monocytes of Patients with Type 1 Diabetes Harbour Enterovirus RNA

BACKGROUND

Intracellular enterovirus (EV) RNA was detected in blood of patients with type 1 diabetes (T1D). The presence of EV RNA in subsets of peripheral blood mononuclear cells (PBMCs) of patients, and the in vitro infection of these cells with an EV, was investigated.

MATERIALS AND METHODS

Blood was collected from 42 patients with T1D, PBMCs were isolated and monocytes were purified. Interferon alpha (IFNα) mRNA and EV RNA were investigated using RT-PCR. Levels of IFNα in plasma were measured using an immunoassay. Cells were inoculated with Coxsackievirus B4 (CBV4) in vitro, and infection was assessed by indirect immunofluorescence (IFI).

RESULTS

Interferon alpha mRNA was detected in blood and in monocytes of 12 of 42 patients with T1D, but not in monocyte-depleted PBMCs of the same individuals. Significant plasma levels of IFNα (≥ 5 IU/mL) were found in six patients. EV RNA was detected in whole blood and in monocytes of seven patients and negative-strand EV RNA was found in monocytes of 6 of them. When monocytes of patients with IFNα and/or EV RNA in their blood were inoculated with CVB4, the proportion of cells stained by an anti-VP1 antibody was 8.8 ± 1%, whereas no VP1 was detected in the monocytes of IFNα, EV RNA negative patients. Nevertheless, when CBV4 was mixed with plasma, VP1 was detected in monocytes of all patients with T1D (staining ranging from 12 to 36%).

CONCLUSIONS

Our data indicate that monocytes of patients with T1D can harbor EV RNA and IFNα mRNA and can be infected with an EV in vitro.

Application of bioinformatics in probe design enables detection of enteroviruses on different taxonomic levels by advanced in situ hybridization technology

BACKGROUND

Enteroviral infections are common, affecting humans across all age groups. RT-PCR is widely used to detect these viruses in clinical samples. However, there is a need for sensitive and specific in situ detection methods for formalin-fixed tissues, allowing for the anatomical localization of the virus and identification of its serotype.

OBJECTIVES

The aim was to design novel enterovirus probes, assess the impact of probe design for the detection and optimize the new single molecule in situ hybridization technology for the detection of enteroviruses in formalin-fixed paraffin-embedded samples.

STUDY DESIGN

Four enterovirus RNA-targeted oligonucleotide RNA probes - two probes for wide range enterovirus detection and two for serotype-targeted detection of Coxsackievirus B1 (CVB1) - were designed and validated for the commercially available QuantiGene ViewRNA in situ hybridization method. The probe specificities were tested using a panel of cell lines infected with different enterovirus serotypes and CVB infected mouse pancreata.

RESULTS

The two widely reactive probe sets recognized 19 and 20 of the 20 enterovirus serotypes tested, as well as 27 and 31 of the 31 CVB1 strains tested. The two CVB1 specific probe sets detected 30 and 14 of the 31 CVB1 strains, with only minor cross-reactivity to other serotypes. Similar results were observed in stained tissues from CVB -infected mice.

CONCLUSIONS

These novel in-house designed probe sets enable the detection of enteroviruses from formalin-fixed tissue samples. Optimization of probe sequences makes it possible to tailor the assay for the detection of enteroviruses on the serotype or species level.

Survival of Enveloped and Non-Enveloped Viruses on Inanimate Surfaces

In the present study, we evaluated the viability of non-enveloped viruses, minute virus of mice (MVM) and coxsackievirus B4 (CVB4), and enveloped-viruses, influenza A virus (H1N1) and herpes simplex virus type 1 (HSV-1), on surfaces. We also investigated the impact of the initial concentration of proteins and sodium chloride on the persistence of infectious CVB4 on surfaces. Viral suspensions (>10^4.5 TCID₅₀) were applied to petri dish lids and dried under the air flow of a biosafety cabinet. The recovered viral preparations were titered on appropriate cell lines. Enveloped viruses persisted for less than 5 days while CVB4 and MVM persisted for weeks. However, repetitive cycles of drying and resuspension had a stronger virucidal effect on CVB4 than on H1N1 and HSV-1. These repetitive cycles had no effect on the infectious titer of MVM. When exposed to drying, the initial concentrations of bovine serum albumin (from 0 to 90 mg mL⁻¹), fetal calf serum (from 0 to 100%), and sodium chloride (from 0 to 300 mg mL⁻¹) affected the viability of CVB4. CVB4 was more likely to be inactivated by drying in a protein-rich medium, whereas the impact of drying was reduced in the presence of sodium chloride. The results of the present study demonstrated that the resistance of viruses to drying, as suggested by iterative drying, was not due to the heterogeneity of viral subpopulations, but was influenced by media compositions and component concentrations, as illustrated in the model of CVB4.

Viral infection of engrafted human islets leads to diabetes

Type 1 diabetes (T1D) is characterized by the destruction of the insulin-producing β-cells of pancreatic islets. Genetic and environmental factors both contribute to T1D development. Viral infection with enteroviruses is a suspected trigger for T1D, but a causal role remains unproven and controversial. Studies in animals are problematic because of species-specific differences in host cell susceptibility and immune responses to candidate viral pathogens such as coxsackievirus B (CVB). In order to resolve the controversial role of viruses in human T1D, we developed a viral infection model in immunodeficient mice bearing human islet grafts. Hyperglycemia was induced in mice by specific ablation of native β-cells. Human islets, which are naturally susceptible to CVB infection, were transplanted to restore normoglycemia. Transplanted mice were infected with CVB4 and monitored for hyperglycemia. Forty-seven percent of CVB4-infected mice developed hyperglycemia. Human islet grafts from infected mice contained viral RNA, expressed viral protein, and had reduced insulin levels compared with grafts from uninfected mice. Human-specific gene expression profiles in grafts from infected mice revealed the induction of multiple interferon-stimulated genes. Thus, human islets can become severely dysfunctional with diminished insulin production after CVB infection of β-cells, resulting in diabetes.

Vaginal Lactobacillus gasseri CMUL57 can inhibit herpes simplex type 2 but not Coxsackievirus B4E2

This study aimed at demonstrating the antiviral activity of Lactobacillus gasseri CMUL57 (L. gasseri CMUL57), L. acidophilus CMUL67 and L. plantarum CMUL140 against herpes simplex type 2 (HSV-2) and Coxsackievirus B4E2 (CVB4E2), which are enveloped and naked viruses, respectively. These lactobacilli were non-cytotoxic and were able to reduce the cytopathic effect induced by HSV-2 in Vero cell monolayers. However, lactobacilli were not active against CVB4E2. Tested lactobacilli displayed anti-HSV-2 activity when they were co-incubated with the virus prior to inoculating the mixture to Vero cell monolayers. The detection of HSV-2 DNA by PCR in pellets of bacteria/virus mixtures let us to hypothesize that anti-HSV-2 activity of lactobacilli resulted from the viruses’ entrapment. This study showed the capabilities of vaginal lactobacilli to inhibit enveloped viruses such as HSV-2.

Persistent infection of human pancreatic cells with Coxsackievirus B4 is cured by fluoxetine

Group B Coxsackieviruses (CVB) are involved in various acute clinical features and they can play a role in the development of chronic diseases like type 1 diabetes. The persistence of CVB has been described in vitro and in vivo in various models. Fluoxetine was reported to inhibit the replication of CVB1-3, which prompted us to study the in vitro antiviral activity of fluoxetine against CVB4 in models of acute infection. In addition we took advantage of a chronically CVB4-infected Panc-1 cell line to evaluate the antiviral effect of fluoxetine in a model of persistent CVB4 infection. An inhibition of the CVB4 replication was obtained when fluoxetine was added at 5.48μM to Hep-2 cell cultures. No inhibitory effect was observed when CVB4 was mixed with fluoxetine for 2h and filtered to eliminate fluoxetine before inoculation to cells, or when cells were treated up to 96h and washed before viral inoculation. Fluoxetine (5.48μM) reduced viral replication by more than 50% in acutely infected Panc-1 cell cultures. A dramatic decrease of infectious particles levels in supernatants of Panc-1 cells chronically infected with CVB4 was obtained a few days after treatment with fluoxetine and no infectious viral particle was found as soon as day 21 of treatment, and intracellular enteroviral RNA was undetectable by RT-PCR after three weeks of treatment. These data display that fluoxetine can inhibit the replication of CVB4 and can cure Panc-1 cells chronically infected with CVB4.

Enteroviruses as causative agents in type 1 diabetes: loose ends or lost cause?

Considerable evidence implies that an enteroviral infection may accelerate or precipitate type 1 diabetes (T1D) in some individuals. However, causality is not proven. We present and critically assess evidence suggesting that islet β cells can become infected with enterovirus, and argue that this may result in one of several consequences. Occasionally, a fully lytic infection may arise and this culminates in fulminant diabetes. Alternatively, an atypical persistent infection develops which can be either benign or promote islet autoimmunity. We propose a model in which the 'strength' of the β cell response to the establishment of a persistent enteroviral infection determines the final disease outcome.

Use of the 5' untranslated region and VP1 region to examine the molecular diversity in enterovirus B species

Human enteroviruses evolve quickly. The 5' untranslated region (UTR) is fundamentally important for efficient viral replication and for virulence; the VP1 region correlates well with antigenic typing by neutralization, and can be used for virus identification and evolutionary studies. In order to investigate the molecular diversity in EV-B species, the 5' UTR and VP1 regions were analysed for 208 clinical isolates from a single public-health laboratory (serving New South Wales, Australia), representing 28 EV-B types. Sequences were compared with the 5' UTR and VP1 regions of 98 strains available in GenBank, representing the same 28 types. The genetic relationships were analysed using two types of software (mega and BioNumerics). The sequence analyses of the 5' UTR and VP1 regions of 306 EV-B strains demonstrated that: (i) comparing the two regions gives strong evidence of epidemiological linkage of strains in some serotypes; (ii) the intraserotypic genetic variation within each gene reveals that they evolve distinctly largely due to their different functions; and (iii) mutation and possible recombination in the two regions play significant roles in the molecular diversity of EV-B. Understanding the tempo and pattern of molecular diversity and evolution is of great importance in the pathogenesis of EV-B enteroviruses, information which will assist in disease prevention and control.