Complete nucleotide sequence of a strain of coxsackie B4 virus of human origin that induces diabetes in mice and its comparison with nondiabetogenic coxsackie B4 JBV strain

Preclinical models of diabetic wound healing: A critical review

The treatment of diabetic wounds (DWs) is always challenging for the medical community because of its multifaceted pathophysiology. Due to practical and ethical considerations, direct studies of therapeutic interventions on human subjects are limited. Thus, it is ideal for performing studies on animals having less genetic and biological variability. An ideal DW model should progress toward reproducibility, quantifiable interpretation, therapeutic significance, and effective translation into clinical use. In the last couple of decades, various animal models were developed to examine the complex cellular and biochemical process of skin restoration in DW healing. Also, these models were used to assess the potency of developed active pharmaceutical ingredients and formulations. However, many animal models lack studying mechanisms that can appropriately restate human DW, stay a huge translational challenge. This review discusses the available animal models with their significance in DW experiments and their limitations, focusing on levels of proof of effectiveness in selecting appropriate models to restate the human DW to improve clinical outcomes. Although numerous newer entities and combinatory formulations are very well appreciated preclinically for DW management, they fail in clinical trials, which may be due to improper selection of the appropriate model. The major future challenge could be developing a model that resembles the human DW environment, can potentiate translational research in DW care.

Variability in Disinfection Resistance between Currently Circulating Enterovirus B Serotypes and Strains

The susceptibility of waterborne viruses to disinfection is known to vary between viruses and even between closely related strains, yet the extent of this variation is not known. Here, different enteroviruses (six strains of coxsackievirus B5, two strains of coxsackievirus B4 and one strain of coxackievirus B1) were isolated from wastewater and inactivated by UV₂₅₄, sunlight, free chlorine (FC), chlorine dioxide (ClO₂), and heat. Inactivation kinetics of these isolates were compared with those of laboratory enterovirus strains (CVB5 Faulkner and echovirus 11 Gregory) and MS2 bacteriophage. FC exhibited the greatest (10-fold) variability in inactivation kinetics between different strains, whereas inactivation by UV₂₅₄ differed only subtly. The variability in inactivation kinetics was greater between serotypes than it was among the seven strains of the CVB5 serotype. MS2 was a conservative surrogate of enterovirus inactivation by UV₂₅₄, sunlight, or heat but frequently underestimated the disinfection requirements for FC and ClO₂. Similarly, laboratory strains did not always reflect the inactivation behavior of the environmental isolates. Overall, there was considerable variability in inactivation kinetics among and within enteroviruses serotypes, as well as between laboratory and environmental isolates. We therefore recommend that future disinfection studies include a variety of serotypes and environmental isolates.

Diabetic aggravation of stroke and animal models

Cerebral ischemia in diabetics results in severe brain damage. Different animal models of cerebral ischemia have been used to study the aggravation of ischemic brain damage in the diabetic condition. Since different disease conditions such as diabetes differently affect outcome following cerebral ischemia, the Stroke Therapy Academic Industry Roundtable (STAIR) guidelines recommends use of diseased animals for evaluating neuroprotective therapies targeted to reduce cerebral ischemic damage. The goal of this review is to discuss the technicalities and pros/cons of various animal models of cerebral ischemia currently being employed to study diabetes-related ischemic brain damage. The rational use of such animal systems in studying the disease condition may better help evaluate novel therapeutic approaches for diabetes related exacerbation of ischemic brain damage.

MicroRNAs in Type 1 Diabetes: Complex Interregulation of the Immune System, β Cell Function and Viral Infections

Since the discovery of the first mammalian microRNA (miRNA) more than two decades ago, a plethora of miRNAs has been identified in humans, now amounting to more than 2500. Essential for post-transcriptional regulation of gene networks integral for developmental pathways and immune response, it is not surprising that dysregulation of miRNAs is often associated with the aetiology of complex diseases including cancer, diabetes and autoimmune disorders. Despite massive expansion of small RNA studies and extensive investigation in diverse disease contexts, the role of miRNAs in type 1 diabetes has only recently been explored. Key studies using human islets have recently implicated virus-induced miRNA dysregulation as a pivotal mechanism of β cell destruction, while the interplay between miRNAs, the immune system and β cell survival has been illustrated in studies using animal and cellular models of disease. The role of specific miRNAs as major players in immune system homeostasis highlights their exciting potential as therapeutics and prognostic biomarkers of type 1 diabetes.

Molecular docking study and antiviral evaluation of 2-thioxo-benzo[g]quinazolin-4(3H)-one derivatives

BACKGROUND

The persistent appearance of viral strains that causes a resistant viral infection has led to continuous trials for the design and development of novel antiviral compounds. Benzoquinazoline compounds have been reported to exhibit an interesting antiviral activity. This work aims to study and evaluate the antiviral activity of a newly prepared 2-thioxo-benzo[g]quinazolin-4(3H)-one series against herpes simplex (HSV-1 & 2) and coxsackievirus (CVB4).

METHODS

The antiviral activity was performed using the MTT assay, in which Vero cells (obtained from the American Type Culture Collection, ATCC) were propagated in fresh Dulbecco's Modified Eagle's Medium (DMEM) and challenged with 10(4) doses of the virus. Thereafter, the cultures were treated simultaneously with two-fold serial dilutions of the tested compound and incubated at 37 °C for 48 h. Molecular docking studies were done on the CVB4 2A proteinase enzyme using Molegro Virtual Docker software.

RESULTS

The cytotoxicity (CC50), effective concentration (EC50) and the selectivity index (SI) values were determined. Based on their EC50 values, a number of the investigated compounds demonstrated weak to moderate activity relative to their parents. Accordingly, compounds 5-9, 11, 15-18, 21, 22, 24, 25, 27 and 28 were active against CVB4, and compounds 5 and 24 were active against HSV-1 and 2 in comparison to ribavirin and acyclovir, which were used as reference drugs.

CONCLUSION

The obtained results gave us some useful insights about the characteristic requirements for future trials to build up and design more active and selective antiviral 2-thioxo-benzo[g]quinazolin-4(3H)-one agents.Graphical abstractCompound 24 superimposed with Ribavirin in CV B4 2A Proteinase enzyme (PDB: 1Z8R) active site.

Enterovirus infection of human islets of Langerhans affects β-cell function resulting in disintegrated islets, decreased glucose stimulated insulin secretion and loss of Golgi structure

AIMS/HYPOTHESIS

In type 1 diabetes (T1D), most insulin-producing β cells are destroyed, but the trigger is unknown. One of the possible triggers is a virus infection and the aim of this study was to test if enterovirus infection affects glucose stimulated insulin secretion and the effect of virus replication on cellular macromolecules and organelles involved in insulin secretion.

METHODS

Isolated human islets were infected with different strains of coxsackievirus B (CVB) virus and the glucose-stimulated insulin release (GSIS) was measured in a dynamic perifusion system. Classical morphological electron microscopy, large-scale electron microscopy, so-called nanotomy, and immunohistochemistry were used to study to what extent virus-infected β cells contained insulin, and real-time PCR was used to analyze virus induced changes of islet specific genes.

RESULTS

In islets infected with CVB, GSIS was reduced in correlation with the degree of virus-induced islet disintegration. The expression of the gene encoding insulin was decreased in infected islets, whereas the expression of glucagon was not affected. Also, in islets that were somewhat disintegrated, there were uninfected β cells. Ultrastructural analysis revealed that virus particles and virus replication complexes were only present in β cells. There was a significant number of insulin granules remaining in the virus-infected β cells, despite decreased expression of insulin mRNA. In addition, no typical Golgi apparatus was detected in these cells. Exposure of islets to synthetic dsRNA potentiated glucose-stimulated insulin secretion.

CONCLUSIONS/INTERPRETATION

Glucose-stimulated insulin secretion; organelles involved in insulin secretion and gene expression were all affected by CVB replication in β cells.

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.

Viruses contained in droplets applied on warmed surface are rapidly inactivated

Heat inactivation of viruses was reported, however, the thermal resistance of viruses in droplets has not been studied. The aim of this study was to evaluate the pattern of heat resistance of minute virus of mice (MVM), coxsackievirus B4 (CVB4), influenza A virus (H1N1), and herpes simplex virus type 1 (HSV1) contained in droplets. Four μL droplets containing viruses (> 10(4.5) TCID50) were applied onto warmed surface obtained by using a self-made heating device. Viral suspensions were exposed to temperatures ranging from 70 to 130°C for 0 to 90 min depending on the virus, and then the recovered viral preparations were tittered. Inactivation rates were calculated from curves that were analysed according to the first order kinetics model. Full inactivation was obtained for MVM in 90 min at 80°C and in 2 s at 130°C, for H1N1 in 14 s at 70°C and in 1 s at 110°C, for CVB4 and HSV-1 in 5 s and 7 s respectively at 70°C and in 1 s at 100°C. Clearly, MVM was more resistant than H1N1 that was more resistant than HSV-1 and CVB4, which was reflected by increasing inactivation rates. The impact of short time exposure to heat onto the infectivity of viruses contained in a small volume of suspension has been determined. For the first time, the inactivation of viral particles contained in drops exposed to temperatures higher than 100°C has been investigated. It appears that heating can have an unexpected faster virucidal effect than previously described.

Inactivation of coxsackievirus B4, feline calicivirus and herpes simplex virus type 1: unexpected virucidal effect of a disinfectant on a non-enveloped virus applied onto a surface

OBJECTIVE

To evaluate the effect of a disinfectant onto viruses in suspension on the one hand and applied onto a surface on the other.

METHODS

A system combining flocked swabs to recover viruses dried onto stainless steel carriers and gel filtration to eliminate cytotoxic products has been developed to study the virucidal effect of a quaternary ammonium-based disinfectant towards herpes simplex virus type 1 (HSV-1), coxsackievirus B4 (CVB4) and feline calicivirus F9 (FCV). The recovery of FCV has been estimated by RT real-time PCR.

RESULTS

HSV-1, CVB4 and FCV had a titer over 10(4) TCID50 · ml(-1) after 2 h drying and were recovered from the carriers using flocked swabs. HSV-1 was inactivated in suspension and on stainless steel carriers by the disinfectant (a reduction factor of 4 and 2.83 log, respectively) whereas CVB4 was resistant. The reduction of infectious titer was moderate, 1.5 log in 30 min, when FCV was in suspension, whereas it was up to 4 log in 10 min when the virus was dried on a carrier. Dried FCV was efficiently recovered from carriers as demonstrated by RT real-time PCR.

CONCLUSION

A non-enveloped virus, FCV, applied on a surface, but not in suspension, was inactivated by a quaternary ammonium-based disinfectant. The resistance of viruses applied onto a surface to the effect of disinfectants should be investigated further.

Viruses and type 1 diabetes: a new look at an old story

Epidemiological data suggesting an infectious origin of diabetes pre-date the discovery of insulin; indeed it was the variation in mortality rates from diabetes that led Gunderson to hypothesise that a virus with 'selective affinity for the pancreas' may cause 'acute diabetes' in youth (1). He noted an increase in deaths from diabetes in young people aged 10-20 yr in Norway from 1900 to 1921 following epidemics of parotitis, with a lag time of 3-4 yr between infection and death. In Norway, Denmark,France, and America, the increase in deaths from diabetes exceeded the expected number based on population growth; lending further weight to the proposal that diabetes was caused by infection. Since that time,a large body of epidemiological, clinical and experimental research, in humans, cellular and animal models, has provided further insights into the contribution of infections in the development of type 1 diabetes.Epidemiological evidence for a viral aetiology of diabetes A substantial body of epidemiological data point to a significant contribution of the environment in the development of type 1 diabetes,although much of the evidence is not specific to viruses per se. These data include rising rates of type 1 diabetes in both developed and developing countries in recent decades (2, 3) and a reduced contribution of high risk human leucocyte antigen (HLA) genotypes (4, 5), indicating that non-genetic factors are important. Similarly, the pairwise concordance between monozygotic twins for type 1 diabetes of less than 40%, and the observation that the incidence of diabetes in migrant children reflects that of their adopted country (6, 7), provide circumstantial evidence that environmental agents contribute to the disease. Space-time clustering in the presentation of type 1 diabetes (8-10) and clustering of births in children who subsequently develop diabetes (11) support a direct role for infections in the initiation and acceleration of the disease process.

The use of animal models in diabetes research

Diabetes is a disease characterized by a relative or absolute lack of insulin, leading to hyperglycaemia. There are two main types of diabetes: type 1 diabetes and type 2 diabetes. Type 1 diabetes is due to an autoimmune destruction of the insulin-producing pancreatic beta cells, and type 2 diabetes is caused by insulin resistance coupled by a failure of the beta cell to compensate. Animal models for type 1 diabetes range from animals with spontaneously developing autoimmune diabetes to chemical ablation of the pancreatic beta cells. Type 2 diabetes is modelled in both obese and non-obese animal models with varying degrees of insulin resistance and beta cell failure. This review outlines some of the models currently used in diabetes research. In addition, the use of transgenic and knock-out mouse models is discussed. Ideally, more than one animal model should be used to represent the diversity seen in human diabetic patients.

Pharmacological and biological antiviral therapeutics for cardiac coxsackievirus infections

Subtype B coxsackieviruses (CVB) represent the most commonly identified infectious agents associated with acute and chronic myocarditis, with CVB3 being the most common variant. Damage to the heart is induced both directly by virally mediated cell destruction and indirectly due to the immune and autoimmune processes reacting to virus infection. This review addresses antiviral therapeutics for cardiac coxsackievirus infections discovered over the last 25 years. One group represents pharmacologically active low molecular weight substances that inhibit virus uptake by binding to the virus capsid (e.g., pleconaril) or inactivate viral proteins (e.g., NO-metoprolol and ribavirin) or inhibit cellular proteins which are essential for viral replication (e.g., ubiquitination inhibitors). A second important group of substances are interferons. They have antiviral but also immunomodulating activities. The third and most recently discovered group includes biological and cellular therapeutics. Soluble receptor analogues (e.g., sCAR-Fc) bind to the virus capsid and block virus uptake. Small interfering RNAs, short hairpin RNAs and antisense oligonucleotides bind to and led to degradation of the viral RNA genome or cellular RNAs, thereby preventing their translation and viral replication. Most recently mesenchymal stem cell transplantation has been shown to possess antiviral activity in CVB3 infections. Taken together, a number of antiviral therapeutics has been developed for the treatment of myocardial CVB infection in recent years. In addition to low molecular weight inhibitors, biological therapeutics have become promising anti-viral agents.

Virus infections and type 1 diabetes risk

Common intestinal infections caused by human enteroviruses (HEVs) are considered major environmental factors predisposing to type 1 diabetes (T1D). In spite of the active research of the field, the HEV-induced pathogenetic processes are poorly understood. Recently, after the first documented report on HEV infections in the pancreatic islets of deceased T1D patients, several groups became interested in the issue and studied valuable human material, the autopsy pancreases of diabetic and/or autoantibody-positive patients for HEV infections. In this review, the data on HEV infections in human pancreatic islets are discussed with special reference to the methods used. Likewise, mechanisms that could increase viral access to the pancreas are reviewed and discussed.

Enteroviruses, type 1 diabetes and hygiene: a complex relationship

Type 1 diabetes (T1D) is an autoimmune disease in which the immune system mounts an attack on the host's insulin‐producing β cells. Because most cases of T1D cannot be attributed only to individual genetics, it is strongly inferred that there is a significant environmental contribution, such as infection, impacting disease development. The human enteroviruses (HEV) are common picornaviruses often implicated as triggers of human T1D, although precisely which of the numerous HEV may be involved in human T1D development is unknown. Experiments using non‐obese diabetic (NOD) mice, commonly used to model T1D, show that induction of T1D by HEV infection in NOD mice is a multifactorial process involving both the virus and the host. Interestingly, results demonstrate that HEV infection of NOD mice can also induce long‐term protection from T1D under certain conditions, suggesting that a similar mechanism may occur in humans. Based upon both experimental animal and observational human studies, we postulate that HEV have a dual role in T1D development and can either cause or prevent autoimmune disease. Whichever outcome occurs depends upon multiple variables in the host‐virus equation, many of which can be deduced from results obtained from NOD mouse studies. We propose that the background to the sharply rising T1D incidences observed in the 20th century correlates with increased levels of hygiene in human societies. Viewing T1D in this perspective suggests that potential preventative options could be developed. Copyright © 2009 John Wiley & Sons, Ltd.

An enterovirus strain isolated from diabetic child belongs to a genetic subcluster of echovirus 11, but is also neutralised with monotypic antisera to coxsackievirus A9

An enterovirus strain (designated D207) isolated from a Slovakian diabetic child and originally serotyped as coxsackievirus A9 (CAV-9) was found to cause rapid cytolysis coinciding with severe functional damage of the surviving cells in primary cultures of human pancreatic islets. This finding prompted us to clone the isolate for full-length genome sequencing and molecular characterization as the prototype strain of CAV-9 is known to cause only minimal damage to insulin-producing β-cells. Based on capsid-coding sequence comparisons, the isolate turned out to be echovirus 11 (E-11). Phylogenetic analyses demonstrated that E-11/D207 was closely related to a specific subgroup B of E-11 strains known to cause uveitis. To study further antigenic properties of isolate E-11/D207 and uveitis-causing E-11 strains, neutralization experiments were carried out with CAV-9- and E-11-specific antisera. Unlike the prototype strains, the isolate E-11/D207 and uveitis-causing E-11 strains were well neutralized with both CAV-9- and E-11-specific antisera. Attempts to identify recombination of the capsid coding sequences as a reason for double-reactivity using the Simplot analysis failed to reveal major transferred motifs. However, peptide scanning technique was able to identify antigenic regions of capsid proteins of E-11/D207 as well as regions cross-reacting with an antiserum raised to CAV-9. Thus, double specificity of E-11/D207 seems to be a real characteristic shared by the phylogenetically closely related virus strains in the genetic subgroup B of E-11.

Complete nucleotide sequence of a coxsackievirus B4 strain that establishes infection in ICR mice pancreas and induces glucose intolerance

Some coxsackievirus B serotypes are potentially diabetogenic. Previous studies revealed that the virulence and the tissue damage varied with the genetics of the virus strain as well as with the genetics of the mice. A single amino acid variation can alter virulence and tropism in both murine and in vitro models. However, the genetic determinants of this phenomenon have not been determined. In this study, infections with a laboratory strain of coxsackievirus B4 resulted in a diabetes-like syndrome in ICR mice, characterized by chronic pancreatic inflammation together with dysregulation in glucose metabolism, loss of pancreatic acinar tissue and persistent infection in islets. To characterize the genetic determinants involved in the mouse pancreas adaptation, the laboratory strain of coxsackievirus B4 was cloned for molecular characterization. Comparing the whole genome sequence of this virus strain with the other coxsackievirus B4 strains revealed some differences. Altogether 15 nucleotides were changed, resulting in 10 amino acid substitutions, which might be responsible for the pathogenic phenotype of this strain in mice.

Group B coxsackievirus diabetogenic phenotype correlates with replication efficiency

Group B coxsackieviruses can initiate rapid onset type 1 diabetes (T1D) in old nonobese diabetic (NOD) mice. Inoculating high doses of poorly pathogenic CVB3/GA per mouse initiated rapid onset T1D. Viral protein was detectable in islets shortly after inoculation in association with beta cells as well as other primary islet cell types. The virulent strain CVB3/28 replicated to higher titers more rapidly than CVB3/GA in the pancreas and in established beta cell cultures. Exchange of 5'-nontranslated regions between the two CVB3 strains demonstrated a variable impact on replication in beta cell cultures and suppression of in vivo replication for both strains. While any CVB strain may be able to induce T1D in prediabetic NOD mice, T1D onset is linked both to the viral replication rate and infectious dose.

Molecular analysis of an echovirus 3 strain isolated from an individual concurrently with appearance of islet cell and IA-2 autoantibodies

Growing evidence has implicated members of the genus Enterovirus of the family Picornaviridae in the etiology of some cases of type 1 diabetes (T1D). To contribute to an understanding of the molecular determinants underlying this association, we determined the complete nucleotide sequence of a strain of echovirus 3 (E3), Human enterovirus B (HEV-B) species, isolated from an individual who soon after virus isolation developed autoantibodies characteristic of T1D. The individual has remained positive for over 6 years for tyrosine phosphatase-related IA-2 protein autoantibodies and islet cell autoantibodies, indicating an ongoing autoimmune process, although he has not yet developed clinical T1D. The sequence obtained adds weight to the observation that recent enterovirus isolates differ significantly from prototype strains and provides further evidence of a role for recombination in enterovirus evolution. In common with most HEV-B species members, the isolate exhibits 2C and VP1 sequences suggested as triggers of autoimmunity through molecular mimicry. However, comparisons with the E3 prototype strain and previously reported diabetogenic and nondiabetogenic HEV-B strains do not reveal clear candidates for sequence features of PicoBank/DM1/E3 that could be associated with autoantibody appearance. This is the first time a virus strain isolated at the time of commencement of beta-cell damage has been analyzed and is an invaluable addition to enterovirus strains isolated previously at the onset of T1D in the search for specific molecular features which could be associated with diabetes induction.

HLA Class II molecules on haplotypes associated with type 1 diabetes exhibit similar patterns of binding affinities for coxsackievirus P2C peptides

Enteroviruses such as coxsackievirus B4 (CVB4) are proposed as possible environmental triggers or accelerants of the autoimmune process that leads to type 1 diabetes mellitus. One putative mechanism to account for this association is mimicry between virus components and islet autoantigens. Particular interest has focused on the CVB4 non-structural protein P2C, which we previously showed to be a major target of the effector memory anti-CVB4 CD4 T-cell response, and which harbours a region of sequence similarity with the islet autoantigen, glutamic acid decarboxylase (GAD65). Since several distinct human leucocyte antigen (HLA) Class II molecules are associated with development of type 1 diabetes, we hypothesized that for functional mimicry to be important, any potential region(s) of mimicry in P2C should bind to each of these susceptibility molecules. In the present study therefore we examined the affinity of 20-mer overlapping P2C peptides for soluble HLA-DR4, -DR3, -DQ2 and -DQ8. We identified one discrete region of P2C with high binding affinities for all of these HLA Class II molecules. Moreover, the binding affinity of P2C peptides was significantly correlated between HLA molecules present on the same susceptibility haplotype (e.g. DR4 and DQ8, P =0.0076; DR3 and DQ2 P = 0.002). We conclude that possession of these haplotypes favours restricted presentation of viral epitopes, and speculate that this could promote the potential for mimicry between microbial proteins and islet autoantigens.

Enterovirus RNA sequences in sera of schoolchildren in the general population and their association with type 1-diabetes-associated autoantibodies

Type 1 diabetes (T1D) is an autoimmune disease linked with genetic factors as well as with environmental triggers, such as virus infections, but the aetiology is still unclear. The authors analysed serum from autoantibody-positive (n=50) and autoantibody-negative (n=50) schoolchildren as well as children newly diagnosed with T1D (n=47; time from diagnosis, median 5 days, interquartile range 1-12 days) for the presence and frequency of enterovirus (EV) and adenovirus sequences. The autoantibody-positive and -negative groups were part of the Karlsburg Type 1 Diabetes Risk Study of a Normal Schoolchild Population, which represents a general population without T1D first-degree relatives. There was no significant seasonality of sampling in any of the three groups investigated. EV RNA sequences were detected in 10 of 50 (20%) autoantibody-positive children and in 17 of 47 (36%) children newly diagnosed with T1D, but only in two of 50 (4%) of the age- and sex-matched controls (P<0.05, P<0.001). Characterization of the EV amplicons by direct sequencing revealed high homology with coxsackievirus B group. For adenovirus we found no data to support an association with T1D. The data support the hypothesis that different enteroviruses may be aetiologically important as a trigger and/or accelerating factor in the process of T1D development.

Tissue tropism of recombinant coxsackieviruses in an adult mouse model

Recombinant viruses, constructed by exchanging the 5′ non-coding region (5′NCR), structural and non-structural protein coding sequences were used to investigate determinants responsible for differences between coxsackievirus A9 (CAV9) and coxsackievirus B3 (CBV3) infections in adult mice and two cell lines. Plaque assay titration of recombinant and parental viruses from different tissues from adult BALB/c mice demonstrated that the structural region of CBV3 determined tropism to the liver tissue due to receptor recognition, and the 5′NCR of CBV3 enhanced viral multiplication in the mouse pancreas. Infection with a chimeric virus, containing the structural region from CBV3 and the rest of the genome from CAV9, and the parental CBV3 strain, caused high levels of viraemia in adult mice. The ability of these viruses to infect the central nervous system suggested that neurotropism is associated with high replication levels and the presence of the CBV3 capsid proteins, which also enhanced formation of neutralizing antibodies. Moreover, the appearance of neutralizing antibodies correlated directly with the clearance of the viruses from the tissues. These results demonstrate potential pathogenicity of intraspecies recombinant coxsackieviruses, and the complexity of the genetic determinants underlying tissue tropism.

Simultaneous type 1 diabetes onset in mother and son coincident with an enteroviral infection

Enterovirus (EV) infections have been implicated in the development of type 1 diabetes. (T1D). They may cause beta-cell destruction either by cytolytic infection of the cells or indirectly by triggering the autoimmune response. Virus was isolated from a woman at diagnosis of T1D (Tuvemo 1) and in addition, virus was isolated from her son at diagnosis of T1D at the same day (Tuvemo 2). None of the isolates could initially be serotyped by conventional methods. The Tuvemo 1 virus was genotyped and after sub-cultivation it was also serotyped as Coxsackievirus B5. The mother revealed antibodies against GAD65. The boy and the father both revealed a significant increase in neutralization antibody titre against two strains of CBV-4, clearly indicating a recent or ongoing EV infection. In addition, the brother showed such a titre rise against another CBV-4 strain (E2) and against a CBV-5 strain (4429). These results show that the whole family had a proven EV infection at the time of T1D diagnosis of the mother and the 10-years-old boy, indicating that the infection might cause or accelerate the T1D.

Identification of a naturally processed cytotoxic CD8 T-cell epitope of coxsackievirus B4, presented by HLA-A2.1 and located in the PEVKEK region of the P2C nonstructural protein

The adaptive immune system generates CD8 cytotoxic T lymphocytes (CTLs) as a major component of the protective response against viruses. Knowledge regarding the nature of the peptide sequences presented by HLA class I molecules and recognized by CTLs is thus important for understanding host-pathogen interactions. In this study, we focused on identification of a CTL epitope generated from coxsackievirus B4 (CVB4), a member of the enterovirus group responsible for several inflammatory diseases in humans and often implicated in the triggering and/or acceleration of the autoimmune disease type 1 diabetes. We identified a 9-mer peptide epitope that can be generated from the P2C nonstructural protein of CVB4 (P2C(1137-1145)) and from whole virus by antigen-presenting cells and presented by HLA-A2.1. This epitope is recognized by effector memory (gamma interferon [IFN-gamma]-producing) CD8 T cells in the peripheral blood at a frequency of responders that suggests that it is a major focus of the anti-CVB4 response. Short-term CD8 T-cell lines generated against P2C(1137-1145) are cytotoxic against peptide-loaded target cells. Of particular interest, the epitope lies within a region of viral homology with the diabetes-related autoantigen, glutamic acid decarboxylase-65 (GAD(65)). However, P2C(1137-1145)-specific cytotoxic T lymphocyte (CTL) lines were not activated to produce IFN-gamma by the GAD(65) peptide homologue and did not show cytotoxic activity in the presence of appropriately labeled targets. These results describe the first CD8 T-cell epitope of CVB4 that will prove useful in the study of CVB4-associated disease.

Enterovirus infections with beta-cell tropic strains are frequent in siblings of children diagnosed with type 1 diabetes children and in association with elevated levels of GAD65 antibodies

Enterovirus infections have been associated with type 1 diabetes in a number of reports. Recent prospective studies have suggested that enterovirus infections initiate the autoimmune process. Variation in virulence and replication pattern between strains of a serotype has also been shown. The aim was to study if there were specific Coxsackievirus strains that were associated more often with the type 1 diabetes children than with controls and/or siblings and to analyse if there was any time-relationship between such infections and the appearance of antibodies against glutamic acid decarboxylase 65 (GAD65). In the present study, serum was tested from newly diagnosed type 1 diabetes children, their siblings and matched controls for neutralising antibodies against different strains of Coxsackievirus B (CBV). Tests for the presence of antibodies against GAD65 in the same groups were also carried out. Newly diagnosed type 1 diabetes children revealed higher titres of neutralising antibodies against a strain of Coxsackievirus B4 (CBV-4, VD2921) that has been shown to cause persistent infection in human pancreatic islet cells. The type 1 diabetes child and its sibling often encountered the same infection. Among the former, 16 of 27 (59%) had a significant rise in neutralising antibodies. Eight of the type 1 diabetes children had such a rise against a recombinant strain, V89 4557. Among the siblings 10 of 13 (77%) had significant titre increases. Among the type 1 diabetes children, increasing neutralising titres was associated positively with increasing antibody levels against GAD65. All siblings with antibodies against GAD 65 had significant titre increase against any of the CBV strains.

Interferon alpha--a potential link in the pathogenesis of viral-induced type 1 diabetes and autoimmunity

The incidence of type 1 diabetes has been rapidly rising. Environmental factors such as viruses have been implicated as a possible agent accounting for this rise. Enteroviruses have recently been the focus in many research studies as a potential agent in the pathogenesis of type 1 diabetes. The mechanism of viral infection leading to beta cell destruction not only involves multiple pathways but also the cytokine-interferon alpha (IFN-alpha). Our hypothesis is that activation of toll receptors by double-stranded RNA or poly-IC (viral mimic) through induction of IFN-alpha may activate or accelerate immune-mediated beta cell destruction. Numerous clinical case reports have implicated that IFN-alpha therapy is associated with autoimmune diseases and that elevated serum IFN-alpha levels have been associated with type 1 diabetes. In multiple animal models, given specific genetic susceptibility, poly-IC can induce insulitis or diabetes. Therapeutic agents targeting IFN-alpha may potentially be beneficial in the prevention of type 1 diabetes and autoimmunity.

Effect of p38 mitogen-activated protein kinase on the replication of encephalomyocarditis virus

Cellular phosphorylation events during viral infection are necessary for effective viral replication. Encephalomyocarditis (EMC) virus has been used for studies on the molecular mechanisms of viral replication, but little is known about the cellular signaling pathways involved. This investigation was initiated to determine whether mitogen-activated protein kinases (MAPKs), which are central components of signal transduction pathways in the regulation of cell proliferation, play a role in the replication of EMC virus. We examined the phosphorylation of MAPKs, including extracellular signal-regulated kinase (ERK1/2), p38 MAPK, and stress-activated protein kinase 1/c-Jun NH(2)-terminal kinase (SAPK/JNK) in EMC virus-infected L929 cells and found that p38 MAPK and SAPK-JNK, but not ERK1/2, were activated during viral infection. We then examined the effect of these kinases on the replication of EMC virus in L929 cells by using specific inhibitors, including genistein or herbimycin A for tyrosine kinase, SB203580 or SB202190 for p38 MAPK, and PD98059 for ERK1/2. We found that the tyrosine kinase and p38 MAPK inhibitors, but not the ERK1/2 inhibitor, suppressed viral replication and that the inhibitory effect was primarily on viral protein synthesis. Finally, we examined whether p38 MAPK is involved in the translation of EMC viral transcripts by using L929 cells transfected with a gene construct containing the internal ribosomal entry site (IRES) of EMC virus and a luciferase reporter gene. We found that the p38 MAPK inhibitor suppressed the translation of EMC viral RNA. On the basis of these observations, we conclude that p38 MAPK plays a critical role in the replication of EMC virus, probably in the translation of viral RNA.

Evolution of the genome of Human enterovirus B: incongruence between phylogenies of the VP1 and 3CD regions indicates frequent recombination within the species

Enteroviruses show a high degree of sequence variation both between and within serotypes due to the lack of proofreading of the viral RNA-dependent RNA polymerase. In addition, recombination is known to occur not only within but also between different serotypes. We have previously shown that capsid coding sequences of coxsackievirus B4 (CVB4) cluster in several coexisting genotypes (intergenotypic nucleotide difference of 12 % or more) whereas a single lineage of echovirus 30 (EV30) has been prevailing and evolving throughout the last two decades. In the major capsid gene, VP1, clustering of both nucleotide and amino acid sequences correlates with serotype. We have now determined a 501 nucleotide sequence in the non-structural 3CD region of CVB4 and EV30 field strains. Phylogenetic analysis revealed that sequences of Human enterovirus B (HEV-B) were segregated in the 3CD region into three distinct clusters without the VP1-associated serotype/genotype correlation. One of the clusters comprised the E2 strain of CVB4, the EV30 prototype and five other CVB4 field strains whereas the other two clusters, in addition to CVB4 and EV30 strains, also included other HEV-B serotypes. We believe that intertypic recombination is the most likely explanation for the observed incongruence. Similarity analysis based on complete genomes of the CVB4 and EV30 prototypes and the CVB4 E2 strain revealed that a putative recombination spot was mapped within the 2B gene. The incongruence observed in the two genomic domains (P1 and P3) suggests a certain degree of independent evolution, which may be explained by interserotypic recombination within an enterovirus species. It is thus difficult to exclude recombination in the history of any given strain.

A new look at viruses in type 1 diabetes

Type 1 diabetes (T1D) results from the destruction of pancreatic beta cells. Genetic factors are believed to be a major component for the development of T1D, but the concordance rate for the development of diabetes in identical twins is only about 40%, suggesting that nongenetic factors play an important role in the expression of the disease. Viruses are one environmental factor that is implicated in the pathogenesis of T1D. To date, 14 different viruses have been reported to be associated with the development of T1D in humans and animal models. Viruses may be involved in the pathogenesis of T1D in at least two distinct ways: by inducing beta cell-specific autoimmunity, with or without infection of the beta cells, [e.g. Kilham rat virus (KRV)] and by cytolytic infection and destruction of the beta cells (e.g. encephalomyocarditis virus in mice). With respect to virus-mediated autoimmunity, retrovirus, reovirus, KRV, bovine viral diarrhoea-mucosal disease virus, mumps virus, rubella virus, cytomegalovirus and Epstein-Barr virus (EBV) are discussed. With respect to the destruction of beta cells by cytolytic infection, encephalomyocarditis virus, mengovirus and Coxsackie B viruses are discussed. In addition, a review of transgenic animal models for virus-induced autoimmune diabetes is included, particularly with regard to lymphocytic choriomeningitis virus, influenza viral proteins and the Epstein-Barr viral receptor. Finally, the prevention of autoimmune diabetes by infection of viruses such as lymphocytic choriomeningitis virus is discussed.

Enterovirus RNA is found in peripheral blood mononuclear cells in a majority of type 1 diabetic children at onset

We have studied the occurrence of enterovirus (EV)-RNA at the onset of childhood type 1 diabetes in all 24 new cases of childhood type 1 diabetes during 1 year in Uppsala county, Sweden. We also studied 24 matched control subjects and 20 siblings of the patients. RNA was isolated from peripheral blood mononuclear cells and EV-RNA detected by RT-PCR. Primers (groups A and B) corresponding to conserved regions in the 5' noncoding region (NCR) of EV were used in the PCRs, and the amplicons were sequenced. By the use of group A primers, EV-RNA was found in 12 (50%) of the 24 type 1 diabetic children, 5 (26%) of 19 siblings, and none of the control subjects. Both patients and siblings showed a higher frequency of EV-RNA compared with the control subjects. The group B primers detected EV-RNA in all three groups but did not show statistically significant differences between the groups. The EV-RNA positivity with the group B primers was 11 (46%) of 24 in the type 1 diabetic children, 11 (58%) of 19 in the siblings, and 7 (29%) of 24 in the control subjects. The significant difference between groups seen with the group A primers but not with the group B primers might indicate the existence of diabetogenic EV strains. The phylogenetic analysis of the PCR products revealed clustering of the sequences from patients and siblings into five major branches when the group A PCR primers were used. With the group B primers, the sequences from patients, siblings, and control subjects formed three major branches in the phylogenetic tree, where 6 of the 7 control subjects clustered together in a sub-branch of CBV-4/VD2921. Seven of the type 1 diabetic children clustered together in another sub-branch of CBV-4/VD2921. Five of the type 1 diabetic children formed a branch together with the CBV-4/E2 strain, four clustered together with CBV-5, and one formed a branch with echovirus serotype. The presence of EV-RNA in the blood cells of most newly diagnosed type 1 diabetic children supports the hypothesis that a viral infection acts as an exogenous factor. In addition, sequencing of the PCR amplicons from the type 1 diabetic children, their siblings, and matched control subjects might reveal differences related to diabetogenic properties of such a virus.

Characterization of the T-cell response to coxsackievirus B4: evidence that effector memory cells predominate in patients with type 1 diabetes

Most of the evidence linking enterovirus (EV) infection with the development and/or acceleration of type 1 diabetes is indirect. Few studies have examined T-cell responses to these viruses, and therefore the nature of the viral targets and the immune cells involved in antiviral responses remain unclear. In the present study, we examined the characteristics of the T-cell response to the EV Coxsackievirus B4 (CVB4) in patients with type 1 diabetes and healthy control subjects. We find that CVB4-specific T-cells preferentially target the envelope proteins VP1, VP2, and VP3, and that the response to these and other CVB4 proteins differs markedly in type 1 diabetic patients compared with nondiabetic control subjects. The frequency of T-cell proliferative responses against VP2 was significantly reduced in type 1 diabetic patients compared with control subjects, especially in patients tested near to diagnosis (P < 0.001). In contrast, median levels of gamma-interferon (IFN-gamma) production by T-cells in response to the CVB4 antigens tested were generally high in new-onset type 1 diabetic patients, who produced significantly higher levels in response to VP3 compared with healthy subjects (P < 0.05) and patients with long-standing disease (P < 0.05). New-onset type 1 diabetic patients also had higher levels in response to P2C compared with healthy subjects (P < 0.005) and to VP2 compared with patients with long-standing disease (P < 0.05). These results suggest that the quality of the immune response to CVB4 antigens differs significantly between type 1 diabetic patients and control subjects, with a predominance of primed effector (IFN-gamma-producing) memory cells near to disease diagnosis. The data are consistent with the notion that the diagnosis of type 1 diabetes is associated with recent or persistent exposure to EV antigens.

The group B coxsackieviruses and myocarditis

The six serotypes of the group B coxsackieviruses (CVB) are common human enteroviruses linked etiologically to inflammatory cardiomyopathies. This has been demonstrated by molecular detection of enteroviral RNA in human heart tissue, serologic associations with disease, and virus isolation from cases of fulminant myocarditis. The murine model of CVB-associated myocarditis has demonstrated that CVB can be attenuated through mutations at different genomic sites. Human CVB3 isolates demonstrate varying degrees of cardiovirulence in the murine model; one site of virulence determination has been mapped to domain II of the 5' non-translated region. The interplay of CVB replication and the immune response to that replication in the heart is a complex interaction determining the extent to which the virus replication is limited and the degree to which a pathogenic inflammation of cardiac muscle occurs. Studies of CVB3-induced myocarditis in murine strains lacking subsets of the immune system or genes regulating the immune response have demonstrated a pivotal role of the T cell response to the generation of myocarditis. While CVB are associated with 20-25% of cases of myocarditis or cardiomyopathy, the severity of the disease and the existence of attenuated strains shown to generate protective immunity in animal models indicates that vaccination against the CVBs would be valuable.

Using recombinant coxsackievirus B3 to evaluate the induction and protective efficacy of CD8+ T cells during picornavirus infection

Coxsackievirus B3 (CVB3) is a common human pathogen that has been associated with serious diseases including myocarditis and pancreatitis. To better understand the effect of cytotoxic T-lymphocyte (CTL) responses in controlling CVB3 infection, we have inserted well-characterized CTL epitopes into the CVB3 genome. Constructs were made by placing the epitope of interest upstream of the open reading frame encoding the CVB3 polyprotein, separated by a poly-glycine linker and an artificial 3Cpro/3CDpro cleavage site. This strategy results in the foreign protein being translated at the amino- terminus of the viral polyprotein, from which it is cleaved prior to viral assembly. In this study, we cloned major histocompatibility complex class I-restricted CTL epitopes from lymphocytic choriomeningitis virus (LCMV) into recombinant CVB3 (rCVB3). In vitro, rCVB3 growth kinetics showed a 1- to 2-h lag period before exponential growth was initiated, and peak titers were approximately 1 log unit lower than for wild-type virus. rCVB3 replicated to high titers in vivo and caused severe pancreatitis but minimal myocarditis. Despite the high virus titers, rCVB3 infection of naive mice failed to induce a strong CD8+ T-cell response to the encoded epitope; this has implications for the proposed role of "cross-priming" during virus infection and for the utility of recombinant picornaviruses as vaccine vectors. In contrast, rCVB3 infection of LCMV-immune mice resulted in direct ex vivo cytotoxic activity against target cells coated with the epitope peptide, demonstrating that the rCVB3-encoded LCMV-specific epitope was expressed and presented in vivo. The preexisting CD8+ memory T cells could limit rCVB replication; compared to naive mice, infection of LCMV-immune mice with rCVB3 resulted in approximately 50-fold-lower virus titers in the heart and approximately 6-fold-lower virus titers in the pancreas. Although the inserted CTL epitope was retained by rCVB3 through several passages in tissue culture, it was lost in an organ-specific manner in vivo; a substantial proportion of viruses from the pancreas retained the insert, compared to only 0 to 1.8% of myocardial viruses. Together, these results show that expression of heterologous viral proteins by recombinant CVB3 provides a useful model for determining the mechanisms underlying the immune response to this viral pathogen.

T-Cell reactivity to the P2C nonstructural protein of a diabetogenic strain of coxsackievirus B4

Enteroviruses are proposed as initiating factors in the etiology of Type 1 diabetes mellitus (Type 1 DM). Molecular mimicry between the autoantigen glutamic acid decarboxylase 65 (GAD65) and the coxsackievirus B4 (CVB4) nonstructural protein P2C is frequently cited as a mechanism by which this virus triggers the disease, but little is known about the immunogenicity of this viral protein in humans, mainly due to the problem of obtaining highly pure preparations of P2C. We generated large amounts of highly pure, soluble P2C protein, coupled to the fusion partner maltose binding protein (MBP-P2C) using the PMAL-c2 bacterial expression plasmid and a two-step purification system comprising amylose resin and ion exchange. Using purified viral protein we show that specific T-cell responses against P2C are detected in the blood of healthy donors and Type 1 DM patients. Proliferation responses to P2C were detected only in subjects also demonstrating T-cell proliferation to CVB4 Vero cell lysates. However, in additional cases T-cell responses to P2C were detectable through the release of interferon-gamma or interleukin-4 in individuals who did not make proliferative responses. Taken together, our data show that the P2C nonstructural protein of CVB4 is targeted by T cells during the antiviral immune response and may trigger the production of T helper 1 and T helper 2 cytokines. The availability of pure, immunogenic P2C should allow the putative role of antiviral responses in the development of autoimmune diabetes to be investigated.

Molecular epidemiology of coxsackievirus B4 and disclosure of the correct VP1/2A(pro) cleavage site: evidence for high genomic diversity and long-term endemicity of distinct genotypes

Genetic diversity among 107 coxsackievirus B4 field isolates has been studied. These isolates included clinical and environmental isolates originating from Finland, the Netherlands and France, and also from several other countries, including the USA. Three genomic regions were used for phylogenetic analyses: the VP1/2A junction, the entire VP1 and the VP4/VP2 region. Alignment of the deduced amino acid sequence in the VP1/2A junction revealed extensive sequence variation at the previously proposed cleavage site. MS analysis of proteolytic fragments from VP1 revealed that the exact cleavage site is situated between amino acid residues Thr-849 and Gly-850. At least seven distinct genetic lineages, or genotypes, had been circulating in Europe during the period 1959-1998. Two genotypes were endemic in the Netherlands during most of the investigated period. Genetically closely related strains could be found in different countries, and different genotypes co-circulated at the same time in a given country. Clustering patterns were identical in the three genomic intervals. In the VP4/VP2 region, the intraserotypic variation approached interserotype variation. Sequence comparisons of the entire VP1 gene gave a reliable genetic identification of enterovirus serotype. It is suggested that, for genotype classification of previously serotyped coxsackievirus B4 isolates, comparison of VP1/2A sequences is sufficient, but for more detailed investigation of genetic relationships, and for 'genetic serotyping', the entire VP1 gene should be used. The VP4/VP2 region is less reliable for genetic serotyping and genotyping, although the primers are able to amplify many different serotypes.

Enterovirus variants in the serum of children at the onset of Type 1 diabetes mellitus

AIMS

This study was designed to assess further the possible links between enterovirus infection and Type 1 diabetes mellitus (DM).

METHODS

Sera from 110 children in the age range 0-15 years was obtained shortly after the diagnosis of Type 1 DM, in paediatric centres throughout the UK. They were tested for the presence of enteroviral sequences by the polymerase chain reaction (PCR) of the 5' nontranslated region (5' NTR). One hundred and eighty-two controls tested were matched for age, geographical location and time of year.

RESULTS

A significantly greater number of diabetic children (27% vs. 4.9%, P <0.005) had evidence of enteroviral RNA sequences. Proportionally, more younger children were enterovirus PCR positive, thus eight out of 20 children aged < or =2 years were enterovirus PCR positive. Sequence analysis showed that there was considerable variation in the sequences detected, although all appeared to be of the coxsackie/echovirus type.

CONCLUSION

This study re-emphasizes that a link exists between enteroviral infection and the onset of Type 1 DM, particularly at a very early age, and suggests that these viruses are aetiologically important in diabetes in a significant proportion of children.

Genetics, Pathogenesis and Evolution of Picornaviruses

The discovery of viruses heralded an exciting new era for research in the medical and biological sciences. It has been realized that the cellular receptor guiding a virus to a target cell cannot be the sole determinant of a virus's pathogenic potential. Comparative analyses of the structures of genomes and their products have placed the picornaviruses into a large “picorna-like” virus family, in which they occupy a prominent place. Most human picornavirus infections are self-limiting, yet the enormously high rate of picornavirus infections in the human population can lead to a significant incidence of disease complications that may be permanently debilitating or even fatal. Picornaviruses employ one of the simplest imaginable genetic systems: they consist of single-stranded RNA that encodes only a single multidomain polypeptide, the polyprotein. The RNA is packaged into a small, rigid, naked, and icosahedral virion whose proteins are unmodified except for a myristate at the N-termini of VP4. The RNA itself does not contain modified bases. The key to ultimately understanding picornaviruses may be to rationalize the huge amount of information about these viruses from the perspective of evolution. It is possible that the replicative apparatus of picornaviruses originated in the precellular world and was subsequently refined in the course of thousands of generations in a slowly evolving environment. Picornaviruses cultivated the art of adaptation, which has allowed them to “jump” into new niches offered in the biological world.

Several different enterovirus serotypes can be associated with prediabetic autoimmune episodes and onset of overt IDDM. Childhood Diabetes in Finland (DiMe) Study Group

In a prospective multicentre study described previously on prediabetic events in siblings of index cases with insulin-dependent diabetes mellitus, 31 children developed clinical diabetes during the observation period and 51 children seroconverted for islet cell antibodies or insulin autoantibodies. By using nonserotype specific EIA and RIA, it has shown recently that enterovirus infections in both groups were frequently associated with increases of islet cell antibody and/or insulin autoantibody titres. Serum specimens sequentially collected from 12 children during the prediabetic period were still available and were then tested for serotype-specific neutralizing antibodies. Plaque-neutralization assays were carried out for coxsackievirus A9, coxsackievirus B types 1 to 6, and echovirus types 1 and 11. An unequivocal monotypic increase in neutralizing antibodies was observed on seven occasions in six children, on one occasion with coxsackievirus A9, one with coxsackievirus B1, two with coxsackievirus B2, two with coxsackievirus B3, and one with coxsackievirus B5. In four patients, the infection was associated temporally with increases in the levels of islet cell antibodies, insulin autoantibodies and/or antibodies to glutamic acid decarboxylase, and in three other patients, it coincided with the clinical onset of insulin-dependent diabetes mellitus. These results suggest that the association of enterovirus infections with insulin-dependent diabetes mellitus is not restricted to serotype 4 of coxsackie B viruses suspected previously, but that several different serotypes might play a role in the pathogenesis of the disease.

Idiopathic dilated cardiomyopathy: a superantigen-driven autoimmune disease

BACKGROUND

Many cases of idiopathic dilated cardiomyopathy (IDC) result from an inflammatory myocarditis. The specific immunological mechanisms are not yet defined. Various autoimmune diseases are associated with superantigen-triggered immune responses, resulting in massive T-cell activation and tissue damage. We studied 3 cases in a search for evidence that such a phenomenon is also implicated in IDC.

METHODS AND RESULTS

Myocardial, lymph node, and thymic tissue samples were obtained from IDC patients who were undergoing heart transplantation. Infiltrating immune-cell phenotypes and gene expression of T-cell receptor (TCR) alpha- and beta-chain variable (Valpha and Vbeta) regions were analyzed by immunostaining and polymerase chain reaction. Similar technical approaches were used to assay the tissues for the presence of coxsackievirus B (CVB). In all the specimens analyzed, an overexpression of the TCR Vbeta3, Vbeta7, and Vbeta13.1 gene families was detected among the infiltrating T cells. These tissues were also found to be CVB3-positive. In vitro exposure of peripheral blood mononuclear cells to lysates of cells infected with CVB3 was capable of stimulating expansion of the same TCR Vbeta families. The TCR Valpha repertoire was never found to be skewed.

CONCLUSIONS

A superantigen-mediated immune response is involved in human heart disease. CVB3 may directly or indirectly trigger this response, suggesting a possible mechanistic link between CVB infection and myocarditis development progressing to IDC.

Nucleotide sequence of an attenuated mutant of coxsackievirus B3 compared with the cardiovirulent wildtype: assessment of candidate mutations by analysis of a revertant to cardiovirulence

BACKGROUND

Coxsackievirus B3 (CVB3) causes myocarditis in the SWR (H2q) mouse model and persistence of CVB3 in myocardium disposes to the development of dilated cardiomyopathy. An attenuated strain of CVB3 has been isolated, sequenced and several candidate mutations for attenuation identified. Derivation of a revertant to cardiovirulence allows the significance of these mutations to be assessed.

OBJECTIVES

To ascertain which candidate mutation(s) determine(s) the attenuated phenotype.

STUDY DESIGN

A revertant to cardiovirulence was isolated following passage through severe combined immunodeficient disease (SCID) mouse heart. The 5'-non-translated region (NTR) and region coding for capsid proteins were sequenced and compared to the wildtype and attenuant.

RESULTS

There are five candidates for attenuation: (1) A-G at base 580 in the 5'-NTR; (2) A-T at base 690 in the 5'-NTR; (3) CG-GC at bases 1401/2 (Thr to Ser at amino acid 151 in VP2); (4) AA-GT at bases 2691/2 (Lys to Ser at amino acid 80 in VP1); (5) A-G at base 2916 (Asp to Gly at amino acid 155 in VP1). It was shown previously that mutations at 580, 690 and 2691/2 are not important in attenuation. Additionally, there are three novel mutations in the coding region of the revertant and one in the 5'-NTR which are unlikely to be relevant for attenuation as they are not present in the attenuant. Of nucleotide changes seen at 1401/2 and 2916 in the attenuant, only 2916 reverts to the wildtype sequence and so is a strong candidate for a determinant of attenuation.

Coxsackie B virus infection and beta cell autoantibodies in newly diagnosed IDDM adult patients

BACKGROUND

Environmental agents such as viruses have been identified as potentially important determinants of insulin-dependent diabetes mellitus (IDDM). Enterovirus infections, Coxsackievirus B especially, could be linked to the beta cell damaging process and to the onset of clinical IDDM.

OBJECTIVES

Enteroviral (EV) infection and beta cell autoimmunity were studied in adult patients at the onset of IDDM.

STUDY DESIGN

A total of 14 newly diagnosed-IDDM patients with ketosis or ketoacidosis were compared to, anteriorly diagnosed IDDM patients with metabolic decompensation, non-IDDM patients with metabolic decompensation and healthy adults. EV infection was studied by genomic RNA detection in whole blood using a RT-PCR assay. In order to assess the level of beta cell autoantibodies at the time of the initial metabolic decompensation, serum specimens from IDDM patients were tested for GAD65 antibodies and islet cell antibodies (ICAs).

RESULTS

Coxsackie B3 or B4 virus genome was detected and genotyped in five of 14 (35.7) newly diagnosed IDDM patients and in one of 12 (8%) patients in the course of IDDM. By contrast, none of the 12 non-IDDM patients and none of the 15 healthy adults was positive for enterovirus RNA detection in whole blood. Positive GAD65 antibodies and ICAs assays were not significantly correlated to a positive EV-RNA detection.

CONCLUSION

The present study demonstrates that Coxsackie B virus RNA sequences can be detected in the peripheral blood from adult patients at the onset or in the course of IDDM and suggests that a Coxsackie B virus infection could initiate or accelerate beta cell autoimmune damaging process.

Molecular epidemiology of enteroviruses with special reference to their potential role in the etiology of insulin-dependent diabetes mellitus (IDDM). A review

BACKGROUND

Several lines of evidence suggest that enterovirus infections may be involved in the etiology of the insulin-dependent diabetes mellitus (IDDM). Often in the literature, a reference is given to specifically diabetogenic strains of enterovirus but there is no systematic assessment about the generation of such strains in the course of evolution or about their abundance among the 64 enterovirus serotypes pathogenic to man. If enteroviruses truly are involved in the etiology of IDDM, a possibility to prevent the disease with enterovirus vaccines might become feasible. In such a situation it would be important to know which serotypes and strains are the most important ones, and whether there would be differences between the strains as regards the pathogenetic mechanisms involved.

OBJECTIVE

To present a brief summary of the basic biology of enteroviruses, on existing data of genetic variation of enteroviruses, and on molecular epidemiology of human enteroviruses with special reference to the different epidemiological modes of their putative involvement in the pathogenesis of IDDM.

CONCLUSIONS

Like RNA viruses in general, enteroviruses exist as a quasispecies, a mixture of genetic microvariants with a vast potential to adapt to new environments. This means that specifically beta cell-tropic and potentially diabetogenic variants could, in theory, emerge sporadically during systemic infection of any individual. The patterns of genetic diversification of enteroviruses, cocirculation of separate genetic lineages in the human populations, and the assumed geographical restrictions of endemic transmission of the lineages, allow one to hypothesize that populations with a high persisting IDDM incidence might be endemically infected by some specific strains of enteroviruses. However, so far, there is no systematically collected data supporting this hypothesis.

Genetic divergence among the group B coxsackieviruses

As documented in the preceding discussion, the noncoding regions, and in particular the 5' NTR, of the CVB are tolerant of a substantial degree of nucleotide diversity while still being capable of fulfilling the life cycle requirements for these viruses. While diversity among the CVB is observed in the sequences encoding for the capsid proteins, it tends to involve predominantly those regions coding for amino acids located at the surface of the virus and not those responsible for the structural integrity of the mature virion, i.e., beta-barrels and alpha-helices. It is these capsid surface differences that define the six serotypes of the CVB and subdivide them antigenically into strains. Additionally, these proteins most likely play the major role in determining host and cellular tropism. The most conserved of the CVB proteins and, therefore those with the least diversity in their coding sequences, appear to be the nonstructural proteins. Perhaps, as speculated earlier, it is a conformational requirement imposed by the necessity to interact with host or viral substrates that maintains the high degree of amino acid identity of this group of viral proteins.

A short history and introductory background on the coxsackieviruses of group B

The past 50 years have revealed an array of significant developments in our documentation and understanding of viruses and their associated diseases. The CVB, as enteroviruses, were discovered in the search for poliomyelitis-related viruses by the inoculation of newborn mice. Future strategies for the discovery of additional viruses will undoubtedly come through the application of differentiating cell culture systems with increased susceptibility to infection by specific viruses. Developments in regulation of the cell cycle also will contribute to the better definition of events controlling persistent infections caused by the CVB. Methods utilizing molecular biological probes in situ will prove to be major aids in identifying the molecular events in CVB pathogenesis. Virology of the CVB continues to be an exciting area for research and application of preventive measures to lesson human suffering. The chapters in this book which follow will amplify most of the themes briefly presented here.

Coxsackieviruses and diabetes

Insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease whose etiology is complex. Both genetic susceptibility, which is polygenic, and environmental factors, including virus infections, appear to be involved in the development of IDDM. In this review, we have tried to balance the discussion of diabetes by examining both immunological and virological perspectives. Several mouse models, including viral and non-viral models, have been used to study diabetes. For this review, we include lessons gleaned from the non-obese diabetic (NOD) mouse and from mouse models of coxsackievirus- and encephalomyocarditis-virus-induced diabetes. Finally, we present a multi-stage model in which several viral infections, including the coxsackieviruses, are postulated to play a role in the autoimmune destruction of pancreatic beta cells.

Detection of coxsackie B virus RNA sequences in whole blood samples from adult patients at the onset of type I diabetes mellitus

Enteroviruses may be linked to insulin-dependent diabetes mellitus (IDDM). The prevalence of enteroviral (EV) infection at onset of adult IDDM was investigated by detection of specific EV sequences in peripheral blood using a reverse transcription and a seminested polymerase chain reaction (seminested RT-PCR). EDTA-treated whole blood samples taken from 12 newly diagnosed IDDM patients with ketosis or ketoacidosis were examined. The comparison groups were 12 adult patients suffering from metabolic decompensation in the course of IDDM, 12 adult patients with decompensated non-IDDM, and 15 healthy adults without any presumed EV infection or metabolic disease. EV genome was detected in five of 12 (42%) newly diagnosed IDDM patients and in one of 12 (8%) patients in the course of IDDM. By contrast, none of the 12 non-IDDM patients and none of the 15 healthy adults had EV sequences in whole blood. Subsequent sequencing of the EV PCR products from the six positive patients showed a significant homology with Coxsackie B3 or B4 viruses, and some common patterns were observed among the sequences. The present study demonstrates that Coxsackie B virus RNA sequences can be detected in peripheral blood from patients at the onset or in the course of IDDM and provides evidence for a role for enteroviruses in adult type I diabetes.