Enterovirus RNA Research Articles

Inflammation and Increased Myxovirus Resistance Protein A Expression in Thyroid Tissue in the Early Stages of Hashimoto's Thyroiditis

The role of viruses as environmental triggers for Hashimoto's thyroiditis (HT) is controversial. Thyroid epithelial cells express a variety of molecules involved in antiviral responses. This study combined histological, immunological, and virological tests to describe changes in tissue from patients with newly diagnosed and untreated HT. To study the early events, patients with positive thyroid peroxidase antibodies (TPO-Ab) and normal thyroid function were also included. This stage was defined as "prethyroiditis." Thyroid tissue was collected from 47 patients with high titers of TPO-Ab and from 24 controls. Seventeen patients had prethyroiditis, 17 had subclinical hypothyroidism, and 13 had overt hypothyroidism. The interferon (IFN)-α/β-inducible myxovirus resistance protein 1 (myxovirus resistance protein A; MxA) was used as a surrogate marker for type I IFN expression. Inflammation, expression of MxA, and the presence of the enteroviralcapsid protein (VP1) were characterized by immunohistochemistry. The presence of enterovirus (EV) RNA was examined by in situ hybridization. The density of CD4+ T cells was increased in all three patient groups, while CD8+ T cells were increased only in patients with overt hypothyroidism. The density of plasma cells increased as the disease progressed. The density of plasmacytoid dendritic cells and the expression of MxA were significantly increased in all patient groups compared with controls (p<0.01). EV RNA was present in 11% of HT patients, but in none of the control subjects, whereas the enteroviral protein was detected in 19% and 16%, respectively. The inflammatory reaction in the thyroid gland is a very early event in the pathogenesis of HT. The increased expression of MxA in the inflamed tissue suggests that type I IFN plays a role in disease development. Whether this is virus-dependent needs to be explored in further studies.

Is alcoholic pancreatitis associated with enteroviral infection?

To investigate whether enteroviral infection might trigger acute pancreatitis in patients made susceptible due to high alcohol consumption. Patients with alcohol-induced acute pancreatitis were analyzed for signs of simultaneous or preceding enteroviral infection. We studied the serum samples of 40 patients hospitalized for alcohol-induced acute pancreatitis and 40 controls recruited from an alcohol detoxification center. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect enterovirus RNA and diagnose acute viremia. Immunoglobulin G (IgG), immunoglobulin A (IgA) and immunoglobulin M (IgM) enteroviral antibodies were measured using enzyme immunoassay to detect subacute and previous infections. The samples were considered positive when the antibody titers were ≥ 15 IU. Furthermore, using RT-PCR, we studied pancreatic biopsy samples obtained during surgery from nine patients with chronic pancreatitis, one patient with acute pancreatitis and ten control patients with pancreatic carcinoma for evidence of persisting enteroviral RNA in the pancreatic tissue. No enterovirus RNA indicating acute viremia was detected by RT-PCR in the serum samples of any patient or control. A high incidence of positive antibody titers was observed in both study groups: IgM antibodies had positive titers in 5/40 (13%) vs 4/40 (10%), P = 0.723; IgG in 15/40 (38%) vs 19/40 (48%), P = 0.366; and IgA in 25/40 (63%) vs 33/40 (83%), P = 0.045, patients and controls, respectively. Ten (25%) patients had severe pancreatitis and two (5%) required treatment in intensive care. The median length of hospitalization was 7 d (range: 3-47 d). The severity of acute pancreatitis or the length of hospitalization was not associated with enteroviral IgM, IgG or IgA antibodies. Five pancreatic biopsy samples tested positive with RT-PCR, three (8%) in the control group and two (5%) in the patient group (P = 0.64). The rate of enteroviral infection is not increased in patients with alcohol-induced acute pancreatitis when compared to alcoholics with similar high alcohol use.

Detection of enterovirus in the thyroid tissue of patients with graves' disease

The etiology and pathogenesis of Graves' disease (GD) are still unknown, although it is thought that both genetic and environmental factors are important. Some indirect evidence implies that a viral infection may be a possible etiologic factor in autoimmunity. The main objective of this study was to examine direct evidence of the presence of enteroviruses (EVs) in the thyroid tissue of patients with GD. Thyroid tissue from 22 patients with newly diagnosed GD was obtained by core needle biopsy, while tissue from 24 patients with chronic GD and 24 control subjects without any autoimmune thyroid diseases was collected during neck surgery. Formalin-fixed, paraffin-embedded thyroid tissue samples were examined for the presence of enterovirus capsid protein using immunohistochemistry and for enterovirus RNA using in situ hybridization. Enterovirus capsid protein was detected in 17 (37%) patients and in 4 (17%) control subjects (P = 0.103). Enterovirus RNA was identified in thyroid tissue from nine (20%) patients, but in none of the control subjects (P = 0.016). Eight (90%) of the nine virus RNA positive patients were also positive for enterovirus protein. This is the first study to analyze thyroid tissue for EVs, including patients with untreated, newly diagnosed GD. The results suggest that EVs are more frequently present in thyroid tissue of patients than controls. Further studies are indicated to explore this association to find out if a low-grade chronic enteroviral infection might be involved in the pathogenesis of GD and if this could offer new therapeutic and preventive opportunities.

Hemolytic Uremic Syndrome Caused by Enteroviral Infection

A 4-year-old boy presented with enteroviral infection complicated with atypical hemolytic uremic syndrome (aHUS). Enterovirus RNA was detected by reverse transcription polymerase chain reaction (RT-PCR) of both blood and kidney biopsy specimens. A survey of the complement system did not reveal a specific complement defect. Supportive therapy with blood components transfusion, plasma therapy, and immunosuppressants was administered, however, renal function did not recover. The results of this report demonstrate that the enterovirus is the cause of aHUS.

Enterovirus RNA in Peripheral Blood May Be Associated with the Variants of rs1990760, a Common Type 1 Diabetes Associated Polymorphism in IFIH1

ObjectivePolymorphisms in the IFIH1 (common rs1990760 and four rare rs35667974, rs35337543, rs35744605, rs35732034) have been convincingly associated with type 1 diabetes. The encoded protein (interferon-induced helicase C domain-containing protein 1) senses double-stranded RNA during replication of Picornavirales, including Enterovirus, a genus suspected in the etiology of type 1 diabetes. We therefore investigated whether the polymorphisms are associated with differences in the frequency of enterovirus RNA in blood.Research Design and MethodsThe study included 1001 blood samples, each from a child participating in the Norwegian ‘Environmental Triggers of Type 1 Diabetes: the MIDIA study’. The enterovirus RNA was tested using qualitative semi-nested real-time reverse transcriptase PCR on RNA extracted from frozen cell packs after removal of plasma. Stool samples previously analyzed for enterovirus RNA were available in 417 children.ResultsThe genotypes of IFIH1 rs1990760 were associated with different frequencies of enterovirus RNA in blood (7.0%, 14.4% and 9.5% bloods were enterovirus positive among children carrying the Ala/Ala, Ala/Thr and Thr/Thr genotypes, respectively, p = 0.012). This association remained essentially unchanged after adjustment for age and calendar year. The presence of enterovirus in the concomitantly sampled stool further increased the likelihood of enterovirus RNA in blood (odds ratio 2.40, CI 95% 1.13–4.70), but did not affect the association with IFIH1 rs1990760. The rare polymorphisms (individually, or pooled) were not significantly associated with enterovirus RNA in blood.ConclusionsThe common IFIH1 SNP may modify the frequency of enterovirus RNA in blood of healthy children. This effect can help explain the association of IFIH1 with type 1 diabetes.

Molecular identification of enteroviruses associated with aseptic meningitis in children from India

We identified and characterized enteroviruses associated with aseptic meningitis in children between April 2009 and March 2010. Enterovirus RNA was detected in 51 (45.5 %) of 112 CSF samples. Molecular typing by RT-PCR and sequencing of a partial VP1 region revealed the predominance of echovirus (ECV) 32 (n = 20), followed by ECV 11 (n = 10), ECV 13 and ECV 14 (n = 5 each), coxsackievirus (CV) B3 and CV B6 (n = 3 each), CV A2, CV A10 and ECV 30 (n = 1 each). Phylogenetic analysis of ECV 32 showed 0 to 4 % sequence divergence among strains of the present study and 20-23 % from the prototype Puerto Rico strain at the nucleotide level. This is the first report of ECV 32 associated with an aseptic meningitis epidemic and identification of seven different enterovirus serotypes (CV A2, CV A10, CV B3, CV B6, ECV 13, ECV 14 and ECV 32) in meningitis cases from India.

An optimized method for elution of enteroviral RNA from a cellulose-based substrate

The Flinders Technology Australia (FTA) Elute Card is a commercial product that facilitates the collection, transport, archiving and processing of nucleic acids from a wide variety of biological samples at room temperature. While the cards have been designed so that sterile/deionized water can elute DNA easily, they are not suitable for some less stable RNAs. This study was undertaken to determine the optimal conditions such as the buffer type, buffer pH and incubation temperature for the elution of enteroviral RNA from FTA Elute Cards prior to quantitative analysis using real-time PCR (qPCR) or consensus degenerate hybrid oligonucleotide primer VP1 RT-semi nested PCR (CODEHOP VP1 RT-snPCR). TE-1 (pH 8.0), rather than sterile water, was the best buffer for high efficiency elution of enteroviral RNA at 95°C. However, as the estimated recovery rate of viral RNA eluted from the cards averaged to be only 6.1%, enterovirus assays using FTA elution should be considered qualitative, especially at low virus titers, and therefore the results of the assay should be interpreted carefully.

Enteroviral Central Nervous System Infections in Children of the Region of Monastir, Tunisia: Diagnosis, Laboratory Findings of Cerebrospinal Fluid and Clinical Manifestations

Human enteroviruses (HEV) are one of the major causes of central nervous system (CNS) infections in pediatrics. A prospective study was conducted to assess the epidemiological, clinical, and laboratory characteristics of enterovirus (EV) infections of the CNS in children under 15-years-old, suspected of having viral CNS infections and admitted to the Pediatric Department of Monastir University Hospital, Tunisia. Enteroviral RNA was detected by 5' NCR nested RT-PCR assay in 33% (20 out of 60) of cerebrospinal fluid specimens, whereas only six samples (10%) were EV positive in cell culture. EV-positive patients were clustered according to their clinical manifestations, predominantly diagnosed as aseptic meningitis (65%) and meningoencephalitis (20%). Fever, headache, vomiting, and neck stiffness were the most pronounced symptoms. Pleocytosis with the predominance of lymphocytes was observed in 60% of EV positive specimens. Although patients suffering from EV infections were encountered throughout the year, most occurred during spring and summer months. Using VP1-2A nested RT-PCR and sequence analysis, three of the 20 positive HEV were identified as Echovirus (E)-9. This is the first report of a cluster of aseptic meningitis cases caused by E-9 in Monastir.

The spectrum of central nervous system infections in an adult referral hospital in Hanoi, Vietnam.

ObjectivesTo determine prospectively the causative pathogens of central nervous system (CNS) infections in patients admitted to a tertiary referral hospital in Hanoi, Vietnam.MethodsFrom May 2007 to December 2008, cerebrospinal fluid (CSF) samples from 352 adults with suspected meningitis or encephalitis underwent routine testing, staining (Gram, Ziehl-Nielsen, India ink), bacterial culture and polymerase chain reaction targeting Neisseria meningitidis, Streptococcus pneumoniae, S. suis, Haemophilus influenzae type b, Herpes simplex virus (HSV), Varicella Zoster virus (VZV), enterovirus, and 16S ribosomal RNA. Blood cultures and clinically indicated radiology were also performed. Patients were classified as having confirmed or suspected bacterial (BM), tuberculous (TBM), cryptococcal (CRM), eosinophilic (EOM) meningitis, aseptic encephalitis/meningitis (AEM), neurocysticercosis and others.Results352 (male: 66%) patients were recruited: median age 34 years (range 13–85). 95/352 (27.3%) diagnoses were laboratory confirmed and one by cranial radiology: BM (n = 62), TBM (n = 9), AEM (n = 19), CRM (n = 5), and neurocysticercosis (n = 1, cranial radiology). S. suis predominated as the cause of BM [48/62 (77.4%)]; Listeria monocytogenese (n = 1), S. pasteurianus (n = 1) and N. meningitidis (n = 2) were infrequent. AEM viruses were: HSV (n = 12), VZV (n = 5) and enterovirus (n = 2). 5 patients had EOM. Of 262/352 (74.4%) patients with full clinical data, 209 (79.8%) were hospital referrals and 186 (71%) had been on antimicrobials. 21 (8%) patients died: TBM (15.2%), AEM (10%), and BM (2.8%).ConclusionsMost infections lacked microbiological confirmation. S. suis was the most common cause of BM in this setting. Improved diagnostics are needed for meningoencephalitic syndromes to inform treatment and prevention strategies.

Persistent Infection of Thymic Epithelial Cells with Coxsackievirus B4 Results in Decreased Expression of Type 2 Insulin-Like Growth Factor

It has been hypothesized that a disturbance of central self-tolerance to islet β cells may play a role in the enteroviral pathogenesis of type 1 diabetes. Whether enteroviruses can induce an impaired expression of β-cell self-antigens in thymic epithelial cells has been investigated in a murine thymic epithelial (MTE) cell line. This cell line was permissive to the diabetogenic group B4 coxsackievirus (CV-B4) strain CV-B4 E2 and spontaneously expressed type 2 insulin-like growth factor (Igf2), the dominant self-antigen of the insulin family. In this model, a persistent replication of CV-B4 E2 was obtained, as attested to by the prolonged detection of intracellular positive- and negative-strand viral RNA by reverse transcription-PCR (RT-PCR) and capsid protein VP1 by immunofluorescent staining and by the release of infectious particles in culture supernatants. The chronic stage of the infection was characterized by a low proportion of VP1-positive cells (1 to 2%), whereas many cells harbored enteroviral RNA, as displayed by RT-PCR without extraction applied directly to a few cells. Igf2 mRNA and IGF-2 protein were dramatically decreased in CV-B4 E2-infected MTE cell cultures compared with mock-infected cultures, whereas housekeeping and interleukin-6 (Il6) gene expression was maintained and Igf1 mRNA was decreased, but to a lower extent. Inoculation of CV-B3, CV-B4 JVB, or echovirus 1 resulted in a low level of IGF-2 in culture supernatants as well, whereas herpes simplex virus 1 stimulated the production of the protein. Thus, a persistent infection of a thymic epithelial cell line with enteroviruses like CV-B4 E2 can result in a disturbed production of IGF-2, a protein involved in central self-tolerance toward islet β cells.

Quantitative Genomic and Antigenomic Enterovirus RNA Detection in Explanted Heart Tissue Samples from Patients with End-Stage Idiopathic Dilated Cardiomyopathy

Standardized one-step real-time RT-PCR assay detected enterovirus RNA in cardiac biopsy samples from 4 of 20 patients suffering from idiopathic dilated cardiomyopathy (IDCM). The median viral load was 287 copies per microgram of total extracted nucleic acids, with positive- to negative-strand RNA ratios ranging from 2 to 20. These results demonstrate enterovirus persistence in the heart of IDCM patients, characterized by low viral loads and low positive- to negative-RNA ratios.

Evaluation of Four Different Systems for Extraction of RNA from Stool Suspensions Using MS-2 Coliphage as an Exogenous Control for RT-PCR Inhibition

Knowing when, and to what extent co-extracted inhibitors interfere with molecular RNA diagnostic assays is of utmost importance. The QIAamp Viral RNA Mini Kit (A); MagNA Pure LC2.0 Automatic extractor (B); KingFisher (C); and NucliSENS EasyMag (D) RNA extraction systems were evaluated for extraction efficiency and co-purification of inhibitors from stool suspensions. Real-Time Reverse Transcriptase Polymerase Chain Reaction (rRT-PCR) of MS-2 coliphage spiked into each system’s lysis buffer served as an external control for both. Cycle thresholds (Cts) of the MS2 were determined for RNA extracted from stool suspensions containing unknown (n = 93) or varying amounts of inhibitors (n = 92). Stool suspensions from the latter group were also used to determine whether MS-2 and enterovirus rRT-PCR inhibitions were correlated. Specifically 23 RNA extracts from stool suspensions were spiked with enterovirus RNA after extraction and 13 of these stool suspension were spiked with intact enterovirus before extraction. MS2 rRT-PCR inhibition varied for RNAs extracted by the different systems. Inhibition was noted in 12 (13.0%), 26 (28.3%), 7 (7.6%), and 7 (7.6%) of the first 93 RNA extracts, and 58 (63.0%), 55 (59.8%), 37 (40.2%) and 30 (32.6%) of the second 92 extracts for A, B, C, and D, respectively. Furthermore, enterovirus rRT-PCR inhibition correlated with MS2 rRT-PCR inhibition for added enterovirus RNA or virus particles. In conclusion, rRT-PCR for MS-2 RNA is a good predictor of inhibition of enterovirus RNA extracted from stool suspensions. EasyMag performed the best, however all four extraction methods were suitable provided that external controls identified problematic samples.

Evolutionary pattern of 5′–UTR of enteroviruses and primer update for the detection of enteroviral RNA in environmental samples

ObjectiveTo study the recombination events among enterovirus strains and the development of specific primers for the detection of enteroviruses in environmental samples. MethodsNucleotide sequence analysis of enteroviruses deposited in the international database GenBank (www.ncbi.nlm.nih.gov/Genbank) was conducted to develop specific primers for the detection of these viruses. The specificity and sensitivity of the method were tested using coxackievirus B3 strain Nancy, environmental isolate of human hepatitis A virus and human rotavirus strain WA. Seventy sewage samples were analyzed. ResultsEnterovirus genome was detected in all positive samples. The genome of enterovirus was not detected in negative samples. The level of detection of these viruses was 102 TCID50/mL. ConclusionsThe development of new primers is an important issue for the detection of enteroviruses in the environment and the assessment of risk factors to human health.

Quantitative real-time RT-PCR assay for research studies on enterovirus infections in the central nervous system

Human enteroviruses are the most frequent cause of aseptic meningitis and are involved in other neurological infections. Qualitative detection of enterovirus genomes in cerebrospinal fluid is a prerequisite in diagnosing neurological diseases. The pathogenesis of these infections is not well understood and research in this domain would benefit from the availability of a quantitative technique to determine viral load in clinical specimens. This study describes the development of a real-time RT-qPCR assay using hydrolysis TaqMan probe and a competitive RNA internal control. The assay has high specificity and can be used for a large sample of distinct enterovirus strains and serotypes. The reproducible limit of detection was estimated at 1875 copies/ml of quantitative standards composed of RNA transcripts obtained from a cloned echovirus 30 genome. Technical performance was unaffected by the introduction of a competitive RNA internal control before RNA extraction. The mean enterovirus RNA concentration in an evaluation series of 15 archived cerebrospinal fluid specimens was determined at 4.78 log(10)copies/ml for the overall sample. The sensitivity and reproducibility of the real time RT-qPCR assay used in combination with the internal control to monitor the overall specimen process make it a valuable tool with applied research into enterovirus infections.

Ribonucleic Acid Extraction From Archival Formalin Fixed Paraffin Embedded Myocardial Tissues for Gene Expression and Pathogen Detection

Archival tissue samples preserved in formalin are a great source of treasure for biomedical research and diagnostics. Formalin, though is a good preservative, causes the modification of nucleic acid limiting the application of fixed tissues. The present study evaluated three methods of RNA extraction for constitutive gene expression and pathogen detection. Sixteen archival formalin-fixed paraffin-embedded (FFPE) myocardial tissues were subjected to RNA extraction by Trizol, SDS, and RNeasy FFPE kit followed by RT-PCR and Taqman Real-Time PCR to study the expression of housekeeping genes. RNA was extracted from all 16 myocardial tissues (100%) by RNeasy FFPE kit, as compared to 14/16 by Trizol and 8/10 by SDS methods. The expression of Glyceraldehyde-3-phosphate dehydrogenase (GAPDH)was observed in RNA extracted by RNeasy FFPE kit and Trizol. High yield of RNA was obtained by RNeasy FFPE kit than Trizol (P = 0.002) and SDS(P = 0.012). Of the three methods, RNeasy FFPE kit was evaluated for Enterovirus RNA detection in 16 other histopathologically confirmed FFPE tissues of dilated cardiomyopathy (DCM) cases and Enterovirus genome was detected in 4/16 (25%) FFPE tissues of DCM cases. The enteroviral sequences of the viral isolates revealed 99% homology with Human coxsackievirus B5. The Qiagen RNeasy FFPE kit resulted in significantly high reproducibility of RNA from FFPE myocardial tissues, which are suitable for amplification by Taq-Man Real-Time and RT-PCR. Thus, the results show that these FFPE tissues can be used for gene expression, pathogen detection, and epidemiological studies.

HLA-DRB1-DQA1-DQB1 genotype and frequency of enterovirus in longitudinal monthly fecal samples from healthy infants.

Enterovirus infections may be involved in the etiology of type 1 diabetes (T1D), which is strongly associated with certain human leukocyte antigen (HLA) class II haplotypes. Our aim was to assess whether HLA genotypes conferring varying degrees of risk for T1D were associated with enterovirus gut infections. From the general Norwegian population, 190 healthy infants at high-risk for T1D (DR4-DQ8/DR3-DQ2), and 383 infants without this genotype were identified. Non-DR4-DQ8/DR3-DQ2 genotypes were further categorized as conferring either an increased-to-moderate risk (DR4-DQ8 or DR3-DQ2), were protective (DQB1*06:02), or were neutral (all other genotypes). A total of 4626 monthly fecal samples taken between age 3 and 12 mo were tested for enterovirus RNA using real-time PCR. Enterovirus prevalence was 11.5% among high-risk children, and 12.2% in other children (adjusted odds ratio: 1.23, p=0.12). The prevalence was 11.3% in those with increased-to-moderate risk, 13.0% in the protective group, and 12.6% in the neutral group (likelihood ratio test, 3 d.f.: p=0.37). In conclusion, there was no statistically significant association between HLA genotype and the occurrence of human enterovirus gut infections.

No evidence of enteroviruses in the intestine of patients with type 1 diabetes

The purpose of this study was to investigate whether the gut mucosa is a reservoir for enterovirus persistence in patients with type 1 diabetes. Small intestine biopsy samples from 25 individuals at different stages of type 1 diabetes, 21 control individuals and 27 individuals with coeliac disease were analysed for the presence of enterovirus RNA by using both radioactive in-situ hybridisation and real-time RT-PCR and for the presence of enterovirus proteins by immunostaining with antibodies against VP1 and VP4-2-3 capsid proteins and virus polymerase. Lymphocytic enteropathy and serum anti-VP1 antibodies were also evaluated at the time of biopsy. Moreover, high-throughput sequencing was performed to identify viral transcripts or genomes. Enterovirus was not detected by in-situ hybridisation or RT-PCR in any of the individuals tested. Immunohistology revealed a few stained cells in the intestinal epithelium in a low number of individuals, with no difference between diabetic and non-diabetic individuals. Levels of serum IgG against VP1 did not differ between control individuals and those with diabetes or coeliac disease and no evidence of diabetes-related lymphocytic enteropathy was detected. High-throughput sequencing did not reveal specific enterovirus sequences in the gut mucosa of individuals with type 1 diabetes. Prolonged/persistent enterovirus infections in gut mucosa are not common in patients with type 1 diabetes.

Multiple virus infection alters rotavirus replication and expression of cytokines and Toll-like receptors in intestinal epithelial cells

Two live oral rotavirus vaccines have shown to be effective in protecting young children from severe illness in developed and middle income countries, but their efficacy is significantly lower in low income countries. One of the reasons for this lower efficacy may be mixed virus infection in the gut that is commonly encountered among infants in the developing world. We investigated whether multiple virus infection interferes with rotavirus replication and alters host response by comparing single and mixed enteric virus infections in Caco-2 cells. We observed a dramatic reduction in rotavirus replication and growth in mixed rotavirus, astrovirus and enterovirus infection compared to single rotavirus infection. By contrast, the levels of astrovirus and enterovirus RNA in mixed infection remained unchanged when compared to those of the corresponding single virus infection. We then examined cells with single or multiple virus infections for the expression of 10 cytokine genes and demonstrated elevated expressions for 7 (IFN-α, IFN-β, IFN-γ, TNF-α, IL-6, IL-8, and IL-17) in dual rotavirus and enterovirus or triple rotavirus, enterovirus and astrovirus-infected cells but only 3 (IFN-β, TNF-α, and IL-8) in dual rotavirus and astrovirus-infected cells. We further observed elevated levels of TLR4, TLR5, TLR7 and TLR9 mRNAs in cells with rotavirus and enterovirus or rotavirus, enterovirus and astrovirus infections when compared to single rotavirus infections. Our data suggest that rotavirus infection is susceptible to interference by other enteric viruses in the gut, which could result in reduced virus replication and contribute to lower immunogenicity and efficacy of oral rotavirus vaccines in low income countries.

Immunology in the clinic review series; focus on type 1 diabetes and viruses: how viral infections modulate beta cell function

Type 1 diabetes mellitus (T1DM) is a multi-factorial immune-mediated disease characterized by the autoimmune destruction of insulin-producing pancreatic islet beta cells in genetically susceptible individuals. Epidemiological evidence has also documented the constant rise in the incidence of T1DM worldwide, with viral infections representing one of the candidate environmental risk factors identified by several independent studies. In fact, epidemiological data showed that T1DM incidence increases after epidemics due to enteroviruses and that enteroviral RNA can be detected in the blood of >50% of T1DM patients at the time of disease onset. Furthermore, both in-vitro and ex-vivo studies have shown that viruses can infect pancreatic beta cells with consequent effects ranging from functional damage to cell death.

Immunology in the clinic review series; focus on type 1 diabetes and viruses: the enterovirus link to type 1 diabetes: critical review of human studies

The hypothesis that under some circumstances enteroviral infections can lead to type 1 diabetes (T1D) was proposed several decades ago, based initially on evidence from animal studies and sero-epidemiology. Subsequently, enterovirus RNA has been detected more frequently in serum of patients than in control subjects, but such studies are susceptible to selection bias and reverse causality. Here, we review critically recent evidence from human studies, focusing on longitudinal studies with potential to demonstrate temporal association. Among seven longitudinal birth cohort studies, the evidence that enterovirus infections predict islet autoimmunity is quite inconsistent in our interpretation, due partially, perhaps, to heterogeneity in study design and a limited number of subjects studied. An association between enterovirus and rapid progression from autoimmunity to T1D was reported by one longitudinal study, but although consistent with evidence from animal models, this novel observation awaits replication. It is possible that a potential association with initiation and/or progression of islet autoimmunity can be ascribed to a subgroup of the many enterovirus serotypes, but this has still not been investigated properly. There is a need for larger studies with frequent sample intervals and collection of specimens of sufficient quality and quantity for detailed characterization of enterovirus. More research into the molecular epidemiology of enteroviruses and enterovirus immunity in human populations is also warranted. Ultimately, this knowledge may be used to devise strategies to reduce the risk of T1D in humans.