Enterovirus strain and type-specific differences in growth kinetics and virus-induced cell destruction in human pancreatic duct epithelial HPDE cells

Enterovirus infections have been suspected to be involved in the development of type 1 diabetes. However, the pathogenetic mechanism of enterovirus-induced type 1 diabetes is not known. Pancreatic ductal cells are closely associated with pancreatic islets. Therefore, enterovirus infections in ductal cells may also affect beta-cells and be involved in the induction of type 1 diabetes. The aim of this study was to assess the ability of different enterovirus strains to infect, replicate and produce cytopathic effect in human pancreatic ductal cells. Furthermore, the viral factors that affect these capabilities were studied. The pancreatic ductal cells were highly susceptible to enterovirus infections. Both viral growth and cytolysis were detected for several enterovirus serotypes. However, the viral growth and capability to induce cytopathic effect (cpe) did not correlate completely. Some of the virus strains replicated in ductal cells without apparent cpe. Furthermore, there were strain-specific differences in the growth kinetics and the ability to cause cpe within some serotypes. Viral adaptation experiments were carried out to study the potential genetic determinants behind these phenotypic differences. The blind-passage of non-lytic CV-B6-Schmitt strain in HPDE-cells resulted in lytic phenotype and increased progeny production. This was associated with the substitution of a single amino acid (K257E) in the virus capsid protein VP1 and the viral ability to use decay accelerating factor (DAF) as a receptor. This study demonstrates considerable plasticity in the cell tropism, receptor usage and cytolytic properties of enteroviruses and underlines the strong effect of single or few amino acid substitutions in cell tropism and lytic capabilities of a given enterovirus. Since ductal cells are anatomically close to pancreatic islets, the capability of enteroviruses to infect and destroy pancreatic ductal cells may also implicate in respect to enterovirus induced type 1 diabetes. In addition, the capability for rapid adaptation to different cell types suggests that, on occasion, enterovirus strains with different pathogenetic properties may arise from less pathogenic ancestors. (C) 2015 Elsevier B.V. All rights reserved.Peer reviewe

Enterovirusten aiheuttama solutuho

This master's thesis focuses primarily on the relationship between coxsackievirus and type I diabetes mellitus. This study is a part of a larger research project which aims to clarify the proposed tendency of different coxsackieviruses to induce cell death in pancreatic cells. Type I diabetes is a chronic disease in which the insulin producing pancreatic cells have gradually been destroyed by cell death. Enteroviruses are believed to have the kinds of characteristics which increase the risk of type I diabetes. The first step of the study was to select a few enterovirus strains that showed the most identical genetical relationships compared to a specific enterovirus which is considered to have diabetogenic features. The second step was to study biological properties of these strains in pancreatic cells. This study showed that coxsackie B -viruses' ability to grow in these cells is dependent on virus strain. During the study, two coxsackie B -virus strains which showed major differences in biological properties were found. These strains reproduced in pancreatic cells but showed no ability to induce cell death. The reproduction was also slow compared to other enterovirus strains studied with a range of different methods. The results of this master's thesis can be valuable for instance in the development of new approaches for prevention of virus induced damage in diabetes type I.Tässä diplomityössä tavoitteena oli tuoda tietoa erityisesti coxsackieviruksien sekä tyypin I diabeteksen muodostumisen väliseen yhteyteen. Tutkimus on osa kokonaisuutta, jossa selvitetään eri coxsackieviruksien taipumuksia aiheuttaa solutuhoa haiman soluissa. Tyypin I diabetes on krooninen sairaus, jossa insuliinia tuottavat haiman solut ovat asteittain tuhoutuneet. Enteroviruksilla uskotaan olevan tyypin I diabetekselle altistumista lisääviä ominaisuuksia. Tässä tutkimuksessa tutkittiin valikoitujen enterovirusten geneettisiä molekulaarisuus suhteita ja näiden mahdollisia yhteyksiä diabetogeeniseen enteroviruskantaan. Tulosten perusteella valikoitiin ne viruskannat, joiden biologisia ominaisuuksia selvitettiin haiman soluissa. Työssä osoitettiin, että coxsackie B -virusten kyky kasvaa baimatiehytsoluissa on eri viruskannoille ominaista ja vaihtelee riippuen kannasta. Tutkimuksissa löytyi kaksi biologisilta ominaisuuksiltaan erityisen poikkeavaa coxsackie B -viruskantaa, jotka eivät lisääntymisestä huolimatta aiheuttaneet solutuhoa haiman soluissa. Näiden valittujen viruskantojen lisääntyminen oli haiman soluissa hidasta verrattuna muihin tutkittuihin kantoihin. Tämä osoitettiin usein erilaisin menetelmin. Saatuja tutkimustuloksia voidaan hyödyntää esimerkiksi taudin puhkeamista ennaltaehkäisevien hoitotoimenpiteiden kehityksessä