Bacterial, viral and parasitic pathogens analysed by qPCR: Findings from a prospective study of travellers' diarrhoea

Background: The diagnostics of travellers' diarrhoea (TD) has been revolutionised by multiplex qPCR assays. While mostly of bacterial aetiology, viruses and parasites account for the disease among 10-20% of travellers. Despite this, prospective studies applying qPCR assays remain scarce that cover not only bacteria, such as the various diarrhoeagenic Escherichia coli (DEC), but also viral and parasitic pathogens. Method: We analysed by qPCR pre- and post-travel stool samples of 146 Finnish travellers for bacterial, viral and parasitic pathogens: enteropathogenic (EPEC), enteroaggregative (EAEC), enterotoxigenic (ETEC), enterohaemorrhagic (EHEC), and enteroinvasive (EIEC) E. coli; Shigella, Campylobacter, Salmonella, Yersinia and Vibrio cholerae; norovirus G1 and G2, rotavirus, enteroviruses, and sapovirus; and Giardia lamblia, Entamoeba histolytica, and Cryptosporidium. Symptoms and medication data during travel were collected by questionnaires. Results: We detected bacterial pathogens in 102/146 samples (69.9%; EAEC, EPEC, ETEC most common), viral ones in 13 (8.9%; norovirus most common), and parasitic ones in one (0.7%; Giardia). Noroviruses were associated with severe symptoms (23.5% versus non-severe 4.9%). In the TD group, 41.7% (5/12) of those with viral pathogens (vs. 13.3%; 11/83 without) took antibiotics. Conclusion: Viral pathogens, particularly noroviruses, prevail in severe TD. The symptoms of viral disease are often severe and lead to unwarranted use of antibiotics.Peer reviewe

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

T Cell Epitopes in Coxsackievirus B4 Structural Proteins Concentrate in Regions Conserved between Enteroviruses

AbstractThe present study aimed to characterize systematically the target epitopes of T cell responses in CBV4 structural proteins. These were studied by synthesizing 86 overlapping 20-aa-long peptides covering the known sequence of CBV4 structural proteins and analyzing the proliferation responses of 18 CBV4-specific T cell lines against these peptides. Recognized peptides differed depending on the HLA-DR genotype of the T cell donor. They were concentrated to the VP4 and VP2 regions as six of seven common peptide epitopes located in this region, whereas there was only one in the VP3 region and none in the VP1 region. Peptides from conserved areas were recognized more often (on average, 15% of them stimulated each T cell line) than those derived from variable areas (3%) (P < 0.0001, Fisher's exact test). Some conserved peptides inducing T cell responsiveness in most subjects were identified, a knowledge which can be useful in the development of new synthetic vaccines