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Stecher B.,Ludwig Maximilians University of Munich | Stecher B.,German Center for Infection Research | Berry D.,University of Vienna | Loy A.,University of Vienna
FEMS Microbiology Reviews | Year: 2013

The highly diverse intestinal microbiota forms a structured community engaged in constant communication with itself and its host and is characterized by extensive ecological interactions. A key benefit that the microbiota affords its host is its ability to protect against infections in a process termed colonization resistance (CR), which remains insufficiently understood. In this review, we connect basic concepts of CR with new insights from recent years and highlight key technological advances in the field of microbial ecology. We present a selection of statistical and bioinformatics tools used to generate hypotheses about synergistic and antagonistic interactions in microbial ecosystems from metagenomic datasets. We emphasize the importance of experimentally testing these hypotheses and discuss the value of gnotobiotic mouse models for investigating specific aspects related to microbiota-host-pathogen interactions in a well-defined experimental system. We further introduce new developments in the area of single-cell analysis using fluorescence in situ hybridization in combination with metabolic stable isotope labeling technologies for studying the in vivo activities of complex community members. These approaches promise to yield novel insights into the mechanisms of CR and intestinal ecophysiology in general, and give researchers the means to experimentally test hypotheses in vivo at varying levels of biological and ecological complexity. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Diepold A.,University of Oxford | Wagner S.,University of Tubingen | Wagner S.,German Center for Infection Research
FEMS Microbiology Reviews | Year: 2014

Many bacteria that live in contact with eukaryotic hosts, whether as symbionts or as pathogens, have evolved mechanisms that manipulate host cell behaviour to their benefit. One such mechanism, the type III secretion system, is employed by Gram-negative bacterial species to inject effector proteins into host cells. This function is reflected by the overall shape of the machinery, which resembles a molecular syringe. Despite the simplicity of the concept, the type III secretion system is one of the most complex known bacterial nanomachines, incorporating one to more than hundred copies of up to twenty different proteins into a multi-MDa transmembrane complex. The structural core of the system is the so-called needle complex that spans the bacterial cell envelope as a tripartite ring system and culminates in a needle protruding from the bacterial cell surface. Substrate targeting and translocation are accomplished by an export machinery consisting of various inner membrane embedded and cytoplasmic components. The formation of such a multimembrane-spanning machinery is an intricate task that requires precise orchestration. This review gives an overview of recent findings on the assembly of type III secretion machines, discusses quality control and recycling of the system and proposes an integrated assembly model. This review discusses the assembly of the type III secretion injectisome, a cell envelope spanning macromolecular machine used by Gram-negative bacteria to translocate bacterial effector proteins into host cells. © 2014 Federation of European Microbiological Societies.

Rockstroh J.K.,University of Bonn | Rockstroh J.K.,German Center for Infection Research
Liver International | Year: 2015

The development of direct acting antivirals (DAAs) against the hepatitis C virus (HCV) has revolutionized treatment paradigms for HCV in HIV co-infected subjects. In the era of DAAs, HIV/HCV co-infected patients have the same cure rates of over 90% with interferon (IFN)-free DAA combinations. Therefore, guidelines no longer separate mono- and co-infected subjects. Indications for HCV therapy and DAA drug selection have become the same for all patients. The only special consideration in HIV/HCV co-infected subjects is the need to check for drug-drug interactions between HIV and HCV drugs, especially HIV and HCV protease inhibitors which have a high risk of clinically significant drug interactions. Because of the faster progression of fibrosis and the higher risk of hepatic decompensation in co-infected subjects, even with combination antiretroviral (ART) therapy, the availability of modern HCV treatments needs to be extended and HCV therapy should be discussed in all co-infected patients. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Xia G.,University of Tubingen | Xia G.,German Center for Infection Research | Wolz C.,University of Tubingen
Infection, Genetics and Evolution | Year: 2014

Most of the dissimilarity between Staphylococcus aureus strains is due to the presence of mobile genetic elements such as bacteriophages or pathogenicity islands. These elements provide the bacteria with additional genes that enable them to establish a new lifestyle that is often accompanied by a shift to increased pathogenicity or a jump to a new host. S. aureus phages may carry genes coding for diverse virulence factors such as Panton-Valentine leukocidin, staphylokinase, enterotoxins, chemotaxis-inhibitory proteins, or exfoliative toxins. Phages also mediate the transfer of pathogenicity islands in a highly coordinated manner and are the primary vehicle for the horizontal transfer of chromosomal and extra-chromosomal genes. Here, we summarise recent advances regarding phage classification, genome organisation and function of S. aureus phages with a particular emphasis on their role in the evolution of the bacterial host. © 2013 Elsevier B.V.

Ringelhan M.,Helmholtz Center Munich | Ringelhan M.,TU Munich | Ringelhan M.,German Center for Infection Research | O'Connor T.,Helmholtz Center Munich | And 2 more authors.
Journal of Pathology | Year: 2015

Chronic hepatitis B virus (HBV) infection remains the number one risk factor for hepatocellular carcinoma (HCC), accounting for more than 600 000 deaths/year. Despite highly effective antiviral treatment options, chronic hepatitis B (CHB), subsequent end-stage liver disease and HCC development remain a major challenge worldwide. In CHB, liver damage is mainly caused by the influx of immune cells and destruction of infected hepatocytes, causing necro-inflammation. Treatment with nucleoside/nucleotide analogues can effectively suppress HBV replication in patients with CHB and thus decrease the risk for HCC development. Nevertheless, the risk of HCC in treated patients showing sufficient suppression of HBV DNA replication is significantly higher than in patients with inactive CHB, regardless of the presence of baseline liver cirrhosis, suggesting direct, long-lasting, predisposing effects of HBV. Direct oncogenic effects of HBV include integration in the host genome, leading to deletions, cis/trans-activation, translocations, the production of fusion transcripts and generalized genomic instability, as well as pleiotropic effects of viral transcripts (HBsAg and HBx). Analysis of these viral factors in active surveillance may allow early identification of high-risk patients, and their integration into a molecular classification of HCC subtypes might help in the development of novel therapeutic approaches. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

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