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Host Pathogen Dynamics

Richard M Johnson, Kathleen A McDonough
Mycobacterium tuberculosis (Mtb) is one of the most successful microbial pathogens, and currently infects over a quarter of the world's population. Mtb's success depends on the ability of the bacterium to sense and respond to dynamic and hostile environments within the host, including the ability to regulate bacterial metabolism and interactions with the host immune system. One of the ways Mtb senses and responds to conditions it faces during infection is through the concerted action of multiple cyclic nucleotide signaling pathways...
July 1, 2018: Pathogens and Disease
Gilberto Sabino-Santos, Felipe Gonçalves Motta Maia, Ronaldo Bragança Martins, Talita Bianca Gagliardi, William Marciel de Souza, Renata Lara Muylaert, Luciano Kleber de Souza Luna, Danilo Machado Melo, Ricardo de Souza Cardoso, Natalia da Silva Barbosa, Marjorie Cornejo Pontelli, Priscila Rosse Mamani-Zapana, Thallyta Maria Vieira, Norma Maria Melo, Colleen B Jonsson, Douglas Goodin, Jorge Salazar-Bravo, Luis Lamberti Pinto daSilva, Eurico Arruda, Luiz Tadeu Moraes Figueiredo
Bats (Order: Chiroptera) harbor a high diversity of emerging pathogens presumably because their ability to fly and social behavior favor the maintenance, evolution, and dissemination of these pathogens. Until 2012, there was only one report of the presence of Hantavirus in bats. Historically, it was thought that these viruses were harbored primarily by rodent and insectivore small mammals. Recently, new species of hantaviruses have been identified in bats from Africa and Asia continents expanding the potential reservoirs and range of these viruses...
June 13, 2018: Scientific Reports
Vandana Solanki, Vishvanath Tiwari
The emergence of drug-resistant Acinetobacter baumannii is the global health problem associated with high mortality and morbidity. Therefore it is high time to find a suitable therapeutics for this pathogen. In the present study, subtractive proteomics along with reverse vaccinology approaches were used to predict suitable therapeutics against A. baumannii. Using subtractive proteomics, we have identified promiscuous antigenic membrane proteins that contain the virulence factors, resistance factors and essentiality factor for this pathogenic bacteria...
June 13, 2018: Scientific Reports
Muriel Dietrich, Teresa Kearney, Ernest C J Seamark, Janusz T Paweska, Wanda Markotter
Seasonal reproduction is a period of extreme physiological and behavioural changes, yet we know little about how it may affect host microbial communities (i.e. microbiota) and pathogen transmission. Here, we investigated shifts of the bacterial microbiota in saliva, urine and faeces during the seasonal reproduction of bats in South Africa, and test for an interaction in shedding patterns of both bacterial ( Leptospira ) and viral (adeno- and herpesviruses) agents. Based on a comparative approach in two cave-dwelling bat species and high-throughput sequencing of the 16S rRNA gene, we demonstrated a clear signature in microbiota changes over the reproduction season, consistent across the multiple body habitats investigated, and associated with the sex, age and reproductive condition of bats...
May 2018: Royal Society Open Science
Spencer C Galen, Janus Borner, Ellen S Martinsen, Juliane Schaer, Christopher C Austin, Christopher J West, Susan L Perkins
The evolutionary relationships among the apicomplexan blood pathogens known as the malaria parasites (order Haemosporida), some of which infect nearly 200 million humans each year, has remained a vexing phylogenetic problem due to limitations in taxon sampling, character sampling and the extreme nucleotide base composition biases that are characteristic of this clade. Previous phylogenetic work on the malaria parasites has often lacked sufficient representation of the broad taxonomic diversity within the Haemosporida or the multi-locus sequence data needed to resolve deep evolutionary relationships, rendering our understanding of haemosporidian life-history evolution and the origin of the human malaria parasites incomplete...
May 2018: Royal Society Open Science
Hye-Young Lee, So Eui Lee, Jongchan Woo, Doil Choi, Eunsook Park
Bacteria, one of the most important causative agents of various plant diseases, secrete a set of effector proteins into the host plant cell to subvert the plant immune system. During infection cytoplasmic effectors are delivered to the host cytosol via a type III secretion system (T3SS). After delivery into the plant cell, the effector(s) targets the specific compartment(s) to modulate host cell processes for survival and replication of the pathogen. Although there has been some research on the subcellular localization of effector proteins in the host cells to understand their function in pathogenicity by using fluorescent proteins, investigation of the dynamics of effectors directly injected from bacteria has been challenging due to the incompatibility between the T3SS and fluorescent proteins...
May 24, 2018: Journal of Visualized Experiments: JoVE
Hannah E Brown, Kyla S Ost, Shannon K Esher, Kaila M Pianalto, Joseph W Saelens, Ziqiang Guan, J Andrew Alspaugh
The mechanisms by which micro-organisms sense and internalize extracellular pH signals are not completely understood. One example of a known external pH-sensing process is the fungal-specific Rim/Pal signal transduction pathway. Fungi, such as the opportunistic pathogen Cryptococcus neoformans, use Rim signaling to sense and respond to changes in environmental pH. Mutations in this pathway result in strains that are attenuated for survival at alkaline pH, and often for survival within the host. Here, we used an insertional mutagenesis screen to identify novel genes required for C...
June 8, 2018: Molecular Microbiology
Johannes Textor, Anke Fähnrich, Martin Meinhardt, Cornelia Tune, Sebastian Klein, Rene Pagel, Peter König, Kathrin Kalies, Jürgen Westermann
Immunological differences between hosts, such as diverse TCR repertoires, are widely credited for reducing the risk of pathogen spread and adaptation in a population. Within-host immunological diversity might likewise be important for robust pathogen control, but to what extent naive TCR repertoires differ across different locations in the same host is unclear. T cell zones (TCZs) in secondary lymphoid organs provide secluded microenvironmental niches. By harboring distinct TCRs, such niches could enhance within-host immunological diversity...
June 8, 2018: Journal of Immunology: Official Journal of the American Association of Immunologists
Yifat Ofir-Birin, Paula Abou Karam, Ariel Rudik, Tal Giladi, Ziv Porat, Neta Regev-Rudzki
Extracellular vesicles are essential for long distance cell-cell communication. They function as carriers of different compounds, including proteins, lipids and nucleic acids. Pathogens, like malaria parasites ( Plasmodium falciparum, Pf ), excel in employing vesicle release to mediate cell communication in diverse processes, particularly in manipulating the host response. Establishing research tools to study the interface between pathogen-derived vesicles and their host recipient cells will greatly benefit the scientific community...
2018: Frontiers in Immunology
Ilona Merikanto, Jouni T Laakso, Veijo Kaitala
BACKGROUND: Environmentally growing pathogens present an increasing threat for human health, wildlife and food production. Treating the hosts with antibiotics or parasitic bacteriophages fail to eliminate diseases that grow also in the outside-host environment. However, bacteriophages could be utilized to suppress the pathogen population sizes in the outside-host environment in order to prevent disease outbreaks. Here, we introduce a novel epidemiological model to assess how the phage infections of the bacterial pathogens affect epidemiological dynamics of the environmentally growing pathogens...
June 8, 2018: Theoretical Biology & Medical Modelling
Frédéric Suffert, Ghislain Delestre, Sandrine Gélisse
This study provides empirical evidence for antagonistic density dependence mechanisms driving sexual reproduction in the wheat fungal pathogen Zymoseptoria tritici. Biparental crosses with 12 increasing inoculum concentrations, in controlled conditions, showed that sexual reproduction in Z. tritici was impacted by an Allee effect due to mate limitation and a competition with asexual multiplication for resource allocation. The highest number of ascospores discharged was reached at intermediate inoculum concentrations (from 5 × 104 conidia mL-1 to 106 conidia mL-1 )...
June 6, 2018: Microbial Ecology
Frédéric Suffert, Henriette Goyeau, Ivan Sache, Florence Carpentier, Sandrine Gélisse, David Morais, Ghislain Delestre
The efficiency of plant resistance to fungal pathogen populations is expected to decrease over time, due to their evolution with an increase in the frequency of virulent or highly aggressive strains. This dynamics may differ depending on the scale investigated (annual or pluriannual), particularly for annual crop pathogens with both sexual and asexual reproduction cycles. We assessed this time-scale effect, by comparing aggressiveness changes in a local Zymoseptoria tritici population over an 8-month cropping season and a 6-year period of wheat monoculture...
June 2018: Evolutionary Applications
Adriana Lima Vallochi, Livia Teixeira, Karina da Silva Oliveira, Clarissa Menezes Maya-Monteiro, Patricia T Bozza
Lipid droplets (lipid bodies, LDs) are dynamic organelles that have important roles in regulating lipid metabolism, energy homeostasis, cell signaling, membrane trafficking, and inflammation. LD biogenesis, composition, and functions are highly regulated and may vary according to the stimuli, cell type, activation state, and inflammatory environment. Increased cytoplasmic LDs are frequently observed in leukocytes and other cells in a number of infectious diseases. Accumulating evidence reveals LDs participation in fundamental mechanisms of host-pathogen interactions, including cell signaling and immunity...
2018: Frontiers in Immunology
Nehemiah Zewde, Dimitrios Morikis
The complement system is an intricate defense network that rapidly removes invading pathogens. Although many complement regulators are present to protect host cells under homeostasis, the impairment of Factor H (FH) regulatory mechanism has been associated with several autoimmune and inflammatory diseases. To understand the dynamics involved in the pivotal balance between activation and regulation, we have developed a comprehensive computational model of the alternative and classical pathways of the complement system...
2018: PloS One
Hayden T Pacl, Vineel P Reddy, Vikram Saini, Krishna C Chinta, Adrie J C Steyn
Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, encounters variable and hostile environments within the host. A major component of these hostile conditions is reductive and oxidative stresses induced by factors modified by the host immune response, such as oxygen tension, NO or CO gases, reactive oxygen and nitrogen intermediates, the availability of different carbon sources and changes in pH. It is therefore essential for Mtb to continuously monitor and appropriately respond to the microenvironment...
July 1, 2018: Pathogens and Disease
Shelly Lachish, Kris A Murray
Wildlife diseases have important implications for wildlife and human health, the preservation of biodiversity and the resilience of ecosystems. However, understanding disease dynamics and the impacts of pathogens in wild populations is challenging because these complex systems can rarely, if ever, be observed without error. Uncertainty in disease ecology studies is commonly defined in terms of either heterogeneity in detectability (due to variation in the probability of encountering, capturing, or detecting individuals in their natural habitat) or uncertainty in disease state assignment (due to misclassification errors or incomplete information)...
2018: Frontiers in Veterinary Science
Stefanie Allert, Toni M Förster, Carl-Magnus Svensson, Jonathan P Richardson, Tony Pawlik, Betty Hebecker, Sven Rudolphi, Marc Juraschitz, Martin Schaller, Mariana Blagojevic, Joachim Morschhäuser, Marc Thilo Figge, Ilse D Jacobsen, Julian R Naglik, Lydia Kasper, Selene Mogavero, Bernhard Hube
Life-threatening systemic infections often occur due to the translocation of pathogens across the gut barrier and into the bloodstream. While the microbial and host mechanisms permitting bacterial gut translocation are well characterized, these mechanisms are still unclear for fungal pathogens such as Candida albicans , a leading cause of nosocomial fungal bloodstream infections. In this study, we dissected the cellular mechanisms of translocation of C. albicans across intestinal epithelia in vitro and identified fungal genes associated with this process...
June 5, 2018: MBio
Rui Cruz, Isabel Pereira-Castro, Maria T Almeida, Alexandra Moreira, Didier Cabanes, Sandra Sousa
The host cytoskeleton is a major target for bacterial pathogens during infection. In particular, pathogens usurp the actin cytoskeleton function to strongly adhere to the host cell surface, to induce plasma membrane remodeling allowing invasion and to spread from cell to cell and disseminate to the whole organism. Keratins are cytoskeletal proteins that are the major components of intermediate filaments in epithelial cells however, their role in bacterial infection has been disregarded. Here we investigate the role of the major epithelial keratins, keratins 8 and 18 (K8 and K18), in the cellular infection by Listeria monocytogenes ...
2018: Frontiers in Cellular and Infection Microbiology
Nermin Akduman, Christian Rödelsperger, Ralf J Sommer
The interplay with bacteria is of crucial importance for the interaction of multicellular organisms with their environments. Studying the associations between the nematode model organisms Caenorhabditis elegans and Pristionchus pacificus with bacteria constitutes a powerful system to investigate these interactions at a mechanistic level. P. pacificus is found in association with scarab beetles in nature and recent studies revealed the succession and dynamics of this nematode and its microbiome during the decomposition of one particular host species, the rhinoceros beetle Oryctes borbonicus on La Réunion Island...
2018: PloS One
William E Stutz, Andrew R Blaustein, Cheryl J Briggs, Jason T Hoverman, Jason R Rohr, Pieter T J Johnson
Associations among parasites affect many aspects of host-parasite dynamics, but a lack of analytical tools has limited investigations of parasite correlations in observational data that are often nested across spatial and biological scales.Here we illustrate how hierarchical, multiresponse modeling can characterize parasite associations by allowing for hierarchical structuring, offering estimates of uncertainty, and incorporating correlational model structures. After introducing the general approach, we apply this framework to investigate coinfections among four amphibian parasites (the trematodes Ribeiroia ondatrae and Echinostoma spp...
April 2018: Methods in Ecology and Evolution
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