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Host Pathogen Dynamics

Roland G Huber, Jan K Marzinek, Daniel A Holdbrook, Peter J Bond
Viral pathogens are a significant source of human morbidity and mortality, and have a major impact on societies and economies around the world. One of the challenges inherent in targeting these pathogens with drugs is the tight integration of the viral life cycle with the host's cellular machinery. However, the reliance of the virus on the host cell replication machinery is also an opportunity for therapeutic targeting, as successful entry- and exit-inhibitors have demonstrated. An understanding of the extracellular and intracellular structure and dynamics of the virion - as well as of the entry and exit pathways in host and vector cells - is therefore crucial to the advancement of novel antivirals...
October 17, 2016: Progress in Biophysics and Molecular Biology
Theresia E B Stradal, Sonia C P Costa
A key aspect of bacterial pathogenesis is the colonization and persistence within the host and, later on, its dissemination to new niches. During evolution, bacteria developed a myriad of virulence mechanisms to usurp the host's sophisticated defense mechanisms in order to establish their colonization niche. Elucidation of the highly dynamic and complex interactions between host and pathogens remains an important field of study. Here, we highlight the conserved manipulation of the actin cytoskeleton by some Gram-negative gastrointestinal pathogens, addressing the role of type III secreted bacterial GEFs at the different steps of pathogenesis...
October 16, 2016: Current Topics in Microbiology and Immunology
Pardeep Kumar, F Matthew Kuhlmann, Kirandeep Bhullar, Hyungjun Yang, Bruce A Vallance, Lijun Xia, Qingwei Luo, James M Fleckenstein
At present, there is no vaccine for enterotoxigenic E. coli (ETEC), an important cause of diarrheal illness. Nevertheless, recent microbial pathogenesis studies have identified a number of molecules produced by ETEC that contribute to its virulence and which provide novel antigenic targets to complement canonical vaccine approaches. EtpA is a secreted two-partner adhesin, that is conserved within the ETEC pathovar. EtpA interacts with the tips of ETEC flagella to promote bacterial adhesion, toxin delivery and intestinal colonization by forming molecular bridges between the bacteria and the epithelial surface...
October 10, 2016: Infection and Immunity
Reinhild Feuerstein, Julia Kolter, Philipp Henneke
The dermis, a major reservoir of immune cells in immediate vicinity to the colonizing skin microflora, serves as an important site of host-pathogen interactions. Macrophages (Mϕ) are the most frequent resident immune cell type in the dermis. They protect the host from invasive infections by highly adapted bacteria, such as staphylococci via pattern recognition of bacterial effectors, phagocytosis, and recruitment of other myeloid cells from the blood. Already under homeostatic conditions, the dermal Mϕ population receives a dynamic input of monocytes invading from the bloodstream...
October 12, 2016: Journal of Leukocyte Biology
Maxime Barbier, Thierry Wirth
With the advent of next-generation sequencing technology, the genotyping of clinical Mycobacterium tuberculosis strains went through a major breakup that dramatically improved the field of molecular epidemiology but also revolutionized our deep understanding of the M. tuberculosis complex evolutionary history. The intricate paths of the pathogen and its human host are reflected by a common geographical origin in Africa and strong biogeographical associations that largely reflect the past migration waves out of Africa...
August 2016: Microbiology Spectrum
Walter J Lukiw
The human microbiome consists of ~3.8 × 10(13) symbiotic microorganisms that form a highly complex and dynamic ecosystem: the gastrointestinal (GI) tract constitutes the largest repository of the human microbiome by far, and its impact on human neurological health and disease is becoming increasingly appreciated. Bacteroidetes, the largest phylum of Gram-negative bacteria in the GI tract microbiome, while generally beneficial to the host when confined to the GI tract, have potential to secrete a remarkably complex array of pro-inflammatory neurotoxins that include surface lipopolysaccharides (LPSs) and toxic proteolytic peptides...
2016: Frontiers in Microbiology
Marla C McPherson, Hans H Cheng, Mary E Delany
Marek's disease (MD) is a lymphotropic and oncogenic disease of chickens that can lead to death in susceptible and unvaccinated host birds. The causative pathogen, MD virus (MDV), a highly oncogenic alphaherpesvirus, integrates into host genome near the telomeres. MD occurrence is controlled across the globe by biosecurity, selective breeding for enhanced MD genetic resistance, and widespread vaccination of flocks using attenuated serotype 1 MDV or other serotypes. Despite over 40 years of usage, the specific mechanism(s) of MD vaccine-related immunity and anti-tumor effects are not known...
October 5, 2016: Vaccine
Punsiri M Colonne, Caylin G Winchell, Daniel E Voth
Intracellular bacterial pathogens replicate within eukaryotic cells and display unique adaptations that support key infection events including invasion, replication, immune evasion, and dissemination. From invasion to dissemination, all stages of the intracellular bacterial life cycle share the same three-dimensional cytosolic space containing the host cytoskeleton. For successful infection and replication, many pathogens hijack the cytoskeleton using effector proteins introduced into the host cytosol by specialized secretion systems...
2016: Frontiers in Cellular and Infection Microbiology
Łukasz Hołubiuk, Jacek Imiela
Helicobacter pylori infection has accompanied man for thousands of years. In some infected patients, a complex and dynamic pathogen-host reaction triggers pathogenic pathways resulting in development, inter alia, of atrophic gastritis, peptic ulcer disease (both gastric and duodenal), gastric adenocarcinoma, and MALT lymphoma. Large-scale eradication therapy is associated with a rapid increase in antibiotic resistance, gut flora composition disturbances, and increased risk of development, inter alia, of paediatric infectious diarrhoeas, atopic diseases, and oesophageal adenocarcinoma...
2016: Przegla̜d Gastroenterologiczny
Caio Graco Zeppelini, Alzira Maria Paiva de Almeida, Pedro Cordeiro-Estrela
As a zoonosis, Plague is also an ecological entity, a complex system of ecological interactions between the pathogen, the hosts, and the spatiotemporal variations of its ecosystems. Five reservoir system models have been proposed: (i) assemblages of small mammals with different levels of susceptibility and roles in the maintenance and amplification of the cycle; (ii) species-specific chronic infection models; (ii) flea vectors as the true reservoirs; (iii) Telluric Plague, and (iv) a metapopulation arrangement for species with a discrete spatial organization, following a source-sink dynamic of extinction and recolonization with naïve potential hosts...
October 2016: PLoS Neglected Tropical Diseases
Martin Vyska, Nik Cunniffe, Christopher Gilligan
The deployment of crop varieties that are partially resistant to plant pathogens is an important method of disease control. However, a trade-off may occur between the benefits of planting the resistant variety and a yield penalty, whereby the standard susceptible variety outyields the resistant one in the absence of disease. This presents a dilemma: deploying the resistant variety is advisable only if the disease occurs and is sufficient for the resistant variety to outyield the infected standard variety. Additionally, planting the resistant variety carries with it a further advantage in that the resistant variety reduces the probability of disease invading...
October 2016: Journal of the Royal Society, Interface
Katrina A Lythgoe, François Blanquart, Lorenzo Pellis, Christophe Fraser
The viral population of HIV-1, like many pathogens that cause systemic infection, is structured and differentiated within the body. The dynamics of cellular immune trafficking through the blood and within compartments of the body has also received wide attention. Despite these advances, mathematical models, which are widely used to interpret and predict viral and immune dynamics in infection, typically treat the infected host as a well-mixed homogeneous environment. Here, we present mathematical, analytical, and computational results that demonstrate that consideration of the spatial structure of the viral population within the host radically alters predictions of previous models...
October 2016: PLoS Biology
Mayte Castellano, German Martinez, Maria Carmen Marques, Jordi Moreno-Romero, Claudia Köhler, Vicente Pallas, Gustavo Gomez
Eukaryotic organisms exposed to adverse conditions are required to show a certain degree of transcriptional plasticity in order to cope successfully with stress. Epigenetic regulation of the genome is a key regulatory mechanism allowing dynamic changes of the transcriptional status of the plant in response to stress. The Hop stunt viroid (HSVd) induces the demethylation of ribosomal RNA (rRNA) in cucumber (Cucumis sativus) leaves, leading to increasing transcription rates of rRNA. In addition to the clear alterations observed in vegetative tissues, HSVd infection is also associated with drastic changes in gametophyte development...
October 2016: Journal of Experimental Botany
Esther Rubio-Portillo, Fernando Santos, Manuel Martínez-García, Asunción de Los Ríos, Carmen Ascaso, Virginia Souza-Egipsy, Alfonso A Ramos-Esplá, Josefa Anton
Corals are known to contain a diverse microbiota that plays a paramount role in the physiology and health of holobiont. However, few studies have addressed the variability of bacterial communities within the coral host. In this study, bacterial community composition from the mucus, tissue and skeleton of the scleractinian coral Oculina patagonica were investigated seasonally at two locations in the Western Mediterranean Sea, to further understand how environmental conditions and the coral microbiome structure are related...
September 30, 2016: Environmental Microbiology
Fumiaki Makino, Dakang Shen, Naoko Kajimura, Akihiro Kawamoto, Panayiota Pissaridou, Henry Oswin, Maria Pain, Isabel Murillo, Keiichi Namba, Ariel J Blocker
Type III secretion systems (T3SSs) are essential devices in the virulence of many Gram-negative bacterial pathogens. They mediate injection of protein effectors of virulence from bacteria into eukaryotic host cells to manipulate them during infection. T3SSs involved in virulence (vT3SSs) are evolutionarily related to bacterial flagellar protein export apparatuses (fT3SSs), which are essential for flagellar assembly and cell motility. The structure of the external and transmembrane parts of both fT3SS and vT3SS is increasingly well-defined...
September 30, 2016: Scientific Reports
Marion A L Picard, Jérôme Boissier, David Roquis, Christoph Grunau, Jean-François Allienne, David Duval, Eve Toulza, Nathalie Arancibia, Conor R Caffrey, Thavy Long, Sabine Nidelet, Marine Rohmer, Céline Cosseau
BACKGROUND: Among more than 20,000 species of hermaphroditic trematodes, Schistosomatidae are unusual since they have evolved gonochorism. In schistosomes, sex is determined by a female heterogametic system, but phenotypic sexual dimorphism appears only after infection of the vertebrate definitive host. The completion of gonad maturation occurs even later, after pairing. To date, the molecular mechanisms that trigger the sexual differentiation in these species remain unknown, and in vivo studies on the developing schistosomulum stages are lacking...
September 2016: PLoS Neglected Tropical Diseases
Emily E Helliwell, Qin Wang, Yinong Yang
Recent studies have suggested that ethylene enhances host resistance to fungal pathogen Magnaporthe oryzae, the causal agent of rice blast disease. Among the six ACS genes in rice, OsACS1 and OsACS2 are induced within 24 hours of inoculation by M. oryzae. This induction occurs simultaneously with an increase in ethylene production that is noticeable 12 hours post inoculation. The purpose of this study was to examine the dynamics of ethylene production and signaling in wild type and RNAi-mediated suppression lines deficient in ethylene production (acs2) or signaling (eil1) after challenge with M...
September 27, 2016: Molecular Plant-microbe Interactions: MPMI
Scott R Loss, Bruce H Noden, Gabriel L Hamer, Sarah A Hamer
Birds play a central role in the ecology of tick-borne pathogens. They expand tick populations and pathogens across vast distances and serve as reservoirs that maintain and amplify transmission locally. Research into the role of birds for supporting ticks and tick-borne pathogens has largely been descriptive and focused in small areas. To expand inference beyond these studies, we conducted a quantitative review at the scale of North America to identify avian life history correlates of tick infestation and pathogen prevalence, calculate species-level indices of importance for carrying ticks, and identify research gaps limiting understanding of tick-borne pathogen transmission...
December 2016: Oecologia
Daozhou Gao, Travis C Porco, Shigui Ruan
A susceptible-infectious-susceptible (SIS) epidemic model that describes the coinfection and cotransmission of two infectious diseases spreading through a single population is studied. The host population consists of two subclasses: susceptible and infectious, and the infectious individuals are further divided into three subgroups: those infected by the first agent/pathogen, the second agent/pathogen, and both. The basic reproduction numbers for all cases are derived which completely determine the global stability of the system if the presence of one agent/pathogen does not affect the transmission of the other...
October 1, 2016: Journal of Mathematical Analysis and Applications
Marcio L Rodrigues, Debora L Oliveira, Gabriele Vargas, Wendell Girard-Dias, Anderson J Franzen, Susana Frasés, Kildare Miranda, Leonardo Nimrichter
Extracellular vesicles (EV) are important carriers of biologically active components in a number of organisms, including fungal cells. Experimental characterization of fungal EVs suggested that these membranous compartments are likely involved in the regulation of several biological events. In fungal pathogens, these events include mechanisms of disease progression and/or control, suggesting potential targets for therapeutic intervention or disease prophylaxis. In this manuscript we describe methods that have been used in the last 10 years for the characterization of EVs produced by yeast forms of several fungal species...
2016: Methods in Molecular Biology
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