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Sánchez-Vallet, Andrea, Simone Fouché, Isabelle Fudal, Fanny E. Hartmann, Jessica L. Soyer, Aurélien Tellier, and Daniel Croll. "The Genome Biology of Effector Gene Evolution in Filamentous Plant Pathogens." Annual Review of Phytopathology 56, no. 1 (August 25, 2018): 21–40. http://dx.doi.org/10.1146/annurev-phyto-080516-035303.
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Filamentous pathogens, including fungi and oomycetes, pose major threats to global food security. Crop pathogens cause damage by secreting effectors that manipulate the host to the pathogen's advantage. Genes encoding such effectors are among the most rapidly evolving genes in pathogen genomes. Here, we review how the major characteristics of the emergence, function, and regulation of effector genes are tightly linked to the genomic compartments where these genes are located in pathogen genomes. The presence of repetitive elements in these compartments is associated with elevated rates of point mutations and sequence rearrangements with a major impact on effector diversification. The expression of many effectors converges on an epigenetic control mediated by the presence of repetitive elements. Population genomics analyses showed that rapidly evolving pathogens show high rates of turnover at effector loci and display a mosaic in effector presence-absence polymorphism among strains. We conclude that effective pathogen containment strategies require a thorough understanding of the effector genome biology and the pathogen's potential for rapid adaptation.
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Ehrlich, Garth D., N. Luisa Hiller, and Fen Hu. "What makes pathogens pathogenic." Genome Biology 9, no. 6 (2008): 225. http://dx.doi.org/10.1186/gb-2008-9-6-225.
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Tkáčová, Z., E. Káňová, I. Jiménez-Munguía, Ľ. Čomor, I. Širochmanová, K. Bhide, and M. Bhide. "Crossing the Blood-Brain Barrier by Neuroinvasive Pathogens." Folia Veterinaria 62, no. 1 (March 1, 2018): 44–51. http://dx.doi.org/10.2478/fv-2018-0007.
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Abstract The penetration of the blood-brain barrier (BBB) and invasion of the central nervous system (CNS) are important steps for all neuroinvasive pathogens. All of the ways of pathogens passing through the BBB are still unclear. Among known pathways, pathogen traversal can occur paracellularly, transcellularly or using a “Trojan horse” mechanism. The first step of translocation across the BBB is the interactions of the pathogen’s ligands with the receptors of the host brain cells. Lyme disease, the most common vector-borne disease in the temperate zones of Europe and North America, are caused by Borreliella species (former Borrelia burgdorferi sensu lato) that affects the peripheral and the CNS. In this review, we have presented various pathogen interactions with endothelial cells, which allow the disruption of the BBB so that the pathogens can pass across the BBB.
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WACHTEL, MARIAN R., JAMES L. McEVOY, YAGUANG LUO, ANISHA M. WILLIAMS-CAMPBELL, and MORSE B. SOLOMON. "Cross-Contamination of Lettuce (Lactuca sativa L.) with Escherichia coli O157:H7 via Contaminated Ground Beef†." Journal of Food Protection 66, no. 7 (July 1, 2003): 1176–83. http://dx.doi.org/10.4315/0362-028x-66.7.1176.
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A lettuce outbreak strain of E. coli O157:H7 was used to quantitate the pathogen's survival in ground beef and its transfer to hands, cutting board surfaces, and lettuce. Overnight storage of inoculated beef at 4°C resulted in no pathogen growth, while room-temperature storage allowed multiplication. Hamburger patty formation allowed the transfer of bacteria to hands. Contaminated fingers subsequently transferred the pathogen to lettuce during handling. E. coli was transferred from hamburgers to cutting board surfaces; overnight storage of boards decreased the numbers of recoverable pathogens by ~1 log CFU. A 15-s water rinse failed to remove significant numbers of pathogens from cutting boards whether it was applied immediately after contamination or following overnight room-temperature storage. Three lettuce leaves were successively applied to a single contaminated cutting board area both immediately after contamination and after overnight room-temperature storage of contaminated boards. Another set of leaves was pressed onto boards immediately following contamination and was then stored overnight at 4°C before pathogen enumeration. The numbers of pathogens transferred to the first pressed leaves were larger than those transferred to the second or third leaves. There were no significant differences in the numbers of pathogens recovered from leaves pressed immediately after contamination whether pathogens were enumerated immediately or following overnight storage at 4°C. However, fewer pathogens were transferred to leaves pressed to boards stored overnight at room temperature prior to contact with lettuce. Twenty-five lettuce pieces were successively pressed onto one area on a board containing 1.25 × 102 CFU of E. coli. Pathogens were transferred to 46% of the leaves, including the 25th exposed leaf.
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Cunze, Sarah, Judith Kochmann, Lisa K. Koch, Korbinian J. Q. Hasselmann, and Sven Klimpel. "Leishmaniasis in Eurasia and Africa: geographical distribution of vector species and pathogens." Royal Society Open Science 6, no. 5 (May 2019): 190334. http://dx.doi.org/10.1098/rsos.190334.
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Leishmaniasis is a vector-borne disease with a broad global occurrence and an increasing number of recorded cases; however, it is still one of the world's most neglected diseases. We here provide climatic suitability maps generated by means of an ecological niche modelling approach for 32 Phlebotomus vector species with proven or suspected vector competence for five Leishmania pathogens occurring in Eurasia and Africa. A GIS-based spatial overlay analysis was then used to compare the distributional patterns of vectors and pathogens to help evaluate the vector species–pathogen relationship currently found in the literature. Based on this single factor of vector incrimination, that is, co-occurrence of both vector and pathogen, most of the pathogens occurred with at least one of the associated vector species. In the case of L. donovani , only a not yet confirmed vector species, P. rodhaini, could explain the occurrence of the pathogen in regions of Africa. Phlebotomus alexandri and P. longiductus on the other hand, proven vector species of L. donovani, do not seem to qualify as vectors for the pathogen. Their distribution is restricted to northern latitudes and does not match the pathogen's distribution, which lies in southern latitudes. Other more locally confined mismatches were discussed for each pathogen species. The comparative geographical GIS-overlay of vector species and pathogens functions as a first indication that testing and re-evaluation of some pathogen–vector relationships might be worthwhile to improve risk assessments of leishmaniasis.
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Kumar, Ankit, Priyanshu Srivastava, PDNN Sirisena, Sunil Dubey, Ramesh Kumar, Jatin Shrinet, and Sujatha Sunil. "Mosquito Innate Immunity." Insects 9, no. 3 (August 8, 2018): 95. http://dx.doi.org/10.3390/insects9030095.
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Mosquitoes live under the endless threat of infections from different kinds of pathogens such as bacteria, parasites, and viruses. The mosquito defends itself by employing both physical and physiological barriers that resist the entry of the pathogen and the subsequent establishment of the pathogen within the mosquito. However, if the pathogen does gain entry into the insect, the insect mounts a vigorous innate cellular and humoral immune response against the pathogen, thereby limiting the pathogen’s propagation to nonpathogenic levels. This happens through three major mechanisms: phagocytosis, melanization, and lysis. During these processes, various signaling pathways that engage intense mosquito–pathogen interactions are activated. A critical overview of the mosquito immune system and latest information about the interaction between mosquitoes and pathogens are provided in this review. The conserved, innate immune pathways and specific anti-pathogenic strategies in mosquito midgut, hemolymph, salivary gland, and neural tissues for the control of pathogen propagation are discussed in detail.
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Mazarei, Mitra, Irina Teplova, M. Hajimorad, and C. Stewart. "Pathogen Phytosensing: Plants to Report Plant Pathogens." Sensors 8, no. 4 (April 14, 2008): 2628–41. http://dx.doi.org/10.3390/s8042628.
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Lepper, Simone, and Sylvia Münter. "Spotlight on pathogens: ‘Imaging Host-Pathogen Interactions’." Cellular Microbiology 11, no. 6 (June 2009): 855–62. http://dx.doi.org/10.1111/j.1462-5822.2009.01321.x.
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Rall, Björn C., and Ellen Latz. "Analyzing pathogen suppressiveness in bioassays with natural soils using integrative maximum likelihood methods in R." PeerJ 4 (November 3, 2016): e2615. http://dx.doi.org/10.7717/peerj.2615.
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The potential of soils to naturally suppress inherent plant pathogens is an important ecosystem function. Usually, pathogen infection assays are used for estimating the suppressive potential of soils. In natural soils, however, co-occurring pathogens might simultaneously infect plants complicating the estimation of a focal pathogen’s infection rate (initial slope of the infection-curve) as a measure of soil suppressiveness. Here, we present a method in R correcting for these unwanted effects by developing a two pathogen mono-molecular infection model. We fit the two pathogen mono-molecular infection model to data by using an integrative approach combining a numerical simulation of the model with an iterative maximum likelihood fit. We show that in presence of co-occurring pathogens using uncorrected data leads to a critical under- or overestimation of soil suppressiveness measures. In contrast, our new approach enables to precisely estimate soil suppressiveness measures such as plant infection rate and plant resistance time. Our method allows a correction of measured infection parameters that is necessary in case different pathogens are present. Moreover, our model can be (1) adapted to use other models such as the logistic or the Gompertz model; and (2) it could be extended by a facilitation parameter if infections in plants increase the susceptibility to new infections. We propose our method to be particularly useful for exploring soil suppressiveness of natural soils from different sites (e.g., in biodiversity experiments).
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Janni, Michela, Luca Sella, Francesco Favaron, Ann E. Blechl, Giulia De Lorenzo, and Renato D'Ovidio. "The Expression of a Bean PGIP in Transgenic Wheat Confers Increased Resistance to the Fungal Pathogen Bipolaris sorokiniana." Molecular Plant-Microbe Interactions® 21, no. 2 (February 2008): 171–77. http://dx.doi.org/10.1094/mpmi-21-2-0171.
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A possible strategy to control plant pathogens is the improvement of natural plant defense mechanisms against the tools that pathogens commonly use to penetrate and colonize the host tissue. One of these mechanisms is represented by the host plant's ability to inhibit the pathogen's capacity to degrade plant cell wall polysaccharides. Polygalacturonase-inhibiting proteins (PGIP) are plant defense cell wall glycoproteins that inhibit the activity of fungal endopolygalacturonases (endo-PGs). To assess the effectiveness of these proteins in protecting wheat from fungal pathogens, we produced a number of transgenic wheat lines expressing a bean PGIP (PvPGIP2) having a wide spectrum of specificities against fungal PGs. Three independent transgenic lines were characterized in detail, including determination of the levels of PvPGIP2 accumulation and its subcellular localization and inhibitory activity. Results show that the transgene-encoded protein is correctly secreted into the apoplast, maintains its characteristic recognition specificities, and endows the transgenic wheat with new PG recognition capabilities. As a consequence, transgenic wheat tissue showed increased resistance to digestion by the PG of Fusarium moniliforme. These new properties also were confirmed at the plant level during interactions with the fungal pathogen Bipolaris sorokiniana. All three lines showed significant reductions in symptom progression (46 to 50%) through the leaves following infection with this pathogen. Our results illustrate the feasibility of improving wheat's defenses against pathogens by expression of proteins with new capabilities to counteract those produced by the pathogens.
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MURAKAMI, TAKU. "Filter-Based Pathogen Enrichment Technology for Detection of Multiple Viable Foodborne Pathogens in 1 Day." Journal of Food Protection 75, no. 9 (September 1, 2012): 1603–10. http://dx.doi.org/10.4315/0362-028x.jfp-12-039.
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Conventional foodborne pathogen assays currently used in the food industry often require long culture enrichments to increase pathogen levels so they can be detected. Even using sensitive real-time PCR assays, culture enrichment at least overnight is necessary especially for detection of pathogens with slow growth rates such as Listeria monocytogenes. To eliminate this cumbersome enrichment step and detect minute amounts of pathogens within 1 day, filter-based pathogen enrichment technology was developed utilizing a unique combination of glass fiber depth filter and porous filter aid materials to efficiently separate pathogens from food homogenates and avoid filter clogging by food particles. After pathogen immobilization in depth filters, only viable pathogens were selectively collected in a small volume of growth medium via microbial multiplication and migration; nonviable pathogens remained inside the filters. By assaying viable pathogens using real-time PCRs, multiple species of foodborne pathogens were detected, including L. monocytogenes, Salmonella enterica, and Escherichia coli O157:H7, at around 1 CFU/ml or 1 CFU/g in various food samples. This filter-based pathogen enrichment technology is a unique bacterial enrichment alternative to the conventional culture enrichment step and can significantly shorten the time necessary to obtain assay results.
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Romano, Julia D., Catherine de Beaumont, Jose A. Carrasco, Karen Ehrenman, Patrik M. Bavoil, and Isabelle Coppens. "Fierce Competition between Toxoplasma and Chlamydia for Host Cell Structures in Dually Infected Cells." Eukaryotic Cell 12, no. 2 (December 14, 2012): 265–77. http://dx.doi.org/10.1128/ec.00313-12.
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ABSTRACTThe prokaryoteChlamydia trachomatisand the protozoanToxoplasma gondii, two obligate intracellular pathogens of humans, have evolved a similarmodus operandito colonize their host cell and salvage nutrients from organelles. In order to gain fundamental knowledge on the pathogenicity of these microorganisms, we have established a cell culture model whereby single fibroblasts are coinfected byC. trachomatisandT. gondii. We previously reported that the two pathogens compete for the same nutrient pools in coinfected cells and thatToxoplasmaholds a significant competitive advantage overChlamydia. Here we have expanded our coinfection studies by examining the respective abilities ofChlamydiaandToxoplasmato co-opt the host cytoskeleton and recruit organelles. We demonstrate that the two pathogen-containing vacuoles migrate independently to the host perinuclear region and rearrange the host microtubular network around each vacuole. However,ToxoplasmaoutcompetesChlamydiato the host microtubule-organizing center to the detriment of the bacterium, which then shifts to a stress-induced persistent state. Solely in cells preinfected withChlamydia, the centrosomes become associated with the chlamydial inclusion, while theToxoplasmaparasitophorous vacuole displays growth defects. Both pathogens fragment the host Golgi apparatus and recruit Golgi elements to retrieve sphingolipids. This study demonstrates that the productive infection by bothChlamydiaandToxoplasmadepends on the capability of each pathogen to successfully adhere to a finely tuned developmental program that aims to remodel the host cell for the pathogen's benefit. In particular, this investigation emphasizes the essentiality of host organelle interception by intravacuolar pathogens to facilitate access to nutrients.
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Tarchevsky, I. A. "Biogenic stress in plants." Kazan medical journal 75, no. 1 (January 15, 1994): 3–9. http://dx.doi.org/10.17816/kazmj89581.
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The picture of the pathogens and plant interaction is presented. That is: recognition; the influence of different hydrolases produced by pathogens on plant biopolimers and lipids; elicitors and phytoalexins formation; pathogen-induced proteins synthesis in plants; induction of supersensitivity in cells, surrounding the pathogen infection area; the influence of plant enzymes and toxins on pathogens and finally working out plant tissues resistance against pathogens (viruses, bacteria and fungi).
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Thakur, Aneesh, Heidi Mikkelsen, and Gregers Jungersen. "Intracellular Pathogens: Host Immunity and Microbial Persistence Strategies." Journal of Immunology Research 2019 (April 14, 2019): 1–24. http://dx.doi.org/10.1155/2019/1356540.
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Infectious diseases caused by pathogens including viruses, bacteria, fungi, and parasites are ranked as the second leading cause of death worldwide by the World Health Organization. Despite tremendous improvements in global public health since 1950, a number of challenges remain to either prevent or eradicate infectious diseases. Many pathogens can cause acute infections that are effectively cleared by the host immunity, but a subcategory of these pathogens called “intracellular pathogens” can establish persistent and sometimes lifelong infections. Several of these intracellular pathogens manage to evade the host immune monitoring and cause disease by replicating inside the host cells. These pathogens have evolved diverse immune escape strategies and overcome immune responses by residing and multiplying inside host immune cells, primarily macrophages. While these intracellular pathogens that cause persistent infections are phylogenetically diverse and engage in diverse immune evasion and persistence strategies, they share common pathogen type-specific mechanisms during host-pathogen interaction inside host cells. Likewise, the host immune system is also equipped with a diverse range of effector functions to fight against the establishment of pathogen persistence and subsequent host damage. This article provides an overview of the immune effector functions used by the host to counter pathogens and various persistence strategies used by intracellular pathogens to counter host immunity, which enables their extended period of colonization in the host. The improved understanding of persistent intracellular pathogen-derived infections will contribute to develop improved disease diagnostics, therapeutics, and prophylactics.
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Veresoglou, Stavros D., and Matthias C. Rillig. "Suppression of fungal and nematode plant pathogens through arbuscular mycorrhizal fungi." Biology Letters 8, no. 2 (October 19, 2011): 214–17. http://dx.doi.org/10.1098/rsbl.2011.0874.
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Arbuscular mycorrhizal (AM) fungi represent ubiquitous mutualists of terrestrial plants. Through the symbiosis, plant hosts, among other benefits, receive protection from pathogens. A meta-analysis was conducted on 106 articles to determine whether, following pathogen infection of AM-colonized plants, the identity of the organisms involved (pathogens, AM fungi and host plants) had implications for the extent of the AM-induced pathogen suppression. Data on fungal and nematode pathogens were analysed separately. Although we found no differences in AM effectiveness with respect to the identity of the plant pathogen, the identity of the AM isolate had a dramatic effect on the level of pathogen protection. AM efficiency differences with respect to nematode pathogens were mainly limited to the number of AM isolates present; by contrast, modification of the ability to suppress fungal pathogens could occur even through changing the identity of the Glomeraceae isolate applied. N-fixing plants received more protection from fungal pathogens than non-N-fixing dicotyledons; this was attributed to the more intense AM colonization in N-fixing plants. Results have implications for understanding mycorrhizal ecology and agronomic applications.
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Recart, Wilnelia, Rover Bernhard, Isabella Ng, Katherine Garcia, and Arietta E. Fleming-Davies. "Meta-Analysis of the Effects of Insect Pathogens: Implications for Plant Reproduction." Pathogens 12, no. 2 (February 18, 2023): 347. http://dx.doi.org/10.3390/pathogens12020347.
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Despite extensive work on both insect disease and plant reproduction, there is little research on the intersection of the two. Insect-infecting pathogens could disrupt the pollination process by affecting pollinator population density or traits. Pathogens may also infect insect herbivores and change herbivory, potentially altering resource allocation to plant reproduction. We conducted a meta-analysis to (1) summarize the literature on the effects of pathogens on insect pollinators and herbivores and (2) quantify the extent to which pathogens affect insect traits, with potential repercussions for plant reproduction. We found 39 articles that fit our criteria for inclusion, extracting 218 measures of insect traits for 21 different insect species exposed to 25 different pathogens. We detected a negative effect of pathogen exposure on insect traits, which varied by host function: pathogens had a significant negative effect on insects that were herbivores or carried multiple functions but not on insects that solely functioned as pollinators. Particular pathogen types were heavily studied in certain insect orders, with 7 of 11 viral pathogen studies conducted in Lepidoptera and 5 of 9 fungal pathogen studies conducted in Hymenoptera. Our results suggest that most studies have focused on a small set of host–pathogen pairs. To understand the implications for plant reproduction, future work is needed to directly measure the effects of pathogens on pollinator effectiveness.
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Conceição, Cinara Souza da, Barbara Victor Souza, Jessica Manya Bittencourt Dias Vieira, and Janaína dos Santos Nascimento. "Pathogen killing pathogen: antimicrobial substance from Acinetobacter active against foodborne pathogens." Journal of Infection in Developing Countries 12, no. 05 (May 31, 2018): 297–304. http://dx.doi.org/10.3855/jidc.9894.
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Introduction: Antimicrobial substances (AMS) produced by bacteria may reduce or prevent the growth of pathogenic and spoilage microorganisms in food. In this study, 16 isolates of Acinetobacter baumannii/calcoaceticus (ABC) complex, previously obtained from reconstituted infant milk formula (IMF) samples and the preparation and distribution utensils from the nursery of a public hospital, were used to screen for AMS production.
Methodology: Antimicrobial substance production and spectrum of activity assays were performed by agar-spot assay. Optimization of growth conditions for AMS production was also evaluated.
Results: Three (17.6%) isolates, namely JE3, JE4, and JE6, produced AMS against the principal indicator strain Salmonella enterica subsp. enterica serotype Typhi ATCC 19214. JE6 was also able to inhibit strains of Klebsiella pneumoniae, Proteus vulgaris, and Bacillus cereus, a Gram-positive bacteria. Remarkably, JE6 was able to inhibit all the tested resistant and multidrug-resistant (MDR) strains of the ABC complex and Shigella dysenteriae associated with IMF and utensils, indicating a potentially valuable application. AMS produced by JE6 does not appear to be affected by proteolytic enzymes and the producer strain showed specific immunity to its own AMS.
Conclusion: This study highlights AMS produced by Acinetobacter with applications against MDR spoilage and foodborne pathogens - some of them, infectious disease causing agents - which, to our knowledge, has not been previously described.
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Porta, Amalia, Annamaria Eletto, Zsolt Török, Silvia Franceschelli, Attila Glatz, László Vígh, and Bruno Maresca. "Changes in Membrane Fluid State and Heat Shock Response Cause Attenuation of Virulence." Journal of Bacteriology 192, no. 7 (February 5, 2010): 1999–2005. http://dx.doi.org/10.1128/jb.00990-09.
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ABSTRACT So far attenuation of pathogens has been mainly obtained by chemical or heat treatment of microbial pathogens. Recently, live attenuated strains have been produced by genetic modification. We have previously demonstrated that in several prokaryotes as well as in yeasts and mammalian cells the heat shock response is controlled by the membrane physical state (MPS). We have also shown that in Salmonella enterica serovar Typhimurium LT2 (Salmonella Typhimurium) overexpression of a Δ12-desaturase gene alters the MPS, inducing a sharp impairment of transcription of major heat shock genes and failure of the pathogen to grow inside macrophage (MΦ) (A. Porta et al., J. Bacteriol. 192:1988-1998, 2010). Here, we show that overexpression of a homologous Δ9-desaturase sequence in the highly virulent G217B strain of the human fungal pathogen Histoplasma capsulatum causes loss of its ability to survive and persist within murine MΦ along with the impairment of the heat shock response. When the attenuated strain of H. capsulatum was injected in a mouse model of infection, it did not cause disease. Further, treated mice were protected when challenged with the virulent fungal parental strain. Attenuation of virulence in MΦ of two evolutionarily distant pathogens was obtained by genetic modification of the MPS, suggesting that this is a new method that may be used to produce attenuation or loss of virulence in both other intracellular prokaryotic and eukaryotic pathogens. This new procedure to generate attenuated forms of pathogens may be used eventually to produce a novel class of vaccines based on the genetic manipulation of a pathogen's membrane fluid state and stress response.
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Voigt, Benjamin, Oliver Fischer, Christian Krumnow, Christian Herta, and Piotr Wojciech Dabrowski. "NGS read classification using AI." PLOS ONE 16, no. 12 (December 22, 2021): e0261548. http://dx.doi.org/10.1371/journal.pone.0261548.
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Clinical metagenomics is a powerful diagnostic tool, as it offers an open view into all DNA in a patient’s sample. This allows the detection of pathogens that would slip through the cracks of classical specific assays. However, due to this unspecific nature of metagenomic sequencing, a huge amount of unspecific data is generated during the sequencing itself and the diagnosis only takes place at the data analysis stage where relevant sequences are filtered out. Typically, this is done by comparison to reference databases. While this approach has been optimized over the past years and works well to detect pathogens that are represented in the used databases, a common challenge in analysing a metagenomic patient sample arises when no pathogen sequences are found: How to determine whether truly no evidence of a pathogen is present in the data or whether the pathogen’s genome is simply absent from the database and the sequences in the dataset could thus not be classified? Here, we present a novel approach to this problem of detecting novel pathogens in metagenomic datasets by classifying the (segments of) proteins encoded by the sequences in the datasets. We train a neural network on the sequences of coding sequences, labeled by taxonomic domain, and use this neural network to predict the taxonomic classification of sequences that can not be classified by comparison to a reference database, thus facilitating the detection of potential novel pathogens.
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Meddya, Sandipan, Shweta Meshram, Deepranjan Sarkar, Rakesh S, Rahul Datta, Sachidanand Singh, Gosangi Avinash, Arun Kumar Kondeti, Ajit Kumar Savani, and Thiyagarajan Thulasinathan. "Plant Stomata: An Unrealized Possibility in Plant Defense against Invading Pathogens and Stress Tolerance." Plants 12, no. 19 (September 25, 2023): 3380. http://dx.doi.org/10.3390/plants12193380.
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Stomata are crucial structures in plants that play a primary role in the infection process during a pathogen’s attack, as they act as points of access for invading pathogens to enter host tissues. Recent evidence has revealed that stomata are integral to the plant defense system and can actively impede invading pathogens by triggering plant defense responses. Stomata interact with diverse pathogen virulence factors, granting them the capacity to influence plant susceptibility and resistance. Moreover, recent studies focusing on the environmental and microbial regulation of stomatal closure and opening have shed light on the epidemiology of bacterial diseases in plants. Bacteria and fungi can induce stomatal closure using pathogen-associated molecular patterns (PAMPs), effectively preventing entry through these openings and positioning stomata as a critical component of the plant’s innate immune system; however, despite this defense mechanism, some microorganisms have evolved strategies to overcome stomatal protection. Interestingly, recent research supports the hypothesis that stomatal closure caused by PAMPs may function as a more robust barrier against pathogen infection than previously believed. On the other hand, plant stomatal closure is also regulated by factors such as abscisic acid and Ca2+-permeable channels, which will also be discussed in this review. Therefore, this review aims to discuss various roles of stomata during biotic and abiotic stress, such as insects and water stress, and with specific context to pathogens and their strategies for evading stomatal defense, subverting plant resistance, and overcoming challenges faced by infectious propagules. These pathogens must navigate specific plant tissues and counteract various constitutive and inducible resistance mechanisms, making the role of stomata in plant defense an essential area of study.
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Delavaux, Camille S., Josh L. Schemanski, Geoffrey L. House, Alice G. Tipton, Benjamin Sikes, and James D. Bever. "Root pathogen diversity and composition varies with climate in undisturbed grasslands, but less so in anthropogenically disturbed grasslands." ISME Journal 15, no. 1 (September 21, 2020): 304–17. http://dx.doi.org/10.1038/s41396-020-00783-z.
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AbstractSoil-borne pathogens structure plant communities, shaping their diversity, and through these effects may mediate plant responses to climate change and disturbance. Little is known, however, about the environmental determinants of plant pathogen communities. Therefore, we explored the impact of climate gradients and anthropogenic disturbance on root-associated pathogens in grasslands. We examined the community structure of two pathogenic groups—fungal pathogens and oomycetes—in undisturbed and anthropogenically disturbed grasslands across a natural precipitation and temperature gradient in the Midwestern USA. In undisturbed grasslands, precipitation and temperature gradients were important predictors of pathogen community richness and composition. Oomycete richness increased with precipitation, while fungal pathogen richness depended on an interaction of precipitation and temperature, with precipitation increasing richness most with higher temperatures. Disturbance altered plant pathogen composition and precipitation and temperature had a reduced effect on pathogen richness and composition in disturbed grasslands. Because pathogens can mediate plant community diversity and structure, the sensitivity of pathogens to disturbance and climate suggests that degradation of the pathogen community may mediate loss, or limit restoration of, native plant diversity in disturbed grasslands, and may modify plant community response to climate change.
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Galle, Jan N., and Johannes H. Hegemann. "Exofacial phospholipids at the plasma membrane: ill-defined targets for early infection processes." Biological Chemistry 400, no. 10 (October 25, 2019): 1323–34. http://dx.doi.org/10.1515/hsz-2019-0187.
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Abstract The eukaryotic plasma membrane (PM) consists largely of phospholipids and proteins, and separates the intracellular compartments from the extracellular space. It also serves as a signaling platform for cell-to-cell communication and an interaction platform for the molecular crosstalk between pathogens and their target cells. Much research has been done to elucidate the interactions between pathogens and host membrane proteins. However, little is known about the interactions between pathogens and membrane phospholipids, although reports have described a contribution of phospholipids to cell recognition and/or invasion during early infection by diverse pathogens. Thus, during adhesion to the host cell, the obligate intracellular bacterial pathogens Chlamydia spp., the facultative intracellular pathogen Helicobacter pylori and the facultative aerobic pathogen Vibrio parahaemolyticus, interact with exofacial phospholipids. This review focuses on several prominent instances of pathogen interaction with host-cell phospholipids.
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Wu, J., S. C. Long, D. Das, and S. M. Dorner. "Are microbial indicators and pathogens correlated? A statistical analysis of 40 years of research." Journal of Water and Health 9, no. 2 (April 25, 2011): 265–78. http://dx.doi.org/10.2166/wh.2011.117.
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Indicator organisms are used to assess public health risk in recreational waters, to highlight periods of challenge to drinking water treatment plants, and to determine the effectiveness of treatment and the quality of distributed water. However, many have questioned their efficacy for indicating pathogen risk. Five hundred and forty cases representing independent indicator–pathogen correlations were obtained from the literature for the period 1970–2009. The data were analyzed to assess factors affecting correlations using a logistic regression model considering indicator classes, pathogen classes, water types, pathogen sources, sample size, the number of samples with pathogens, the detection method, year of publication and statistical methods. Although no single indicator was identified as the most correlated with pathogens, coliphages, F-specific coliphages, Clostridium perfringens, fecal streptococci and total coliforms were more likely than other indicators to be correlated with pathogens. The most important factors in determining correlations between indicator–pathogen pairs were the sample size and the number of samples positive for pathogens. Pathogen sources, detection methods and other variables have little influence on correlations between indicators and pathogens. Results suggest that much of the controversy with regards to indicator and pathogen correlations is the result of studies with insufficient data for assessing correlations.
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Rotem, Shahar, Erez Bar-Haim, Uri Elia, Hila Cohen, Shirley Lazar, Ofer Cohen, Theodor Chitlaru, and Yoav Gal. "A Novel Approach to Vaccine Development: Concomitant Pathogen Inactivation and Host Immune Stimulation by Peroxynitrite." Vaccines 10, no. 10 (September 22, 2022): 1593. http://dx.doi.org/10.3390/vaccines10101593.
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The design of efficient vaccines for long-term protective immunity against pathogens represents an objective of utmost public health priority. In general, live attenuated vaccines are considered to be more effective than inactivated pathogens, yet potentially more reactogenic. Accordingly, inactivation protocols which do not compromise the pathogen’s ability to elicit protective immunity are highly beneficial. One of the sentinel mechanisms of the host innate immune system relies on the production of reactive nitrogen intermediates (RNI), which efficiently inactivate pathogens. Peroxynitrite (PN) is a prevalent RNI, assembled spontaneously upon the interaction of nitric oxide (NO) with superoxide. PN exerts its bactericidal effect by via the efficient oxidation of a broad range of biological molecules. Furthermore, the interaction of PN with proteins results in structural/chemical modifications, such as the oxidation of tryptophan, tyrosine, and cysteine residues, as well as the formation of carbonyl, dityrosine, and nitrotyrosine (NT). In addition to their role in innate immunity, these PN-mediated modifications of pathogen components may also augment the antigenicity of pathogen peptides and proteins, hence contributing to specific humoral responses. In the study reported here, a novel approach for vaccine development, consisting of pathogen inactivation by PN, combined with increased immunity of NT-containing peptides, is implemented as a proof-of-concept for vaccination against the intracellular pathogen Francisella tularensis (F. tularensis). In vivo experiments in a murine model of tularemia confirm that PN-inactivated F. tularensis formulations may rapidly stimulate innate and adaptive immune cells, conferring efficient protection against a lethal challenge, superior to that elicited by bacteria inactivated by the widely used formalin treatment.
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Zhao, Lei, Minrui Wang, Jingwei Li, Zhenhua Cui, Gayle M. Volk, and Qiaochun Wang. "Cryobiotechnology: A Double-Edged Sword for Obligate Plant Pathogens." Plant Disease 103, no. 6 (June 2019): 1058–67. http://dx.doi.org/10.1094/pdis-11-18-1989-fe.
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Pathogen-free stock plants are required as propagation materials in nurseries and healthy materials are needed in germplasm exchange between countries or regions through quarantine programs. In addition, plant gene banks also prefer to maintain pathogen-free germplasm collections. Shoot tip cryotherapy is a novel biotechnology method whereby cryopreservation methods are used to eradicate obligate pathogens from vegetatively propagated plants. Long-term preservation of pathogens is necessary in all types of virus-related basic research and applications such as antigen preparation for virus detection by immunology-based methods, production of plant-based vaccines, genetic transformation to produce virus-derived resistant transgenic plants, and bionanotechnology to produce nano drugs. Obligate plant pathogens such as viruses and viroids are intracellular parasites that colonize only living cells of the hosts. Therefore, their long-term preservation is difficult. Cryotreatments cannot completely eradicate the obligate pathogens that do not infect meristematic cells and certain proportions of plants recovered from cryotreatments are still pathogen-infected. Furthermore, cryotreatments often fail to eradicate the obligate pathogens that infect meristematic cells. Cryopreservation can be used for the long-term cryopreservation of the obligate plant pathogens. Thus, cryobiotechnology functions as a double-edged sword for plant pathogen eradication and cryopreservation. This review provides updated a synthesis of advances in cryopreservation techniques for eradication and cryopreservation of obligate plant pathogens.
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Lanzas, Cristina, Kale Davies, Samantha Erwin, and Daniel Dawson. "On modelling environmentally transmitted pathogens." Interface Focus 10, no. 1 (December 13, 2019): 20190056. http://dx.doi.org/10.1098/rsfs.2019.0056.
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Many pathogens are able to replicate or survive in abiotic environments. Disease transmission models that include environmental reservoirs and environment-to-host transmission have used a variety of functional forms and modelling frameworks without a clear connection to pathogen ecology or space and time scales. We present a conceptual framework to organize microparasites based on the role that abiotic environments play in their lifecycle. Mean-field and individual-based models for environmental transmission are analysed and compared. We show considerable divergence between both modelling approaches when conditions do not facilitate well mixing and for pathogens with fast dynamics in the environment. We conclude with recommendations for modelling environmentally transmitted pathogens based on the pathogen lifecycle and time and spatial scales of the host–pathogen system under consideration.
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Inal, Jameel M., Ephraim A. Ansa-Addo, and Sigrun Lange. "Interplay of host–pathogen microvesicles and their role in infectious disease." Biochemical Society Transactions 41, no. 1 (January 29, 2013): 258–62. http://dx.doi.org/10.1042/bst20120257.
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The release of extracellular vesicles, whether MVs (microvesicles) or exosomes, from host cells or intracellular pathogens is likely to play a significant role in the infection process. Host MVs may fuse with pathogen surfaces to deliver host complement regulatory proteins. They may also deliver cytokines that enhance invasion. Decoy functions are also possible. Whereas host MVs may direct pathogens away from their target cells, pathogen MVs may in turn redirect complement membrane-attack complexes away from their target pathogen. An understanding of the mechanisms of this interplay, bringing about both immune evasion and enhanced invasion, will help to direct future research with a view to rendering pathogens more susceptible to immune attack or in improving drug efficacy. It should also be possible to use MVs or exosomes isolated directly from the pathogens, or from the cells infected with pathogens, to provide alternative vaccination strategies.
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Fonville, Judith M. "Expected Effect of Deleterious Mutations on Within-Host Adaptation of Pathogens." Journal of Virology 89, no. 18 (June 24, 2015): 9242–51. http://dx.doi.org/10.1128/jvi.00832-15.
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ABSTRACTAdaptation is a common theme in both pathogen emergence, for example, in zoonotic cross-species transmission, and pathogen control, where adaptation might limit the effect of the immune response and antiviral treatment. When such evolution requires deleterious intermediate mutations, fitness ridges and valleys arise in the pathogen's fitness landscape. The effect of deleterious intermediate mutations on within-host pathogen adaptation is examined with deterministic calculations, appropriate for pathogens replicating in large populations with high error rates. The effect of deleterious intermediate mutations on pathogen adaptation is smaller than their name might suggest: when two mutations are required and each individual single mutation is fully deleterious, the pathogen can jump across the fitness valley by obtaining two mutations at once, leading to a proportion of adapted mutants that is 20-fold lower than that in the situation where the fitness of all mutants is neutral. The negative effects of deleterious intermediates are typically substantially smaller and outweighed by the fitness advantages of the adapted mutant. Moreover, requiring a specific mutation order has a substantially smaller effect on pathogen adaptation than the effect of all intermediates being deleterious. These results can be rationalized when the number of routes of mutation available to the pathogen is calculated, providing a simple approach to estimate the effect of deleterious mutations. The calculations discussed here are applicable when the effect of deleterious mutations on the within-host adaptation of pathogens is assessed, for example, in the context of zoonotic emergence, antigenic escape, and drug resistance.IMPORTANCEAdaptation is critical for pathogens after zoonotic transmission into a new host species or to achieve antigenic immune escape and drug resistance. Using a deterministic approach, the effects of deleterious intermediate mutations on pathogen adaptation were calculated while avoiding commonly made simplifications that do not apply to large pathogen populations replicating with high mutation rates. Perhaps unexpectedly, pathogen adaptation does not halt when the intermediate mutations are fully deleterious. The negative effects of deleterious mutations are substantially outweighed by the fitness gains of adaptation. To gain an understanding of the effect of deleterious mutations on pathogen adaptation, a simple approach that counts the number of routes available to the pathogen with and without deleterious intermediate mutations is introduced. This methodology enables a straightforward calculation of the proportion of the pathogen population that will cross a fitness valley or traverse a fitness ridge, without reverting to more complicated mathematical models.
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Qiao, Yongli, Rui Xia, Jixian Zhai, Yingnan Hou, Li Feng, Yi Zhai, and Wenbo Ma. "Small RNAs in Plant Immunity and Virulence of Filamentous Pathogens." Annual Review of Phytopathology 59, no. 1 (August 25, 2021): 265–88. http://dx.doi.org/10.1146/annurev-phyto-121520-023514.
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Gene silencing guided by small RNAs governs a broad range of cellular processes in eukaryotes. Small RNAs are important components of plant immunity because they contribute to pathogen-triggered transcription reprogramming and directly target pathogen RNAs. Recent research suggests that silencing of pathogen genes by plant small RNAs occurs not only during viral infection but also in nonviral pathogens through a process termed host-induced gene silencing, which involves trans-species small RNA trafficking. Similarly, small RNAs are also produced by eukaryotic pathogens and regulate virulence. This review summarizes the small RNA pathways in both plants and filamentous pathogens, including fungi and oomycetes, and discusses their role in host–pathogen interactions. We highlight secondarysmall interfering RNAs of plants as regulators of immune receptor gene expression and executors of host-induced gene silencing in invading pathogens. The current status and prospects of trans-species gene silencing at the host–pathogen interface are discussed.
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Magunda, Forgivemore, Chelsea Wright Thompson, David A. Schneider, and Susan M. Noh. "Anaplasma marginale Actively Modulates Vacuolar Maturation during Intracellular Infection of Its Tick Vector, Dermacentor andersoni." Applied and Environmental Microbiology 82, no. 15 (May 27, 2016): 4715–31. http://dx.doi.org/10.1128/aem.01030-16.
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ABSTRACTTick-borne transmission of bacterial pathogens in the orderRickettsialesis responsible for diverse infectious diseases, many of them severe, in humans and animals. Transmission dynamics differ among these pathogens and are reflected in the pathogen-vector interaction.Anaplasma marginalehas been shown to establish and maintain infectivity withinDermacentorspp. for weeks to months while escaping the complex network of vacuolar peptidases that are responsible for digestion of the tick blood meal. How this prolonged maintenance of infectivity in a potentially hostile environment is achieved has been unknown. Using the natural vectorDermacentor andersoni, we demonstrated thatA. marginale-infected tick vacuoles (AmVs) concurrently recruit markers of the early endosome (Rab5), recycling endosome (Rab4 and Rab11), and late endosome (Rab7), are maintained near neutral pH, do not fuse with lysosomes, exclude the protease cathepsin L, and engage the endoplasmic reticulum and Golgi apparatus for up to 21 days postinfection. Maintenance of this safe vacuolar niche requires activeA. marginaleprotein synthesis; in its absence, the AmVs mature into acidic, protease-active phagolysosomes. Identification of this bacterially directed modeling of the tick midgut endosome provides a mechanistic basis for examination of the differences in transmission efficiency observed amongA. marginalestrains and among vector populations.IMPORTANCETicks transmit a variety of intracellular bacterial pathogens that cause significant diseases in humans and animals. For successful transmission, these bacterial pathogens must first gain entry into the tick midgut digestive cells, avoid digestion, and establish a replicative niche without harming the tick vector. Little is known about how this replicative niche is established and maintained. Using the ruminant pathogenA. marginaleand its natural tick vector,D. andersoni, this study characterized the features of theA. marginaleniche in the tick midgut and demonstrates thatA. marginaleprotein synthesis is required for the maintenance of this niche. This work opens a new line of inquiry about the pathogen effectors and their targets within the tick that mediate tick-pathogen interactions and ultimately serve as the determinants of pathogen success.
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Melgar, Mario, Molly Lamb, Diva M. Calvimontes, Edwin J. Asturias, Ingrid Contreras-Roldan, Samuel Dominguez, Christine C. Robinson, Stephen Berman, and James Gaensbauer. "Enteropathogen Identification by Multiplex PCR in Guatemalan Children with Acute, Non-bloody Diarrhea." Open Forum Infectious Diseases 4, suppl_1 (2017): S361. http://dx.doi.org/10.1093/ofid/ofx163.877.
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Abstract Background Diarrhea is a leading cause of morbidity and mortality in children in low and middle income countries (LMICs). Assessing diarrhea etiology in LMICs is of great importance in order to better develop both therapeutic and public health strategies, but is hampered by the complexity of potential diarrheal pathogens, and diverse methodology needed for pathogen identification Methods Subjects 6 to 35 months old with acute, moderate severity, non-bloody diarrhea were enrolled in a diarrheal treatment trial, conducted at one rural (N = 172) and two urban sites (N = 144) in Guatemala. Diarrheal pathogens were determined in stool by multiplex PCR (FilmArray GI® Biofire) which allows simultaneous identification of 23 bacterial, viral, parasitic pathogens. Descriptive statistics on demographics, pathogen load, and differences in pathogen occurrence by site were performed; differences were assessed with t-test and chi2 test Results Nearly all (96.8%) subjects had pathogens identified, and most had multiple potential pathogens identified (mean pathogen count: 2.7 urban and 4.8 rural; P < 0.001 (Figure 1). Notable pathogen differences were observed between rural and urban populations. Bacteria (particularly E.coli pathotypes and Campylobacter) and protozoa (particularly giardia) were more common in the rural population (Figure2). Viral pathogens were either similar or more common (norovirus; P = 0.04) in the urban population; rotavirus was uncommon in both sites (10 rural and 12 urban cases). A similar pattern of pathogen evolution with patient age was noted in both settings, with a decrease in the relative number of viral and increase in parasitic pathogens (Figure 3). Important demographic and socioeconomic differences between rural and urban were noted: rural subjects had poorer nutritional status, underdeveloped water and sanitation facilities and more domestic animal exposure Conclusion Acute diarrheal episodes in Guatemalan children were associated with a complex spectrum of pathogens when determined by multiplex PCR, with distinct patterns in rural and urban populations. Future studies to precisely determine diarrheal etiologies in LMICs will need to incorporate controls to sort causative organisms from those colonizing the intestine. Disclosures All authors: No reported disclosures.
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Cleaveland, S., M. K. Laurenson, and L. H. Taylor. "Diseases of humans and their domestic mammals: pathogen characteristics, host range and the risk of emergence." Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 356, no. 1411 (July 29, 2001): 991–99. http://dx.doi.org/10.1098/rstb.2001.0889.
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Pathogens that can be transmitted between different host species are of fundamental interest and importance from public health, conservation and economic perspectives, yet systematic quantification of these pathogens is lacking. Here, pathogen characteristics, host range and risk factors determining disease emergence were analysed by constructing a database of disease–causing pathogens of humans and domestic mammals. The database consisted of 1415 pathogens causing disease in humans, 616 in livestock and 374 in domestic carnivores. Multihost pathogens were very prevalent among human pathogens (61.6%) and even more so among domestic mammal pathogens (livestock 77.3%, carnivores 90.0%). Pathogens able to infect human, domestic and wildlife hosts contained a similar proportion of disease–causing pathogens for all three host groups. One hundred and ninety–six pathogens were associated with emerging diseases, 175 in humans, 29 in livestock and 12 in domestic carnivores. Across all these groups, helminths and fungi were relatively unlikely to emerge whereas viruses, particularly RNA viruses, were highly likely to emerge. The ability of a pathogen to infect multiple hosts, particularly hosts in other taxonomic orders or wildlife, were also risk factors for emergence in human and livestock pathogens. There is clearly a need to understand the dynamics of infectious diseases in complex multihost communities in order to mitigate disease threats to public health, livestock economies and wildlife.
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Leach, Clinton B., Colleen T. Webb, and Paul C. Cross. "When environmentally persistent pathogens transform good habitat into ecological traps." Royal Society Open Science 3, no. 3 (March 2016): 160051. http://dx.doi.org/10.1098/rsos.160051.
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Habitat quality plays an important role in the dynamics and stability of wildlife metapopulations. However, the benefits of high-quality habitat may be modulated by the presence of an environmentally persistent pathogen. In some cases, the presence of environmental pathogen reservoirs on high-quality habitat may lead to the creation of ecological traps, wherein host individuals preferentially colonize high-quality habitat, but are then exposed to increased infection risk and disease-induced mortality. We explored this possibility through the development of a stochastic patch occupancy model, where we varied the pathogen’s virulence, transmission rate and environmental persistence as well as the distribution of habitat quality in the host metapopulation. This model suggests that for pathogens with intermediate levels of spread, high-quality habitat can serve as an ecological trap, and can be detrimental to host persistence relative to low-quality habitat. This inversion of the relative roles of high- and low-quality habitat highlights the importance of considering the interaction between spatial structure and pathogen transmission when managing wildlife populations exposed to an environmentally persistent pathogen.
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Brusina, Е. В., E. A. Chezganova, and О. M. Drozdova. "Airborne transmission of hospital pathogens." Fundamental and Clinical Medicine 5, no. 4 (December 25, 2020): 97–103. http://dx.doi.org/10.23946/2500-0764-2020-5-4-97-103.
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For decades, there have been a number of controversial issues regarding the airborne transmission of hospital pathogens. Here we decided to perform a critical review on this topic in light of the current COVID-19 pandemic. We summarise the existing knowledge on biological aerosols including techniques of their generation, propagation of bioaerosol particles in a hospital environment, particle size-, shape- and composition-dependent airborne transmission, and microorganisms inhabitating such particles. It is still unclear which of the particles transfer the pathogens, which of the pathogens are capable of adhering to the particulate matter, and whether such adhesion affects pathogen virulence. Intriguingly, viruses, bacteria and fungi seemingly have distinct patterns of interactions with the bioaerosols. Moreover, particle formation and their colonization may be separated in time, further complicating the puzzle. Apparently, pathogen interactions with the particulate matter are of paramount importance to better understand the role of bioaerosol particles as a potential pathogen reservoir in the hospital environment and to properly assess the influence of environmental pollutants, novel biomedical materials and treatment technologies on airborne transmission of hospital pathogens.
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Charudattan, Raghavan. "A Reflection on My Research in Weed Biological Control: Using What We Have Learned for Future Applications." Weed Technology 24, no. 2 (June 2010): 208–17. http://dx.doi.org/10.1614/wt-d-09-00012.1.
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When I began my foray into the field of biological control of weeds in 1971, the concept of deliberately using pathogens to control weeds was novel and untested and met with skepticism and resistance. Soon, a worldwide network of plant pathologists, weed scientists, microbial technologists, formulation specialists, and regulatory personnel came together to study, develop, and apply pathogens in safe and effective ways of control of a variety of weeds in crops and natural areas. Several new weed–pathogen systems were studied; a few dozen products and pathogens were brought to use, albeit on a very small scale compared to conventional weed-control products; and along the way, some valuable lessons were learned in phytopathology and weed ecology. A seminal body of information was published on the etiology and epidemiology of several diseases of weeds, many new pathogens were discovered and described, and methods were developed for mass production, formulation, and storage of pathogens. Numerous pathogen-produced herbicidal metabolites were discovered and characterized. Protocols were developed, tested, and applied for safe importation and release of exotic pathogens and for registration of microbial herbicides. Spectacular success was achieved with some pathogens used as classical biocontrol agents, and a new class of herbicide, the bioherbicides, came on the scene. Yet some key opportunities were missed. Notably, weed biocontrol research remained largely preoccupied with agent or product development and deployment while great strides were made during this period in phytopathology to understand the genetic–molecular basis of virulence, host range, host specificity, host response to infection, cell death, and pathogen population structure. Nevertheless, the accomplishments in the field of weed biocontrol by pathogens are truly significant. Certainly, we are poised to apply the knowledge gained toward discovery and development of additional weed-control pathogens, but increased effort should be directed also at using pathogen genes, gene products, and genetic mechanisms for weed control. An investment in the latter could help us gain insights into genetically programmed host–pathogen interactions that may be exploited to kill weeds, restrain weed growth, or knock out traits for invasiveness. In our continuing struggle to manage weeds, biocontrol with pathogens should remain a major thrust. Here I present perceptions I have gained from the work that my students, postdoctoral and technical associates, colleagues, and I have done with several weed–pathogen systems.
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Aleta, Alberto, Andreia N. S. Hisi, Sandro Meloni, Chiara Poletto, Vittoria Colizza, and Yamir Moreno. "Human mobility networks and persistence of rapidly mutating pathogens." Royal Society Open Science 4, no. 3 (March 2017): 160914. http://dx.doi.org/10.1098/rsos.160914.
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Rapidly mutating pathogens may be able to persist in the population and reach an endemic equilibrium by escaping hosts’ acquired immunity. For such diseases, multiple biological, environmental and population-level mechanisms determine the dynamics of the outbreak, including pathogen's epidemiological traits (e.g. transmissibility, infectious period and duration of immunity), seasonality, interaction with other circulating strains and hosts’ mixing and spatial fragmentation. Here, we study a susceptible-infected-recovered-susceptible model on a metapopulation where individuals are distributed in sub-populations connected via a network of mobility flows. Through extensive numerical simulations, we explore the phase space of pathogen's persistence and map the dynamical regimes of the pathogen following emergence. Our results show that spatial fragmentation and mobility play a key role in the persistence of the disease whose maximum is reached at intermediate mobility values. We describe the occurrence of different phenomena including local extinction and emergence of epidemic waves, and assess the conditions for large-scale spreading. Findings are highlighted in reference to previous studies and to real scenarios. Our work uncovers the crucial role of hosts’ mobility on the ecological dynamics of rapidly mutating pathogens, opening the path for further studies on disease ecology in the presence of a complex and heterogeneous environment.
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Amano, A., C. Chen, K. Honma, C. Li, R. P. Settem, and A. Sharma. "Genetic Characteristics and Pathogenic Mechanisms of Periodontal Pathogens." Advances in Dental Research 26, no. 1 (April 15, 2014): 15–22. http://dx.doi.org/10.1177/0022034514526237.
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Catanzariti, Ann-Maree, and David A. Jones. "Effector proteins of extracellular fungal plant pathogens that trigger host resistance." Functional Plant Biology 37, no. 10 (2010): 901. http://dx.doi.org/10.1071/fp10077.
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An understanding of the molecular mechanisms that plant pathogens use to successfully colonise host tissue can be gained by studying the biological activity of pathogen proteins secreted during infection. Several secreted ‘effector’ proteins with possible roles in virulence have been isolated from extracellular fungal pathogens, including three that have been shown to negate host defences. In most cases, significant effector variation is observed between different pathogen isolates, driven by the recognitional capacity of disease resistance proteins arrayed against the pathogen by the host plant. This review summarises what is known about the expression, function and variation of effectors isolated from extracellular fungal pathogens.
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Potgieter, Natasha, Lee Heine, Jean Pierre Kabue Ngandu, Solanka Ellen Ledwaba, Tinyiko Zitha, Lutendo Sylvia Mudau, Piet Becker, Afsatou Ndama Traore, and Tobias George Barnard. "High Burden of Co-Infection with Multiple Enteric Pathogens in Children Suffering with Diarrhoea from Rural and Peri-Urban Communities in South Africa." Pathogens 12, no. 2 (February 14, 2023): 315. http://dx.doi.org/10.3390/pathogens12020315.
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Infectious diarrhoea contributes to high morbidity and mortality in young children from sub-Saharan Africa. The aim of this study was to assess the prevalence of single and multiple diarrhoeal-causing pathogen combinations in children suffering from diarrhoea from rural and peri-urban communities in South Africa. A total of 275 diarrhoea stool specimens were collected between 2014 and 2016 from Hospitals and Primary Health Care clinics. The BioFire® FilmArray® Gastrointestinal panel was used to simultaneously detect 22 diarrhoea pathogens (viruses, bacteria, parasites) known to cause diarrhoea. A total of 82% (226/275) enteric pathogens were detected in the stool specimens. The two most detected bacterial, viral and parasitic pathogens each included: EAEC (42%), EPEC (32%), Adenovirus F40/41 (19%), Norovirus (15%), Giardia (8%) and Cryptosporidium (6%), respectively. Single enteric pathogen infections were recorded in 24% (65/275) specimens with EAEC, and Norovirus was found in 26% (17/65) and 14% (9/65) of the specimens, respectively. Multiple enteric pathogen combinations were recorded in 59% (161/275) of the stool specimens with 53% (85/161) containing two pathogens, 22% (35/161) containing three pathogens and 25% (41/161) containing four or more pathogens. The results from this study demonstrated the complex nature of pathogen co-infections in diarrhoeal episodes which could have an impact on treatment effectiveness.
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Leggett, Helen C., Charlie K. Cornwallis, Angus Buckling, and Stuart A. West. "Growth rate, transmission mode and virulence in human pathogens." Philosophical Transactions of the Royal Society B: Biological Sciences 372, no. 1719 (March 13, 2017): 20160094. http://dx.doi.org/10.1098/rstb.2016.0094.
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The harm that pathogens cause to hosts during infection, termed virulence, varies across species from negligible to a high likelihood of rapid death. Classic theory for the evolution of virulence is based on a trade-off between pathogen growth, transmission and host survival, which predicts that higher within-host growth causes increased transmission and higher virulence. However, using data from 61 human pathogens, we found the opposite correlation to the expected positive correlation between pathogen growth rate and virulence. We found that (i) slower growing pathogens are significantly more virulent than faster growing pathogens, (ii) inhaled pathogens and pathogens that infect via skin wounds are significantly more virulent than pathogens that are ingested, but (iii) there is no correlation between symptoms of infection that aid transmission (such as diarrhoea and coughing) and virulence. Overall, our results emphasize how virulence can be influenced by mechanistic life-history details, especially transmission mode, that determine how parasites infect and exploit their hosts. This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’.
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Harwood, Catherine, and Reeta Rao. "Host Pathogen Relations: Exploring Animal Models for Fungal Pathogens." Pathogens 3, no. 3 (June 30, 2014): 549–62. http://dx.doi.org/10.3390/pathogens3030549.
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Rovenich, Hanna, Jordi C. Boshoven, and Bart PHJ Thomma. "Filamentous pathogen effector functions: of pathogens, hosts and microbiomes." Current Opinion in Plant Biology 20 (August 2014): 96–103. http://dx.doi.org/10.1016/j.pbi.2014.05.001.
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Young, John A. T. "PLoS Pathogens—A High-Impact Journal for Pathogen Research." PLoS Pathogens 1, no. 1 (2005): e12. http://dx.doi.org/10.1371/journal.ppat.0010012.
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Brugman, E., A. Widiastuti, and A. Wibowo. "Population genetics of Phytophthora species based on short sequence repeat (SSR) marker: a review of its importance and recent studies." IOP Conference Series: Earth and Environmental Science 1230, no. 1 (September 1, 2023): 012102. http://dx.doi.org/10.1088/1755-1315/1230/1/012102.
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Abstract Phytophthora is a genus of oomycete (water molds) whose member species mostly live as plant pathogens and have been reported to cause enormous economic losses on crops worldwide. In recent years, population genetics of Phytophthora pathogens have been broadly studied to evaluate their adaptive evolution. Population genetic studies focus on analyzing the level of genetic diversity and the structure of the pathogen population. A population’s genetic diversity is proportional to its evolutionary potential. The generation and maintenance of genetic variation in pathogen populations are influenced by the biology of the pathogen and its host, environments, agricultural practices, and human activities. Understanding the population genetics of plant pathogens allows us to track the dynamic of the pathogen population and their adaptive ability, assisting the development of sustainable disease management strategies. This review presents the importance of population genetics, short sequence repeat (SSR) marker utilization in population genetic studies, and recent population genetics studies of Phytophthora pathogens related to agricultural practices.
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Chen, Shanshan, Yijun Ran, Hebo Huang, Zhenzhen Wang, and Ke-ke Shang. "Epidemic Dynamics of Two-Pathogen Spreading for Pairwise Models." Mathematics 10, no. 11 (June 2, 2022): 1906. http://dx.doi.org/10.3390/math10111906.
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In the real world, pathogens do not exist in isolation. The transmission of one pathogen may be affected by the presence of other pathogens, and certain pathogens generate multiple strains with different spreading features. Hence, the behavior of multi-pathogen transmission has attracted much attention in epidemiological research. In this paper, we use the pairwise approximation method to formulate two-pathogen models capturing cross-immunity, super-infection, and co-infection phenomena, in which each pathogen follows a susceptible-infected-susceptible (SIS) mechanism. For each model, we calculate the basic reproduction number and analyze the stability of equilibria, and discuss the differences from the mean-field approach. We demonstrate that simulations are in good agreement with the analytical results.
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WHITE, L. J., Y. H. SCHUKKEN, T. J. G. M. LAM, G. F. MEDLEY, and M. J. CHAPPELL. "A multispecies model for the transmission and control of mastitis in dairy cows." Epidemiology and Infection 127, no. 3 (December 2001): 567–76. http://dx.doi.org/10.1017/s0950268801006100.
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Mastitis in dairy cows is a significant economic and animal welfare issue in the dairy industry. The bacterial pathogens responsible for infection of the mammary gland may be split into two main categories: major and minor pathogens. Infection with major pathogens generally results in clinical illness or strong inflammatory responses and reduced milk yields, whereas minor pathogen infection is usually subclinical. Previous investigations have considered the transmission of these pathogens independently. Experimental evidence has shown cross-protection between species of pathogens. In this study a mathematical model for the coupled transmission of major and minor pathogens along with their interaction via the host was developed in order to consider various methods for controlling the incidence of major pathogen infection. A stability analysis of the model equilibria provides explanations for observed phenomena and previous decoupled modelling results. This multispecies model structure has provided a basis for quantifying the extent of cross-protection between species and assessing possible control strategies against the disease.
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Gallet, Romain, Colin Fontaine, François Bonnot, Joëlle Milazzo, Christophe Tertois, Henri Adreit, Virginie Ravigné, Elisabeth Fournier, and Didier Tharreau. "Evolution of Compatibility Range in the Rice−Magnaporthe oryzae System: An Uneven Distribution of R Genes Between Rice Subspecies." Phytopathology® 106, no. 4 (April 2016): 348–54. http://dx.doi.org/10.1094/phyto-07-15-0169-r.
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Efficient strategies for limiting the impact of pathogens on crops require a good understanding of the factors underlying the evolution of compatibility range for the pathogens and host plants, i.e., the set of host genotypes that a particular pathogen genotype can infect and the set of pathogen genotypes that can infect a particular host genotype. Until now, little is known about the evolutionary and ecological factors driving compatibility ranges in systems implicating crop plants. We studied the evolution of host and pathogen compatibility ranges for rice blast disease, which is caused by the ascomycete Magnaporthe oryzae. We challenged 61 rice varieties from three rice subspecies with 31 strains of M. oryzae collected worldwide from all major known genetic groups. We determined the compatibility range of each plant variety and pathogen genotype and the severity of each plant−pathogen interaction. Compatibility ranges differed between rice subspecies, with the most resistant subspecies selecting for pathogens with broader compatibility ranges and the least resistant subspecies selecting for pathogens with narrower compatibility ranges. These results are consistent with a nested distribution of R genes between rice subspecies.
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Kimura, Hirokazu, Yuriko Hayashi, Masanari Kitagawa, Miwa Yoshizaki, Kensuke Saito, Kazuhiko Harada, Kaori Okayama, et al. "Pathogen Profiles in Outpatients with Non-COVID-19 during the 7th Prevalent Period of COVID-19 in Gunma, Japan." Microorganisms 11, no. 9 (August 24, 2023): 2142. http://dx.doi.org/10.3390/microorganisms11092142.
Full textAbstract:
The identification of pathogens associated with respiratory symptoms other than the novel coronavirus disease 2019 (COVID-19) can be challenging. However, the diagnosis of pathogens is crucial for assessing the clinical outcome of patients. We comprehensively profiled pathogens causing non-COVID-19 respiratory symptoms during the 7th prevalent period in Gunma, Japan, using deep sequencing combined with a next-generation sequencer (NGS) and advanced bioinformatics technologies. The study included nasopharyngeal swabs from 40 patients who tested negative for severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) using immuno-chromatography and/or quantitative reverse transcription polymerase chain reaction (qRT-PCR) methods. Comprehensive pathogen sequencing was conducted through deep sequencing using NGS. Additionally, short reads obtained from NGS were analyzed for comprehensive pathogen estimation using MePIC (Metagenomic Pathogen Identification Pipeline for Clinical Specimens) and/or VirusTap. The results revealed the presence of various pathogens, including respiratory viruses and bacteria, in the present subjects. Notably, human adenovirus (HAdV) was the most frequently detected virus in 16 of the 40 cases (40.0%), followed by coryneforms, which were the most frequently detected bacteria in 21 of the 40 cases (52.5%). Seasonal human coronaviruses (NL63 type, 229E type, HKU1 type, and OC43 type), human bocaviruses, and human herpesviruses (human herpesvirus types 1–7) were not detected. Moreover, multiple pathogens were detected in 50% of the subjects. These results suggest that various respiratory pathogens may be associated with non-COVID-19 patients during the 7th prevalent period in Gunma Prefecture, Japan. Consequently, for an accurate diagnosis of pathogens causing respiratory infections, detailed pathogen analyses may be necessary. Furthermore, it is possible that various pathogens, excluding SARS-CoV-2, may be linked to fever and/or respiratory infections even during the COVID-19 pandemic.
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Slimmen, Lisa J. M., Hettie M. Janssens, Annemarie M. C. van Rossum, and Wendy W. J. Unger. "Antigen-Presenting Cells in the Airways: Moderating Asymptomatic Bacterial Carriage." Pathogens 10, no. 8 (July 28, 2021): 945. http://dx.doi.org/10.3390/pathogens10080945.
Full textAbstract:
Bacterial respiratory tract infections (RTIs) are a major global health burden, and the role of antigen-presenting cells (APCs) in mounting an immune response to contain and clear invading pathogens is well-described. However, most encounters between a host and a bacterial pathogen do not result in symptomatic infection, but in asymptomatic carriage instead. The fact that a pathogen will cause infection in one individual, but not in another does not appear to be directly related to bacterial density, but rather depend on qualitative differences in the host response. Understanding the interactions between respiratory pathogens and airway APCs that result in asymptomatic carriage, will provide better insight into the factors that can skew this interaction towards infection. This review will discuss the currently available knowledge on airway APCs in the context of asymptomatic bacterial carriage along the entire respiratory tract. Furthermore, in order to interpret past and futures studies into this topic, we propose a standardized nomenclature of the different stages of carriage and infection, based on the pathogen’s position with regard to the epithelium and the amount of inflammation present.
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Ruzante, Juliana M., Katherine Olin, Breda Munoz, Jeff Nawrocki, Rangaraj Selvarangan, and Lindsay Meyers. "Real-time gastrointestinal infection surveillance through a cloud-based network of clinical laboratories." PLOS ONE 16, no. 4 (April 30, 2021): e0250767. http://dx.doi.org/10.1371/journal.pone.0250767.
Full textAbstract:
Acute gastrointestinal infection (AGI) represents a significant public health concern. To control and treat AGI, it is critical to quickly and accurately identify its causes. The use of novel multiplex molecular assays for pathogen detection and identification provides a unique opportunity to improve pathogen detection, and better understand risk factors and burden associated with AGI in the community. In this study, de-identified results from BioFire® FilmArray® Gastrointestinal (GI) Panel were obtained from January 01, 2016 to October 31, 2018 through BioFire® Syndromic Trends (Trend), a cloud database. Data was analyzed to describe the occurrence of pathogens causing AGI across United States sites and the relative rankings of pathogens monitored by FoodNet, a CDC surveillance system were compared. During the period of the study, the number of tests performed increased 10-fold and overall, 42.6% were positive for one or more pathogens. Seventy percent of the detections were bacteria, 25% viruses, and 4% parasites. Clostridium difficile, enteropathogenic Escherichia coli (EPEC) and norovirus were the most frequently detected pathogens. Seasonality was observed for several pathogens including astrovirus, rotavirus, and norovirus, EPEC, and Campylobacter. The co-detection rate was 10.2%. Enterotoxigenic E. coli (ETEC), Plesiomonas shigelloides, enteroaggregative E. coli (EAEC), and Entamoeba histolytica were detected with another pathogen over 60% of the time, while less than 30% of C. difficile and Cyclospora cayetanensis were detected with another pathogen. Positive correlations among co-detections were found between Shigella/Enteroinvasive E. coli with E. histolytica, and ETEC with EAEC. Overall, the relative ranking of detections for the eight GI pathogens monitored by FoodNet and BioFire Trend were similar for five of them. AGI data from BioFire Trend is available in near real-time and represents a rich data source for the study of disease burden and GI pathogen circulation in the community, especially for those pathogens not often targeted by surveillance.