scholarly journals A model symbiosis reveals a role for sheathed-flagellum rotation in the release of immunogenic lipopolysaccharide

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Caitlin A Brennan ◽  
Jason R Hunt ◽  
Natacha Kremer ◽  
Benjamin C Krasity ◽  
Michael A Apicella ◽  
...  
Keyword(s):  
Immune Responses ◽  
Unknown Function ◽  
Vibrio Fischeri ◽  
Host Responses ◽  
Tissue Tropism ◽  
Human Pathogens ◽  
Bacterial Flagella ◽  
Host Immune Responses ◽  
Microbe Interactions ◽  
Host Microbe Interactions

Bacterial flagella mediate host–microbe interactions through tissue tropism during colonization, as well as by activating immune responses. The flagellar shaft of some bacteria, including several human pathogens, is encased in a membranous sheath of unknown function. While it has been hypothesized that the sheath may allow these bacteria to evade host responses to the immunogenic flagellin subunit, this unusual structural feature has remained an enigma. Here we demonstrate that the rotation of the sheathed flagellum in both the mutualist Vibrio fischeri and the pathogen Vibrio cholerae promotes release of a potent bacteria-derived immunogen, lipopolysaccharide, found in the flagellar sheath. We further present a new role for the flagellar sheath in triggering, rather than circumventing, host immune responses in the model squid-vibrio symbiosis. Such an observation not only has implications for the study of bacterial pathogens with sheathed flagella, but also raises important biophysical questions of sheathed-flagellum function.

scholarly journals Comparative evaluation of the genomes of common bacterial members of the Drosophila intestinal community

2016 ◽  
Author(s):  
Kristina Petkau ◽  
David Fast ◽  
Aashna Duggal ◽  
Edan Foley
Keyword(s):  
Immune Responses ◽  
Intestinal Bacteria ◽  
Lactobacillus Brevis ◽  
Host Responses ◽  
Gene Products ◽  
Starting Point ◽  
Microbe Interactions ◽  
Microbial Products ◽  
Host Microbe Interactions ◽  
Alternative Sources

Drosophila melanogaster is an excellent model to explore the molecular exchanges that occur between an animal intestine and their microbial passengers. For example, groundbreaking studies in flies uncovered a sophisticated web of host responses to intestinal bacteria. The outcomes of these responses define critical events in the host, such as the establishment of immune responses, access to nutrients, and the rate of larval development. Despite our steady march towards illuminating the host machinery that responds to bacterial presence in the gut, we know remarkably little about the microbial products that influence bacterial association with a fly host. To address this deficiency, we sequenced and characterized the genomes of three common Drosophila-associated microbes: Lactobacillus plantarum, Lactobacillus brevis and Acetobacter pasteurianus. In each case, we compared the genomes of Drosophila-associated strains to the genomes of strains isolated from alternative sources. This approach allowed us to identify molecular functions common to Drosophila-associated microbes, and, in the case of A. pasteurianus, to identify genes that are essential for association with the host. Of note, many of the gene products unique to fly-associated strains have established roles in the stabilization of host-microbe interactions. We believe that these data provide a valuable starting point for a more thorough examination of the microbial perspective on host-microbe relationships.

scholarly journals A Cell Atlas of Microbe-Responsive Processes in the Zebrafish Intestine

2020 ◽  
Author(s):  
Reegan J. Willms ◽  
Jennifer C. Hocking ◽  
Edan Foley
Keyword(s):  
Transcriptional Activity ◽  
Cell Types ◽  
Cellular Heterogeneity ◽  
Host Responses ◽  
Cellular Specificity ◽  
Direct Growth ◽  
A Cell ◽  
Microbe Interactions ◽  
Regulatory Effects ◽  
Host Microbe Interactions

ABSTRACTGut microbial products direct growth, differentiation and development in the animal host. Disruptions to host-microbe interactions have profound health consequences, that include onset of chronic inflammatory illnesses. However, we lack system-wide understanding of cell-specific responses to the microbiome. We profiled transcriptional activity in individual cells from the intestine, and associated tissue, of zebrafish larvae that we raised in the presence, or absence, of a microbiome. We uncovered extensive cellular heterogeneity in the conventional zebrafish intestinal epithelium, including previously undescribed cell types with known mammalian homologs. By comparing conventional to germ-free profiles, we mapped microbial impacts on transcriptional activity in each cell population. We revealed intricate degrees of cellular specificity in host responses to the microbiome, that included regulatory effects on patterning, metabolic and immune activity. For example, we showed that removal of microbes hindered transduction of vascular endothelial growth factor-dependent signals in the developing vasculature, resulting in impaired intestinal vascularization. Our work provides a high-resolution atlas of intestinal cellular composition in the developing fish gut and details the effects of the microbiome on each cell type.

scholarly journals Drawing Comparisons between SARS-CoV-2 and the Animal Coronaviruses

2020 ◽  
Vol 8 (11) ◽  
pp. 1840
Author(s):  
Souvik Ghosh ◽  
Yashpal S. Malik
Keyword(s):  
Immune Responses ◽  
Current Knowledge ◽  
Effective Control ◽  
Tissue Tropism ◽  
Prevention Strategies ◽  
Host Immune Responses ◽  
Clinical Presentations ◽  
Control And Prevention ◽  
Diversity Transmission ◽  
Complex Origin

The COVID-19 pandemic, caused by a novel zoonotic coronavirus (CoV), SARS-CoV-2, has infected 46,182 million people, resulting in 1,197,026 deaths (as of 1 November 2020), with devastating and far-reaching impacts on economies and societies worldwide. The complex origin, extended human-to-human transmission, pathogenesis, host immune responses, and various clinical presentations of SARS-CoV-2 have presented serious challenges in understanding and combating the pandemic situation. Human CoVs gained attention only after the SARS-CoV outbreak of 2002–2003. On the other hand, animal CoVs have been studied extensively for many decades, providing a plethora of important information on their genetic diversity, transmission, tissue tropism and pathology, host immunity, and therapeutic and prophylactic strategies, some of which have striking resemblance to those seen with SARS-CoV-2. Moreover, the evolution of human CoVs, including SARS-CoV-2, is intermingled with those of animal CoVs. In this comprehensive review, attempts have been made to compare the current knowledge on evolution, transmission, pathogenesis, immunopathology, therapeutics, and prophylaxis of SARS-CoV-2 with those of various animal CoVs. Information on animal CoVs might enhance our understanding of SARS-CoV-2, and accordingly, benefit the development of effective control and prevention strategies against COVID-19.

scholarly journals Fighting the Monster: Applying the Host Damage Framework to Human Central Nervous System Infections

mBio ◽  
2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Anil A. Panackal ◽  
Kim C. Williamson ◽  
Diederik van de Beek ◽  
David R. Boulware ◽  
Peter R. Williamson
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Immune Responses ◽  
Host Responses ◽  
Microbial Pathogenesis ◽  
Central Nervous System Infections ◽  
Human Central Nervous System ◽  
Host Immune Responses ◽  
Immune Mediated ◽  
Damage Response

ABSTRACTThe host damage-response framework states that microbial pathogenesis is a product of microbial virulence factors and collateral damage from host immune responses. Immune-mediated host damage is particularly important within the size-restricted central nervous system (CNS), where immune responses may exacerbate cerebral edema and neurological damage, leading to coma and death. In this review, we compare human host and therapeutic responses in representative nonviral generalized CNS infections that induce archetypal host damage responses: cryptococcal menigoencephalitis and tuberculous meningitis in HIV-infected and non-HIV-infected patients, pneumococcal meningitis, and cerebral malaria. Consideration of the underlying patterns of host responses provides critical insights into host damage and may suggest tailored adjunctive therapeutics to improve disease outcome.

scholarly journals Host immune responses to enzootic and invasive pathogen lineages vary in magnitude, timing, and efficacy

2021 ◽  
Author(s):  
Coby A McDonald ◽  
C. Guilherme Becker ◽  
Carolina Lambertini ◽  
Luis Felipe Toledo ◽  
Celio FB Haddad ◽  
...  
Keyword(s):  
Immune Responses ◽  
Late Stage ◽  
Infection Intensity ◽  
Differentially Expressed ◽  
Host Responses ◽  
Host Immune Responses ◽  
Network Analyses ◽  
Stage Disease ◽  
Late Stage Disease ◽  
Stage Infection

Infectious diseases of wildlife continue to pose a threat to biodiversity worldwide, yet pathogens are far from monolithic in virulence. Within the same pathogen species, virulence can vary considerably depending on strain or lineage, in turn eliciting variable host responses. One pathogen that has caused extensive biodiversity loss is the amphibian-killing fungus, Batrachochytrium dendrobatidis (Bd), which is comprised of a globally widespread hypervirulent lineage (Bd-GPL), and multiple geographically restricted lineages. Whereas host immunogenomic responses to Bd-GPL have been characterized in a number of amphibian species, immunogenomic responses to geographically-restricted, enzootic Bd lineages are unknown. To examine lineage-specific host immune responses to Bd, we exposed a species of pumpkin toadlet, Brachycephalus pitanga, which is endemic to Brazil's Southern Atlantic Forest, to either the Bd-GPL or the enzootic Bd-Asia-2/Brazil (hereafter Bd-Brazil) lineage. We quantified functional immunogenomic responses over the course of infection using differential gene expression tests and coexpression network analyses. Host immune responses varied significantly with Bd lineage. Toadlet responses to Bd-Brazil were weak at early infection (26 genes differentially expressed), peaked by mid-stage infection (435 genes) and were nearly fully resolved by late-stage disease (9 genes). In contrast, responses to Bd-GPL were magnified and delayed; toadlets differentially expressed 97 genes early, 86 genes at mid-stage infection, and 728 genes by late-stage infection. Given that infection intensity did not vary between mid- and late-stage disease, this suggests that pumpkin toadlets may be at least partially tolerant to the geographically-restricted Bd-Brazil lineage. In contrast, mortality was higher in Bd-GPL-infected toadlets, suggesting that late-stage immune activation against Bd-GPL was not protective and was consistent with immune dysregulation previously observed in other species. Our results demonstrate that both the timing of immune response and the particular immune pathways activated are specific to Bd lineage. Within regions where multiple Bd lineages co-occur, and given continued global Bd movement, these differential host responses may influence not only individual disease outcome, but transmission dynamics at the population and community levels.

scholarly journals GH18 family glycoside hydrolase Chitinase A of Salmonella facilitates bacterial invasion and survival by modulating host immune responses

2021 ◽  
Author(s):  
Kasturi Chandra ◽  
Dipshikha Chakravortty
Keyword(s):  
Immune Responses ◽  
Defense Mechanisms ◽  
Salmonella Typhi ◽  
Bacterial Invasion ◽  
Human Pathogens ◽  
C Elegans ◽  
Host Immune Responses ◽  
Gut Colonization ◽  
Chitinase A

Salmonella is a facultative intracellular pathogen that has co-evolved with its host and has also developed various strategies to evade the host immune responses. Salmonella recruits an array of virulence factors to escape from host defense mechanisms. Previously chitinase A (chiA) was found to be upregulated in intracellular Salmonella. Although studies show that chitinases and chitin binding proteins (CBP) of many human pathogens have a profound role in various aspects of pathogenesis, like adhesion, virulence and immune evasion, the role of chitinase in strict intravacuolar pathogen Salmonella has not yet been elucidated. In this study, we deciphered the role of chitinase of Salmonella in the pathogenesis of the serovars, Typhimurium and Typhi. Our data propose that ChiA mediated modification of the glycosylation on the epithelial cell surface facilitates the invasion of the pathogen into the epithelial cells. Further we found that ChiA aids in reactive nitrogen species (RNS) and reactive oxygen species (ROS) production in phagocytes, leading to MHCII downregulation followed by suppression of antigen presentation and antibacterial responses. In continuation of the study in animal model C. elegans, Salmonella Typhi ChiA was found to facilitate attachment to the intestinal epithelium, gut colonization and persistence by downregulating antimicrobial peptides.

scholarly journals Protective Plant Immune Responses are Elicited by Bacterial Outer Membrane Vesicles

2020 ◽  
Author(s):  
Hannah M. McMillan ◽  
Sophia G. Zebell ◽  
Jean B. Ristaino ◽  
Xinnian Dong ◽  
Meta J. Kuehn
Keyword(s):  
Immune Responses ◽  
Outer Membrane ◽  
Pseudomonas Syringae ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Plant Responses ◽  
Bacterial Survival ◽  
Microbe Interactions ◽  
Bacterial Outer Membrane ◽  
Host Microbe Interactions

SummaryBacterial outer membrane vesicles (OMVs) perform a variety of functions in bacterial survival and virulence. In mammalian systems, OMVs activate immune responses and have been exploited as vaccines. However, little work has focused on the role that OMVs play during interactions with plant hosts. Here we report that OMVs from the pathogenic Pseudomonas syringae and the beneficial Pseudomonas fluorescens activate plant immune responses that protect against bacterial and oomycete pathogens. OMVs from these two species display different sensitivity to biochemical stressors, which could indicate differences in OMV cargo packaging. Furthermore, our study shows that OMV-induced protective immune responses are T3SS- and protein-independent, while OMV-mediated seedling growth inhibition largely depends on protein cargo. Importantly, OMV-mediated plant responses are distinct from those triggered by PAMP/MAMPs or effector molecules alone. OMVs provide a unique opportunity to study virulence factors in combination and add a new layer of interaction and complexity to host-microbe interactions.

scholarly journals Adaptation to pH stress by Vibrio fischeri can affect its symbiosis with the Hawaiian bobtail squid (Euprymna scolopes)

Microbiology ◽  
2020 ◽  
Vol 166 (3) ◽  
pp. 262-277 ◽  
Author(s):  
Meagan Leah Cohen ◽  
Ekaterina Vadimovna Mashanova ◽  
Sveta Vivian Jagannathan ◽  
William Soto
Keyword(s):  
Type Species ◽  
Vibrio Fischeri ◽  
Acid Stress ◽  
Alkaline Stress ◽  
Euprymna Scolopes ◽  
Free Living ◽  
Content Type ◽  
Link Type ◽  
Microbe Interactions ◽  
Host Microbe Interactions

Many microorganisms engaged in host-microbe interactions pendulate between a free-living phase and a host-affiliated stage. How adaptation to stress during the free-living phase affects host-microbe associations is unclear and understudied. To explore this topic, the symbiosis between Hawaiian bobtail squid (Euprymna scolopes) and the luminous bacterium Vibrio fischeri was leveraged for a microbial experimental evolution study. V. fischeri experienced adaptation to extreme pH while apart from the squid host. V. fischeri was serially passaged for 2000 generations to the lower and upper pH growth limits for this microorganism, which were pH 6.0 and 10.0, respectively. V. fischeri was also serially passaged for 2000 generations to vacillating pH 6.0 and 10.0. Evolution to pH stress both facilitated and impaired symbiosis. Microbial evolution to acid stress promoted squid colonization and increased bioluminescence for V. fischeri , while symbiont adaptation to alkaline stress diminished these two traits. Oscillatory selection to acid and alkaline stress also improved symbiosis for V. fischeri , but the facilitating effects were less than that provided by microbial adaptation to acid stress. In summary, microbial adaptation to harsh environments amid the free-living phase may impact the evolution of host-microbe interactions in ways that were not formerly considered.

scholarly journals Niche-Specific Impact of a Symbiotic Function on the Persistence of Microbial Symbionts within a Natural Host

2016 ◽  
Vol 82 (19) ◽  
pp. 5990-5996 ◽  
Author(s):  
Subhash C. Verma ◽  
Tim Miyashiro
Keyword(s):  
Vibrio Fischeri ◽  
Fundamental Aspect ◽  
Light Organ ◽  
Content Type ◽  
Host Environment ◽  
Microbe Interactions ◽  
Host Microbe Interactions ◽  
Microbial Symbionts ◽  
Function Relationship ◽  
The Impact

ABSTRACTHow the function of microbial symbionts is affected by their population/consortium structure within a host remains poorly understood. The symbiosis established betweenEuprymna scolopesandVibrio fischeriis a well-characterized host-microbe association in which the function and structure ofV. fischeripopulations within the host are known:V. fischeripopulations produce bioluminescence from distinct crypt spaces within a dedicated host structure called the light organ. Previous studies have revealed that luminescence is required forV. fischeripopulations to persist within the light organ and that deletion of theluxgene locus, which is responsible for luminescence inV. fischeri, leads to a persistence defect. In this study, we investigated the impact of bioluminescence onV. fischeripopulation structure within the light organ. We report that the persistence defect is specific to crypt I, which is the most developmentally mature crypt space within the nascent light organ. This result provides insight into the structure/function relationship that will be useful for future mechanistic studies of squid-Vibriosymbiosis. In addition, our report highlights the potential impact of the host developmental program on the spatiotemporal dynamics of host-microbe interactions.IMPORTANCEMetazoan development and physiology depend on microbes. The relationship between the symbiotic function of microbes and their spatial structure within the host environment remains poorly understood. Here we demonstrate, using a binary symbiosis, that the host requirement for the symbiotic function of the microbial symbiont is restricted to a specific host environment. Our results also suggest a link between microbial function and host development that may be a fundamental aspect of the more complex host-microbe interactions.

scholarly journals Bactericidal Permeability-Increasing Proteins Shape Host-Microbe Interactions

mBio ◽  
2017 ◽  
Vol 8 (2) ◽  
Author(s):  
Fangmin Chen ◽  
Benjamin C. Krasity ◽  
Suzanne M. Peyer ◽  
Sabrina Koehler ◽  
Edward G. Ruby ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Vibrio Fischeri ◽  
Molecular Characteristics ◽  
Light Organ ◽  
Euprymna Scolopes ◽  
Lipopolysaccharide Binding Protein ◽  
Ambient Seawater ◽  
Microbe Interactions ◽  
Acidic Conditions ◽  
Host Microbe Interactions

ABSTRACT We characterized bactericidal permeability-increasing proteins (BPIs) of the squid Euprymna scolopes , EsBPI2 and EsBPI4. They have molecular characteristics typical of other animal BPIs, are closely related to one another, and nest phylogenetically among invertebrate BPIs. Purified EsBPIs had antimicrobial activity against the squid’s symbiont, Vibrio fischeri , which colonizes light organ crypt epithelia. Activity of both proteins was abrogated by heat treatment and coincubation with specific antibodies. Pretreatment under acidic conditions similar to those during symbiosis initiation rendered V. fischeri more resistant to the antimicrobial activity of the proteins. Immunocytochemistry localized EsBPIs to the symbiotic organ and other epithelial surfaces interacting with ambient seawater. The proteins differed in intracellular distribution. Further, whereas EsBPI4 was restricted to epithelia, EsBPI2 also occurred in blood and in a transient juvenile organ that mediates hatching. The data provide evidence that these BPIs play different defensive roles early in the life of E. scolopes , modulating interactions with the symbiont. IMPORTANCE This study describes new functions for bactericidal permeability-increasing proteins (BPIs), members of the lipopolysaccharide-binding protein (LBP)/BPI protein family. The data provide evidence that these proteins play a dual role in the modulation of symbiotic bacteria. In the squid-vibrio model, these proteins both control the symbiont populations in the light organ tissues where symbiont cells occur in dense monoculture and, concomitantly, inhibit the symbiont from colonizing other epithelial surfaces of the animal.

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