Microbial Population Dynamics in the Hemolymph of Manduca sexta Infected with Xenorhabdus nematophila and the Entomopathogenic Nematode Steinernema carpocapsae

ABSTRACTXenorhabdus nematophilaengages in a mutualistic association with the nematodeSteinernema carpocapsae. The nematode invades and traverses the gut of susceptible insects.X. nematophilais released in the insect blood (hemolymph), where it suppresses host immune responses and functions as a pathogen.X. nematophilaproduces diverse antimicrobials in laboratory cultures. The natural competitors thatX. nematophilaencounters in the hemolymph and the role of antimicrobials in interspecies competition in the host are poorly understood. We show that gut microbes translocate into the hemolymph when the nematode penetrates the insect intestine. During natural infection,Staphylococcus saprophyticuswas initially present and subsequently disappeared from the hemolymph, whileEnterococcus faecalisproliferated.S. saprophyticuswas sensitive toX. nematophilaantibiotics and was eliminated from the hemolymph when coinjected withX. nematophila. In contrast,E. faecaliswas relatively resistant toX. nematophilaantibiotics. When injected by itself,E. faecalispersisted (∼103CFU/ml), but when coinjected withX. nematophila, it proliferated to ∼109CFU/ml. Injection ofE. faecalisinto the insect caused the upregulation of an insect antimicrobial peptide, while the transcript levels were suppressed whenE. faecaliswas coinjected withX. nematophila. Its relative antibiotic resistance together with suppression of the host immune system byX. nematophilamay account for the growth ofE. faecalis. At higher injected levels (106CFU/insect),E. faecaliscould kill insects, suggesting that it may contribute to virulence in anX. nematophilainfection. These findings provide new insights into the competitive events that occur early in infection afterS. carpocapsaeinvades the host hemocoel.

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Role of Secondary Metabolites in Establishment of the Mutualistic Partnership between Xenorhabdus nematophila and the Entomopathogenic Nematode Steinernema carpocapsae

Applied and Environmental Microbiology ◽

10.1128/aem.02650-14 ◽

2014 ◽

Vol 81 (2) ◽

pp. 754-764 ◽

Cited By ~ 20

Author(s):

Swati Singh ◽

David Orr ◽

Emmanuel Divinagracia ◽

Joseph McGraw ◽

Kellen Dorff ◽

...

Keyword(s):

Secondary Metabolites ◽

Entomopathogenic Nematode ◽

Water Soluble ◽

Steinernema Carpocapsae ◽

Xenorhabdus Nematophila ◽

Interspecies Competition ◽

Nematode Reproduction ◽

Content Type

ABSTRACTXenorhabdus nematophilaengages in a mutualistic partnership with the nematodeSteinernema carpocapsae, which invades insects, migrates through the gut, and penetrates into the hemocoel (body cavity). We showed previously that during invasion ofManduca sexta, the gut microbeStaphylococcus saprophyticusappeared transiently in the hemocoel, whileEnterococcus faecalisproliferated asX. nematophilabecame dominant.X. nematophilaproduces diverse secondary metabolites, including the major water-soluble antimicrobial xenocoumacin. Here, we study the role ofX. nematophilaantimicrobials in interspecies competition under biologically relevant conditions using strains lacking either xenocoumacin (ΔxcnKLstrain), xenocoumacin and the newly discovered antibiotic F (ΔxcnKL:F strain), or allngrA-derived secondary metabolites (ngrAstrain). Competition experiments were performed in Grace's insect medium, which is based on lepidopteran hemolymph.S. saprophyticuswas eliminated when inoculated into growing cultures of either the ΔxcnKLstrain or ΔxcnKL:F strain but grew in the presence of thengrAstrain, indicating thatngrA-derived antimicrobials, excluding xenocoumacin or antibiotic F, were required to eliminate the competitor. In contrast,S. saprophyticuswas eliminated when coinjected intoM. sextawith either the ΔxcnKLorngrAstrain, indicating thatngrA-derived antimicrobials were not required to eliminate the competitorin vivo.E. faecalisgrowth was facilitated when coinjected with either of the mutant strains. Furthermore, nematode reproduction inM. sextanaturally infected with infective juveniles colonized with thengrAstrain was markedly reduced relative to the level of reproduction when infective juveniles were colonized with the wild-type strain. These findings provide new insights into interspecies competition in a host environment and suggest thatngrA-derived compounds serve as signals forin vivonematode reproduction.

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MHO_0730 as a Surface-Exposed Calcium-Dependent Nuclease of Mycoplasma hominis Promoting Neutrophil Extracellular Trap Formation and Escape

The Journal of Infectious Diseases ◽

10.1093/infdis/jiz406 ◽

2019 ◽

Vol 220 (12) ◽

pp. 1999-2008 ◽

Cited By ~ 5

Author(s):

Carla Cacciotto ◽

Daniele Dessì ◽

Tiziana Cubeddu ◽

Anna Rita Cocco ◽

Andrea Pisano ◽

...

Keyword(s):

Natural Infection ◽

Mycoplasma Hominis ◽

Neutrophil Extracellular Trap ◽

Host Immune System ◽

Potent Inducer ◽

Calcium Dependent ◽

Relevant Role ◽

Extracellular Trap

Abstract Mycoplasma lipoproteins play a relevant role in pathogenicity and directly interact with the host immune system. Among human mycoplasmas, Mycoplasma hominis is described as a commensal bacterium that can be associated with a number of genital and extragenital conditions. Mechanisms of M. hominis pathogenicity are still largely obscure, and only a limited number of proteins have been associated with virulence. The current study focused on investigating the role of MHO_0730 as a virulence factor and demonstrated that MHO_0730 is a surface lipoprotein, potentially expressed in vivo during natural infection, acting both as a nuclease with its amino acidic portion and as a potent inducer of Neutrophil extracellular trapsosis with its N-terminal lipid moiety. Evidence for M. hominis neutrophil extracellular trap escape is also presented. Results highlight the relevance of MHO_0730 in promoting infection and modulation and evasion of innate immunity and provide additional knowledge on M. hominis virulence and survival in the host.

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The Global Transcription Factor Lrp Controls Virulence Modulation in Xenorhabdus nematophila

Journal of Bacteriology ◽

10.1128/jb.00272-15 ◽

2015 ◽

Vol 197 (18) ◽

pp. 3015-3025 ◽

Cited By ~ 16

Author(s):

Elizabeth A. Hussa ◽

Ángel M. Casanova-Torres ◽

Heidi Goodrich-Blair

Keyword(s):

Transcription Factor ◽

Phenotypic Variation ◽

Pathogenic Bacteria ◽

Regulatory Protein ◽

Inverse Correlation ◽

Xenorhabdus Nematophila ◽

Insect Larvae ◽

Content Type ◽

Expression Levels

ABSTRACTThe bacteriumXenorhabdus nematophilaengages in phenotypic variation with respect to pathogenicity against insect larvae, yielding both virulent and attenuated subpopulations of cells from an isogenic culture. The global regulatory protein Lrp is necessary forX. nematophilavirulence and immunosuppression in insects, as well as colonization of the mutualistic host nematodeSteinernema carpocapsae, and mediates expression of numerous genes implicated in each of these phenotypes. Given the central role of Lrp inX. nematophilahost associations, as well as its involvement in regulating phenotypic variation pathways in other bacteria, we assessed its function in virulence modulation. We discovered that expression oflrpvaries within an isogenic population, in a manner that correlates with modulation of virulence. Unexpectedly, although Lrp is necessary for optimal virulence and immunosuppression, cells expressing high levels oflrpwere attenuated in these processes relative to those with low to intermediatelrpexpression. Furthermore, fixed expression oflrpat high and low levels resulted in attenuated and normal virulence and immunosuppression, respectively, and eliminated population variability of these phenotypes. These data suggest that fluctuatinglrpexpression levels are sufficient to drive phenotypic variation inX. nematophila.IMPORTANCEMany bacteria use cell-to-cell phenotypic variation, characterized by distinct phenotypic subpopulations within an isogenic population, to cope with environmental change. Pathogenic bacteria utilize this strategy to vary antigen or virulence factor expression. Our work establishes that the global transcription factor Lrp regulates phenotypic variation in the insect pathogenXenorhabdus nematophila, leading to attenuation of virulence and immunosuppression in insect hosts. Unexpectedly, we found an inverse correlation between Lrp expression levels and virulence: high levels of expression of Lrp-dependent putative virulence genes are detrimental for virulence but may have an adaptive advantage in other aspects of the life cycle. Investigation ofX. nematophilaphenotypic variation facilitates dissection of this phenomenon in the context of a naturally occurring symbiosis.

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Spodoptera frugiperda transcriptional response to infestation by Steinernema carpocapsae

Scientific Reports ◽

10.1038/s41598-019-49410-8 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 4

Author(s):

Louise Huot ◽

Simon George ◽

Pierre-Alain Girard ◽

Dany Severac ◽

Nicolas Nègre ◽

...

Keyword(s):

Spodoptera Frugiperda ◽

Fat Body ◽

Entomopathogenic Nematode ◽

Transcriptional Response ◽

Early Time ◽

Symbiotic Bacterium ◽

Steinernema Carpocapsae ◽

Differentially Expressed ◽

Xenorhabdus Nematophila ◽

Transcriptional Responses

Abstract Steinernema carpocapsae is an entomopathogenic nematode (EPN) used in biological control of agricultural pest insects. It enters the hemocoel of its host via the intestinal tract and releases its symbiotic bacterium Xenorhabdus nematophila. In order to improve our knowledge about the physiological responses of its different hosts, we examined the transcriptional responses to EPN infestation of the fat body, the hemocytes and the midgut in the lepidopteran pest Spodoptera frugiperda. The tissues poorly respond to the infestation at an early time post-infestation of 8 h with only 5 genes differentially expressed in the fat body of the caterpillars. Strong transcriptional responses are observed at a later time point of 15 h post-infestation in all three tissues. Few genes are differentially expressed in the midgut but tissue-specific panels of induced metalloprotease inhibitors, immune receptors and antimicrobial peptides together with several uncharacterized genes are up-regulated in the fat body and the hemocytes. Among the most up-regulated genes, we identified new potential immune effectors, unique to Lepidoptera, which show homology with bacterial genes of unknown function. Altogether, these results pave the way for further functional studies of the responsive genes’ involvement in the interaction with the EPN.

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Chlamydia Lipooligosaccharide Has Varied Direct and Indirect Roles in Evading both Innate and Adaptive Host Immune Responses

Infection and Immunity ◽

10.1128/iai.00198-20 ◽

2020 ◽

Vol 88 (8) ◽

Author(s):

Xisheng Wang ◽

Daniel D. Rockey ◽

Brian P. Dolan

Keyword(s):

Immune Responses ◽

Cytotoxic T Cell ◽

Innate Immune Responses ◽

Content Type ◽

E Coli ◽

Host Immune Responses ◽

Cell Responses ◽

Direct Delivery ◽

Cytotoxic T Cell Responses

ABSTRACT Chlamydia bacteria are obligate intracellular pathogens which can cause a variety of disease in humans and other vertebrate animals. To successfully complete its life cycle, Chlamydia must evade both intracellular innate immune responses and adaptive cytotoxic T cell responses. Here, we report on the role of the chlamydial lipooligosaccharide (LOS) in evading the immune response. Chlamydia infection is known to block the induction of apoptosis. However, when LOS synthesis was inhibited during Chlamydia trachomatis infection, HeLa cells regained susceptibility to apoptosis induction following staurosporine treatment. Additionally, the delivery of purified LOS to the cytosol of cells increased the levels of the antiapoptotic protein survivin. An increase in survivin levels was also detected following C. trachomatis infection, which was reversed by blocking LOS synthesis. Interestingly, while intracellular delivery of lipopolysaccharide (LPS) derived from Escherichia coli was toxic to cells, LOS from C. trachomatis did not induce any appreciable cell death, suggesting that it does not activate pyroptosis. Chlamydial LOS was also a poor stimulator of maturation of bone marrow-derived dendritic cells compared to E. coli LPS. Previous work from our group indicated that LOS synthesis during infection was necessary to alter host cell antigen presentation. However, direct delivery of LOS to cells in the absence of infection did not alter antigenic peptide presentation. Taken together, these data suggest that chlamydial LOS, which is remarkably conserved across the genus Chlamydia, may act both directly and indirectly to allow the pathogen to evade the innate and adaptive immune responses of the host.

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Early Colonization Events in the Mutualistic Association between Steinernema carpocapsae Nematodes and Xenorhabdus nematophila Bacteria

Journal of Bacteriology ◽

10.1128/jb.185.10.3147-3154.2003 ◽

2003 ◽

Vol 185 (10) ◽

pp. 3147-3154 ◽

Cited By ~ 109

Author(s):

Eric C. Martens ◽

Kurt Heungens ◽

Heidi Goodrich-Blair

Keyword(s):

Fluorescent Protein ◽

Ex Vivo ◽

Entomopathogenic Nematode ◽

Steinernema Carpocapsae ◽

Infective Juvenile ◽

Bacterial Cells ◽

Biological Interactions ◽

Xenorhabdus Nematophila ◽

Molecular Events ◽

Final Population

ABSTRACT The bacterium Xenorhabdus nematophila is a mutualist of the entomopathogenic nematode Steinernema carpocapsae. During its life cycle, the bacterium exists both separately from the nematode and as an intestinal resident of a nonfeeding nematode form, the infective juvenile (IJ). The progression of X. nematophila from an ex vivo existence to a specific and persistent colonization of IJs is a model to understand the mechanisms mediating the initiation and maintenance of benign host-microbe interactions. To help characterize this process, we constructed an X. nematophila strain that constitutively expresses green fluorescent protein, which allowed its presence to be monitored within IJs. Using this strain, we showed that few bacterial cells initiate colonization of an individual IJ and that these grow inside the lumen of the IJ intestine in a reproducible polyphasic pattern during colonization. In accordance with these two observations, we demonstrated that the final population of bacteria in a nematode is of predominantly monoclonal origin, suggesting that only one or two bacterial clones initiate or persist during colonization of an individual nematode. These data suggest that X. nematophila initiates IJ colonization by competing for limited colonization sites or resources within the nematode intestine. This report represents the first description of the biological interactions occurring between X. nematophila and S. carpocapsae during the early stages of the colonization process, provides insights into the physiology of X. nematophila in its host niche, and will facilitate interpretation of future data regarding the molecular events mediating this process.

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Detoxification of 7-Dehydrocholesterol Fatal to Helicobacter pylori Is a Novel Role of Cholesterol Glucosylation

Journal of Bacteriology ◽

10.1128/jb.01495-12 ◽

2012 ◽

Vol 195 (2) ◽

pp. 359-367 ◽

Cited By ~ 12

Author(s):

Hirofumi Shimomura ◽

Kouichi Hosoda ◽

David J. McGee ◽

Shunji Hayashi ◽

Kenji Yokota ◽

...

Keyword(s):

Helicobacter Pylori ◽

Cell Membrane ◽

Membrane Lipid ◽

Host Immune System ◽

Content Type ◽

Mucosal Tissues ◽

Gene Mutant ◽

A Cell ◽

H Pylori

ABSTRACTThe glucosylation of free cholesterol (FC) byHelicobacter pyloricells has various biological significances for the survival of this bacterium.H. pyloricells with glucosylated FC are capable of evading host immune systems, such as phagocytosis by macrophages and activation of antigen-specific T cells, and surviving in the gastric mucosal tissues for long periods. An additional role of cholesterol glucosylation in the survival ofH. pyloriwhich is distinct from the role of escaping the host immune system, however, has yet to be identified. This study demonstrated that 7-dehydrocholesterol (7dFC), an FC precursor, is a toxic compound fatal toH. pyloricells, but the cell membrane ofH. pyloriis capable of absorbing this toxic sterol via glucosylation. In contrast to the case with 7dFC, no toxicity toH. pyloricells was detected from the glucosylated 7dFC. In addition,cgtgene mutantH. pyloricells that cannot glucosylate cholesterols had higher susceptibility to the toxic action of 7dFC than wild-typeH. pyloricells. These results indicate that thecgtgene product ofH. pyloriserves to detoxify the sterol fatal to this bacterium and to permit this toxic sterol as a cell membrane lipid component. In summary, this study defined a novel role of cholesterol glucosylation inH. pylori.

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Antigenicity of Recombinant Maltose Binding Protein-Mycobacterium avium subsp. paratuberculosis Fusion Proteins with and without Factor Xa Cleaving

Clinical and Vaccine Immunology ◽

10.1128/cvi.00596-13 ◽

2013 ◽

Vol 20 (12) ◽

pp. 1817-1826 ◽

Cited By ~ 6

Author(s):

Ratna B. Gurung ◽

Douglas J. Begg ◽

Auriol C. Purdie ◽

John P. Bannantine ◽

Richard J. Whittington

Keyword(s):

Mycobacterium Avium ◽

Fusion Proteins ◽

Physiological Stress ◽

Binding Protein ◽

Natural Infection ◽

Factor Xa ◽

Maltose Binding Protein ◽

Host Immune System ◽

Serum Samples ◽

Content Type

ABSTRACTMycobacterium aviumsubsp.paratuberculosiscauses Johne's disease (JD) in ruminants. Proteomic studies have shown thatM. aviumsubsp.paratuberculosisexpresses certain proteins when exposed toin vitrophysiological stress conditions similar to the conditions experienced within a host during natural infection. Such proteins are hypothesized to be expressedin vivo, are recognized by the host immune system, and may be of potential use in the diagnosis of JD. In this study, 50 recombinant maltose binding protein (MBP)-M. aviumsubsp.paratuberculosisfusion proteins were evaluated using serum samples from sheep infected withM. aviumsubsp.paratuberculosis, and 29 (58%) were found to be antigenic. Among 50 fusion proteins, 10 were evaluated in MBP fusion and factor Xa-cleaved forms. A total of 31 proteins (62%) were found to be antigenic in either MBP fusion or factor Xa-cleaved forms. Antigenicity after cleavage and removal of the MBP tag was marginally enhanced.

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Xenorhabdus ishibashii sp. nov., isolated from the entomopathogenic nematode Steinernema aciari

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY ◽

10.1099/ijs.0.041145-0 ◽

2013 ◽

Vol 63 (Pt_5) ◽

pp. 1690-1695 ◽

Cited By ~ 13

Author(s):

Ryusei Kuwata ◽

Li-hong Qiu ◽

Wen Wang ◽

Yuki Harada ◽

Mutsuhiro Yoshida ◽

...

Keyword(s):

Type Species ◽

Entomopathogenic Nematode ◽

Sequence Similarity ◽

Phenotypic Traits ◽

Rrna Gene ◽

Protein Coding ◽

Content Type ◽

Link Type ◽

Mutualistic Association ◽

Reference Strains

Gram-negative bacteria of the genus Xenorhabdus exhibit a mutualistic association with steinernematid entomopathogenic nematodes and a pathogenic relationship with insects. Here we describe two isolates of the entomopathogenic nematode Steinernema aciari collected from China and Japan. 16S rRNA gene sequence similarity and phylogenetic analysis indicated that the isolates obtained from S. aciari belonged to the genus Xenorhabdus . Multilocus sequence analysis based on five universal protein-coding gene sequences revealed that the isolates were closely related to Xenorhabdus ehlersii DSM 16337T and Xenorhabdus griffiniae ID10T but that they exhibited <97 % sequence similarity with these reference strains, which indicated that the isolates were distinct from previously described species. Based on these genetic differences and several differential phenotypic traits, we propose that the isolates represent a novel species of the genus Xenorhabdus , for which we propose the name Xenorhabdus ishibashii sp. nov. The type strain is GDh7T ( = DSM 22670T = CGMCC 1.9166T).

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Effects of Nanoparticles of Metal Oxides on the Survival of the Entomopathogenic Nematode: Steinernema carpocapsae

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2020.17164 ◽

2020 ◽

Vol 20 (3) ◽

pp. 1434-1439

Author(s):

Winisia E. Makirita ◽

Liu Yong ◽

Nongyue He ◽

Ernest R. Mbega ◽

Musa Chacha ◽

...

Keyword(s):

Electron Microscope ◽

Metal Oxides ◽

Entomopathogenic Nematodes ◽

Entomopathogenic Nematode ◽

Chemical Properties ◽

Steinernema Carpocapsae ◽

Xenorhabdus Nematophila ◽

Zno Nps ◽

Significant Difference ◽

Toxicity Effects

Nanoparticles (NPs) are technological engineered materials with unique physical and chemical properties, and dimension of less than 100 nm. Nanotechnology has developed at a rapid pace, resulting into tremendous wide application that has resulted into concerns and ecotoxicological consequences. The antimicrobial potentials of the nanoparticles have been extensively studied, however, little has been done on the allied health and environmental toxicity assessments. Thus, the current work evaluated the toxicity effects of the ZnO, TiO2 and Fe3O4 NPs on the survival of the entomopathogenic nematodes (Steinernema carpocapsae), as well as their growth inhibition effects on the nematode symbiotic bacteria (Xenorhabdus nematophila). The metal oxides NPs were characterized by scanning electron microscope and transmission electron microscope. Their toxicity effects were evaluated at various concentrations with the consideration of the media on the toxicity influence. All metal oxides had less influence on the survival of the entomopathogenic nematode and growth of the nematode symbiotic bacterial partner in a concentration dependant manner NPs. The observed toxicity was in the order of Fe3O4 < TiO2 < ZnO NPs respectively, with no significant difference between the NPs. The less toxic effect of the NPs noted may be associated with the ability of entomopathogenic nematodes and their bacterial partner to tolerate toxicants. Nonetheless, other toxicity parameter of NPs on the beneficial nematodes needs to be evaluated for consideration of the compatibility potential of the nematodes and NPs for pest management.

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