scholarly journals Functional and Phylogenetic Characterization of Vaginolysin, the Human-Specific Cytolysin from Gardnerella vaginalis

2008 ◽  
Vol 190 (11) ◽  
pp. 3896-3903 ◽  
Author(s):  
Shari E. Gelber ◽  
Jorge L. Aguilar ◽  
Kanako L. T. Lewis ◽  
Adam J. Ratner
Keyword(s):  
Pathogenic Bacteria ◽  
Bacterial Species ◽  
Cytolytic Activity ◽  
Mitogen Activated Protein Kinase ◽  
Single Amino Acid ◽  
Gardnerella Vaginalis ◽  
Target Cells ◽  
Phylogenetic Characterization ◽  
Protein Toxin ◽  
Species Specific

ABSTRACT Pore-forming toxins are essential to the virulence of a wide variety of pathogenic bacteria. Gardnerella vaginalis is a bacterial species associated with bacterial vaginosis (BV) and its significant adverse sequelae, including preterm birth and acquisition of human immunodeficiency virus. G. vaginalis makes a protein toxin that generates host immune responses and has been hypothesized to be involved in the pathogenesis of BV. We demonstrate that G. vaginalis produces a toxin (vaginolysin [VLY]) that is a member of the cholesterol-dependent cytolysin (CDC) family, most closely related to intermedilysin from Streptococcus intermedius. Consistent with this predicted relationship, VLY lyses target cells in a species-specific manner, dependent upon the complement regulatory molecule CD59. In addition to causing erythrocyte lysis, VLY activates the conserved epithelial p38 mitogen-activated protein kinase pathway and induces interleukin-8 production by human epithelial cells. Transfection of human CD59 into nonsusceptible cells renders them sensitive to VLY-mediated lysis. In addition, a single amino acid substitution in the VLY undecapeptide [VLY(P480W)] generates a toxoid that does not form pores, and introduction of the analogous proline residue into another CDC, pneumolysin, significantly decreases its cytolytic activity. Further investigation of the mechanism of action of VLY may improve understanding of the functions of the CDC family as well as diagnosis and therapy for BV.

scholarly journals Antimicrobial Susceptibility Testing and Tentative Epidemiological Cutoff Values for FiveBacillusSpecies Relevant for Use as Animal Feed Additives or for Plant Protection

2018 ◽  
Vol 84 (19) ◽  
Author(s):  
Yvonne Agersø ◽  
Birgitte Stuer-Lauridsen ◽  
Karin Bjerre ◽  
Michelle Geervliet Jensen ◽  
Eric Johansen ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Resistance Genes ◽  
Pathogenic Bacteria ◽  
Animal Feed ◽  
Bacterial Species ◽  
Feed Additives ◽  
Content Type ◽  
Cutoff Values ◽  
Antimicrobial Resistance Genes ◽  
Species Specific

ABSTRACTBacillus megaterium(n= 29),Bacillus velezensis(n= 26),Bacillus amyloliquefaciens(n= 6),Bacillus paralicheniformis(n= 28), andBacillus licheniformis(n= 35) strains from different sources, origins, and time periods were tested for the MICs for nine antimicrobial agents by the CLSI-recommended method (Mueller-Hinton broth, 35°C, for 18 to 20 h), as well as with a modified CLSI method (Iso-Sensitest [IST] broth, 37°C [35°C forB. megaterium], 24 h). This allows a proposal of species-specific epidemiological cutoff values (ECOFFs) for the interpretation of antimicrobial resistance in these species. MICs determined by the modified CLSI method were 2- to 16-fold higher than with the CLSI-recommended method for several antimicrobials. The MIC distributions differed between species for five of the nine antimicrobials. Consequently, use of the modified CLSI method and interpretation of resistance by use of species-specific ECOFFs is recommended. The genome sequences of all strains were determined and used for screening for resistance genes against the ResFinder database and for multilocus sequence typing. A putative chloramphenicol acetyltransferase (cat) gene was found in oneB. megateriumstrain with an elevated chloramphenicol MIC compared to the otherB. megateriumstrains. InB. velezensisandB. amyloliquefaciens, a putative tetracycline efflux gene,tet(L), was found in all strains (n= 27) with reduced tetracycline susceptibility but was absent in susceptible strains. AllB. paralicheniformisand 23% ofB. licheniformisstrains had elevated MICs for erythromycin and harboredermD. The presence of these resistance genes follows taxonomy suggesting they may be intrinsic rather than horizontally acquired. Reduced susceptibility to chloramphenicol, streptomycin, and clindamycin could not be explained in all species.IMPORTANCEWhen commercializing bacterial strains, likeBacillusspp., for feed applications or plant bioprotection, it is required that the strains are free of acquired antimicrobial resistance genes that could potentially spread to pathogenic bacteria, thereby adding to the pool of resistance genes that may cause treatment failures in humans or animals. Conversely, if antimicrobial resistance is intrinsic to a bacterial species, the risk of spreading horizontally to other bacteria is considered very low. Reliable susceptibility test methods and interpretation criteria at the species level are needed to accurately assess antimicrobial resistance levels. In the present study, tentative ECOFFs for fiveBacillusspecies were determined, and the results showed that the variation in MICs followed the respective species. Moreover, putative resistance genes, which were detected by whole-genome sequencing and suggested to be intrinsic rather that acquired, could explain the resistance phenotypes in most cases.

Costimulatory Effects of Interleukin-18 (IL-18) on Human Natural Killer (NK) Cells Activated through Fc Receptors for Immunoglobulin (IgG)

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2780-2780
Author(s):  
Shivani Srivastava ◽  
Hailin Feng ◽  
Menggang Yu ◽  
David Pelloso ◽  
Michael Robertson
Keyword(s):  
Monoclonal Antibodies ◽  
Nk Cells ◽  
Cell Function ◽  
Nk Cell ◽  
Conflicts Of Interest ◽  
Fc Receptors ◽  
Cytolytic Activity ◽  
Mitogen Activated Protein Kinase ◽  
Target Cells

Abstract Abstract 2780 NK cells play an important role in innate and adaptive immune responses. Most human NK cells express CD16, an Fc receptor for IgG that mediates lysis of antibody-coated target cells and costimulates interferon (IFN)-g production in response to cytokines. IL-18 is an immunostimulatory cytokine with antitumor activity in preclinical animal models. The effects of IL-18 on human NK cell function were examined. Here we show that NK cells stimulated with immobilized IgG in vitro secreted IFN-g; such IFN-g production was partially inhibited by blocking CD16 with monoclonal antibodies. IL-18 augmented IFN-g production by NK cells stimulated with immobilized IgG or CD16 antibodies (Figure 1). NK cell IFN-g production in response to immobilized IgG and/or IL-18 was inhibited by chemical inhibitors of Syk, extracellular signal-related kinases (ERK), p38 mitogen-activated protein kinase (MAPK), and phosphatidylinositol 3-kinase (PI3-K). Stimulation with IL-18 or immobilized IgG could augment IL-12-induced IFN-g production by STAT4-deficient lymphocytes obtained from lymphoma patients after autologous stem cell transplantation (Figure 2). IL-18 also augmented the in vitro lysis of rituximab-coated Raji cells by human NK cells (Figure 3). These observations that IL-18 can co stimulate IFN-g production and cytolytic activity of NK cells activated through Fc receptors makes it an attractive cytokine to combine with monoclonal antibodies for treatment of cancer. Disclosure: No relevant conflicts of interest to declare.

scholarly journals Bacterial Species-Specific Modulatory Effects on Phenotype and Function of Camel Blood Leukocytes

2020 ◽  
Author(s):  
Jamal Hussen
Keyword(s):  
Pathogenic Bacteria ◽  
Bacterial Species ◽  
Monocyte Subset ◽  
Ros Production ◽  
Blood Leukocytes ◽  
E Coli ◽  
Mhc Ii ◽  
Bacterial Stimulation ◽  
Species Specific ◽  
And Function

Abstract Background: Recent studies have reported pathogen-species-specific modulating effects on the innate immune system. Escherichia coli, Staphylococcus aureus, and Streptococcus agalactiae are important pathogenic bacteria responsible for different infectious diseases in several animal species. In the present study, a whole blood culture and flow cytometry were used to investigate, whether stimulation with different bacterial species induces different immunomodulation patterns in camel leukocytes. Results: Stimulation with either of the bacterial species resulted in the expansion of the camel CD14highMHCIIhigh monocyte subset with a reduced fraction of CD14highMHCIIlow monocytes. For the CD14highMHCIIlow monocytes, however, only stimulation with S. aureus or S. agalactiae increased their fractions in blood. Although all bacterial species elicited the upregulation of cell surface MHC-II molecules on granulocytes, the increase was, however, highest on cells stimulated with S. aureus. The expression levels of the two adhesion molecules, CD11a and CD18, on neutrophils and monocytes were differently affected by bacterial stimulation. Functionally, E. coli failed to stimulate ROS production in monocytes, while induced a strong ROS production response in granulocytes. S. agalactiae elicited a week ROS production in granulocytes when compared to the other two pathogens. Conclusions: The different responsiveness of monocytes and granulocytes toward different bacterial species indicates different host-pathogen interaction mechanisms for the two cell populations. In addition, the phenotypic and functional differences between cells stimulated with E. coli, S. aureus, or S. agalactiae suggests pathogen-species-specific modulating effects of the bacterial pathogens on the camel innate myeloid cells.

scholarly journals Cross-kingdom recognition of bacterial small RNAs induces transgenerational pathogenic avoidance

2019 ◽  
Author(s):  
Rachel Kaletsky ◽  
Rebecca S. Moore ◽  
Lance L. Parsons ◽  
Coleen T. Murphy
Keyword(s):  
Small Rnas ◽  
Pathogenic Bacteria ◽  
Escape Behavior ◽  
Bacterial Species ◽  
Future Generations ◽  
Transgenerational Inheritance ◽  
Signaling System ◽  
Specific Behavior ◽  
C Elegans ◽  
Species Specific

AbstractWe recently discovered that C. elegans can pass on a learned avoidance of pathogenic Pseudomonas aeruginosa (PA14) to four generations of its progeny. This transgenerational inheritance is bacterial species-specific, but how C. elegans recognizes and distinguishes different bacteria and transmits this information to future generations is not apparent. Here we show that small RNAs purified from pathogenic PA14 are sufficient not only to induce avoidance of pathogens in mothers, but also to confer transgenerational inheritance of this species-specific behavior for four generations, all without direct contact with pathogenic bacteria. This behavior requires the small RNA transporters SID-1 and SID-2, RNA interference pathway components, the piRNA Piwi/Argonaute pathway, a functioning germline, and TGF-β ligand daf-7 expression in the ASI sensory neuron. Our results suggest that C. elegans “reads” small RNAs expressed by pathogenic bacteria, and uses this information to induce an escape behavior that lasts for four additional generations. C. elegans may have evolved this trans-kingdom signaling system to avoid pathogens in abundant classes of bacteria in its environment and its microbiome.

scholarly journals Short Communication: Serratia rubidaea as contaminant in laboratory environment

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Dewi Peti Virgianti
Keyword(s):  
Pathogenic Bacteria ◽  
Bacterial Contamination ◽  
Short Communication ◽  
Bacterial Species ◽  
16S Rdna Gene ◽  
Laboratory Environment ◽  
Phylogenetic Characterization ◽  
Related Information ◽  
Positive Results ◽  
Serratia Rubidaea

Abstract. Virgianti DP. 2020. Short Communication: Serratia rubidaea as contaminant in laboratory environment. Nusantara Bioscience 13: 47-51. There have been many cases of bacterial contamination in the laboratory. The bacterial genera identified as contaminants are Bacillus, Staphylococcus, Micrococcus, Pseudomonas, Shigella and Serratia. These bacteria are classified as non-pathogenic and pathogenic bacteria that can interfere with the test and potentially develop false-positive results. The present research has shown that red-colored contaminant bacteria develop in unused sterile media in our laboratory. Based on related information, Serratia marcescens is a red bacterial species that have been reported as a contaminant in the laboratory. The purpose of this study was to identifiy contaminant bacteria at the molecular level. Based on the phylogenetic characterization using the 16S rDNA gene region, this red contaminant bacterium was identified as Serratia rubidaea.

scholarly journals Vaginolysin Drives Epithelial Ultrastructural Responses to Gardnerella vaginalis

2013 ◽  
Vol 81 (12) ◽  
pp. 4544-4550 ◽  
Author(s):  
Tara M. Randis ◽  
Joanne Zaklama ◽  
Timothy J. LaRocca ◽  
Ferdinand C. O. Los ◽  
Emma L. Lewis ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Bacterial Species ◽  
Gardnerella Vaginalis ◽  
Target Cells ◽  
Vaginal Mucosa ◽  
Content Type ◽  
Induced Membrane ◽  
Membrane Blebbing ◽  
Bleb Formation ◽  
Complex Signaling

ABSTRACTGardnerella vaginalis, the bacterial species most frequently isolated from women with bacterial vaginosis (BV), produces a cholesterol-dependent cytolysin (CDC), vaginolysin (VLY). At sublytic concentrations, CDCs may initiate complex signaling cascades crucial to target cell survival. Using live-cell imaging, we observed the rapid formation of large membrane blebs in human vaginal and cervical epithelial cells (VK2 and HeLa cells) exposed to recombinant VLY toxin and to cell-free supernatants from growing liquid cultures ofG. vaginalis. Binding of VLY to its human-specific receptor (hCD59) is required for bleb formation, as antibody inhibition of either toxin or hCD59 abrogates this response, and transfection of nonhuman cells (CHO-K1) with hCD59 renders them susceptible to toxin-induced membrane blebbing. Disruption of the pore formation process (by exposure to pore-deficient toxoids or pretreatment of cells with methyl-β-cyclodextrin) or osmotic protection of target cells inhibits VLY-induced membrane blebbing. These results indicate that the formation of functional pores drives the observed ultrastructural rearrangements. Rapid bleb formation may represent a conserved response of epithelial cells to sublytic quantities of pore-forming toxins, and VLY-induced epithelial cell membrane blebbing in the vaginal mucosa may play a role in the pathogenesis of BV.

scholarly journals Adding Selectivity to Antimicrobial Peptides: Rational Design of a Multidomain Peptide against Pseudomonas spp

2006 ◽  
Vol 50 (4) ◽  
pp. 1480-1488 ◽  
Author(s):  
Randal Eckert ◽  
Fengxia Qi ◽  
Daniel K. Yarbrough ◽  
Jian He ◽  
Maxwell H. Anderson ◽  
...  
Keyword(s):  
Bactericidal Activity ◽  
Rational Design ◽  
Pathogenic Bacteria ◽  
Bacterial Species ◽  
Specific Targeting ◽  
Chimeric Peptide ◽  
Clinical Consequences ◽  
Conventional Antibiotics ◽  
Species Specific ◽  
Synthetic Target

ABSTRACT Currently available antimicrobials exhibit broad killing with regard to bacterial genera and species. Indiscriminate killing of microbes by these conventional antibiotics can disrupt the ecological balance of the indigenous microbial flora, often resulting in negative clinical consequences. Species-specific antimicrobials capable of precisely targeting pathogenic bacteria without damaging benign microorganisms provide a means of avoiding this problem. In this communication, we report the successful creation of the first synthetic, target-specific antimicrobial peptide, G10KHc, via addition of a rationally designed Pseudomonas-specific targeting moiety (KH) to a generally killing peptide (novispirin G10). The resulting chimeric peptide showed enhanced bactericidal activity and faster killing kinetics against Pseudomonas spp. than G10 alone. The enhanced killing activities are due to increased binding and penetration of the outer membrane of Pseudomonas sp. cells. These properties were not observed in tests of untargeted bacterial species, and this specificity allowed G10KHc to selectively eliminate Pseudomonas spp. from mixed cultures. This work lays a foundation for generating target-specific “smart” antimicrobials to complement currently available conventional antibiotics.

scholarly journals Fluorescence in situ hybridization in species-specific diagnosis of ovine Campylobacter abortions

2020 ◽  
Vol 32 (3) ◽  
pp. 413-419
Author(s):  
Godelind A. Wolf-Jäckel ◽  
Mette Boye ◽  
Øystein Angen ◽  
Matthias Müller ◽  
Tim K. Jensen
Keyword(s):  
In Situ Hybridization ◽  
Fluorescence In Situ Hybridization ◽  
Pathogenic Bacteria ◽  
Bacterial Species ◽  
Detection Tool ◽  
Major Species ◽  
Species Specific ◽  
Campylobacter Infection ◽  
Culture Negative

Campylobacter infection is a leading cause of ovine abortion worldwide. Campylobacter fetus and C. jejuni are the major species involved. We report herein on abortion storms in 4 Danish sheep flocks. Initially, no pathogenic bacteria were isolated from placental and fetal tissues on aerobic and selective media despite the presence of severe suppurative and necrotizing placentitis with numerous bacteria located intracellularly in trophoblasts. Fluorescence in situ hybridization (FISH) was then applied on abortion material from 13 cases; species-specific oligonucleotide probes directed against either C. fetus or C. jejuni were used in combination with a general bacterial probe. C. fetus was detected as the only lesion-associated bacterial species in 4 cases from 2 flocks, and C. jejuni in 6 cases from the other 2 flocks, thereby establishing the likely etiology of the abortion storms in all 4 flocks. FISH is a useful detection tool in culture-negative cases with tissue lesions suggestive of bacterial infection. Furthermore, FISH is a fast and economical method to detect and identify the zoonotic agent Campylobacter within ovine abortion material.

scholarly journals Bacterial species-specific modulatory effects on phenotype and function of camel blood leukocytes

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Jamal Hussen
Keyword(s):  
Cell Surface ◽  
Adhesion Molecules ◽  
Mhc Class Ii ◽  
Pathogenic Bacteria ◽  
Bacterial Species ◽  
Monocyte Subset ◽  
Ros Production ◽  
Blood Leukocytes ◽  
Species Specific ◽  
And Function

Abstract Background Recent studies have reported pathogen-species-specific modulating effects on the innate immune system. Escherichia coli, Staphylococcus aureus, and Streptococcus agalactiae are important pathogenic bacteria responsible for different infectious diseases in several animal species. In the present study, a whole blood culture with S. aureus, E. coli, or S. agalactiae and flow cytometry were used to investigate, whether stimulation with different bacterial species induces different immunomodulation patterns in camel leukocytes. The expression of different cell surface myeloid markers and cell adhesion molecules on monocytes and neutrophils was investigated. In addition, the capacity of monocytes and neutrophils to produce reactive oxygen species (ROS) was analyzed. Results Stimulation with either of the bacterial species resulted in the expansion of the camel CD14highMHCIIhigh monocyte subset with a reduced fraction of CD14highMHCIIlow monocytes. For the CD14lowMHCIIhigh monocytes, however, only stimulation with S. aureus or S. agalactiae increased their fractions in blood. Although all bacterial species elicited the upregulation of cell surface MHC class II molecules on granulocytes, the increase was, however, highest on cells stimulated with S. aureus. The expression levels of the two adhesion molecules, CD11a and CD18, on neutrophils and monocytes were differently affected by bacterial stimulation. Functionally, E. coli failed to stimulate ROS production in monocytes, while induced a strong ROS production response in granulocytes. S. agalactiae elicited a week ROS production in granulocytes when compared to the other two pathogens. Conclusions The different responsiveness of monocytes and granulocytes toward different bacterial species indicates different host-pathogen interaction mechanisms for the two cell populations. In addition, the phenotypic and functional differences between cells stimulated with E. coli, S. aureus, or S. agalactiae suggests pathogen-species-specific modulating effects of the bacterial pathogens on the camel innate myeloid cells.

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