scholarly journals Characterization of Human Bactericidal Antibodies to Bordetella pertussis

1999 ◽  
Vol 67 (3) ◽  
pp. 1424-1431 ◽  
Author(s):  
Alison A. Weiss ◽  
Paula S. Mobberley ◽  
Rachel C. Fernandez ◽  
ChrisAnna M. Mink
Keyword(s):  
Immune Response ◽  
Bactericidal Activity ◽  
Bordetella Pertussis ◽  
Type Strain ◽  
Wild Type Strain ◽  
Resistance Mechanism ◽  
Wild Type ◽  
Occupationally Exposed ◽  
Bactericidal Activities

ABSTRACT The Bordetella pertussis BrkA protein protects against the bactericidal activity of complement and antibody; however, some individuals mount an immune response that overcomes this bacterial defense. To further characterize this process, the bactericidal activities of sera from 13 adults with different modes of exposure toB. pertussis (infected as adults, occupational exposure, immunized with an acellular vaccine, or no identified exposure) against a wild-type strain and a BrkA complement-sensitive mutant were evaluated. All of the sera killed the BrkA mutant, suggesting past exposure to B. pertussis or cross-reactive organisms. Several samples had no or minimal activity against the wild type. All of the sera collected from the infected and occupationally exposed individuals but not all of the sera from vaccinated individuals had bactericidal activity against the wild-type strain, suggesting that some types of exposure can induce an immune response that can overcome the BrkA resistance mechanism. Adsorbing serum with the wild-type strain removed the bactericidal antibodies; however, adsorbing the serum with a lipopolysaccharide (LPS) mutant or an avirulent (bvg mutant) strain did not always result in loss of bactericidal activity, suggesting that antibodies to either LPS orbvg-regulated proteins could be bactericidal. All the samples, including those that lacked bactericidal activity, contained antibodies that recognized the LPS of B. pertussis. Bactericidal activity correlated best with the presence of the immunoglobulin G3 (IgG3) antibodies to LPS, the IgG subtype that is most effective at fixing complement.

scholarly journals Combined Roles of Human IgG Subclass, Alternative Complement Pathway Activation, and Epitope Density in the Bactericidal Activity of Antibodies to Meningococcal Factor H Binding Protein

2011 ◽  
Vol 80 (1) ◽  
pp. 187-194 ◽  
Author(s):  
Serena Giuntini ◽  
Donald C. Reason ◽  
Dan M. Granoff
Keyword(s):  
Bactericidal Activity ◽  
Type Strain ◽  
Wild Type Strain ◽  
Factor H ◽  
Complement Pathway ◽  
Wild Type ◽  
Alternative Complement ◽  
Igg1 Mabs ◽  
Human Igg1 ◽  
Epitope Density

ABSTRACTMeningococcal vaccines containing factor H binding protein (fHbp) are in clinical development. fHbp binds human fH, which enables the meningococcus to resist complement-mediated bacteriolysis. Previously, we found that chimeric human IgG1 mouse anti-fHbp monoclonal antibodies (MAbs) had human complement-mediated bactericidal activity only if the MAb inhibited fH binding. Since IgG subclasses differ in their ability to activate complement, we investigated the role of human IgG subclasses on antibody functional activity. We constructed chimeric MAbs in which three different murine fHbp-specific binding domains were each paired with human IgG1, IgG2, or IgG3. Against a wild-type group B isolate, all three IgG3 MAbs, irrespective of their ability to inhibit fH binding, had bactericidal activity that was >5-fold higher than the respective IgG1 MAbs, while the IgG2 MAbs had the least activity. Against a mutant with increased fHbp expression, the anti-fHbp MAbs elicited greater C4b deposition (classical pathway) and greater bactericidal activity than against the wild-type strain, and the IgG1 MAbs had similar or greater activity than the respective IgG3 MAbs. The bactericidal activity against both wild-type and mutant strains also was dependent, in part, on activation of the alternative complement pathway. Thus, at lower epitope density in the wild-type strain, the IgG3 anti-fHbp MAbs had the greatest bactericidal activity. At a higher epitope density in the mutant, the IgG1 MAbs had similar or greater bactericidal activity than the IgG3 MAbs, and the activity was less dependent on the inhibition of fH binding than at a lower epitope density.

scholarly journals Circulating γδ T Cells in Response to Salmonellaenterica Serovar Enteritidis Exposure in Chickens

2006 ◽  
Vol 74 (7) ◽  
pp. 3967-3978 ◽  
Author(s):  
Angela Berndt ◽  
Jana Pieper ◽  
Ulrich Methner
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
Peripheral Blood ◽  
Type Strain ◽  
Wild Type Strain ◽  
Γδ T Cells ◽  
Immunohistochemical Analysis ◽  
Wild Type ◽  
Γδt Cells

ABSTRACT γδT cells are considered crucial to the outcome of various infectious diseases. The present study was undertaken to characterizeγδ (T-cell receptor 1+ [TCR1+]) T cells phenotypically and functionally in avian immune response. Day-old chicks were orally immunized with Salmonella enterica serovar Enteritidis live vaccine or S. enterica serovar Enteritidis wild-type strain and infected using the S. enterica serovar Enteritidis wild-type strain on day 44 of life. Between days 3 and 71, peripheral blood was examined flow cytometrically for the occurrence of γδ T-cell subpopulations differentiated by the expression of T-cell antigens. Three different TCR1+ cell populations were found to display considerable variation regarding CD8α antigen expression: (i) CD8α+high TCR1+ cells, (ii) CD8α+dim TCR1+ cells, and (iii) CD8α− TCR1+ cells. While most of the CD8α+high TCR1+ cells expressed the CD8αβ heterodimeric antigen, the majority of the CD8α+dim TCR1+ cells were found to express the CD8αα homodimeric form. After immunization, a significant increase of CD8αα+high γδ T cells was observed within the CD8α+high TCR1+ cell population. Quantitative reverse transcription-PCR revealed reduced interleukin-7 receptor α (IL-7Rα) and Bcl-x expression and elevated IL-2Rα mRNA expression of the CD8αα+highγδ T cells. Immunohistochemical analysis demonstrated a significant increase of CD8α+ and TCR1+ cells in the cecum and spleen and a decreased percentage of CD8β+ T cells in the spleen after Salmonella immunization. After infection of immunized animals, immune reactions were restricted to intestinal tissue. The study showed that Salmonella immunization of very young chicks is accompanied by an increase of CD8αα+high γδ T cells in peripheral blood, which are probably activated, and thus represent an important factor for the development of a protective immune response to Salmonella organisms in chickens.

scholarly journals Pertussis Toxin and Adenylate Cyclase Toxin Provide a One-Two Punch for Establishment of Bordetella pertussis Infection of the Respiratory Tract

2005 ◽  
Vol 73 (5) ◽  
pp. 2698-2703 ◽  
Author(s):  
Nicholas H. Carbonetti ◽  
Galina V. Artamonova ◽  
Charlotte Andreasen ◽  
Nicholas Bushar
Keyword(s):  
Adenylate Cyclase ◽  
Respiratory Tract ◽  
Pertussis Toxin ◽  
Bordetella Pertussis ◽  
Type Strain ◽  
Wild Type Strain ◽  
Infection Model ◽  
Wild Type ◽  
Adenylate Cyclase Toxin ◽  
Tract Infections

ABSTRACT Previously we found that pertussis toxin (PT), an exotoxin virulence factor produced by Bordetella pertussis, plays an important early role in colonization of the respiratory tract by this pathogen, using a mouse intranasal infection model. In this study, we examined the early role played by another exotoxin produced by this pathogen, adenylate cyclase toxin (ACT). By comparing a wild-type strain to a mutant strain (ΔCYA) with an in-frame deletion of the cyaA gene encoding ACT, we found that the lack of ACT confers a significant peak (day 7) colonization defect (1 to 2 log10). In mixed-infection experiments, the ΔCYA strain was significantly outcompeted by the wild-type strain, and intranasal administration of purified ACT did not increase colonization by ΔCYA. These data suggest that ACT benefits the bacterial cells that produce it and, unlike PT, does not act as a soluble factor benefiting the entire infecting bacterial population. Comparison of lower respiratory tract infections over the first 4 days after inoculation revealed that the colonization defect of the PT deletion strain was apparent earlier than that of ΔCYA, suggesting that PT plays an earlier role than ACT in the establishment of B. pertussis infection. Examination of cells in the bronchoalveolar lavage fluid of infected mice revealed that, unlike PT, ACT does not appear to inhibit neutrophil influx to the respiratory tract early after infection but may combat neutrophil activity once influx has occurred.

scholarly journals Characterization of a Wild-Type Strain ofFrancisella TularensisIsolated from a Cat

2004 ◽  
Vol 16 (5) ◽  
pp. 374-381 ◽  
Author(s):  
Thomas J. Inzana ◽  
Gretchen E. Glindemann ◽  
Gerald Snider ◽  
Susan Gardner ◽  
Lisa Crofton ◽  
...  
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Wild Type

scholarly journals Control of β-glucan exposure by the endo-1,3-glucanase Eng1 in Candida albicans modulates virulence

2020 ◽  
Author(s):  
Mengli Yang ◽  
Norma V. Solis ◽  
Michaela Marshall ◽  
Rachel Garleb ◽  
Tingting Zhou ◽  
...  
Keyword(s):  
Immune Response ◽  
Candida Albicans ◽  
Innate Immune Response ◽  
Type Strain ◽  
Wild Type Strain ◽  
Innate Immune ◽  
Yeast Cells ◽  
Parallel Mechanisms ◽  
Wild Type ◽  
Lectin Receptor

AbstractCandida albicans is a major cause of invasive candidiasis, which has a high mortality rate. The hyphal form of C. albicans is virulent and activates the host innate immune response, while the yeast form is hypovirulent and less immunogenic. The innate immune response is critical for host defense, but overactivation can cause tissue damage and sepsis. The innate immune response can be triggered when the C-type lectin receptor Dectin-1 recognizes β-glucans, which is protected by the outer mannan layer of the cell wall on C. albicans. Here, we demonstrate that there is low level of Dectin-1 binding at the septum of yeast cells, but high level of Dectin-1 binding over the entire surface of hyphae. We find that β-glucan masking in yeast is controlled by two highly expressed yeast proteins, the endo-1,3-β-glucanase Eng1 and the Yeast Wall Protein Ywp1. An eng1 deletion mutant shows enhanced Dectin-1 binding at the septa, while an eng1 ywp1 double mutant, but not an ywp1 single mutant, shows strong overall Dectin-1 binding. Thus, Eng1-mediated β-glucan trimming and Ywp1-mediated β-glucan masking are two parallel mechanisms utilized by C. albicans yeast to minimize recognition by Dectin-1. In the model of disseminated candidiasis, mice infected with the eng1 deletion mutant showed delayed mortality with an increased renal immune response in males compared to mice infected with the wild-type strain, but earlier mortality with a higher renal immune response in females. Using the eng1 mutant that is specifically defective in β-glucan masking in yeast, this study demonstrates that the level of β-glucan exposure is important for modulating the balance between immune protection and immunopathogenesis.Abstract ImportanceCandida albicans is a major opportunistic fungal pathogen of humans. Systemic Candidiasis has high mortality rates. C. albicans is also a constituent of the human microbiome and found in gastrointestinal and genitourinary tracts of most healthy individuals. C. albicans is able to switch reversibly between yeast and hyphae in response to environmental cues. The hyphal form is virulent, while the yeast form is hypovirulent and less immunogenic. This study demonstrates that β-glucan exposure in yeast is protected by two highly expressed yeast proteins, the endo-1,3-β-glucanase Eng1 and the Yeast Wall Protein Ywp1. Eng1-mediated β-glucan trimming and Ywp1-mediated β-glucan masking are two parallel mechanisms utilized by C. albicans yeast to minimize recognition by the host C-type lectin receptor Dectin-1. The eng1 mutant triggers a higher immune response and leads to earlier mortality compared to the wild-type strain. Thus, β-glucan masking in yeast keeps yeast cells less immunogenic and hypovirulent.

scholarly journals Regulation and Characterization of a Newly Deduced Cell Wall Hydrolase Gene (cwlJ) Which Affects Germination of Bacillus subtilis Spores

1998 ◽  
Vol 180 (6) ◽  
pp. 1375-1380 ◽  
Author(s):  
Shu Ishikawa ◽  
Kunio Yamane ◽  
Junichi Sekiguchi
Keyword(s):  
Bacillus Subtilis ◽  
Type Strain ◽  
Wild Type Strain ◽  
Catalytic Domain ◽  
Slow Release ◽  
Dipicolinic Acid ◽  
Northern Hybridization ◽  
Predicted Amino Acid Sequence ◽  
Wild Type

ABSTRACT The predicted amino acid sequence of Bacillus subtilis ycbQ (renamed cwlJ) exhibits high similarity to those of the deduced C-terminal catalytic domain of SleBs, the specific cortex-hydrolyzing enzyme of B. cereus and the deduced one of B. subtilis. We constructed acwlJ::lacZ fusion in the B. subtilischromosome. The β-galactosidase activity and results of Northern hybridization and primer extension analyses of the cwlJgene indicated that it is transcribed by EςE RNA polymerase. cwlJ-deficient spores responded to bothl-alanine and AGFK, the A 580 values of spore suspensions decreased more slowly than in the case of the wild-type strain, and the mutant spores released less dipicolinic acid than did those of the wild-type strain during germination. However, the mutant spores released only slightly less hexosamine than did the wild-type spores. In contrast, B. subtilis sleB spores did not release hexosamine at a significant level. While cwlJand sleB spores were able to germinate, CJSB (cwlJ sleB) spores could not germinate but exhibited initial germination reactions, e.g., partial decrease inA 580 and slow release of dipicolinic acid. CJSB spores became slightly gray after 6 h in the germinant, but their refractility was much greater than that of sleB mutant spores. The roles of the sleB and cwlJmutations in germination and spore maturation are also discussed.

scholarly journals Characterization of melanin produced by a wild-type strain of Bacillus thuringiensis

2004 ◽  
Vol 50 (4) ◽  
pp. 183-188 ◽  
Author(s):  
Yuehua Chen ◽  
Yinyue Deng ◽  
Jinhong Wang ◽  
Jun Cai ◽  
Gaixin Ren
Keyword(s):  
Bacillus Thuringiensis ◽  
Type Strain ◽  
Wild Type Strain ◽  
Wild Type

Purification and characterization of a β-glucosidase from Streptomyces lividans 66

1990 ◽  
Vol 36 (1) ◽  
pp. 53-56 ◽  
Author(s):  
Anca Mihoc ◽  
Dieter Kluepfel
Keyword(s):  
High Performance Liquid Chromatography ◽  
Molecular Sieve ◽  
Type Strain ◽  
High Performance ◽  
Wild Type Strain ◽  
Streptomyces Lividans ◽  
Wild Type ◽  
Purification And Characterization ◽  
Anion Exchange Column

An intracellular β-1, 4-D-glucosidase (EC 3.2.1.21) was isolated from the mutant strain HP-3 of Streptomyces lividans 66 which produced about 12 times more enzyme than the wild-type strain. The purification was carried out by anion exchange column chromatography followed by high-performance liquid chromatography on DEAE and on molecular sieve columns. The enzyme is glycosylated and has an apparent Mr of 51 000 and a pI of 4.3. Its activity was optimal at pH 6.5 and at a temperature of 40 °C. The Km and the Vmax on cellobiose were 3.1 mM and 65.6 μmol min−1 mg−1 of enzyme. Key words: β-glucosidase, Streptomyces lividans, purification, characterization.

scholarly journals Helicobacter pyloriOuter Membrane Protein 18 (Hp1125) Is Involved in Persistent Colonization by Evading Interferon-γSignaling

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Yuqun Shan ◽  
Xingxiao Lu ◽  
Yingnan Han ◽  
Xinpeng Li ◽  
Xiao Wang ◽  
...  
Keyword(s):  
Immune Response ◽  
Type Strain ◽  
Wild Type Strain ◽  
Outer Membrane Proteins ◽  
Immune Surveillance ◽  
Survival Rates ◽  
Wild Type ◽  
Qrt Pcr ◽  
H Pylori ◽  
Host Immune Surveillance

Outer membrane proteins (OMPs) can induce an immune response. Omp18 (HP1125) ofH. pyloriis a powerful antigen that can induce significant interferon-γ(IFN-γ) levels. Previous studies have suggested that IFN-γplays an important role inH. pyloriclearance. However,H. pylorihas multiple mechanisms to avoid host immune surveillance for persistent colonization. We generated anomp18mutant (H. pylori26695 andH. pyloriSS1) strain to examine whether Omp18 interacts with IFN-γand is involved inH. pyloricolonization. qRT-PCR revealed that IFN-γinduced Omp18 expression. qRT-PCR and western blot analysis revealed reduced expressions of virulence factors CagA and NapA inH. pylori26695 with IFN-γtreatment, but they were induced in the Δomp18strain. In C57BL/6 mice infected withH. pyloriSS1 and the Δomp18strain, the Δomp18strain conferred defective colonization and activated a stronger inflammatory response. Signal transducer phosphorylation and transcription 1 (STAT1) activator was downregulated by the wild-type strain but not the Δomp18strain in IFN-γ-treated macrophages. Furthermore, Δomp18strain survival rates were poor in macrophages compared to the wild-type strain. We concluded thatH. pyloriOmp18 has an important function influencing IFN-γ-mediated immune response to participate in persistent colonization.

scholarly journals Characterization of emeA, anorA Homolog and Multidrug Resistance Efflux Pump, inEnterococcus faecalis

2001 ◽  
Vol 45 (12) ◽  
pp. 3574-3579 ◽  
Author(s):  
Brandie M. Jonas ◽  
Barbara E. Murray ◽  
George M. Weinstock
Keyword(s):  
Drug Resistance ◽  
Multidrug Resistance ◽  
Type Strain ◽  
Deletion Mutant ◽  
Wild Type Strain ◽  
Efflux Pump ◽  
Wild Type ◽  
Type Gene ◽  
Encoding Genes

ABSTRACT We hypothesized that multidrug resistance efflux pumps (MDRs) may be contributing to the drug resistance of enterococci. We recently identified potential MDR-encoding genes in the Enterococcus faecalis V583 genome. Among the putative MDRs, we found a gene that encodes a NorA homolog and have characterized this enterococcal MDR in the present study. A mutant from which the enterococcal NorA homolog has been deleted has reduced resistance to several NorA substrates. Complementation of the deletion mutant with the wild-type gene verified the involvement of this enterococcal gene in resistance to ethidium bromide (EtBr) and norfloxacin. Known MDR inhibitors (reserpine, lansoprazole, and verapamil) inhibit the efflux of EtBr and norfloxacin in wild-type strain OG1RF. A fluorescence assay with EtBr allowed us to quantitate the efflux capability of the enterococcal NorA pump. On the basis of these results, we have named this enterococcal gene emeA (enterococcal multidrug resistance efflux).

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