bluuebunny/crossref_metadata_2025_split huggingface dataset:
Delivery of the p67 Sporozoite Antigen of
Theileria parva
by Using Recombinant
Salmonella dublin
: Secretion of the Product Enhances Specific Antibody Responses in Cattle
Authors: Gentschev Ivo , Glaser Ines , Goebel Werner , McKeever Declan J. , Musoke Anthony , Heussler Volker T. 
Published: December 2019

ABSTRACT

The p67 sporozoite antigen of
Theileria parva
has been fused to the C-terminal secretion signal of
Escherichia coli
hemolysin and expressed in secreted form by attenuated
Salmonella dublin aroA
strain SL5631. The recombinant p67 antigen was detected in the supernatant of transformed bacterial cultures. Immunization trials in cattle revealed that SL5631 secreting the antigen provoked a 10-fold-higher antibody response to p67 than recombinant SL5631 expressing but not secreting p67. Immunized calves were challenged with a 80% lethal dose of
T. parva
sporozoites and monitored for the development of infection. Two of three calves immunized intramuscularly with the p67-secreting SL5631 strain were found to be protected, whereas only one of three animals immunized with the nonsecreting p67-expressing SL5631 strain was protected. This is the first demonstration that complete eukaryotic antigens fused to the C-terminal portion of
E. coli
hemolysin can be exported from attenuated
Salmonella
strains and that such exported antigens can protect cattle against subsequent parasite challenge.
Clearance ofBorrelia burgdorferiMay Not Be Required for Resistance to Experimental Lyme Arthritis
Authors: Brown Charles R. , Reiner Steven L. 
Published: December 2019

ABSTRACTInfection of inbred mouse strains withBorrelia burgdorferiresults in the development of experimental Lyme arthritis. The degree of arthritic pathology has been suggested to correlate with the level of spirochete burden within tissues. To investigate this further, we infected resistant DBA/2 (DBA) and susceptible C3H/HeJ (C3H) mice in the hind footpads and monitored arthritis development for 21 days. To quantitate levels of spirochetes within tissues, we created a competitive PCR molecule containing modifiedospAandflagene segments. C3H mice developed severe arthritis of the tibiotarsal joints, while DBA mice developed only mild inflammation throughout the experimental period. At day 21, when the gross size and histologic composition of ankles revealed significant differences in arthritis between the strains, there was little difference in levels of spirochete DNA as determined by competitive PCR. Cultures of ankle tissue at day 21 were also uniformly positive in both C3H and DBA animals and contained relatively similar levels of spirochetes. These results indicate that the presence of spirochetes in the ankles of experimental animals is not sufficient for arthritis development. Since arthritic and nonarthritic animals can harbor relatively equal spirochete burdens yet retain their distinct phenotypic outcomes, an aberrant or overly exuberant immune response may be an additional requirement for pathology in arthritis-prone mice.
A Tumor Necrosis Factor Mimetic Peptide Activates a Murine Macrophage Cell Line To Inhibit Mycobacterial Growth in a Nitric Oxide-Dependent Fashion
Authors: Britton W. J. , Meadows N. , Rathjen D. A. , Roach D. R. , Briscoe H. 
Published: December 2019

ABSTRACTThe control of mycobacterial infections depends on the cytokine-mediated activation of mononuclear phagocytes to inhibit the growth of intracellular mycobacteria. Optimal activation requires the presence of T-cell-derived gamma interferon (IFN-γ) and other signals, including tumor necrosis factor (TNF). Recently, an 11-mer peptide based on amino acids 70 to 80 of the human TNF sequence, TNF(70-80), was found to have TNF mimetic properties, which include the activation of human and mouse neutrophils to killPlasmodiaspp. Therefore, we investigated the capacity of TNF(70-80)to activate the murine macrophage cell line RAW264.7 infected with the vaccine strainMycobacterium bovisbacillus Calmette-Guérin (BCG). When RAW264.7 cells were pretreated with human TNF or TNF(70-80)in the presence of IFN-γ, there was a dose-dependent reduction in the replication of BCG as measured by the uptake of3H-labeled uracil and a concomitant release of nitric oxide as measured by the nitrite in the culture supernatants. TNF- or TNF(70-80)-induced macrophage activation was dependent on IFN-γ and was inhibited by neutralizing monoclonal antibody to human TNF and by anti-IFN-γ antisera. Both nitrite release and BCG growth inhibition were abrogated by competitive inhibitors ofl-arginine, which blocked the activation of inducible nitric oxide synthase. A soluble form of the Type 1 TNF receptor blocked the activation of BCG-infected macrophages by human TNF and TNF(70-80), demonstrating that the effect of TNF(70-80)is dependent on signaling through TNF receptor I. The mimetic effects of TNF(70-80)on macrophage activation in vitro suggest that treatment with TNF(70-80)may modulate mycobacterial infections in vivo.
Kinetics of Infection and Effects on Placental Cell Populations in a Murine Model ofChlamydia psittaci-Induced Abortion
Authors: Buendía Antonio J. , Sánchez Joaquín , Martínez María C. , Cámara Paulina , Navarro Jose A. , Rodolakis Annie , Salinas Jesus 
Published: December 2019

ABSTRACTThe anatomical progression of chlamydial infection was studied in different areas of the placenta, using a mouse model and two inoculation times: early pregnancy (day 7, group A) and midpregnancy (day 11, group B). The first population cells affected were decidual cells and neutrophils located just at the limits of the maternal and fetal placenta. The following invaded area was the layer of giant cells. Complete colonization of the maternal placenta occurred after day 15 of pregnancy independently of the inoculation time, the metrial gland being the last area to be invaded; numerous granulated metrial gland (GMG) cells were infected. Finally, chlamydial inclusions were observed in labyrinthine trophoblastic cells from day 18 of pregnancy onward. Since no fetal damage was observed, it seems that an indirect mechanism involving the lysis of GMG cells and neutrophil infiltration of the decidua and metrial gland may be the pathogenic mechanism that leads to abortion.
Proteins Encoded by thecagPathogenicity Island ofHelicobacter pyloriAre Required for NF-κB Activation
Authors: Glocker Erik , Lange Christina , Covacci Antonello , Bereswill Stefan , Kist Manfred , Pahl Heike L. 
Published: December 2019

ABSTRACTHelicobacter pyloriis the etiological agent in the development of chronic gastritis, duodenal ulceration, and gastric adenocarcinoma. The difference in virulence between individual strains is reflected in their ability to induce interleukin-8 (IL-8) secretion from gastric epithelial cells. It has been shown that virulence is associated with the presence of a bacterial gene cluster (a pathogenicity island). We have recently demonstrated thatH. pylori-mediated IL-8 secretion requires activation of the transcription factor NF-κB. Here, we show that NF-κB induction requires six membrane proteins encoded within the pathogenicity island.
Lethal Factor Active-Site Mutations Affect Catalytic Activity In Vitro
Authors: Hammond S. E. , Hanna P. C. 
Published: December 2019

ABSTRACTThe lethal factor (LF) protein ofBacillus anthracislethal toxin contains the thermolysin-like active-site and zinc-binding consensus motif HEXXH (K. R. Klimpel, N. Arora, and S. H. Leppla, Mol. Microbiol. 13:1093–1100, 1994). LF is hypothesized to act as a Zn2+metalloprotease in the cytoplasm of macrophages, but no proteolytic activities have been previously shown on any target substrate. Here, synthetic peptides are hydrolyzed by LF in vitro. Mass spectroscopy and peptide sequencing of isolated cleavage products separated by reverse-phase high-pressure liquid chromatography indicate that LF seems to prefer proline-containing substrates. Substitution mutations within the consensus active-site residues completely abolish all in vitro catalytic functions, as does addition of 1,10-phenanthroline, EDTA, and certain amino acid hydroxamates, including the novel zinc metalloprotease inhibitor ZINCOV. In contrast, the protease inhibitors bestatin and lysine CMK, previously shown to block LF activity on macrophages, did not block LF activity in vitro. These data provide the first direct evidence that LF may act as an endopeptidase.
Cryptosporidium parvum
Infection of Human Intestinal Xenografts in SCID Mice Induces Production of Human Tumor Necrosis Factor Alpha and Interleukin-8
Authors: Seydel Karl B. , Zhang Tonghai , Champion Gretchen A. , Fichtenbaum Carl , Swanson Paul E. , Tzipori Saul , Griffiths Jeffrey K. , Stanley Samuel L. 
Published: December 2019

ABSTRACT

The protozoan parasite
Cryptosporidium parvum
invades intestinal epithelial cells and can cause life-threatening diarrhea in immunocompromised individuals. Despite the clinical importance of this organism, much remains to be learned about the pathogenesis of
C. parvum
-induced diarrhea. To explore the role of the intestinal inflammatory response in
C. parvum
disease, using
C. parvum
oocysts we infected human intestinal xenografts in severe combined immunodeficient (SCID) mice. Seven days after infection, we found levels of human tumor necrosis factor alpha and interleukin-8 in
C. parvum
-infected human intestinal xenografts that were significantly higher than those seen in uninfected control xenografts. These results demonstrate that human intestinal cells produce proinflammatory cytokines in response to
C. parvum
infection and establish SCID-HU-INT mice as a model system to study the interactions of
C. parvum
with the human intestine.
Cytochalasin-Induced Actin Disruption of Polarized Enterocytes Can Augment Internalization of Bacteria
Authors: Wells Carol L. , van de Westerlo Elisabeth M. A. , Jechorek Robert P. , Haines Holly M. , Erlandsen Stanley L. 
Published: December 2019

ABSTRACT

Cytochalasin-induced actin disruption has often been associated with decreased bacterial internalization by cultured epithelial cells, although polarized enterocytes have not been systematically studied. In assays using confluent polarized HT-29 enterocytes, cytochalasin D appeared to increase internalization of wild-type
Salmonella typhimurium
,
Proteus mirabilis
, and
Escherichia coli
. HeLa and HEp-2 epithelial cells, as well as HT-29 and Caco-2 enterocytes, were used to clarify this unexpected observation. Resulting data showed that cytochalasin D was associated with increased internalization of
S. typhimurium
and
P. mirabilis
by both HT-29 and Caco-2 enterocytes and with increased internalization of
E. coli
by HT-29 enterocytes; with either HeLa or HEp-2 cells, cytochalasin was associated with no change or a decrease in internalization of these same bacterial strains. Cytochalasin caused decreased internalization of
Listeria monocytogenes
by HT-29, Caco-2, HeLa, and HEp-2 cells, indicating that cytochalasin did not consistently augment bacterial internalization by polarized enterocytes. Fluorescein-labeled phalloidin confirmed marked disruption of filamentous actin in cytochalasin-treated HT-29, Caco-2, HeLa, and HEp-2 cells. Cytochalasin had no noticeable effect on epithelial viability but caused distorted apical microvilli, cell rounding, and separation of adjacent enterocytes in confluent cultures (with a corresponding decrease in transepithelial electrical resistance). Scanning electron microscopy showed that cytochalasin-induced enhanced bacterial internalization was associated with preferential bacterial adherence on the exposed enterocyte lateral surface. Colchicine, used to disrupt microtubules, had no noticeable effect on bacterial internalization by HT-29 or Caco-2 enterocytes. These data indicated that for HT-29 and Caco-2 enterocytes, cytochalasin-induced disruption of filamentous actin might augment internalization of some bacterial species by a mechanism that appeared to involve exposure of the enterocyte lateral surface.
Differential Gene Expression in Response to Adjunctive Recombinant Human Interleukin-2 Immunotherapy in Multidrug-Resistant Tuberculosis Patients
Authors: Johnson Barbara J. , Estrada Iris , Shen Zhu , Ress Stan , Willcox Paul , Colston M. Joseph , Kaplan Gilla 
Published: December 2019

ABSTRACTAdministration of low-dose recombinant human interleukin 2 (rhuIL-2) in combination with multidrug chemotherapy to patients with multidrug-resistant tuberculosis (MDR TB) induces measurable changes in in vitro immune response parameters which are associated with changes in the clinical and bacteriologic status of the patients. To determine the molecular basis of these changes, we have used semiquantitative reverse transcriptase-initiated PCR (RT-PCR) and differential display technology. During rhuIL-2 treatment of MDR TB patients, decreased levels of gamma interferon (IFN-γ) mRNA in peripheral blood mononuclear cells (PBMC) relative to baseline levels were observed. However, at the site of a delayed-type hypersensitivity (DTH) response to purified protein derivative of tuberculin (PPD), the expression of cellular IFN-γ and IL-2 mRNAs was increased during rhuIL-2 therapy. Levels of other cytokine mRNAs were not significantly affected by rhuIL-2 administration. Using differential-display RT-PCR, we identified several genes expressed at the DTH skin test site which were up- or down-regulated during rhuIL-2 treatment. Cytochrome oxidase type I mRNA was increased in response to rhuIL-2 therapy relative to baseline levels, as was heterogeneous nuclear ribonuclear protein G mRNA. CD63, clathrin heavy chain, and β-adaptin mRNAs, all of which encode proteins associated with the endocytic vacuolar pathway of cells, were also differentially regulated by rhuIL-2 administration. The differential effects of IL-2 were confirmed in vitro by using PBMC obtained from PPD-positive individuals stimulated withMycobacterium tuberculosisand IL-2. The differential expression of genes may provide a surrogate marker for leukocyte activation at a mycobacterial antigen-specific response site and for the development of an enhanced antimicrobial response which may result in improved outcomes in MDR TB patients.
Streptococcus pneumoniaeType 14 Polysaccharide-Conjugate Vaccines: Length Stabilization of Opsonophagocytic Conformational Polysaccharide Epitopes
Authors: Laferriere Craig A. , Sood Ramesh K. , de Muys Jean-Marc , Michon Francis , Jennings Harold J. 
Published: December 2019

ABSTRACTA simple and convenient method was developed for the preparation ofStreptococcus pneumoniaetype 14 polysaccharide (Pn14PS)-tetanus toxoid (TT) conjugate vaccines, using terminally linked Pn14PS fragments of different lengths. Native Pn14PS was simultaneously depolymerized and activated for conjugation by partial N-deacetylation followed by nitrous acid deamination which yielded fragments (1.4 to 150.0 kDa) having a free aldehyde at the reducing end. These were then conjugated to TT through their terminal aldehydic groups, using the reductive amination procedure. All of the above conjugates, when injected in rabbits, induced anti-Pn14PS antibodies, whereas the native Pn14PS did not. The amounts of anti-Pn14PS antibodies elicited by these conjugates, as determined by enzyme-linked immunosorbent assay, followed a trend with conjugates containing the highest-molecular-weight Pn14PS eliciting the highest titers. The same trend was also observed in the ability of the antibodies to opsonize and kill live type 14 pneumococci, although the increase in opsonophagocytic activity was more pronounced and did not correlate linearly with increases in antibody titer. Competitive inhibition of the binding of different conjugate antisera to the native Pn14PS, using Pn14PS fragments as inhibitors, established that the conjugates induced antibodies with specificities for different lengths of Pn14PS beginning at 2 repeating units (RU). It was also established, both immunologically and antigenically, that at least 4 RU of Pn14PS were required to form an extended conformational epitope and that approximately 22 RU of Pn14PS were required to duplicate the same epitope on the same saccharide chain. The conformational epitope was found to be essential for the induction of antibodies with high opsonophagocytic activity and that augmentation of opsonophagocytic activity was also dependent on further chain extension.
Age-DependentNeisseria meningitidisSerogroup C Class-Specific Antibody Concentrations and Bactericidal Titers in Sera from Young Children from Montana Immunized with a Licensed Polysaccharide Vaccine
Authors: Maslanka Susan E. , Tappero Jordan W. , Plikaytis Brian D. , Brumberg Robert S. , Dykes Janet K. , Gheesling Linda L. , Donaldson Kimberley B. J. , Schuchat Anne , Pullman John , Jones MaryAnn , Bushmaker Julie , Carlone George M. 
Published: December 2019

ABSTRACTNeisseria meningitidisserogroup C bactericidal titers and class-specific enzyme-linked immunosorbent assay (ELISA) antibody concentrations were measured in sera from 173 children (1 to 5 years old) before and 6 weeks and 7 months following vaccination with a quadrivalent (A/C/Y/W-135) polysaccharide vaccine. The immune responses of the children were compared with those of 40 adults 6 weeks postvaccination. Both bactericidal titers and ELISA antibody concentrations were significantly higher in the adults than in the children (P< 0.05). In addition, the ratio of immunoglobulin G (IgG) to IgM was higher in the children than in the adults. With an ELISA total antibody concentration of ≥2 μg/ml used as a measure of seroconversion, ≥84% of the individuals from each age group responded to the serogroup C polysaccharide. However, with a ≥4-fold-increase in bactericidal titer used, only 18% of 1-year-olds, 32% of 2-year-olds, and 50 to 60% of 3-, 4-, and 5-year-olds seroconverted. The ELISA results suggest that >50% of all children retained ≥2 μg of total antibody per ml at 7 months postimmunization. However, the bactericidal titers suggest that <10% of children <4 years old retained a ≥4-fold increase at 7 months following vaccination. Of particular note, 59 of 79 sera (75%) from the 1- and 2-year-olds had high ELISA antibody concentrations (2 to 20 μg/ml) with no associated bactericidal titer (<1:8). Discordant results between bactericidal titers and ELISA antibody concentrations were not explained by the presence of IgA blocking antibody or relative levels of IgG and IgM. The bactericidal results show age-dependent differences in the production and retention of antibody in young children immunized with serogroup C polysaccharide; these differences are not evident with the ELISA data.
Analysis of Host Cells Associated with the Spv-Mediated Increased Intracellular Growth Rate ofSalmonella typhimuriumin Mice
Authors: Gulig Paul A. , Doyle Thomas J. , Hughes Jeffrey A. , Matsui Hidenori 
Published: December 2019

ABSTRACTThe 90-kb virulence plasmid ofSalmonella typhimuriumencodes fivespvgenes which increase the growth rate of the bacteria within host cells within the first week of systemic infection of mice (P. A. Gulig and T. J. Doyle, Infect. Immun. 61:504–511, 1993). The presently described study was aimed at identifying the host cells associated with Spv-mediated virulence by manipulating the mouse host and the salmonellae. To test the effects of T cells and B cells on the Spv phenotype, salmonellae were orally inoculated into nude and SCID BALB/c mice. Relative to normal BALB/c mice, nude and SCID BALB/c mice were unaffected for splenic infection with either the Spv+or Spv−S. typhimuriumstrains at 5 days postinoculation. When mice were pretreated with cyclophosphamide to induce granulocytopenia, there was a variable increase in total salmonella infection, but the relative splenic CFU of Spv+versus Spv−S. typhimuriumwas not changed after oral inoculation. In contrast, depletion of macrophages from mice by treatment with cyclophosphamide plus liposomes containing dichloromethylene diphosphate resulted in equivalent virulence of Spv+and Spv−salmonellae. To examine if thespvgenes affected the growth of salmonellae in nonphagocytic cells, aninvA::aphTmutation was transduced into Spv+and Spv−S. typhimuriumstrains. InvA−Spv+salmonellae were not significantly affected for splenic infection after subcutaneous inoculation compared with the wild-type strain, and InvA−Spv−salmonellae were only slightly attenuated relative to InvA+Spv−salmonellae. Invasion-defective salmonellae still exhibited the Spv phenotype. Therefore, infection of nonphagocytes is not involved with the Spv virulence function. Taken together, these data demonstrate that macrophages are essential for suppressing the infection by Spv−S. typhimurium, by serving as the primary host cell for Spv-mediated intracellular replication and possibly by inhibiting the replication of salmonellae within other macrophages.
Identification of Persistent Infection in Experimental Syphilis by PCR
Authors: Wicher Konrad , Abbruscato Frank , Wicher Victoria , Collins Doris N. , Auger Ivan , Horowitz Harold W. 
Published: December 2019

ABSTRACTThe studies described herein were designed to evaluate the usefulness of the PCR in detecting persistent syphilitic infection. Three groups of animals were used: a nonimmune group infected withTreponema pallidum(NI/TP), a nonimmune group injected with heat-killed treponemes (NI/HKTP), and an immune and reinfected group (I/TP). All animals were inoculated with similar numbers of organisms distributed at 10 sites on the clipped back and in both testes. The persistence of the treponemes was examined by PCR and the rabbit infectivity test (RIT). The kinetic studies and statistical analysis of their results demonstrated that the rate of bacterial clearance from the NI/TP group was very low and incomplete at 4 months after infection. It was significantly different from those of both the NI/HKTP (P< 0.001) and I/TP (P< 0.05) groups. No statistically significant differences in treponemal elimination were found between the NI/HKTP and I/TP groups. PCR can detect the DNA of dead organisms, but the latter are eliminated by the host relatively quickly (15 to 30 days) as compared to elimination of live treponemes (>120 days). PCR results correlated well with RIT results. These data suggest that PCR-positive specimens obtained from an untreated patient(s) or collected weeks after treatment indicate persistent infection. They also show that the process of elimination ofT. pallidumfrom primary sites of infection is prolonged and incomplete.
In Vitro Expression of Adhesion Receptors and Diapedesis by Polymorphonuclear Neutrophils during Experimentally InducedStreptococcus uberisMastitis
Authors: Smits Elke , Burvenich Christian , Guidry Albert J. , Roets Eddy 
Published: December 2019

ABSTRACTThe expression of adhesion receptors and diapedesis by polymorphonuclear neutrophils (PMN) were studied before and during experimentally inducedStreptococcus uberismastitis. Both quarters of the left half of the udders of five midlactation cows were inoculated with a suspension containing approximately 500 CFU ofS. uberis0140J. Clinical signs of an inflammatory reaction and leukocyte influx were observed 24 h after challenge. The expression of CD11b/CD18 adhesion receptors, determined by flow cytometry, was upregulated 24 h after challenge. A confluent monolayer of bovine secretory mammary epithelial cells on collagen-coated inserts was used to study PMN diapedesis. Bovine C5a was used as the chemoattractant. An 80% decrease in PMN diapedesis was observed 24 h after challenge. The decrease in diapedesis continued for 3 weeks after challenge.