bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distinct Immunoglobulin Class and Immunoglobulin G Subclass Patterns against Ganglioside GQ1b in Miller Fisher Syndrome following Different Types of Infection
Authors: Schwerer Beatrix , Neisser Andrea , Bernheimer Hanno 
Published: December 2019

ABSTRACT
We studied serum antibodies against gangliosides GQ1b and GM1 in 13 patients with Miller Fisher syndrome (MFS) and in 18 patients with Guillain-Barré syndrome (GBS) with cranial nerve involvement. Anti-GQ1b titers were elevated in all patients with MFS cases (immunoglobulin G [IgG] > IgA, IgM), and in 8 of the 18 with GBS. Lower frequencies of increased anti-GM1 titers were observed in MFS patients (3 of 13), as well as in GBS patients (5 of 18). During the course of MFS, anti-GQ1b titers of all Ig classes decreased within 3 weeks after onset. By contrast, anti-GM1 titers (mainly IgM) transiently increased during the course of MFS in five of six patients, suggesting a nonspecific secondary immune response. In patients with MFS following respiratory infections, IgG was the major anti-GQ1b Ig class (six of six patients) and IgG3 was the major subclass (five of six). In contrast, four of five patients with MFS following gastrointestinal infections showed predominance of anti-GQ1b IgA or IgM over IgG and predominance of the IgG2 subclass; anti-GQ1b IgG (IgG3) prevailed in one patient only. These distinct Ig patterns strongly suggest that different infections may trigger different mechanisms of anti-GQ1b production, such as via T-cell-dependent as opposed to T-cell-independent pathways. Thus, the origin of antibodies against GQ1b in MFS may be determined by the type of infectious agent that precipitates the disease.
Membrane Permeabilization by Thrombin-Induced Platelet Microbicidal Protein 1 Is Modulated by Transmembrane Voltage Polarity and Magnitude
Authors: Koo Su-Pin , Bayer Arnold S. , Kagan Bruce L. , Yeaman Michael R. 
Published: December 2019

ABSTRACT

Thrombin-induced platelet microbicidal protein 1 (tPMP-1) is a small, cationic peptide generated from rabbit platelets when they are exposed to thrombin in vitro. It has potent microbicidal activity against a broad spectrum of bacterial and fungal pathogens, including
Staphylococcus aureus
. Previous in vitro studies involving whole staphylococcal cells and planar lipid bilayers (as artificial bacterial membrane models) suggested that membrane permeabilization by tPMP-1 is voltage dependent (S.-P. Koo, M. R. Yeaman, and A. S. Bayer, Infect. Immun. 64:3758–3764, 1996; M. R. Yeaman, A. S. Bayer, S. P. Koo, W. Foss, and P. M. Sullam, J. Clin. Investig. 101:178–187, 1998). Thus, the aims of the present study were to specifically characterize the electrophysiological events associated with membrane permeabilization by tPMP-1 by using artificial planar lipid bilayer membranes. We assessed the influence of transmembrane voltage polarity and magnitude on the initiation and modulation of tPMP-1 membrane permeabilization at various concentrations of tPMP-1 (range, 1 to 100 ng/ml) added to the
cis
side of the membranes. The incidence of membrane permeabilization induced by tPMP-1 at all of the concentrations tested was more frequent at −90 mV than at +90 mV. It is noteworthy that membrane permeabilization due to 1-ng/ml tPMP-1 was successfully initiated at −90 mV but not at +90 mV. Further, the mean onset times of induction of tPMP-1 activity were comparable under the various conditions. Modulation of ongoing membrane permeabilization was dependent on voltage and tPMP-1 concentration. Membrane permeabilization at a low tPMP-1 concentration (1 ng/ml) was directly correlated with
trans
-negative voltages, while a higher tPMP-1 concentration (100 ng/ml) induced conductance which was more dependent on
trans
-positive voltages. Collectively, these data indicate that the mechanism of tPMP-1 microbicidal activity at the bacterial cytoplasmic membrane may involve distinct induction and propagation stages of membrane permeabilization which, in turn, are modulated by transmembrane potential, as well as peptide concentration.
Alpha C Protein as a Carrier for Type III Capsular Polysaccharide and as a Protective Protein in Group B Streptococcal Vaccines
Authors: Gravekamp Claudia , Kasper Dennis L. , Paoletti Lawrence C. , Madoff Lawrence C. 
Published: December 2019

ABSTRACTThe alpha C protein, a protective surface protein of group B streptococci (GBS), is present in most non-type III GBS strains. Conjugate vaccines composed of the alpha C protein and type III capsular polysaccharide (CPS) might be protective against most GBS infections. In this study, the type III CPS was covalently coupled to full-length, nine-repeat alpha C protein (resulting in III-α9r conjugate vaccine) or to two-repeat alpha C protein (resulting in III-α2r conjugate vaccine) by reductive amination. Initial experiments with the III-α9r vaccine showed that it was poorly immunogenic in mice with respect to both vaccine antigens and was suboptimally efficacious in providing protection in mice against challenge with GBS. Therefore, modified vaccination protocols were used with the III-α2r vaccine. Female mice were immunized three times with 0.5, 5, or 20 μg of the III-α2r vaccine with an aluminum hydroxide adjuvant and bred. Ninety-five percent of neonatal mice born to dams immunized with the III-α2r vaccine survived challenge with GBS expressing type III CPS, and 60% survived challenge with GBS expressing wild-type (nine-repeat) alpha C protein; 18 and 17%, respectively, of mice in the negative control groups survived (P, <0.0001). These protection levels did not differ significantly from those obtained with the type III CPS-tetanus toxoid conjugate vaccine and the unconjugated two-repeat alpha C protein, which protected 98 and 58% of neonates from infection with GBS expressing type III CPS or the alpha C protein, respectively. Thus, the two-repeat alpha C protein in the vaccine was immunogenic and simultaneously enhanced the immunogenicity of type III CPS. III-α vaccines may be alternatives to GBS polysaccharide-tetanus toxoid vaccines, eliciting additional antibodies protective against GBS infection.
A Murine Model for the Study of
Chlamydia trachomatis
Genital Infections during Pregnancy
Authors: Pal Sukumar , Peterson Ellena M. , de la Maza Luis M. 
Published: December 2019

ABSTRACT

Pregnant BALB/c mice were inoculated intravaginally on day 5 of gestation with the
Chlamydia trachomatis
mouse pneumonitis biovar. Animals that received 10
5
, 10
6
, or 10
7
inclusion-forming units (IFU) of
C. trachomatis
delivered prematurely on days 15 to 16 of gestation. A focal inflammatory infiltrate was observed in the wall of the uterus on the day 14 of gestation in animals inoculated with 10
5
IFU. In this group of mice, immunohistochemical analysis showed chlamydial inclusions in the endometrium and fetal membranes.
The Siderophore 2,3-Dihydroxybenzoic Acid Is Not Required for Virulence of
Brucella abortus
in BALB/c Mice
Authors: Bellaire Bryan H. , Elzer Philip H. , Baldwin Cynthia L. , Roop R. Martin 
Published: December 2019

ABSTRACT

2,3-Dihydroxybenzoic acid (DHBA) is the only siderophore described for
Brucella
, and previous studies suggested that DHBA might contribute to the capacity of these organisms to persist in host macrophages. Employing an isogenic siderophore mutant (
ΔentC
) constructed from virulent
Brucella abortus
2308, however, we found that production of DHBA is not required for replication in cultured murine macrophages or for the establishment and maintenance of chronic infection in the BALB/c mouse model.
Characterization ofStaphylococcus epidermidisPolysaccharide Intercellular Adhesin/Hemagglutinin in the Pathogenesis of Intravascular Catheter-Associated Infection in a Rat Model
Authors: Rupp Mark E. , Ulphani Joseph S. , Fey Paul D. , Mack Dietrich 
Published: December 2019

ABSTRACTBiofilm production is thought to be a crucial factor in the ability ofStaphylococcus epidermidisto produce a biomaterial-based infection. A rat central venous catheter (CVC)-associated infection model was used to assess the importance of biofilm production, mediated by polysaccharide intercellular adhesin/hemagglutinin (PIA/HA), in the pathogenesis of intravascular catheter-associated infection. PIA/HA-positiveS. epidermidis1457 was significantly more likely to cause a CVC-associated infection (71 versus 14%,P< 0.03) resulting in bacteremia and metastatic disease than its isogenic PIA/HA-negative mutant. These results confirm the importance of biofilm production, mediated by PIA/HA, in the pathogenesis ofS. epidermidisexperimental CVC-associated infection.
Profiles of Th1 and Th2 Cytokines after Primary and Secondary Infection bySchistosoma mansoniin the Semipermissive Rat Host
Authors: Cêtre Catherine , Pierrot Christine , Cocude Cécile , Lafitte Sophia , Capron André , Capron Monique , Khalife Jamal 
Published: December 2019

ABSTRACTIn contrast to most mouse strains, rats eliminate the primary schistosome burden around 4 weeks postinfection and subsequently develop protective immunity to reinfection. In rat schistosomiasis, we have shown predominant expression of a Th2-type cytokine response at the mRNA level after primary infection. In the present study, we showed a significant increase in interleukin-4 (IL-4) mRNA expression in inguinal lymph nodes early after a secondary infection. IL-5 mRNA expression showed a significant increase at days 2 and 4 postreinfection in the spleen and lymph nodes, respectively. We did not detect any gamma interferon (IFN-γ) mRNA after a challenge infection. Analysis of cytokine secretion by stimulated spleen cells after a primary infection showed predominant expression of IL-4 with maximum production on day 21, accompanied by production of IL-5 from day 11 to day 67. A significant increase in IFN-γ secretion was detected at day 21. Analysis of immunoglobulin G2b (IgG2b) and IgG2c (Th1-related isotypes) showed undetectable levels of IgG2b, but detectable levels of specific IgG2c antibodies were observed from day 42. The analysis of Th2-related isotypes showed high specific IgG1 and IgG2a antibody titers from day 29. After a secondary infection, only IL-4 and IL-5 secretion was sustained. This is supported by the increased production of Th2-related isotypes. These findings showed thatS. mansoniinfection can drive Th2 responses in rats in the absence of egg production which is required to induce a Th2 response in mice and are in favor of the role of Th2-type cytokines in protective immunity against reinfection.
Effect of Multiple Mutations in the Hemoglobin- and Hemoglobin-Haptoglobin-Binding Proteins, HgpA, HgpB, and HgpC, of
Haemophilus influenzae
Type b
Authors: Morton Daniel J. , Whitby Paul W. , Jin Hongfan , Ren Zhen , Stull Terrence L. 
Published: December 2019

ABSTRACT

Haemophilus influenzae
requires heme for growth and can utilize hemoglobin and hemoglobin-haptoglobin as heme sources. We previously identified two hemoglobin- and hemoglobin-haptoglobin-binding proteins, HgpA and HgpB, in
H. influenzae
HI689. Insertional mutation of
hgpA
and
hgpB
, either singly or together, did not abrogate the ability to utilize or bind either hemoglobin or the hemoglobin-haptoglobin complex. A hemoglobin affinity purification method was used to isolate a protein of approximately 120 kDa from the
hgpA hgpB
double mutant. We have cloned and sequenced the gene encoding this third hemoglobin/hemoglobin-haptoglobin binding protein and designate it
hgpC
. Insertional mutation of
hgpC
did not affect the ability of the strain to utilize either hemoglobin or hemoglobin-haptoglobin. An
hgpA hgpB hgpC
triple mutant constructed by insertional mutagenesis showed a reduced ability to use the hemoglobin-haptoglobin complex but was unaltered in the ability to use hemoglobin. A second class of mutants was constructed in which the entire structural gene of each of the three proteins was deleted. The
hgpA hgpB hgpC
complete-deletion triple mutant was unable to utilize the hemoglobin-haptoglobin complex and showed a reduced ability to use hemoglobin. We have identified three hemoglobin/hemoglobin-haptoglobin-binding proteins in
Haemophilus influenzae
. Any one of the three proteins is sufficient to support growth with hemoglobin-haptoglobin as the heme source, and expression of at least one of the three is essential for hemoglobin-haptoglobin utilization. Although the three proteins play a role in hemoglobin utilization, an additional hemoglobin acquisition mechanism(s) exists.
Requirement of MrpH for Mannose-Resistant
Proteus
-Like Fimbria-Mediated Hemagglutination by
Proteus mirabilis
Authors: Li Xin , Johnson David E. , Mobley Harry L. T. 
Published: December 2019

ABSTRACT

Two new genes,
mrpH
and
mrpJ
, were identified downstream of
mrpG
in the
mrp
gene cluster encoding mannose-resistant
Proteus
-like (MR/P) fimbriae of uropathogenic
Proteus mirabilis
. Since the predicted MrpH has 30% amino acid sequence identity to PapG, the Galα(1-4)Gal-binding adhesin of
Escherichia coli
P fimbriae, we hypothesized that
mrpH
encodes the functional MR/P hemagglutinin. MR/P fimbriae, expressed in
E. coli
DH5α, conferred on bacteria both the ability to cause mannose-resistant hemagglutination and the ability to aggregate to form pellicles on the broth surface. Both a Δ
mrpH
mutant expressed in
E. coli
DH5α and an isogenic
mrpH
::
aphA
mutant of
P. mirabilis
were unable to produce normal MR/P fimbriae efficiently, suggesting that MrpH was involved in fimbrial assembly. Amino acid residue substitution of the N-terminal cysteine residues (C66S and C128S) of MrpH abolished the receptor-binding activity (hemagglutinating ability) of MrpH but allowed normal fimbrial assembly, supporting the notion that MrpH was the functional MR/P hemagglutinin. Immunogold electron microscopy of
P. mirabilis
HI4320 revealed that MrpH was located at the tip of MR/P fimbriae, also consistent with its role in receptor binding. The isogenic
mrpH
::
aphA
mutant of HI4320 was less able to colonize the urine, bladder, and kidneys in a mouse model of ascending urinary tract infection (
P
< 0.01), and therefore MR/P fimbriae contribute significantly to bacterial colonization in mice. While there are similarities between
P. mirabilis
MR/P and
E. coli
P fimbriae, there are more notable differences: (i) synthesis of the MrpH adhesin is required to initiate fimbrial assembly, (ii) MR/P fimbriae confer an aggregation phenotype, (iii) site-directed mutation of specific residues can abolish receptor binding but allows fimbrial assembly, and (iv) mutation of the adhesin gene abolishes virulence in a mouse model of ascending urinary tract infection.
Persistence and Protective Efficacy of a
Mycobacterium tuberculosis
Auxotroph Vaccine
Authors: Jackson Mary , Phalen Susan W. , Lagranderie Micheline , Ensergueix Danielle , Chavarot Pierre , Marchal Gilles , McMurray David N. , Gicquel Brigitte , Guilhot Christophe 
Published: December 2019

ABSTRACT

New vaccines against tuberculosis are urgently required because of the impressive incidence of this disease worldwide and the highly variable protective efficacy of the current vaccine. The possibility of creating new live vaccines by the rational attenuation of strains from the
Mycobacterium tuberculosis
complex was investigated. Two auxotrophic mutants of
M. tuberculosis
and
M. bovis
BCG were constructed by disruption of one of their purine biosynthetic genes. These mutants appeared unable to multiply in vitro within mouse bone-marrow derived macrophages. They were also attenuated in vivo in the mouse and guinea pig animal models. In guinea pigs, the two mutants induced strong delayed-type hypersensitivity response to purified protein derivative. In a preliminary experiment, the two mutants were compared to the BCG vaccine for their protective efficacy in a challenge against aerosolized virulent
M. tuberculosis
in the guinea pig model. Both mutants conferred some level of protection. These experiments demonstrate that the rational attenuation of
M. tuberculosis
could lead to the design of new candidate live vaccines against tuberculosis.
Characterization of a Murine Model of Melioidosis: Comparison of Different Strains of Mice
Authors: Hoppe I. , Brenneke B. , Rohde M. , Kreft A. , Häußler S. , Reganzerowski A. , Steinmetz I. 
Published: December 2019

ABSTRACT

Melioidosis is an infectious disease caused by the saprophytic gram-negative rod
Burkholderia pseudomallei
. The aim of this study was to establish and characterize a murine model of melioidosis to provide a basis for further investigations on the pathogenesis of the disease. After intravenous infection with
B. pseudomallei
, C57BL/6 mice were found to be significantly more resistant than BALB/c mice. There was a marked organotropism of
B. pseudomallei
for the spleen and liver in both strains of mice, with the highest bacterial load in the spleen. Electron microscopic investigations of the spleen clearly demonstrated intracellular replication within membrane-bound phagosomes. Electron micrographs of the liver provided evidence that
B. pseudomallei
-containing phagosomes in hepatocytes fuse with lysosomes, leading to degradation of bacteria. In both strains of mice, the course of infection was highly dependent on the infective dose and the bacterial strain used, ranging from death within a few days to death after several weeks. In comparison with BALB/c mice, the bacterial counts in C57BL/6 mice were decreased 12 h after infection, which is suggestive of an innate immune mechanism against
B. pseudomallei
in this early phase of infection contributing to the lower susceptibility of C57BL/6 mice. BALB/c mice developed a more pronounced lymphopenia, granulocytosis, and splenomegaly at a lower infective dose compared to C57BL/6 mice. Analysis of the antibody response against
B. pseudomallei
11 days after infection revealed a significantly higher immunoglobulin G2A (IgG2a)/IgG1 ratio in C57BL/6 mice than in BALB/c mice, indicating that a T helper type 1 immune response is associated with resistance to infection with
B. pseudomallei.
Identification and Molecular Analysis of Rough-Colony-Specific Outer Membrane Proteins of
Actinobacillus actinomycetemcomitans
Authors: Haase Elaine M. , Zmuda Joyce L. , Scannapieco Frank A. 
Published: December 2019

ABSTRACT

Actinobacillus actinomycetemcomitans
, a gram-negative bacterium isolated from the human mouth, has been implicated in the pathogenesis of early-onset periodontitis. Primary isolates cultured from subgingival plaque exhibit an adherent, rough colony phenotype which spontaneously converts to a nonadherent, smooth phenotype upon in vitro subculture. The rough colony variant produces abundant fimbriae and autoaggregates, while the smooth colony variant is planktonic and produces scant fimbriae. To begin to understand the significance of colony variation in biofilm formation by
A. actinomycetemcomitans
, outer membrane protein profiles of four isogenic rough and smooth colony variants were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Two proteins with relative molecular masses of 43 and 20 kDa were expressed by the rough colony variants exclusively. Expression of these proteins was not found to be dependent on growth phase, oxygen tension, or type of complex medium. N-terminal amino acid sequences of these proteins obtained by Edman degradation were compared with sequences from the University of Oklahoma
A. actinomycetemcomitans
genome database. Two contiguous open reading frames (ORFs) encoding proteins having sequence homology with these proteins were identified. The 43-kDa protein (RcpA [rough colony protein A]) was similar to precursor protein D of the general secretion pathway of gram-negative bacilli, while the 20-kDa protein (RcpB [rough colony protein B]) appeared to be unique. The genes encoding these proteins have been cloned from
A. actinomycetemcomitans
283 and sequenced. A BLASTX (gapped BLAST) search of the surrounding ORFs revealed homology with other fimbria-related proteins. These data suggest that the genes encoding the 43-kDa (
rcpA
) and 20-kDa (
rcpB
) proteins may be functionally related to each other and to genes that may encode fimbria-associated proteins.
Helicobacter pylori
-Associated Gastritis in Mice is Host and Strain Specific
Authors: van Doorn Nathalie E. M. , Namavar Ferry , Sparrius Marion , Stoof Jeroen , van Rees Emmelien P. , van Doorn Leen-Jan , Vandenbroucke-Grauls Christina M. J. E. 
Published: December 2019

ABSTRACT

The
vacA
and
cagA
geno- and phenotypes of two mouse-adapted strains of
Helicobacter pylori
, SS1 and SPM326, were determined. The SS1 strain, which had the
cagA
+
and
vacA
s2-m2 genotype, induced neither vacuole formation in HeLa cells nor interleukin-8 (IL-8) production in KATO III cells. In contrast,
H. pylori
SPM326, with the
cagA
+
and
vacA
s1b-m1 genotype, induced vacuoles as well as IL-8 production in vitro. Furthermore, a spontaneous mutant of SPM326, which produced a vacuolating cytotoxin but was not able to induce IL-8 production (SPM326/IL-8
−
), was detected. C57Bl/6 and BALB/c mice were infected with these three strains to investigate the colonization pattern and the effect on the immune response in vivo. The SS1 strain colonized the stomachs of all mice in large numbers which remained constant over time. Colonization with the SPM326/IL-8
+
and SPM326/IL-8
−
strains was lesser, or even absent, and decreased over time. At 5 weeks postinoculation all three
H. pylori
strains induced a mild increase of neutrophil count in the gastric corpus of C57Bl/6 mice, which disappeared by 12 weeks. At both 5 and 12 weeks postinoculation C57Bl/6 mice colonized with SPM326/IL-8
+
showed an increased expression of major histocompatibility complex (MHC) class II antigen in the cardia which was accompanied by an increased number of T cells. C57Bl/6 mice that were infected with SS1 and SPM326/IL-8
−
did not show chronic inflammation. BALB/c mice colonized with SS1 and SPM326/IL-8
−
also showed an increase in neutrophil count at 5 weeks, which normalized again by 12 weeks postinoculation. At this time point SS1-infected mice showed inflammation in the corpus and antrum. At these sites an increased expression of MHC class II antigens and an increased number of T cells were observed. Although small lymphoid follicles were already observed 5 weeks after inoculation with SS1, their incidence as well as their number was increased at 12 weeks. These results show that inflammation induced by
H. pylori
depends both on the bacterial strain and the host.
Proteasome Activity Is Required for Anthrax Lethal Toxin To Kill Macrophages
Authors: Tang Guangqing , Leppla Stephen H. 
Published: December 2019

ABSTRACTAnthrax lethal toxin (LeTx), consisting of protective antigen (PA) and lethal factor (LF), rapidly kills primary mouse macrophages and macrophage-like cell lines such as RAW 264.7. LF is translocated by PA into the cytosol of target cells, where it acts as a metalloprotease to cleave mitogen-activated protein kinase kinase 1 (MEK1) and possibly other proteins. In this study, we show that proteasome inhibitors such as acetyl-Leu-Leu-norleucinal, MG132, and lactacystin efficiently block LeTx cytotoxicity, whereas other protease inhibitors do not. The inhibitor concentrations that block LF cytotoxicity are similar to those that inhibit the proteasome-dependent IκB-α degradation induced by lipopolysaccharide. The inhibitors did not interfere with the proteolytic cleavage of MEK1 in LeTx-treated cells, indicating that they do not directly block the proteolytic activity of LF. However, the proteasome inhibitors did prevent ATP depletion, an early effect of LeTx. No overall activation of the proteasome by LeTx was detected, as shown by the cleavage of fluorogenic substrates of the proteasome. All of these results suggest that the proteasome mediates a toxic process initiated by LF in the cell cytosol. This process probably involves degradation of unidentified molecules that are essential for macrophage homeostasis. Moreover, this proteasome-dependent process is an early step in LeTx intoxication, but it is downstream of the cleavage by LF of MEK1 or other putative substrates.