bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Controlled Clinical Study of the Effect of Nasal Immunization with aStreptococcus mutansAntigen Alone or Incorporated into Liposomes on Induction of Immune Responses
Authors: Childers Noel K. , Tong Giang , Mitchell Stephen , Kirk Katharine , Russell Michael W. , Michalek Suzanne M. 
Published: December 2019

ABSTRACTRecent attention to mucosal immunization strategies has been focused on the nasal route for vaccine delivery. This study was designed to determine the effectiveness of a liposome-protein vaccine compared to that of a protein-only vaccine in inducing immune responses in humans. Healthy subjects were randomly assigned to two groups and immunized intranasally with a crude antigen preparation rich in glucosyltransferase (C-GTF) fromStreptococcus mutans, alone or in liposomes. Parotid saliva, nasal wash, and serum were collected prior to and at weekly intervals following immunization and were analyzed for anti-C-GTF activity by enzyme-linked immunosorbent assay. The levels of immunoglobulin A (IgA) anti-C-GTF activity in the nasal wash from both groups after immunization increased to a mean peak of fivefold over the baseline level on day 28. Salivary IgA anti-C-GTF responses were induced to a lesser extent. IgG and IgA anti-C-GTF responses in serum were detected on day 14. The IgA responses were predominantly of the IgA1 subclass. These results show that C-GTF vaccines were more effective in inducing a local secretory IgA antibody response than a salivary or serum response when they were given intranasally. The IgA1 anti-C-GTF response in nasal wash samples for liposomal antigen versus antigen only was the only response which was significantly different (P< 0.04). This suggests that the form of the antigen affects the magnitude of the local mucosal response but not that of a disseminated response. These results provide evidence for the effective use of a nasal protein vaccine in humans for the induction of mucosal and systemic responses.
Surface Antigen Exposure by Bismuth Dimercaprol Suppression of
Klebsiella pneumoniae
Capsular Polysaccharide
Authors: Domenico Philip , Tomas J. M. , Merino S. , Rubires X. , Cunha Burke A. 
Published: December 2019

ABSTRACT

The bacterial capsule is an important virulence determinant in animal and plant disease. Bacterial capsule and slime can be inhibited by bismuth compounds, especially when complexed with lipophilic thiol chelators. Bismuth dimercaprol (BisBAL) at 1 ppm of Bi
3+
repressed
Klebsiella pneumoniae
capsule expression in defined medium by nearly 90%, which exposed subsurface structures. The phagocytic index for BisBAL-treated bacteria increased from <10 to 360 bacteria per 100 neutrophils in the presence of complement and anticapsular or anti-O antigen antiserum. BisBAL treatment also enhanced the reactivity of monoclonal antibodies (MAbs) specific for the O1-antigen lipopolysaccharide (LPS) or the LPS core in a dose-dependent manner as indicated by the results of enzyme-linked immunosorbent assays. When anti-O1 MAb was used, the reactivity increased significantly for fully encapsulated O1:K1 or O1:K2 cells but not for O1:K
−
cells. Deposition of C3b also increased significantly for BisBAL-treated O1:K1 or O1:K2 cells but not for O1:K
−
cells. Survival of a serum-sensitive strain was <0.1% when nonimmune human serum absorbed with O1:K1 cells was used and 107% when BisBAL-treated cells were used for absorption. Outer membrane proteins were also more accessible on the surface of
K. pneumoniae
after BisBAL treatment. Thus, at subinhibitory levels, BisBAL inhibited capsule expression, which promoted phagocytosis, enhanced the reactivity of specific antibodies for LPS O antigen, LPS core epitopes, or outer-membrane proteins, and enhanced complement interaction with encapsulated
K. pneumoniae
. By unmasking bacterial surface structures and enhancing the immune system reactivity to bacteria, bismuth thiols may prove useful as adjuncts for vaccination.
Characterization of Candidate Live Oral
Salmonella typhi
Vaccine Strains Harboring Defined Mutations in
aroA
,
aroC
, and
htrA
Authors: Lowe David C. , Savidge Tor C. , Pickard Derek , Eckmann Lars , Kagnoff Martin F. , Dougan Gordon , Chatfield Steven N. 
Published: December 2019

ABSTRACT

The properties of two candidate
Salmonella typhi
-based live oral typhoid vaccine strains, BRD691 (
S. typhi
Ty2 harboring mutations in
aroA
and
aroC
) and BRD1116 (
S. typhi
Ty2 harboring mutations in
aroA
,
aroC
, and
htrA
), were compared in a number of in vitro and in vivo assays. BRD1116 exhibited an increased susceptibility to oxidative stress compared with BRD691, but both strains were equally resistant to heat shock. Both strains showed a similar ability to invade Caco-2 and HT-29 epithelial cells and U937 macrophage-like cells, but BRD1116 was less efficient at surviving in epithelial cells than BRD691. BRD1116 and BRD691 were equally susceptible to intracellular killing within U937 cells. Similar findings were demonstrated in vivo, with BRD1116 being less able to survive and translocate to secondary sites of infection when inoculated into the lumen of human intestinal xenografts in SCID mice. However, translocation of BRD1116 to spleens and livers in SCID mice occurred as efficiently as that of BRD691 when inoculated intraperitonally. The ability of BRD1116 to increase the secretion of interleukin-8 following infection of HT-29 epithelial cells was comparable to that of BRD691. Therefore, loss of the HtrA protease in
S. typhi
does not seem to alter its ability to invade epithelial cells or macrophages or to induce proinflammatory cytokines such as IL-8 but significantly reduces intracellular survival in human intestinal epithelial cells in vitro and in vivo.
YopJ of
Yersinia
spp. Is Sufficient To Cause Downregulation of Multiple Mitogen-Activated Protein Kinases in Eukaryotic Cells
Authors: Palmer Lance E. , Pancetti Alessandra R. , Greenberg Steven , Bliska James B. 
Published: December 2019

ABSTRACT

Pathogenic
Yersinia
spp. utilize a plasmid-encoded type III secretion system to deliver a set of Yop effector proteins into eukaryotic cells. Previous studies have shown that the effector YopJ is required for
Yersinia
to cause downregulation of the mitogen-activated protein (MAP) kinases c-Jun N-terminal kinase (JNK), p38, and extracellular signal-regulated kinase (ERK) 1 and 2 in infected macrophages. Here we demonstrate that YopJ is sufficient to cause downregulation of multiple MAP kinases in eukaryotic cells. Cellular fractionation experiments confirmed that YopJ is delivered into the cytoplasmic fraction of macrophages by the type III system. Production of YopJ in COS-1 cells by transfection significantly reduced (5- to 10-fold) activation of JNK, p38, and ERK in response to several different stimuli, including serum and tumor necrosis factor alpha. JNK activation mediated by RacV12, an activated mutant of Rac1, was also blocked by YopJ in COS-1 cells, indicating that YopJ acts downstream of this small GTPase to downregulate MAP kinase signaling. Analysis of transfected COS-1 cells by immunofluorescence microscopy revealed that YopJ is recruited from the cytoplasmic compartment to the cell periphery in response to stimuli (e.g., serum) that induce membrane ruffling. These data indicate that YopJ functions as a “MAP kinase toxin” to selectively block nuclear responses that are triggered by
Yersinia
-host cell interaction.
Antibody Recognition of
Plasmodium falciparum
Erythrocyte Surface Antigens in Kenya: Evidence for Rare and Prevalent Variants
Authors: Bull Peter C. , Lowe Brett S. , Kortok Moses , Marsh Kevin 
Published: December 2019

ABSTRACT

Plasmodium falciparum
erythrocyte membrane protein 1 (PfEMP1) is the name given to a family of parasite proteins that are inserted into the infected erythrocyte surface. Studies using agglutination assays have shown previously that PfEMP1 epitopes are extremely diverse. In a study in Kenya, 21 parasite isolates, including nine from children with severe malaria, were tested for agglutination by 33 pairs of plasma, 21 of which were from the corresponding children. Each plasma pair consisted of a sample taken at the time of disease (acute) and one taken 3 weeks later (convalescent). In agreement with previous studies, infection was generally followed by the induction of antibodies specific to the homologous parasite isolate. In addition however, the results show that (i) some isolates were agglutinated very frequently by heterologous plasma; (ii) unexpectedly, these frequently agglutinated isolates tended to be from individuals with severe malaria; (iii) an inverse relationship existed between the agglutination frequency of each parasite isolate in heterologous plasma and the agglutinating antibody repertoire of the homologous child at the time of disease; and (iv) A 3-month-old child apparently still carrying maternal antibodies was infected by a rarely agglutinated isolate. This child’s plasma agglutinated all isolates at the time of disease, apart from the homologous isolate. These results support the idea that preexisting anti-PfEMP1 antibodies can select the variants that are expressed during a new infection and may suggest the existence of a dominant subset of PfEMP1 variants.
Identification and Characterization of PtlC, an Essential Component of the Pertussis Toxin Secretion System
Authors: Cook David M. , Farizo Karen M. , Burns Drusilla L. 
Published: December 2019

ABSTRACT

PtlC is a member of a set of proteins necessary for the secretion of pertussis toxin (PT) from
Bordetella pertussis
. Using polyclonal antibodies specific for PtlC, we identified PtlC as a protein with an apparent molecular weight of 85,000 that localizes to the membrane fraction of bacterial cell extracts. We found that a mutant strain of
B. pertussis
that contains an in-frame deletion in
ptlC
is unable to secrete PT and that PT secretion is fully restored by expressing
ptlC
in
trans
, indicating that PtlC is essential for transport of PT across the bacterial membrane(s). PT secretion was inhibited in wild-type
B. pertussis
after introduction of a plasmid expressing a mutant
ptlC
altered in the putative nucleotide-binding region, suggesting that this region of PtlC is essential for proper function. Moreover, the observed dominant negative phenotype suggests that PtlC either functions as a multimer or interacts with some other component(s) necessary for secretion of PT.
Expression and Distribution of Leptospiral Outer Membrane Components during Renal Infection of Hamsters
Authors: Barnett Jeanne K. , Barnett Dean , Bolin Carole A. , Summers Theresa A. , Wagar Elizabeth A. , Cheville Norman F. , Hartskeerl Rudy A. , Haake David A. 
Published: December 2019

ABSTRACTThe outer membrane of pathogenicLeptospiraspecies grown in culture media contains lipopolysaccharide (LPS), a porin (OmpL1), and several lipoproteins, including LipL36 and LipL41. The purpose of this study was to characterize the expression and distribution of these outer membrane antigens during renal infection. Hamsters were challenged with host-derivedLeptospira kirschnerito generate sera which contained antibodies to antigens expressed in vivo. Immunoblotting performed with sera from animals challenged with these host-derived organisms demonstrated reactivity with OmpL1, LipL41, and several other proteins but not with LipL36. Although LipL36 is a prominent outer membrane antigen of cultivatedL. kirschneri, its expression also could not be detected in infected hamster kidney tissue by immunohistochemistry, indicating that expression of this protein is down-regulated in vivo. In contrast, LPS, OmpL1, and LipL41 were demonstrated on organisms colonizing the lumen of proximal convoluted renal tubules at both 10 and 28 days postinfection. Tubular epithelial cells around the luminal colonies had fine granular cytoplasmic LPS. When the cellular inflammatory response was present in the renal interstitium at 28 days postinfection, LPS and OmpL1 were also detectable within interstitial phagocytes. These data establish that outer membrane components expressed during infection have roles in the induction and persistence of leptospiral interstitial nephritis.
The Cell Wall and Membrane ofCryptococcus neoformansPossess a Mitogen for Human T Lymphocytes
Authors: Mody Christopher H. , Wood Cynthia J. , Syme Rachel M. , Spurrell Jason C. L. 
Published: December 2019

ABSTRACTThe mechanism of human T-lymphocyte activation by the pathogenic yeastCryptococcus neoformanshas not been established. Previous investigations have suggested thatC. neoformanscontains a mitogen for T lymphocytes, while other investigators have attributed lymphocyte proliferation in vitro to a recall antigen. Because of the potential importance of the mechanism of T-cell activation for our understanding of the immune response toC. neoformans, the present studies were performed to determine whetherC. neoformanscontains a mitogen for T lymphocytes.C. neoformansstimulates fetal blood lymphocytes to proliferate and stimulates proliferation of CD45RA+cells from adults, indicating that it stimulates naive T cells. The T-cell response toC. neoformanswas dependent upon the presence of accessory cells. However, allogeneic cells were sufficient for accessory cell function, indicating that the response was not major histocompatibility complex restricted. The percentage of T cells in the cell cycle was higher than that with the recall antigen tetanus toxoid but lower than that with the mitogenic lectin phytohemagglutinin A or the superantigenStaphylococcusenterotoxin B. Precursor frequency analysis established that 1 in 7,750 ± 2,270 T cells proliferated in response to the cryptococcal cell wall and membrane. Compared to the case for most mitogens or superantigens, the proliferative response is late and the number of T cells that enter the cell cycle and the precursor frequency are low, indicating that the mitogenic effect is modest. However, the mitogenic effect ofC. neoformansshould be considered when interpreting the immune response toC. neoformans, since even weak mitogens can have profound effects on host defense.
Role of Antibodies against
Bordetella pertussis
Virulence Factors in Adherence of
Bordetella pertussis
and
Bordetella parapertussis
to Human Bronchial Epithelial cells
Authors: van den Berg Bernard M. , Beekhuizen Henry , Mooi Frits R. , van Furth Ralph 
Published: December 2019

ABSTRACT

Immunization with whole-cell pertussis vaccines (WCV) containing heat-killed
Bordetella pertussis
cells and with acellular vaccines containing genetically or chemically detoxified pertussis toxin (PT) in combination with filamentous hemagglutinin (FHA), pertactin (Prn), or fimbriae confers protection in humans and animals against
B. pertussis
infection. In an earlier study we demonstrated that FHA is involved in the adherence of these bacteria to human bronchial epithelial cells. In the present study we investigated whether mouse antibodies directed against
B. pertussis
FHA, PTg, Prn, and fimbriae, or against two other surface molecules, lipopolysaccharide (LPS) and the 40-kDa outer membrane porin protein (OMP), that are not involved in bacterial adherence, were able to block adherence of
B. pertussis
and
B. parapertussis
to human bronchial epithelial cells. All antibodies studied inhibited the adherence of
B. pertussis
to these epithelial cells and were equally effective in this respect. Only antibodies against LPS and 40-kDa OMP affected the adherence of
B. parapertussis
to epithelial cells. We conclude that antibodies which recognize surface structures on
B. pertussis
or on
B. parapertussis
can inhibit adherence of the bacteria to bronchial epithelial cells, irrespective whether these structures play a role in adherence of the bacteria to these cells.
Role ofListeria monocytogenesExotoxins Listeriolysin and Phosphatidylinositol-Specific Phospholipase C in Activation of Human Neutrophils
Authors: Sibelius Ulf , Schulz Eva-Cathrin , Rose Frank , Hattar Katja , Jacobs Thomas , Weiss Siegfried , Chakraborty Trinad , Seeger Werner , Grimminger Friedrich 
Published: December 2019

ABSTRACTPolymorphonuclear leukocytes (PMN) are essential for resolution of infections withListeria monocytogenes. The present study investigated the role of the listerial exotoxins listeriolysin (LLO) and phosphatidylinositol-specific phospholipase C (PlcA) in human neutrophil activation. DifferentListeriastrains, mutated in individual virulence genes, as well as purified LLO were used. Coincubation of human neutrophils with wild-typeL. monocytogenesprovoked PMN activation, occurring independently of phagocytosis events, with concomitant elastase secretion, leukotriene generation, platelet-activating factor (PAF) synthesis, respiratory burst, and enhanced phosphoinositide hydrolysis. Degranulation and leukotriene formation were noted to be solely dependent on LLO expression, as these features were absent when the LLO-defective mutant EGD− and the avirulent strainL. innocuawere used. These effects were fully reproduced by a recombinantL. innocuastrain expressing LLO (INN+) and by the purified LLO molecule. LLO secretion was also required for PAF synthesis. However, wild-typeL. monocytogeneswas more potent in eliciting PAF formation than mutants expressing LLO, suggesting the involvement of additional virulence factors. This was even more obvious for phosphoinositide hydrolysis and respiratory burst: these events were provoked not only by INN+ but also by the LLO-defective mutant EGD− and by a recombinantL. innocuastrain producing listerial PlcA. We conclude that human neutrophils react to extracellularly provided listerial exotoxins by rapid cell activation. Listeriolysin is centrally involved in triggering degranulation and lipid mediator generation, and further virulence factors such as PlcA apparently contribute to trigger neutrophil phosphoinositide hydrolysis and respiratory burst. In this way, listerial exotoxins may influence the host defense against infections withL. monocytogenes.
Invasion of Human Mucosal Epithelial Cells byNeisseria gonorrhoeaeUpregulates Expression of Intercellular Adhesion Molecule 1 (ICAM-1)
Authors: Jarvis Gary A. , Li Jing , V. Swanson Karen 
Published: December 2019

ABSTRACTInfection of the mucosa byNeisseria gonorrhoeaeinvolves adherence to and invasion of epithelial cells. Little is known, however, about the expression by mucosal epithelial cells of molecules that mediate cellular interactions between epithelial cells and neutrophils at the site of gonococcal infection. The aim of this study was to determine the expression of intercellular adhesion molecule 1 (ICAM-1) by epithelial cells during the process of gonococcal invasion. The highly invasive strain FA1090 and the poorly invasive strain MS11 were incubated with human endometrial adenocarcinoma (HEC-1-B) or human cervical carcinoma (ME-180) epithelial cells, after which ICAM-1 expression was measured by flow cytometry. After 15 h of infection with FA1090, expression of ICAM-1 increased 4.7- and 2.1-fold for HEC-1-B and ME-180 cells, respectively, whereas 15 h of infection of HEC-1-B cells with MS11 increased ICAM-1 expression only 1.6-fold. ICAM-1 expression was restricted to the cell surface, since no soluble ICAM-1 was detected. The distribution of staining was heterogeneous and mimicked that seen after treatment of HEC-1-B cells with the ICAM-1 agonist tumor necrosis factor alpha (TNF-α) in the absence of bacteria. PCR and dot blot analyses of ICAM-1 mRNA showed no change in levels over time in response to infection. Although TNF-α was produced by HEC-1-B cells after infection, the extent of ICAM-1 upregulation was not affected by neutralizing anti-TNF-α antiserum. Dual-fluorescence flow cytometry showed that the cells with the highest levels of ICAM-1 expression were cells with associated gonococci. We conclude that epithelial cells upregulate the expression of ICAM-1 in response to infection with invasive gonococci. On the mucosa, upregulation of ICAM-1 by infected epithelial cells may function to maintain neutrophils at the site of infection, thereby reducing further invasion of the mucosa by gonococci.
A 55-Kilodalton Immunodominant Antigen of
Porphyromonas gingivalis
W50 Has Arisen via Horizontal Gene Transfer
Authors: Hanley Shirley A. , Aduse-Opoku Joseph , Curtis Michael A. 
Published: December 2019

ABSTRACT

A 55-kDa outer membrane protein of
Porphyromonas gingivalis
W50 is a significant target of the serum immunoglobulin G antibody response of periodontal disease patients and hence may play an important role in host-bacterium interactions in periodontal disease. The gene encoding the 55-kDa antigen (
ragB
, for receptor antigen B) was isolated on a 9.5-kb partial
Sau
3AI fragment of
P. gingivalis
W50 chromosomal DNA in pUC18 by immunoscreening with a monoclonal antibody to this antigen. The 1.6-kb open reading frame (ORF) encoding RagB was located via subcloning and nested-deletion analysis. Sequence analysis demonstrated the presence of an upstream 3.1-kb ORF (
ragA
) which is cotranscribed with
ragB
. A number of genetic characteristics suggest that the
ragAB
locus was acquired by a horizontal gene transfer event. These include a significantly reduced G+C content relative to that of the
P. gingivalis
chromosome (42 versus 48%) and the presence of mobility elements flanking this locus in
P. gingivalis
W50. Furthermore, Southern blotting and PCR analyses showed a restricted distribution of this locus in laboratory and clinical isolates of this bacterium. The association of

ragAB
+
P. gingivalis

with clinical status was examined by PCR analysis of subgingival samples.
ragAB
+
was not detected in
P. gingivalis
-positive shallow pockets from periodontal disease patients but was present in 36% of the
P. gingivalis
-positive samples from deep pockets. These data suggest that the
ragAB
locus was acquired by certain
P. gingivalis
strains via horizontal gene transfer and that the acquisition of this locus may facilitate the survival of these strains at sites of periodontal destruction.
Repertoire of Human Antibodies against the Polysaccharide Capsule ofStreptococcus pneumoniaeSerotype 6B
Authors: Sun Yan , Park Moon K. , Kim Jihye , Diamond Betty , Solomon Alan , Nahm Moon H. 
Published: December 2019

ABSTRACTWe examined the repertoire of antibodies toStreptococcus pneumoniae6B capsular polysaccharide induced with the conventional polysaccharide vaccine in adults at the molecular level two ways. In the first, we purified from the sera of seven vaccinees antipneumococcal antibodies and determined their amino acid sequences. Their VH regions are mainly the products of VH3 family genes (candidate genes, 3-23, 3-07, 3-66, and 3-74), but the product of a VH1 family gene (candidate gene, 1-03) is occasionally used. All seven individuals have small amounts of polyclonal κ+antibodies (Vκ1 to Vκ4 families), although κ+antibodies are occasionally dominated by antibodies formed with the product of the A27 Vκ gene. In contrast, λ+anti-6B antibodies are dominated by the antibodies derived from one of 3 very similar Vλ2 family genes (candidate genes, 2c, 2e, and 2a2) and Cλ1 gene product. The Vλ2+antibodies express the 8.12 idiotype, which is expressed on anti-double-stranded-DNA antibodies. In one case, Vλ is derived from a rarely expressed Vλ gene, 10a. In the second approach, we studied a human hybridoma (Dob1) producing anti-6B antibody. Its VH region sequence is closely related to those of the 3-15 VH gene (88% nucleotide homology) and JH4 (92% homology). Its VL region is homologous to the 2a2 Vλ2 gene (91%) and Jλ1/Cλ1. Taken together, the V region of human anti-6B antibodies is commonly formed by a VH3 and a Vλ2 family gene product.