bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monoclonal Antibody-Mediated Modulation of the Humoral Immune Response against Mucosally AppliedStreptococcus mutans
Authors: Brady L. Jeannine , van Tilburg Marloes L. J. A. , Alford Connie E. , McArthur William P. 
Published: July 2002

ABSTRACTSystemic immunization with antigen coupled to monoclonal antibody (MAb) has been used by several investigators to increase the number of MAb-producing hybridomas against an antigen and to elicit antibodies specific for poorly immunogenic epitopes. This strategy has implications for vaccine design in that protective immunity is not necessarily directed at immunodominant epitopes of pathogens and may be improved by deliberately shifting the immune response toward subdominant epitopes. To our knowledge, no studies to date have addressed the potential for immunomodulatory activity mediated by MAbs bound to mucosally applied antigen. To test whether administration of an exogenous MAb directed against a streptococcal surface protein could influence the humoral immune response, BALB/c mice were immunized orally by gastric intubation or intranasally withStreptococcus mutansalone orS. mutanscomplexed with a MAb directed against the major surface protein P1. Significant changes in the subclass distribution, as well as the specificity, of anti-P1 serum immunoglobulin G antibodies were demonstrated in groups of mice which receivedS. mutanscoated with the anti-P1 MAb versus those which receivedS. mutansalone. Alterations in the humoral immune response were dependent on the amount of anti-P1 MAb used to coat the bacteria. In addition, differences in the anti-P1 immune responses were observed between groups of mice immunized via oral versus intranasal routes. In summary, an exogenous MAb complexed with a streptococcal antigen prior to mucosal immunization can influence the immunoglobulin isotype and specificity of the host humoral immune response against the antigen.
Biochemical and Genetic Evidence for Phospholipase C Activity inMycobacterium ulcerans
Authors: Gomez Arley , Mve-Obiang Armand , Vray Bernard , Remacle José , Chemlal Karim , Meyers Wayne M. , Portaels Françoise , Fonteyne Pierre-Alain 
Published: July 2002

ABSTRACTThis study reports the existence of phospholipase C and D enzymatic activities inMycobacterium ulceranscultures as determined by use of thin-layer chromatography to detect diglycerides in hydrolysates of radiolabeled phosphatidylcholine.M. ulceransDNA sequences homologous to the genes encoding phospholipase C inMycobacterium tuberculosisandPseudomonas aeruginosawere identified by sequence analysis and DNA-DNA hybridization. Whether or not the phospholipase C and D enzymes ofM. ulceransplays a role in the pathogenesis of the disease needs further investigation.
Ineffective Cellular Immune Response Associated with T-Cell Apoptosis in SusceptibleMycobacterium bovisBCG-Infected Mice
Authors: Kremer Laurent , Estaquier Jérôme , Wolowczuk Isabelle , Biet Franck , Ameisen Jean-Claude , Locht Camille 
Published: July 2002

ABSTRACTIt has previously been reported that inhibition of delayed-type hypersensitivity-mediating functions of T cells during mycobacterial infection in mice is haplotype dependent. In the present study, we show thatMycobacterium bovisBCG infection induced, in susceptible C57BL/6 and BALB/c mice but not in resistant C3H/HeJ and DBA/2 mice, an important splenomegaly. An in vitro defect in T-cell proliferation in response to T-cell receptor (TCR) stimulation with mitogens or anti-CD3 antibodies was associated with enhanced levels of CD4+and CD8+T-cell apoptosis in susceptible but not in resistant mice 2 weeks after infection. Further investigations of C57BL/6 and C3H/HeJ mice revealed that in vivo splenomegaly was associated with destruction of the lymphoid tissue architecture, liver cellular infiltrates, and increased numbers of apoptotic cells in both spleen and liver tissue sections. Infection of C57BL/6 mice but not of C3H/HeJ mice induced massive production of tumor necrosis factor alpha (TNF-α) in serum, as well as an increase in Fas and Fas ligand (FasL) expression in T cells. In vitro addition of neutralizing anti-TNF-α antibodies led to a significant reduction in CD3-induced T-cell apoptosis of both CD4+and CD8+T cells of C57BL/6 mice, while the blockade of Fas-FasL interactions reduced apoptosis only in CD4+but not in CD8+T cells. Together, these results suggest that TNF-α and Fas-FasL interactions play a role in the activation-induced cell death (AICD) process associated with a defect in T-cell proliferation of the susceptible C57BL/6 mice. T-cell death by apoptosis may represent one of the important components of the ineffective immune response against mycobacterium-induced immunopathology in susceptible hosts.
Does Inhibition of Tumor Necrosis Factor Alpha Affect Chlamydial Genital Tract Infection in Mice and Guinea Pigs?
Authors: Darville Toni , Andrews C. W. , Rank R. G. 
Published: July 2002

ABSTRACTThe role of tumor necrosis factor alpha (TNF-α) in host defense against chlamydial infection remains unclear. In order to further evaluate the relevance of TNF-α to host resistance in chlamydial genital tract infection, we examined the effect of local inhibition of the TNF-α response in normal C57 mice and in interferon gamma gene-deficient C57 mice infected intravaginally with the mouse pneumonitis agent ofChlamydia trachomatis. Since the guinea pig model of female genital tract infection more closely approximates the human in terms of ascending infection and development of pathology, we also examined the effect of local inhibition of the TNF-α response in guinea pigs infected intravaginally with the guinea pig strain ofChlamydia psittaci. We successfully blocked the early TNF-α response in the respective animal models. This blockade had no effect on the numbers of organisms isolated from the genital tract during the time of TNF-α inhibition in mice or guinea pigs. Analysis of interleukin-1β, macrophage inflammatory protein-2, and granulocyte macrophage-colony stimulating factor in the mouse model revealed that blockade of the TNF-α response did not alter the release of these proinflammatory proteins. Yet, in TNF-α-depleted mice, increased numbers of neutrophils were detected in the genital tract, and, in TNF-α-depleted guinea pigs, increased numbers of neutrophils as well as infiltrating lymphocytes were seen in the endocervix. Blockade of TNF-α does not affect the level of infection in mice or guinea pigs, but it may decrease TNF-α-induced apoptosis of infiltrating inflammatory cells.
Novel Group of Virulence Activators within the AraC Family That Are Not Restricted to Upstream Binding Sites
Authors: Munson George P. , Holcomb Lisa G. , Scott June R. 
Published: July 2002

ABSTRACT

Several regulators within the AraC family control the expression of genes known or thought to be required for virulence of bacterial pathogens. One of these, Rns, activates transcription from an unprecedented variety of binding-site locations. Although nearly all prokaryotic activators bind within a small region upstream and adjacent to the promoter that they regulate, Rns does not bind within this region to activate its own promoter, P
rns
. Instead, to activate P
rns
, Rns requires one binding site 224.5 bp upstream and one downstream of the transcription start site. We show in this study that several other AraC family activators recognize the same binding sites as Rns and share with it the ability to utilize a downstream binding site. Like Rns, other members of this group of activators positively regulate the expression of virulence factors in pathogenic bacteria. These regulators are also able to activate transcription from promoter-proximal upstream binding sites since they are able to substitute for Rns at P
coo
, a promoter with only upstream binding sites. Thus, Rns is the prototype for a group of regulators, which include CfaR, VirF, AggR, and CsvR and which activate transcription from locations that are more diverse than those of any other known activator.
Group BStreptococcusCapsular Polysaccharide-Cholera Toxin B Subunit Conjugate Vaccines Prepared by Different Methods for Intranasal Immunization
Authors: Shen Xuzhuang , Lagergård Teresa , Yang Yonghong , Lindblad Marianne , Fredriksson Margareta , Holmgren Jan 
Published: July 2002

ABSTRACTGroup BStreptococcus(GBS) type III capsular polysaccharide (CPS III) was conjugated to recombinant cholera toxin B subunit (rCTB) using three different methods which employed (i) cystamine andN-succinimidyl-3-(2-pyridyldithio)propionate (SPDP), (ii) carbodiimide with adipic acid dihydrazide (ADH) as a spacer, or (iii) reductive amination (RA). The CPS III-rCTB conjugates were divided into large- and small-molecular-weight (Mr) fractions, and the immunogenicities of the different preparations after intranasal (i.n.) immunization were studied in mice. Both large- and small-Mrconjugates of CPS III-rCTBRAor CPS III-rCTBADHinduced high, almost comparable levels of CPS-specific immunoglobulin G (IgG) in serum, lungs, and vagina that were generally superior to those obtained with CPS III-rCTBSPDPconjugates or a CPS III and rCTB mixture. However, the smaller-Mrconjugates of CPS III-rCTBRAor CPS III-rCTBADHin most cases elicited a lower anti-CPS IgA immune response than the large-Mrconjugates, and the highest anti-CPS IgA titers in both tissues and serum were obtained with the large-MrCPS III-rCTBRAconjugate. Serum IgG anti-CPS titers induced by the CPS III-rCTBRAconjugate had high levels of specific IgG1, IgG2a, IgG2b, and IgG3 antibodies. Based on the effectiveness of RA for coupling CPS III to rCTB, RA was also tested for conjugating GBS CPS Ia with rCTB. As for the CPS III-rCTB conjugates, the immunogenicity of CPS Ia was greatly increased by conjugation to rCTB. Intranasal immunization with a combination of CPS Ia-rCTB and CPS III-rCTB conjugates was shown to induce anti-CPS Ia and III immune responses in serum and lungs that were fully comparable with the responses to immunization with the monovalent CPS Ia-rCTB or CPS III-rCTB conjugates. These results suggest that the GBS CPS III-rCTB and CPS Ia-rCTB conjugates prepared by the RA method may be used in bivalent and possibly also in multivalent mucosal GBS conjugate vaccines.
Severity of Group B Streptococcal Arthritis in Selected Strains of Laboratory Mice
Authors: Puliti Manuela , Bistoni Francesco , von Hunolstein Christina , Orefici Graziella , Tissi Luciana 
Published: July 2002

ABSTRACT
The susceptibilities of C3H/HeN, BALB/c, and C57BL/6N mouse strains to group B streptococci (GBS) infection were evaluated. C3H/HeN mice developed severe polyarthitis; mild lesions and no lesions were observed in BALB/c and C57BL/6N mice, respectively. A correlation between the severity of arthritis, the number of GBS in the joints, and local interleukin-6 and interleukin-1β production was evident.
Cytotoxic Necrotizing Factor from
Escherichia coli
Induces RhoA-Dependent Expression of the Cyclooxygenase-2 Gene
Authors: Thomas Warren , Ascott Zoe K. , Harmey Dympna , Slice Lee W. , Rozengurt Enrique , Lax Alistair J. 
Published: July 2002

ABSTRACT

Cytotoxic necrotizing factor 1 (CNF) is a toxin produced by some isolates of
Escherichia coli
that cause extraintestinal infections. CNF can initiate signaling pathways that are mediated by the Rho family of small GTPases through a covalent modification that results in constitutive activation. In addition to regulating the assembly of actin stress fibers and focal adhesion complexes, RhoA can also regulate gene expression at the level of transcription. Here we demonstrate for the first time, by using a luciferase-based reporter system, that the transcription of cyclooxygenase-2 (COX-2) is strongly upregulated in NIH 3T3 fibroblasts treated with CNF and that this effect is dependent upon the activation of RhoA by the toxin. Subsequent protein tyrosine phosphorylation events modulate the induction, but the transcription signal is not mediated by Rho-associated kinase (p160/ROCK) and so must rely upon another effector that is activated by RhoA. CNF therefore induces COX-2 expression via a RhoA-dependent signaling pathway that diverges from the pathway that regulates cytoskeletal rearrangements in response to RhoA activation.
Effect of SpeB and EndoS from
Streptococcus pyogenes
on Human Immunoglobulins
Authors: Collin Mattias , Olsén Arne 
Published: July 2002

ABSTRACT

Streptococcus pyogenes
secretes a specific immunoglobulin G (IgG)-protease, SpeB, as well as the IgG glycan-hydrolyzing enzyme EndoS. Here we show that SpeB also degrades IgA, IgM, IgD, and IgE. We also show that EndoS only hydrolyzes the glycan moiety on native but not denatured IgG. Thus, SpeB has a broad immunoglobulin-degrading activity, while EndoS is highly specific for IgG.
Glycocalyx on Rabbit Intestinal M Cells Displays Carbohydrate Epitopes from Muc2
Authors: Lelouard Hugues , Reggio Hubert , Roy Christian , Sahuquet Alain , Mangeat Paul , Montcourrier Philippe 
Published: July 2002

ABSTRACT
It is essential to investigate the apical surface properties of both M cells and dome enterocytes to understand the mechanisms involved in the binding of pathogens to M cells. In rabbit appendix tissue, monoclonal antibodies (MAbs) highlight differences between M cells (MAb 58) and dome enterocytes (MAb 214). Such antibodies ultimately recognized intestinal mucin-related epitopes. To further characterize these differences, the labeling patterns obtained with these MAbs were compared to those obtained with other antibodies to intestinal mucins on dissected domes from all gut-associated lymphoid tissues. A glycoprotein recognized by MAb 58 was purified on a CsCl isopycnic density gradient and microsequenced, and its mRNA expression was localized by in situ hybridization. It was identified as the rabbit homologue of human Muc2, i.e., the major mucin secreted in intestine tissue. Two other Muc2 carbohydrate epitopes were also expressed on M cells, although Muc2 mRNA was not detected. All results indicated that M cells express, on their apical membrane, glycoconjugates bearing at least three glycosidic epitopes from Muc2. MAb 214 and MAb 6G2, which recognized a partially characterized mucin expressed on dome enterocytes, were negative markers for M cells in rabbit gut-associated lymphoid tissues. We propose that the presence, on the surface of M cells, of carbohydrates also expressed on Muc2, together with the absence of an enterocyte-associated mucin, could favor pathogen attachment and accessibility to the M-cell luminal membrane.
The Common Vaccine Adjuvant Aluminum Hydroxide Up-Regulates Accessory Properties of Human Monocytes via an Interleukin-4-Dependent Mechanism
Authors: Ulanova Marina , Tarkowski Andrej , Hahn-Zoric Mirjana , Hanson Lars Å. 
Published: July 2002

ABSTRACTAluminum adjuvants are widely used in human vaccines based on their ability to enhance antibody production. However, the mechanisms underlying these effects remain unknown. In the present study we assessed the direct in vitro effect of aluminum hydroxide on human peripheral blood monocytes, specifically with regard to its impact on the phenotype and functional properties of this cell population. Our results revealed significant changes in the accessory properties of monocytes following short-term exposure of cultured cells to aluminum hydroxide. Thus, flow cytometry analyses showed an increase in the expression of major histocompatibility complex (MHC) class II, CD40, CD54, CD58, CD83, and CD86 molecules on the monocytes. In addition, many cells in the cultures containing aluminum hydroxide acquired typical dendritic morphology. Increased synthesis of interleukin-4 (IL-4) mRNA, but not gamma interferon mRNA, was also noted after exposure to aluminum hydroxide. The increase in cell surface expression of MHC class II did not occur in the presence of neutralizing IL-4 antibody or in cultures of highly purified monocytes or CD4-depleted mononuclear cells. Our findings suggest that aluminum hydroxide directly stimulates monocytes to produce proinflammatory cytokines activating T cells. Activated Th2 cells release IL-4, which in turn can induce an increase in the expression of MHC class II molecules on monocytes. The increase in the expression of antigen-presenting and costimulatory molecules leads to enhanced accessory functions of monocytes. These properties of aluminum hydroxide observed in vitro may explain its potent in vivo adjuvant effect.
Comparison of theexoSGene and Protein Expression in Soil and Clinical Isolates ofPseudomonas aeruginosa
Authors: Ferguson Michael W. , Maxwell Jill A. , Vincent Timothy S. , da Silva Jack , Olson Joan C. 
Published: July 2002

ABSTRACTExoenzyme S (ExoS) is translocated into eukaryotic cells by the type III secretory process and has been hypothesized to function in conjunction with other virulence factors in the pathogenesis ofPseudomonas aeruginosa. To gain further understanding of how ExoS might contribute toP. aeruginosasurvival and virulence, ExoS expression and the structural gene sequence were determined inP. aeruginosasoil isolates and compared with ExoS of clinical isolates. Significantly higher levels of ExoS ADP-ribosyltransferase (ADPRT) activity were detected in culture supernatants of soil isolates compared to those of clinical isolates. The higher levels of ADPRT activity of soil isolates reflected both the increased production of ExoS and the production of ExoS having a higher specific activity.ExoSstructural gene sequence comparisons found the gene to be highly conserved among soil and clinical isolates, with the greatest number of nonsynonymous substitutions occurring within the region of ExoS encoding GAP function. The lack of amino acid changes in the ADPRT region in association with a higher specific activity implies that other factors produced byP. aeruginosaor residues outside the ADPRT region are affecting ExoS ADPRT activity. The data are consistent with ExoS being integral toP. aeruginosasurvival in the soil and suggest that, in the transition ofP. aeruginosafrom the soil to certain clinical settings, the loss of ExoS expression is favored.
Involvement of HxuC Outer Membrane Protein in Utilization of Hemoglobin by
Haemophilus influenzae
Authors: Cope Leslie D. , Love Robert P. , Guinn Sarah E. , Gilep Andrei , Usanov Sergei , Estabrook Ronald W. , Hrkal Zbynek , Hansen Eric J. 
Published: July 2002

ABSTRACT

Haemophilus influenzae
can utilize different protein-bound forms of heme for growth in vitro. A previous study from this laboratory indicated that nontypeable
Haemophilus influenzae
(NTHI) strain N182 expressed three outer membrane proteins, designated HgbA, HgbB, and HgbC, that bound hemoglobin or hemoglobin-haptoglobin and were encoded by open reading frames (ORFs) that contained a CCAA nucleotide repeat. Testing of mutants expressing the HgbA, HgbB, and HgbC proteins individually revealed that expression of any one of these proteins was sufficient to allow wild-type growth with hemoglobin. In contrast, mutants that expressed only HgbA or HgbC grew significantly better with hemoglobin-haptoglobin than did a mutant expressing only HgbB. Construction of an isogenic
hgbA hgbB hgbC
mutant revealed that the absence of these three gene products did not affect the ability of NTHI N182 to utilize hemoglobin as a source of heme, although this mutant was severely impaired in its ability to utilize hemoglobin-haptoglobin. The introduction of a
tonB
mutation into this triple mutant eliminated its ability to utilize hemoglobin, indicating that the pathway for hemoglobin utilization in the absence of HgbA, HgbB, and HgbC involved a TonB-dependent process. Inactivation in this triple mutant of the
hxuC
gene, which encodes a predicted TonB-dependent outer membrane protein previously shown to be involved in the utilization of free heme, resulted in loss of the ability to utilize hemoglobin. The results of this study reinforce the redundant nature of the heme acquisition systems expressed by
H. influenzae
.
Delineation of
Borrelia burgdorferi
p66 Sequences Required for Integrin α
IIb
β
3
Recognition
Authors: Defoe Gillianne , Coburn Jenifer 
Published: July 2002

ABSTRACT

The outer membrane protein p66 of the Lyme disease agent,
Borrelia burgdorferi
, has been identified as a candidate ligand for β
3
-chain integrins. To identify portions of p66 required for integrin recognition, fusions of maltose-binding protein to fragments of p66 were tested for binding to integrin α
IIb
β
3
, and synthetic peptides derived from the p66 amino acid sequence were tested for the ability to inhibit
B. burgdorferi
attachment to the same integrin. The data identify two noncontiguous segments of p66 that are important for α
IIb
β
3
recognition, suggesting that, as is true for other integrin ligands, the tertiary structure of p66 is important for receptor recognition.
Construction, Genotypic and Phenotypic Characterization, and Immunogenicity of Attenuated ΔguaBA Salmonella entericaSerovar Typhi Strain CVD 915
Authors: Wang Jin Yuang , Pasetti Marcela F. , Noriega Fernando R. , Anderson Richard J. , Wasserman Steven S. , Galen James E. , Sztein Marcelo B. , Levine Myron M. 
Published: July 2002

ABSTRACTA promising live attenuated typhoid vaccine candidate strain for mucosal immunization was developed by introducing a deletion in theguaBAlocus of pathogenicSalmonella entericaserovar Typhi strain Ty2. The resultant ΔguaBAmutant, serovar Typhi CVD 915, has a gene encoding resistance to arsenite replacing the deleted sequence withinguaBA, thereby providing a marker to readily identify the vaccine strain. CVD 915 was compared in in vitro and in vivo assays with wild-type strain Ty2, licensed live oral typhoid vaccine strain Ty21a, or attenuated serovar Typhi vaccine strain CVD 908-htrA(harboring mutations inaroC, aroD, andhtrA). CVD 915 was less invasive than CVD 908-htrAin tissue culture and was more crippled in its ability to proliferate after invasion. In mice inoculated intraperitoneally with serovar Typhi and hog gastric mucin (to estimate the relative degree of attenuation), the 50% lethal dose of CVD 915 (7.7 × 107CFU) was significantly higher than that of wild-type Ty2 (1.4 × 102CFU) and was only slightly lower than that of Ty21a (1.9 × 108CFU). Strong serum O and H antibody responses were recorded in mice inoculated intranasally with CVD 915, which were higher than those elicited by Ty21a and similar to those stimulated by CVD 908-htrA. CVD 915 also elicited potent proliferative responses in splenocytes from immunized mice stimulated with serovar Typhi antigens. Used as a live vector, CVD 915(pTETlpp) elicited high titers of serum immunoglobulin G anti-fragment C. These encouraging preclinical data pave the way for phase 1 clinical trials with CVD 915.