bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of Toll-Like Receptor 4 in Induction of Cell-Mediated Immunity and Resistance toBrucella abortusInfection in Mice
Authors: Campos Marco A. , Rosinha Gracia M. S. , Almeida Igor C. , Salgueiro Xirlene S. , Jarvis Bruce W. , Splitter Gary A. , Qureshi Nilofer , Bruna-Romero Oscar , Gazzinelli Ricardo T. , Oliveira Sergio C. 
Published: December 2003

ABSTRACTInitial host defense to bacterial infection is executed by innate immunity, and therefore the main goal of this study was to examine the contribution of Toll-like receptors (TLRs) duringBrucella abortusinfection. CHO reporter cell lines transfected with CD14 and TLRs showed thatB. abortustriggers both TLR2 and TLR4. In contrast, lipopolysaccharide (LPS) and lipid A derived fromBrucellarough (R) and smooth (S) strains activate CHO cells only through TLR4. Consistently, macrophages from C3H/HePas mice exposed to R and S strains and their LPS produced higher levels of tumor necrosis factor alpha (TNF-α) and interleukin-12 compared to C3H/HeJ, a TLR4 mutant mouse. The essential role of TLR4 for induction of proinflammatory cytokines was confirmed with diphosphoryl lipid A fromRhodobacter sphaeroides. Furthermore, to determine the contribution of TLR2 and TLR4 in bacterial clearance, numbers ofBrucellawere monitored in the spleen of C3H/HeJ, C3H/HePas, TLR2 knockout, and wild-type mice at 1, 3, and 6 weeks followingB. abortusinfection. Interestingly, murine brucellosis was markedly exacerbated at weeks 3 and 6 after infection in animals that lacked functional TLR4 (C3H/HeJ) compared to C3H/HePas that paralleled the reduced gamma interferon production by this mouse strain. Finally, by mass spectrometry analysis we found dramatic differences on the lipid A profiles of R and S strains. In fact, S lipid A was shown to be more active to trigger TLR4 than R lipid A in CHO cells and more effective in inducing dendritic cell maturation. In conclusion, these results indicate that TLR4 plays a role in resistance toB. abortusinfection and that S lipid A has potent adjuvant activity.
Immunization of Female Mice with Glycoconjugates Protects Their Offspring against Encapsulated Bacteria
Authors: Richter Margret Y. , Jakobsen Håvard , Birgisdottir Alda , Haeuw Jean-François , Power Ultan F. , Del Giudice Giuseppe , Bartoloni Antonella , Jonsdottir Ingileif 
Published: December 2003

ABSTRACTThe immune system of the newborn is immature, and therefore it is difficult to induce protective immunity by vaccination in the neonatal period. Immunization of mothers during pregnancy against infections caused by encapsulated bacteria could thus be particularly attractive, as infants do not respond to polysaccharide (PS) antigens. Transmission of maternal vaccine-specific antibodies and protection of offspring against pneumococcal bacteremia and/or lung infection were studied in a neonatal murine model of pneumococcal immunization and infections. Adult female mice were immunized with native pneumococcal PS (PPS) of serotypes 1, 6B, and 19F or PPS conjugated to tetanus protein (Pnc-TT), and PPS-specific antibodies were measured in sera of mothers and their offspring. Effective transmission of maternal antibodies was observed, as PPS-specific immunoglobulin G levels in 3-week-old offspring of immunized mothers were 37 to 322% of maternal titers, and a significant correlation between maternal and offspring antibody levels was observed. The PPS-specific antibodies persisted for several weeks but slowly decreased over time. Offspring of Pnc-TT-immunized mothers were protected against pneumococcal infections with homologous serotypes, whereas PPS immunization of mothers did not protect their offspring, in agreement with the low titer of maternal PPS specific antibodies. When adult female mice were immunized with a meningococcal serogroup C conjugate vaccine (MenC-CRM), antibody response and transmission were similar to those observed for pneumococcal antibodies. Importantly, bactericidal activity was demonstrated in offspring of MenC-CRM-immunized mothers. These results demonstrate that this murine model of pneumococcal immunization and infections is suitable to study maternal immunization strategies for protection of offspring against encapsulated bacteria.
Immunogenicity and Efficacy ofCryptococcus neoformansCapsular Polysaccharide Glucuronoxylomannan Peptide Mimotope-Protein Conjugates in Human Immunoglobulin Transgenic Mice
Authors: Maitta Robert W. , Datta Kausik , Lees Andrew , Belouski Shelley Sims , Pirofski Liise-anne 
Published: December 2003

ABSTRACTPeptide mimotopes of capsular polysaccharides have been proposed as antigens for vaccines against encapsulated pathogens. In this study, we determined the antibody response to and efficacy of P13, a peptide mimetic of theCryptococcus neoformanscapsular polysaccharide glucuronoxylomannan (GXM), in mice that produce human antibodies. P13 was conjugated to tetanus toxoid (TT) or diphtheria toxoid (DT) and administered subcutaneously in Alhydrogel with or without CpG to mice transgenic for human immunoglobulin loci (XenoMouse mice) and expressing either immunoglobulin G2 (IgG2) (G2 mice) or IgG4 (G4 mice). Mice were vaccinated and revaccinated two or three times. The serum antibody responses of the mice to GXM and P13 and antibody idiotype expression were analyzed by an enzyme-linked immunosorbent assay. The results showed that both P13-TT and P13-DT were antigenic, inducing a mimetic response to P13 in both G2 and G4 mice, and immunogenic, inducing a mimotope response including VH3 (idiotype)-positive antibodies to GXM in G2 but not G4 mice. CpG led to higher titers of IgG to P13 and GXM in P13-TT-vaccinated G2 mice.C. neoformanschallenge of P13-protein conjugate-vaccinated and control G2 mice induced anamnestic IgG- and VH3-positive responses to GXM and was associated with a significantly decreased risk of death and a prolongation of survival in P13-DT-vaccinated mice compared to phosphate-buffered saline-treated or protein carrier-vaccinated mice. These findings reveal that P13 elicited a human antibody response with VH3 expression in human immunoglobulin transgenic mice that has been observed for human antibodies to GXM and support the concept that peptide mimotope-based vaccines may hold promise for the treatment ofC. neoformansinfections.
Biological Activities of Naturally Occurring Antibodies Reactive withCandida albicansMannan
Authors: Kozel Thomas R. , MacGill Randall S. , Percival Ann , Zhou Qing 
Published: December 2003

ABSTRACTSera from normal adult humans may contain high levels of antibody reactive withCandida albicansmannan. This study examined selected biological activities of such antibodies, focusing on sera that were collected from 34 donors and analyzed individually. The results showed that antimannan titers were normally distributed. Reactivity as determined by enzyme-linked immunosorbent assay with serotype A mannan generally paralleled reactivity with serotype B. Analysis of the kinetics for activation of the complement system and deposition of complement component 3 (C3) onto serotype A and serotype B cells showed a decrease in the lag time that occurred before the onset of rapid accumulation of C3 that correlated with increasing antimannan titers. In contrast, there was a decrease in the overall rate of accumulation of C3 on serotype A cells that was strongly correlated with increasing antibody titers; serotype B cells showed no such decrease. An evaluation of the contribution of mannan antibody to opsonophagocytic killing showed that mannan antibody in individual sera and antimannan immunoglobulin G (IgG) affinity purified from human plasma contributed to killing by neutrophils in a dose-dependent fashion in the absence of a functional complement system. However, affinity-purified antibody in very high concentrations was inhibitory to both complement-dependent and complement-independent opsonophagocytosis, and this finding suggests a prozone-like effect. In contrast, if the complement system was functional, antimannan IgG was not needed for opsonophagocytic killing. These results suggest that naturally occurring mannan antibodies and the complement system are functionally redundant for opsonophagocytic killing by neutrophils.
Camelysin Is a Novel Surface Metalloproteinase from
Bacillus cereus
Authors: Grass Gregor , Schierhorn Angelika , Sorkau Eduard , Müller Helmut , Rücknagel Peter , Nies Dietrich H. , Fricke Beate 
Published: December 2003

ABSTRACT

Bacillus cereus
frequently causes food poisoning or nosocomial diseases. Vegetative cells express the novel surface metalloproteinase camelysin (casein-cleaving metalloproteinase) during exponential growth on complex, peptide-rich media. Camelysin is strongly bound to the cell surface and can be solubilized only by detergents or butanol. Camelysin spontaneously migrates from the surface of intact bacterial cells to preformed liposomes. The complete sequence of the camelysin-encoding gene,
calY
, was determined by reverse PCR on the basis of the N-terminal sequence and some internal tryptic cleavage peptides. The
calY
gene codes for a polypeptide of 21.569 kDa with a putative signal peptide of 27 amino acids (2.513 kDa) preceding the mature protein (19.056 kDa). Although the predicted amino acid sequence of CalY does not exhibit a typical metalloprotease consensus sequence, high-pressure liquid chromatography-purified camelysin contains one zinc ion per protein molecule. Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry and tryptic peptide mass fingerprinting confirmed the identity of this zinc-binding protein as CalY. Disruption of the
calY
gene results in a strong decrease in the cell-bound proteolytic activity on various substrates.
Salmonella enterica
Serovar Paratyphi C Carries an Inactive Shufflon
Authors: Tam Connie K. P. , Hackett Jim , Morris Christina 
Published: December 2003

ABSTRACT

Salmonella enterica
serovar Typhi uses type IVB pili to facilitate bacterial self-association, but only when the PilV proteins (potential minor pilus proteins) are not synthesized. This pilus-mediated event may be important in typhoid fever pathogenesis. We initially show that
S. enterica
serovar Paratyphi C strains harbor a
pil
operon very similar to that of serovar Typhi. An important difference, however, is located in the shufflon which concludes the
pil
operon. In serovar Typhi, the Rci recombinase acts upon two 19-bp inverted repeats to invert the terminal region of the
pilV
gene, thereby disrupting PilV synthesis and permitting bacterial self-association. In serovar Paratyphi C, however, the shufflon is essentially inactive because each of the Rci 19-bp substrates has acquired a single base pair insertion. A PilV protein is thus synthesized whenever the
pil
operon is active, and bacterial self-association therefore does not occur in serovar Paratyphi C. The data thus suggest that serovar Typhi bacterial self-association using type IVB pili may be important in the pathogenesis of epidemic enteric fever.
Melanin fromFonsecaea pedrosoiInduces Production of Human Antifungal Antibodies and Enhances the Antimicrobial Efficacy of Phagocytes
Authors: Alviano Daniela S. , Franzen Anderson J. , Travassos Luiz R. , Holandino Carla , Rozental Sonia , Ejzemberg Regina , Alviano Celuta S. , Rodrigues Marcio L. 
Published: December 2003

ABSTRACTFonsecaea pedrosoiis a fungal pathogen that produces melanin. The functions of melanin and its possible influence in the protective immunological response during infection byF. pedrosoiare not known. In this work, treatment ofF. pedrosoimycelia with proteases and glycosidases followed by a denaturing agent and hot concentrated acid left a black residue. Scanning electron microscopy demonstrated that this processed melanized residue resembled very closely the intact mycelium in shape and size. Melanin particles were also isolated from culture fluids of conidia or sclerotic forms ofF. pedrosoi. Secreted melanins were reactive with sera from infected human patients, suggesting thatF. pedrosoisynthesizes melanin in vivo. The antibodies against melanin were purified from patients’ sera and analyzed by indirect immunofluorescence. They reacted with sclerotic cells from patients’ lesions as well as with sclerotic bodies cultivated in vitro, conidia, mycelia, and digested residues. Treatment ofF. pedrosoiwith purified antibodies against melanin inhibited fungal growth in vitro. The interaction ofF. pedrosoiwith phagocytes in the presence of melanin resulted in higher levels of fungal internalization and destruction by host cells, which was accompanied by greater degrees of oxidative burst. Taken together, these results indicate that melanin fromF. pedrosoiis an immunologically active fungal structure that activates humoral and cellular responses that could help the control of chromoblastomycosis by host defenses.
Single Intranasal MucosalMycobacterium bovisBCG Vaccination Confers Improved Protection Compared to Subcutaneous Vaccination against Pulmonary Tuberculosis
Authors: Chen Lihao , Wang Jun , Zganiacz Anna , Xing Zhou 
Published: December 2003

ABSTRACTWhether the intranasal (i.n.) route ofMycobacterium bovisBCG vaccination provides better protection against pulmonary tuberculosis than subcutaneous (s.c.) vaccination remains an incompletely solved issue. In the present study, we compared both immune responses and protection elicited by single BCG vaccinations via the i.n. or s.c. route in BALB/c mice. While both i.n. and s.c. vaccination triggered comparable levels of primary immune activation in the spleen and draining lymph nodes, i.n. vaccination led to a greater antigen-specific gamma interferon recall response in splenocytes than s.c. vaccination upon secondary respiratory mycobacterial challenge, accompanied by an increased frequency of antigen-specific lymphocytes. There was also a quicker cellular response in the lungs of i.n. vaccinated mice upon mycobacterial challenge. Mice vaccinated i.n. were found to be much better protected, particularly in the lung, than s.c. vaccinated counterparts against pulmonary tuberculosis at both 3 and 6 months postvaccination. These results suggest that the i.n. route of vaccination improves the protective effect of the current BCG vaccine.
Association between Protection against Clinical Malaria and Antibodies to Merozoite Surface Antigens in an Area of Hyperendemicity in Myanmar: Complementarity between Responses to Merozoite Surface Protein 3 and the 220-Kilodalton Glutamate-Rich Protein
Authors: Soe Soe , Theisen Michael , Roussilhon Christian , Aye Khin-Saw- , Druilhe Pierre 
Published: December 2003

ABSTRACT

We performed a longitudinal clinical and parasitological follow-up study in OoDo, a village in southeast Asia in which malaria is hyperendemic, in order to assess the association between protection against malaria attacks and antibodies to three currently evaluated vaccine candidates, merozoite surface protein 1 (MSP1), MSP3, and the 220-kDa glutamate-rich protein (GLURP) from
Plasmodium falciparum.
Our results showed that the levels of cytophilic immunoglobulin G3 (IgG3) antibodies against conserved regions of MSP3 and GLURP were significantly correlated with protection against clinical
P. falciparum
malaria. In contrast, the levels of noncytophilic IgG4 antibodies against GLURP increased with the number of malaria attacks. Furthermore, we observed a complementary effect of the MSP3- and GLURP-specific IgG3 antibodies in relation to malaria protection. In the individuals that did not respond to one of the antigens, a strong response to the other antigen was consistently detected and was associated with protection, suggesting that induction of antibodies against both MSP3 and GLURP could be important for the development of protective immunity. The complementarity of the responses to the two main targets of antibody-dependent cellular inhibition identified to date provides the first rational basis for combining these two antigens in a hybrid vaccine formulation.
Induction of
Plasmodium falciparum
Transmission-Blocking Antibodies in Nonhuman Primates by a Combination of DNA and Protein Immunizations
Authors: Coban Cevayir , Philipp Mario T. , Purcell Jeanette E. , Keister David B. , Okulate Mobolaji , Martin Dale S. , Kumar Nirbhay 
Published: December 2003

ABSTRACT

Malaria transmission-blocking vaccination can effectively reduce and/or eliminate transmission of parasites from the human host to the mosquito vector. The immunity achieved by inducing an antibody response to surface antigens of male and female gametes and parasite stages in the mosquito. Our laboratory has developed DNA vaccine constructs, based on Pfs25 (a
Plasmodium falciparum
surface protein of 25 kDa), that induce a transmission-blocking immune response in mice (C. A. Lobo, R. Dhar, and N. Kumar, Infect. Immun. 67:1688-1693, 1999). To evaluate the safety, immunogenicity, and efficacy of the Pfs25 DNA vaccine in nonhuman primates, we immunized rhesus macaques (
Macaca mulatta
) with a DNA vaccine plasmid encoding Pfs25 or a Pfg27-Pfs25 hybrid or with the plasmid (empty plasmid) alone. Immunization with four doses of these DNA vaccine constructs elicited antibody titers that were high but nonetheless unable to reduce the parasite's infectivity in membrane feeding assays. Further boosting of the antibody response with recombinant Pfs25 formulated in Montanide ISA-720 increased antibody titers (30-fold) and significantly blocked transmission of
P. falciparum
gametocytes to
Anopheles
mosquitoes (∼90% reduction in oocyst numbers in the midgut). Our data show that a DNA prime-protein boost regimen holds promise for achieving transmission-blocking immunity in areas where malaria is endemic and could be effective in eradicating malaria in isolated areas where the level of malaria endemicity is low.
l
-Serine Catabolism via an Oxygen-Labile
l
-Serine Dehydratase Is Essential for Colonization of the Avian Gut by
Campylobacter jejuni
Authors: Velayudhan Jyoti , Jones Michael A. , Barrow Paul A. , Kelly David J. 
Published: December 2003

ABSTRACT

Campylobacter jejuni
is a microaerophilic, asaccharolytic bacterium. The identity of the carbon and energy sources used by
C. jejuni
in vivo is unknown, but the genome sequence of strain NCTC11168 indicates the presence of genes for catabolism of a limited range of amino acids, including serine. Specific omission of
l
-serine from a defined medium containing a mixture of amino acids led to a dramatic decrease in cell yields. As
C. jejuni
does not have a biosynthetic serine requirement, this supports earlier suggestions that
l
-serine is a preferentially catabolized amino acid. Serine transport was found to be mediated by at least two systems in strain 11168; a high-capacity, low-affinity
l
-serine-specific system encoded by
Cj1625c
(
sdaC
) and a higher-affinity
l
-serine/
l
-threonine system responsible for residual
l
-serine transport in an
sdaC
mutant. Catabolism of
l
-serine to pyruvate and ammonia is carried out by SdaA (encoded by
Cj1624c
), which was overexpressed, purified, and shown to be an oxygen-labile iron-sulfur enzyme.
l
-Serine dehydratase activity in an
sdaA
mutant was reduced 10-fold compared to that in the wild type, but the residual activity (due to the anabolic
l
-threonine dehydratase) could not support either growth on or utilization of
l
-serine in defined media. However, although
sdaA
mutants showed no obvious growth defect in complex media, they completely failed to colonize 3-week-old chickens as assayed both by cloacal swabs taken over a 6-week period and by cecal colony counts postmortem. In contrast, the isogenic parent strain colonized chickens to high levels within 1 week of inoculation. The results show that an active SdaA is essential for colonization of the avian gut by
C. jejuni
and imply that catabolism of
l
-serine is crucially important for the growth of this bacterium in vivo.
Tumor Necrosis Factor Alpha Enhances
Actinobacillus actinomycetemcomitans
Leukotoxin-Induced HL-60 Cell Apoptosis by Stimulating Lymphocyte Function-Associated Antigen 1 Expression†
Authors: Yamaguchi Noboru , Kubo Chie , Masuhiro Yoshikazu , Lally Edward T. , Koga Toshihiko , Hanazawa Shigemasa 
Published: December 2003

ABSTRACT

We demonstrated previously that
Actinobacillus actinomycetemcomitans
leukotoxin (Ltx) is greatly able to induce apoptotic signaling in cells that are positive for lymphocyte function-associated antigen 1 (LFA-1), a cell receptor of Ltx. We investigated in this study whether inflammatory cytokines can regulate apoptosis of human leukemic HL-60 cells induced by Ltx. Of the cytokines tested, tumor necrosis factor alpha (TNF-α) significantly enhanced the Ltx-induced cell apoptosis. Northern and Western blotting analyses showed that TNF-α enhanced the expression of CD11a in the cells at both the mRNA and protein levels but did not do so for CD18 expression. TNF-α also enhanced the binding of Ltx to the cells. We also observed by measuring the mitochondrial transmembrane potential and the generation of superoxide anion that the cytokine enhanced Ltx-induced apoptosis in HL-60 cells. In addition, interleukin-1β significantly enhanced Ltx-induced cell apoptosis, although the enhancing activity was lower than that of TNF-α. These stimulatory effects of both cytokines were also observed for human polymorphonuclear leukocytes. The ability of TNF-α to increase cell susceptibility to Ltx could be inhibited by preincubation of the cells with a monoclonal antibody against TNF receptor 1 but not by preincubation of the cells with a monoclonal antibody against anti-TNF receptor 2. Furthermore, the results of an assay of caspase 3 intracellular activity (PhiPhiLuxG
1
D
2
) showed that Ltx-induced caspase 3 activation was completely neutralized by CD18 antibody treatment, although significant neutralization was also observed with anti-CD11a antibody. Taken together, the results of the present study indicate that TNF-α acts as a potent stimulator of Ltx-induced HL-60 cell apoptosis via TNF receptor 1-mediated upregulation of LFA-1 expression.
Immunogenicity of Gonococcal Transferrin Binding Proteins during Natural Infections
Authors: Price Gregory A. , Hobbs Marcia M. , Cornelissen Cynthia Nau 
Published: December 2003

ABSTRACTIn this study, we examined the immune response during gonococcal infection to the individual transferrin binding proteins by using a quantitative enzyme-linked immunosorbent assay (ELISA). Recombinant transferrin binding protein A (rTbpA) and rTbpB were purified under nondenaturing conditions for use as ELISA antigens. Sera and secretions from culture-positive individuals were analyzed for antibodies to rTbpA and rTbpB and compared to samples from individuals with no history of gonococcal infection. Although antibodies to both rTbpA and rTbpB were detected in serum, in most cases the antibody levels were not significantly different from those measured in the control population. Also, previous history of gonococcal infection did not increase antibody levels in serum, suggesting the lack of an anamnestic response. Analysis of secretion samples revealed antibody levels that were generally below the limits of detection in our assay. Overall, this study demonstrated a paucity of systemic and local antibody responses to rTbps as a result of natural infection and represents a baseline over which a protective antibody response will have to be generated in order to develop an efficacious gonococcal vaccine.