bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antigenic Importance of the Carboxy-Terminal Beta-Strand of the Porcine Reproductive and Respiratory Syndrome Virus Nucleocapsid Protein
Authors: Wootton Sarah , Koljesar Gabriella , Yang Liuzhan , Yoon Kyoung-Jin , Yoo Dongwan 
Published: July 2002

ABSTRACT
Five domains of antigenic importance were previously mapped on the nucleocapsid protein (N) of the porcine reproductive and respiratory syndrome virus (PRRSV), and a domain comprised of the 11 C-terminal-most amino acids (residues 112 to 123) was shown to be essential for binding of N-specific conformation-dependent monoclonal antibodies (MAbs). In the present study, the importance of individual residues within this C-terminal domain for antigenicity was investigated using eight different mutant constructs of N expressed in HeLa cells. Single amino acid substitutions were introduced into the C-terminal domain of the N protein, and the significance of individual amino acids for MAb reactivity was determined by immunoprecipitation. None of the MAbs tested recognized the mutant with a leucine-to-proline substitution at residue 114 (L114P), while V112P, R113P, R113D, I115P, and R116P reduced MAb binding significantly. Conversely, substitution of amino acids at positions 118 (T118S) and 121 (P121A) had little effect on MAb binding. Secondary-structure predictions indicate that amino acids 111 to 117 form a beta-strand. In view of the fact that replacement of beta-strand-forming amino acids with proline elicited the greatest effect on MAb binding, it appears that secondary structure in the C terminus of the N protein is an important determinant of conformational epitope formation. While the crystal structure of the PRRSV N protein remains to be determined, results from these studies broaden our understanding of the secondary structures that make up the PRRSV N protein and shed some light on how they may relate to function.
Reliability of
Helicobacter pylori
and CagA Serological Assays
Authors: Everhart James E. , Kruszon-Moran Deanna , Perez-Perez Guillermo 
Published: July 2002

ABSTRACT

Background serological assays for
Helicobacter pylori
are commonly used without knowledge of reliability. This information is needed to define the ability of serological tests to determine either new cases of infection or loss of infection in longitudinal studies. We evaluated the reproducibility and the interrelationships of serological test results for
H. pylori
and cytotoxin-associated gene product A (CagA) enzyme-linked immunoassays within a subset of participants in a population-based study. Stored samples from 1,229 participants in the third U.S. National Health and Nutrition Examination Survey were replicate serologically tested for
H. pylori
and CagA. Overall disagreement was 3.4% between duplicate tests for
H. pylori
(or 2.3% if equivocal results were disregarded). Six percent of samples positive on the first test had an immune serum ratio at least 30% lower on repeat testing. The odds ratio for
H. pylori
seropositivity on retesting was 2.8 (95% confidence interval [CI] = 1.8 to 4.5) when CagA serology was positive versus when it was negative. CagA antibody was found among 47.8% of
H. pylori
-equivocal and 7.0% of
H. pylori
-negative samples. CagA-positive yet
H. pylori
-negative samples were more likely to occur among Mexican Americans (odds ratio, 5.2; 95% CI = 2.4 to 11.4) and non-Hispanic blacks (odds ratio, 5.5; 95% CI = 2.3 to 13.0) than among non-Hispanic whites. Relying on repeated
H. pylori
serological tests over time to determine infection rates may result in misinterpretation due to limits in test reproducibility. CagA testing may have a role in verifying infection.
Induction of Protective Immunity againstChlamydia trachomatisGenital Infection by a Vaccine Based on Major Outer Membrane Protein–Lipophilic Immune Response-Stimulating Complexes
Authors: Igietseme Joseph U. , Murdin Andrew 
Published: July 2002

ABSTRACTThe significance of delivery systems in modern vaccine design strategies is underscored by the fact that a promising vaccine formulation may fail in vivo due to an inappropriate delivery method. We evaluated the immunogenicity and efficacy of a candidate vaccine comprising the major outer membrane protein (MOMP) ofChlamydia trachomatisdelivered with the lipophilic immune response-stimulating complexes (ISCOMs) as a vehicle with adjuvant properties, in a murine model of chlamydial genital infection. Immunocompetent BALB/c mice were immunized intranasally (IN) or intramuscularly (IM) with MOMP, MOMP-ISCOMs, and live or heat-inactivatedC. trachomatisserovar D. The level of local genital mucosal Th1 response was measured by assaying for antigen-specific Th1 cell induction and recruitment into the genital mucosa at different times after immunization. Immunization with MOMP-ISCOMs by the IM route induced the greatest and fastest local genital mucosal Th1 response, first detectable 2 weeks after exposure. Among the other routes and regimens tested, only IN immunization with MOMP-ISCOMs induced detectable and statistically significant levels of local genital mucosal Th1 response during the 8-week test period (P< 0.001). In addition, when T cells from immunized mice were adoptively transferred into syngeneic naive animals and challenged intravaginally withChlamydia, recipients of IM immunization of MOMP-ISCOMs cleared their infection within 1 week and were resistant to reinfection. Animals that received IN immunization of MOMP-ISCOMs were partially protected, shedding fewer chlamydiae than did control mice. Altogether, the results suggested that IM delivery of MOMP-ISCOMs may be a suitable vaccine regimen potentially capable of inducing protective mucosal immunity againstC. trachomatisinfection.
Listeria monocytogenesas a Short-Lived Delivery System for the Induction of Type 1 Cell-Mediated Immunity against the p36/LACK Antigen ofLeishmania major
Authors: Soussi Neirouz , Milon Geneviève , Colle Jean-Hervé , Mougneau Evelyne , Glaichenhaus Nicolas , Goossens Pierre L. 
Published: July 2002

ABSTRACTListeria monocytogeneshas been used as an experimental live vector for the induction of CD8-mediated immune responses in various viral and tumoral experimental models. Susceptibility of BALB/c mice toLeishmania majorinfection has been correlated to the preferential development of Th2 CD4 T cells through an early production of interleukin 4 (IL-4) by a restricted population of CD4 T cells which react to a single parasite antigen, LACK (stands forLeishmaniahomologue of receptors for activated C kinase). Experimental vaccination with LACK can redirect the differentiation of CD4+T cells towards the Th1 pathway if LACK is coadministrated with IL-12. As IL-12 is known to be induced byL. monocytogenes, we have tested the ability of a recombinant attenuatedactAmutantL. monocytogenesstrain expressing LACK to induce the development of LACK-specific Th1 cells in both B10.D2 and BALB/c mice, which are resistant and susceptible toL. major, respectively. After a single injection of LACK-expressingL. monocytogenes, IL-12/p40 transcripts showed a rapid burst, and peaks of gamma interferon (IFN-γ)-secreting LACK-specific Th1 cells were detected around day 5 in the spleens and livers of mice of both strains. These primed IFN-γ-secreting LACK-reactive T cells were not detected ex vivo after day 7 of immunization but could be recruited and detected 15 days later in the draining lymph node after anL. majorfootpad challenge. Although immunization of BALB/c mice with LACK-expressingL. monocytogenesdid not change the course of the infection withL. major, immunized B10.D2 mice exhibited significantly smaller lesions than nonimmunized controls. Thus, our results demonstrate that, in addition of its recognized use for the induction of effector CD8 T cells,L. monocytogenescan also be used as a live recombinant vector to favor the development of potentially protective IFN-γ-secreting Th1 CD4 T lymphocytes.
Cell Vacuolation, a Manifestation of the El Tor Hemolysin of
Vibrio cholerae
Authors: Mitra Rupak , Figueroa Paula , Mukhopadhyay Asish K. , Shimada Toshio , Takeda Yoshifumi , Berg Douglas E. , Nair G. Balakrish 
Published: July 2002

ABSTRACT

Culture supernatants of nontoxigenic nonepidemic clinical strains of
Vibrio cholerae
belonging to diverse serogroups were found to induce vacuolation of nonconfluent HeLa cells. The vacuoles became prominent 18 h after introduction of culture supernatant, and vacuolated cells survived for 48 h and then died. Only a fraction of the vacuolated cells took up neutral red dye, implying that there were differences in the vacuolar microenvironment. Further tests showed that the factor responsible for vacuolation was heat labile and proteinaceous. Vacuolating activity was completely neutralized by antibody to hemolysin of
V. cholerae
but not by antibody to vacuolating cytotoxin of
Helicobacter pylori
. Partial purification of the vacuolating factor led to elution of fractions, which showed both hemolytic and vacuolating activity. PCR amplification and cloning of the hemolysin structural gene (
hlyA
) into
Escherichia coli
DH5α led to isolation of clones producing cell vacuolating factor in a cell-associated form. Further, a null insertion mutation in the
hlyA
gene of a high-vacuolating-factor-producing strain led to complete abolition of both cell vacuolating and hemolytic activities. These analyses establish vacuolation as a potentially important but previously unrecognized property of
V. cholerae
El Tor hemolysin.
Effects of Shiga Toxin 2 on Lethality, Fetuses, Delivery, and Puerperal Behavior in Pregnant Mice
Authors: Yoshimura Kazuaki , Fujii Jun , Tanimoto Akihide , Yutsudo Takashi , Kashimura Masamichi , Yoshida Shin-ichi 
Published: July 2002

ABSTRACT

Shiga toxin 2 (Stx2) is produced by enterohemorrhagic
Escherichia coli
(EHEC) and is known as the major virulence factor of EHEC. The aim of this study was to evaluate the effects of Stx2 on (i) maternal lethality, (ii) fetuses, (iii) delivery period, and (iv) maternal behavior after delivery. Timed pregnant ICR mice were injected intravenously with Stx2 on day 5 of pregnancy (early stage) or on day 15 (late stage). In early-stage experiments, the number of normal fetuses of mice injected with Stx2 was significantly lower than that of control mice. In late-stage experiments, mothers injected with Stx2 delivered normal numbers of neonates, but could not take care of them. The lethal doses of Stx2 were not different for pregnant and nonpregnant female mice at either stage. We conclude that Stx2 is toxic to the fetus in early pregnancy and affects maternal puerperal behavior in late pregnancy.
Interleukin-4 and Interleukin-10 Are Involved in Host Resistance toStaphylococcus aureusInfection through Regulation of Gamma Interferon
Authors: Sasaki Sanae , Nishikawa Shinsuke , Miura Tomisato , Mizuki Mayuko , Yamada Kyogo , Madarame Hiroo , Tagawa Yoh-Ichi , Iwakura Yoichiro , Nakane Akio 
Published: July 2002

ABSTRACTOur previous study showed that gamma interferon (IFN-γ), a T-helper 1 (Th1)-type cytokine, plays a detrimental role inStaphylococcus aureusinfection in mice. In this study, the role of Th2-type cytokines such as interleukin-4 (IL-4) and IL-10 inS. aureusinfection was investigated. IL-10 mRNA was induced in parallel with IFN-γ in the spleens and kidneys of mice duringS. aureusinfection, whereas IL-4 mRNA was induced in the spleens but not in the kidneys of these animals. Spleen cells obtained fromS. aureus-infected mice produced lower titers of IFN-γ and higher titers of IL-4 and IL-10 in response to heat-killedS. aureusthan did those from uninfected mice. Administration of anti-IL-4 monoclonal antibody (MAb) or anti-IL-10 MAb inhibited the elimination ofS. aureuscells from the kidneys of mice. IFN-γ mRNA expression was enhanced in the spleens of anti-IL-4 MAb- or anti-IL-10 MAb-treated mice and also in the kidneys of anti-IL-4 MAb-treated animals. Next, we evaluated the role of IFN-γ inS. aureusinfection in IFN-γ−/−mice. An increase in survival rates, a decrease in bacterial numbers in the kidneys, and an amelioration of histologic abnormalities in these organs were observed in IFN-γ−/−mice compared with those in IFN-γ+/+mice. Administration of MAb against IL-4 or IL-10 failed to affect bacterial growth in the spleens and kidneys of IFN-γ−/−mice irrespective of the expression of Th2 response. These results suggest thatS. aureusinfection induced a Th2 response and that IL-4 and IL-10 might play a protective role through the regulation of IFN-γ inS. aureusinfection.
Yersinia enterocoliticaInvasin Protein Triggers Differential Production of Interleukin-1, Interleukin-8, Monocyte Chemoattractant Protein 1, Granulocyte-Macrophage Colony-Stimulating Factor, and Tumor Necrosis Factor Alpha in Epithelial Cells: Implications for Understanding the Early Cytokine Network inYersiniaInfections
Authors: Kampik Daniel , Schulte Ralf , Autenrieth Ingo B. 
Published: July 2002

ABSTRACTYersinia enterocoliticainfection of epithelial cells results in interleukin-8 (IL-8) mRNA expression. Herein we demonstrate that besides IL-8, increased mRNA levels of five other cytokines, IL-1α, IL-1β, monocyte chemoattractant protein 1 (MCP-1), granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor alpha (TNF-α), can be detected upon infection of HeLa cells withYersinia. Yersinia-triggered cytokine production was not affected by blocking phosphatidylinositol-3-phosphate kinase with wortmannin, which inhibited bacterial invasion. Comparable cytokine mRNA responses were triggered byEscherichia coliexpressingYersinia inv, while no response was triggered by aninv-deficientYersiniamutant. Moreover, cytokine responses were independent from metabolic activity of the bacteria, as killed bacterial cells were sufficient for triggering cytokine responses in HeLa cells. Semiquantitative reverse transcription-PCR analysis was used to assess the kinetics of cytokine mRNA expression in infected HeLa cells. IL-8, IL-1α, IL-1β, MCP-1, GM-CSF, and TNF-α mRNA expression increased within 1 h postinfection, reached a maximum after 3 to 4 h, and then declined to preinfection levels within 3 h. IL-8, MCP-1, and GM-CSF were secreted by HeLa cells, whereas IL-1α and IL-1β were not secreted and thus were found exclusively intracellularly. TNF-α protein could not be detected in cell lysates or supernatants. Stimulation of HeLa cells with IL-1α was followed by increased IL-8 mRNA expression, whereas stimulation with IL-8 did not induce cytokine production. Likewise, MCP-1 and GM-CSF did not induce significant cytokine responses in HeLa cells. Our results implicate that the initial host response toYersiniainfection might be sustained by IL-8, MCP-1, and GM-CSF produced by epithelial cells.
Transforming Growth Factor β1 Is Expressed in the Jejunum after ExperimentalCryptosporidium parvumInfection in Humans
Authors: Robinson Prema , Okhuysen Pablo C. , Chappell Cynthia L. , Lewis Dorothy E. , Shahab Imran , Lahoti Sandeep , White A. Clinton 
Published: July 2002

ABSTRACTBiopsies from volunteers challenged withCryptosporidium parvumwere examined for transforming growth factor β1 (TGF-β1). None of the prechallenge biopsies exhibited TGF-β. Seven of 12 volunteers with oocyst shedding expressed TGF-β versus 2 of 13 volunteers without detected oocysts. The association of TGF-β expression with oocyst excretion and the timing of symptoms suggests that TGF-β mediates intestinal healing.
Carboxy-Terminal Proteolytic Processing of
Helicobacter pylori
Vacuolating Toxin
Authors: Nguyen Viet Q. , Caprioli Richard M. , Cover Timothy L. 
Published: July 2002

ABSTRACT

The
vacA
gene of
Helicobacter pylori
strain 60190 encodes a 1,287-amino-acid protoxin, which undergoes cleavage of a 33-amino-acid amino-terminal signal sequence and carboxy-terminal proteolytic processing to yield a mature secreted toxin. Several features of VacA suggest that it belongs to the autotransporter family of gram-negative bacterial secreted proteins. Based on matrix-assisted laser desorption ionization–time of flight mass spectrometric analysis, we calculate that the mature toxin has a mass of 88.2 ± 0.2 kDa and consists of approximately 821 amino acids.
Effect on Polymorphonuclear Cell Function of a Human-Specific Cytotoxin, Intermedilysin, Expressed by
Streptococcus intermedius
Authors: Macey M. G. , Whiley R. A. , Miller L. , Nagamune H. 
Published: July 2002

ABSTRACT

Streptococcus intermedius
is a member of the normal flora of the mouth but is also an opportunistic pathogen associated with purulent infections at oral and nonoral sites. Intermedilysin (ILY) has been shown to be a cytolysin capable of generating pores in the cell membrane of erythrocytes demonstrable by electron microscopy. This effect has been shown to be specific for human cells. Since polymorphonuclear cells (PMNs) are the main cell involved in innate immunity we investigated the effect of purified intermedilysin from
Streptococcus intermedius
on PMN function. Active ILY at a concentration of 40 ng/μl caused a significant decrease in the number of intact PMNs after 60 min. The active cytolysin, when compared with heat-inactivated ILY, did not appear to be chemotactic for the PMNs but did cause an increase in intracellular calcium, with increased cell surface CD11b expression, metabolic burst, and phagocytosis of
Staphylococcus aureus
. These findings may have implications for the role of ILY in deep-seated abscesses.
Toxicity of Shiga Toxin 1 in the Central Nervous System of Rabbits
Authors: Fujii Jun , Kinoshita Yoshimasa , Yutsudo Takashi , Taniguchi Hatsumi , Obrig Tom , Yoshida Shin-Ichi 
Published: July 2002

ABSTRACT
The action of Shiga toxin (Stx) on the central nervous system was examined in rabbits. Intravenous Stx1 was 44 times more lethal than Stx2 and acted more rapidly than Stx2. However, Stx1 accumulated more slowly in the cerebrospinal fluid than did Stx2. Magnetic resonance imaging demonstrated a predominance of Stx1-dependent lesions in the spinal cord. Pretreatment of the animals with anti-Stx1 antiserum intravenously completely protected against both development of brain lesions and mortality.
Interaction ofNeisseria meningitidiswith Human Dendritic Cells
Authors: Kolb-Mäurer Annette , Unkmeir Alexandra , Kämmerer Ulrike , Hübner Claudia , Leimbach Thomas , Stade Anne , Kämpgen Eckhart , Frosch Matthias , Dietrich Guido 
Published: July 2002

ABSTRACTInfection withNeisseria meningitidisserogroup B is responsible for fatal septicemia and meningococcal meningitis. The severity of disease directly correlates with the production of the proinflammatory cytokines tumor necrosis factor alpha (TNF-α), interleukin-1 (IL-1), IL-6, and IL-8. However, the source of these cytokines has not been clearly defined yet. Since bacterial infection involves the activation of dendritic cells (DCs), we analyzed the interaction ofN. meningitidiswith monocyte-derived DCs. UsingN. meningitidisserogroup B wild-type and unencapsulated bacteria, we found that capsule expression significantly impaired neisserial adherence to DCs. In addition, phagocytic killing of the bacteria in the phagosome is reduced by at least 10- to 100-fold. However, all strains induced strong secretion of proinflammatory cytokines TNF-α, IL-6, and IL-8 by DCs (at least 1,000-fold at 20 h postinfection [p.i.]), with significantly increased cytokine levels being measurable by as early as 6 h p.i. Levels of IL-1β, in contrast, were increased only 200- to 400-fold at 20 h p.i. with barely measurable induction at 6 h p.i. Moreover, comparable amounts of cytokines were induced by bacterium-free supernatants ofNeisseriacultures containing neisserial lipooligosaccharide as the main factor. Our data suggest that activated DCs may be a significant source of high levels of proinflammatory cytokines in neisserial infection and thereby may contribute to the pathology of meningococcal disease.
Phase Variation among Major Surface Antigens of
Mycoplasma penetrans
Authors: Röske Kerstin , Blanchard Alain , Chambaud Isabelle , Citti Christine , Helbig Jürgen H. , Prevost Marie-Christine , Rosengarten Renate , Jacobs Enno 
Published: July 2002

ABSTRACT

The pathogenicity and prevalence of
Mycoplasma penetrans
, a
Mycoplasma
species recently isolated from humans, are still debated. A major P35 antigen, which is used as target epitope in serological assays, was shown to be a phase-variable lipid-associated membrane protein (LAMP). In this study, we performed a comparative analysis of the LAMP patterns from five
M. penetrans
clinical isolates and from the type strain. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles and immunoblots with sera serially collected from an
M. penetrans
-infected patient indicated that these strains expressed different LAMP repertoires. Furthermore, the intraclonal variation in the expression of LAMPs (P34A, P34B, P35, and P38) was monitored by immunoblot analysis with three specific monoclonal antibodies (MAbs) developed in this study and MAb 7 to P35. The phase variation of these LAMPs occurs in an independent manner, with frequencies of variation ranging from 10
−2
to 10
−4
per cell per generation. Consistent with their amphipathic nature, the P34B and P38 antigens were found exposed at the cell surface. The DNA sequence encoding the P38 antigen was defined and found to be related to those of the P35 gene and other putative LAMP-encoding genes, suggesting that these variable antigens are encoded by a family of related genes. Finally, the serum samples from an
M. penetrans
-infected patient contained antibodies that reacted with a P36 antigen expressed in different
M. penetrans
strains but not in the isolate recovered from this patient. This result suggested that in vivo phase variation of P36 occurred, which would support a role for these LAMP variations in avoiding the host's immune vigilance.
Schistosome Infection Stimulates Host CD4+T Helper Cell and B-Cell Responses against a Novel Egg Antigen, Thioredoxin Peroxidase
Authors: Williams David L. , Asahi Hiroko , Botkin Douglas J. , Stadecker Miguel J. 
Published: July 2002

ABSTRACTEgg granuloma formation during schistosome infections is mediated by CD4+T helper (Th) cells sensitized to egg antigens; however, most of the relevant sensitizing egg antigens are still unknown. Here we show that schistosome thioredoxin peroxidase (TPx)-1 is a novel T- and B-cell egg antigen in schistosome-infected mice. CD4+Th cell responses to fractionated egg components identified a significant response against a 26-kDa antigen; a partial amino acid sequence of this antigen was found to be identical to that ofSchistosoma mansoniTPx-1. The native TPx-1 elicited significant proliferative responses as well as gamma interferon (IFN-γ), interleukin-2 (IL-2), IL-4, and IL-5 secretion in CD4+cells from 8.5-week-infected CBA and C57BL/6 mice. By comparison, recombinant TPx-1 elicited a smaller, more type 1-polarized response, with significant production of IFN-γ and IL-2, less IL-5, and essentially no IL-4. In C57BL/6 mice the responses to TPx-1 were relatively more prominent than that directed against the major egg antigen, Sm-p40, whereas in CBA mice the reverse was true. B-cell responses were also monitored in infected C57BL/6, C3H, CBA, and BALB/c mice. All strains had significant antibody levels against the TPx-1 protein, but the most significant antibody production ensued following parasite oviposition. TPx-1 was localized in eggs and shown to be secreted by eggs. The identification of egg antigens is important to understand the specific basis of granuloma formation in schistosome infections and may prove to be useful in strategies to ameliorate pathological responses.