bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cloning and Molecular Characterization of an Immunogenic LigA Protein of
Leptospira interrogans
Authors: Palaniappan Raghavan U. M. , Chang Yung-Fu , Jusuf S. S. D. , Artiushin S. , Timoney John F. , McDonough Sean P. , Barr Steve C. , Divers Thomas J. , Simpson Kenneth W. , McDonough Patrick L. , Mohammed Hussni O. 
Published: October 2002

ABSTRACT

A clone expressing a novel immunoreactive leptospiral immunoglobulin-like protein A of 130 kDa (LigA) from
Leptospira interrogans
serovar pomona type kennewicki was isolated by screening a genomic DNA library with serum from a mare that had recently aborted due to leptospiral infection. LigA is encoded by an open reading frame of 3,675 bp, and the deduced amino acid sequence consists of a series of 90-amino-acid tandem repeats. A search of the NCBI database found that homology of the LigA repeat region was limited to an immunoglobulin-like domain of the bacterial intimin binding protein of
Escherichia coli
, the cell adhesion domain of
Clostridium acetobutylicum
, and the invasin of
Yersinia pestis
. Secondary structure prediction analysis indicates that LigA consists mostly of beta sheets with a few alpha-helical regions. No LigA was detectable by immunoblot analysis of lysates of the leptospires grown in vitro at 30°C or when cultures were shifted to 37°C. Strikingly, immunohistochemistry on kidney from leptospira-infected hamsters demonstrated LigA expression. These findings suggest that LigA is specifically induced only in vivo. Sera from horses, which aborted as a result of natural
Leptospira
infection, strongly recognize LigA. LigA is the first leptospiral protein described to have 12 tandem repeats and is also the first to be expressed only during infection. Thus, LigA may have value in serodiagnosis or as a protective immunogen in novel vaccines.
Infection Outcome and Cytokine Gene Expression inBrugia pahangi- Infected Gerbils (Meriones unguiculatus) Sensitized withBrucella abortus
Authors: Chirgwin Sharon R. , Elzer Philip H. , Coleman Sharon U. , Nowling Jena M. , Hagius Sue D. , Edmonds Matthew D. , Klei Thomas R. 
Published: October 2002

ABSTRACTFilarial infections have been associated with the development of a strongly polarized Th2 host immune response and a severe impairment of mitogen-driven proliferation and type 1 cytokine production in mice and humans. The role of this polarization in the development of the broad spectra of clinical manifestations of lymphatic filariasis is still unknown. Recently, data gathered from humans as well as from immunocompromised mouse models suggest that filariasis elicits a complex host immune response involving both Th1 and Th2 components. However, responses of a similar nature have not been reported in immunologically intact permissive models ofBrugiainfection.Brucella abortus-killed S19 was inoculated into theBrugia-permissive gerbil host to induce gamma interferon (IFN-γ) production. Gerbils were then infected withB. pahangi,and the effect of the polarized Th1 responses on worm establishment and host cellular response was measured. Animals infected with bothB. abortusandB. pahangishowed increased IFN-γ and interleukin-10 (IL-10) and decreased IL-4 and IL-5 mRNA levels compared with those in animals infected withB. pahangialone. These data suggest that the prior sensitization withB. abortusmay induce a down regulation of the Th2 response associated withBrugiainfection. This reduced Th2 response was associated with a reduced eosinophilia and an increased neutrophilia in the peritoneal exudate cells. The changes in cytokine and cellular environment did not inhibit the establishment ofB. pahangiintraperitoneally. The data presented here suggest a complex relationship between the host immune response and parasite establishment and survival that cannot be simply ascribed to the Th1/Th2 paradigm.
Mycobacterium tuberculosisin Chemokine Receptor 2-Deficient Mice: Influence of Dose on Disease Progression
Authors: Scott Holly M. , Flynn JoAnne L. 
Published: October 2002

ABSTRACTWithin aMycobacterium tuberculosis-induced granuloma, lymphocytes and macrophages work together to control bacterial growth and limit the spread of infection. Chemokines and chemokine receptors are involved in cell migration and are logical candidates for a role in granuloma formation. In the present study we addressed the role of CC chemokine receptor 2 (CCR2) inM. tuberculosisinfection. In previous studies (W. Peters et al., Proc. Natl. Acad. Sci. USA 98:7958-7963, 2001), CCR2−/−mice were found to be highly susceptible to a moderate or high dose of H37Rv administered intravenously (i.v.). We have expanded those studies to demonstrate that the susceptibility of CCR2−/−mice is dose dependent. After low-dose aerosol or i.v. infection of CCR2−/−mice withM. tuberculosis, there was a substantial delay in cell migration to the lungs and delayed expression of gamma interferon and inducible nitric oxide synthase. The CCR2−/−mice had a severe and prolonged deficiency in the number of macrophages in the lungs and an early increase in the number of neutrophils. Despite these deficiencies in cell migration, the CCR2−/−mice did not have increased bacterial loads in the lungs compared to wild-type (C57BL/6) mice and successfully formed granulomas. This finding is in contrast to CCR2−/−mice infected with a high dose ofM. tuberculosisadministered i.v. These results indicate that with low-dose infection, a delay in immune response in the lungs does not necessarily have detrimental long-term effects on the progression of the disease. The fact that CCR2−/−mice survive with substantially fewer macrophages in the low-dose models implies that the immune response to low-doseM. tuberculosisinfection in mice is more robust than necessary to control the infection. Finally, these data demonstrate that, in cases of infectious disease in knockout models, clear phenotypes may not be evident when one is solely evaluating bacterial numbers and survival. Functional assays may be necessary to reveal roles for components of the multifactorial immune system.
Neisseria gonorrhoeae
Porin P1.B Induces Endosome Exocytosis and a Redistribution of Lamp1 to the Plasma Membrane
Authors: Ayala Patricia , Vasquez Brandi , Wetzler Lee , So Magdalene 
Published: October 2002

ABSTRACT

The immunoglobulin A (IgA) protease secreted by pathogenic
Neisseria
spp. cleaves Lamp1, thereby altering lysosomes in a cell and promoting bacterial intracellular survival. We sought to determine how the IgA protease gains access to cellular Lamp1 in order to better understand the role of this cleavage event in bacterial infection. In a previous report, we demonstrated that the pilus-induced Ca
2+
transient triggers lysosome exocytosis in human epithelial cells. This, in turn, increases the level of Lamp1 at the plasma membrane, where it can be cleaved by IgA protease. Here, we show that porin also induces a Ca
2+
flux in epithelial cells. This transient is similar in nature to that observed in phagocytes exposed to porin. In contrast to the pilus-induced Ca
2+
transient, the porin-induced event does not trigger lysosome exocytosis. Instead, it stimulates exocytosis of early and late endosomes and increases Lamp1 on the cell surface. These results indicate that
Neisseria
pili and porin perturb Lamp1 trafficking in epithelial cells by triggering separate and distinct Ca
2+
-dependent exocytic events, bringing Lamp1 to the cell surface, where it can be cleaved by IgA protease.
Primary Dendritic Cells PhagocytoseCryptococcus neoformansvia Mannose Receptors and Fcγ Receptor II for Presentation to T Lymphocytes
Authors: Syme Rachel M. , Spurrell Jason C. L. , Amankwah Ernest K. , Green Francis H. Y. , Mody Christopher H. 
Published: October 2002

ABSTRACTDifferent “professional” antigen-presenting cells (APC) have unique characteristics that favor or restrict presentation of microbial antigens to T cells, depending on the organism.Cryptococcus neoformansis a pathogenic yeast that presents unique challenges to APC, including its large size, its rigid cell wall, and its ability to stimulate T cells as a mitogen. T-cell proliferation in response to theC. neoformansmitogen (CnM) requires phagocytosis and processing of the organisms by accessory cells prior to presentation of CnM to T cells. Because of the requirement for uptake of the organism and more limited costimulatory requirements of mitogens, macrophages might be the most likely cellular source for the accessory cell. However, the present study demonstrates that a transiently adherent cell that was CD3−, CD14−, CD19−, CD56−, HLA-DR+, and CD83+with a dendritic morphology, rather than monocyte-derived or tissue (alveolar) macrophages, was the most efficient APC for presentation of CnM. A large number of these cells bound and internalized the organism, and only a small number of dendritic cells were required for presentation of the mitogen to T cells. Further, the mannose receptor and Fcγ receptor II were required for presentation ofC. neoformans, as blocking either of these receptors abrogated both uptake ofC. neoformansand lymphocyte proliferation in response to CnM. These studies demonstrate the surprising fact that dendritic cells are the most efficient accessory cells for CnM.
Merozoite Surface Protein 1-Specific Immune Response Is Protective against Exoerythrocytic Forms ofPlasmodium yoelii
Authors: Kawabata Yuko , Udono Heiichiro , Honma Kiri , Ueda Masakatsu , Mukae Hiroshi , Kadota Jun-ichi , Kohno Shigeru , Yui Katsuyuki 
Published: October 2002

ABSTRACTOne of the difficulties in developing an effective malaria vaccine is the antigenic change of the parasite during the life cycle. It is desirable that vaccine-induced protective immunity be effective at different stages of parasite development. Merozoite surface protein 1 (MSP1) is a candidate vaccine antigen against blood-stage malaria, but it is also expressed in the exoerythrocytic forms. It was not known, however, whether the anti-MSP1 immune response is effective against the liver-stage malaria parasite. We generated a recombinant protein of MSP1 fused to heat-shock cognate protein 70 (hsc70) and studied its vaccination effect. When C57BL/6 mice were immunized with the fusion protein prior to challenge infection withPlasmodium yoeliisporozoites, the onset of parasitemia was delayed or no parasitemia was observed. To determine whether this was due to the protective immunity against liver-stage parasites,P. yoelii-specific rRNA in the infected liver was quantitated by real-time reverse transcription-PCR analysis. The level of parasite-specific rRNA was reduced in mice immunized with the fusion protein of MSP1 and hsc70 but not with hsc70 alone, indicating that MSP1-specific immunity can be protective against the exoerythrocytic form of the parasite. Furthermore, the adoptive transfer experiments of immune lymphocytes and serum into naive mice suggested that the protective immunity was dependent on cellular and not humoral immunity. Finally, the vaccine-induced protection was also observed in A/J, C3H, and BALB/c mice, suggesting that MSP1-specific protective immunity at the exoerythrocytic stage can be induced in animals over a wide range of genetic backgrounds.
Local Delivery of the Viral Interleukin-10 Gene Suppresses Tissue Inflammation in MurinePneumocystis cariniiInfection
Authors: Ruan Sanbao , Tate Chandra , Lee Janet J. , Ritter Thomas , Kolls Jay K. , Shellito Judd E. 
Published: October 2002

ABSTRACTThe relationship between tissue inflammation and clearance of the opportunistic pathogenPneumocystis cariniiis poorly understood. We asked whether the anti-inflammatory cytokine interleukin-10 (IL-10) is released during the host response to infection withP. cariniiand whether local delivery of the IL-10 gene could suppress tissue inflammatory responses without compromising clearance of infection. Control and CD4-depleted mice were inoculated withP. carinii, and at serial intervals after inoculation, lung tissue was assayed for IL-10 by enzyme-linked immunosorbent assay. We found that IL-10 was released in lung tissue in control mice and was present in higher concentrations in CD4-depleted mice with progressive infection. Control and CD4-depleted mice were then pretreated with 109PFU of intratracheally administered adenoviral vector containing the viral IL-10 gene or the luciferase gene followed by inoculation withP. carinii. Pretreatment with viral IL-10 did not alter clearance of infection in control mice or severity of infection in CD4-depleted mice but did decrease tissue inflammation. We then asked whether gene transfer of viral IL-10 could decrease tissue inflammation during immune reconstitution. In these experiments, immunodeficientscidmice were inoculated withP. cariniiand were heavily infected after 4 weeks. When these mice are immunologically reconstituted by intravenous administration of spleen cells from normal mice, a hyperinflammatory reaction developed in lung tissue, associated with high mortality. In comparison to control mice, mice treated with viral IL-10 prior to reconstitution showed significantly decreased lung wet weight, bronchoalveolar lavage fluid (BALF) lactate dehydrogenase, and BALF neutrophils. In contrast, infection intensity, as measured by PCR forP. cariniirRNA, was unchanged between the IL-10 and luciferase groups. Survival was also improved in the IL-10-treated mice. We conclude that release of IL-10 is part of the host response to infection withP. cariniiand that gene therapy with viral IL-10 can lessen excessive tissue inflammation without altering pathogen clearance. In the setting of immune reconstitution andP. cariniipneumonia, pretreatment with the viral IL-10 gene decreases excessive tissue inflammation and improves survival. These results are relevant to acute respiratory failure after initiation of antibiotic treatment for humanP. cariniipneumonia and to immune reconstitution syndromes in human immunodeficiency virus-positive patients started on highly active antiretroviral therapy.
Contributions of the N- and C-Terminal Domains of Surfactant Protein D to the Binding, Aggregation, and Phagocytic Uptake of Bacteria
Authors: Hartshorn Kevan L. , White Mitchell R. , Crouch Erika C. 
Published: October 2002

ABSTRACTCollectins play important roles in host defense against infectious microorganisms. We now demonstrate that the serum collectins mannose-binding lectin (MBL) and conglutinin have less ability to bind to, aggregate, and enhance neutrophil uptake of several strains of gram-negative and gram-positive bacteria than pulmonary surfactant protein D (SP-D). Collectins are composed of four major structural domains (i.e., N-terminal, collagen, and neck and carbohydrate recognition domains). To determine which domains of SP-D are responsible for its greater bacterial binding or aggregating activity, activities of chimeric collectins containing the N-terminal and collagen domains of SP-D coupled to the neck recognition domains and carbohydrate recognition domains (CRD) of MBL or conglutinin (SP-D/Congneck+CRDand SP-D/MBLneck+CRD) were tested. The SP-D/Congneck+CRDand SP-D/MBLneck+CRDchimeras bound to and aggregated the bacteria more strongly than did wild-type MBL or conglutinin. SP-D/MBLneck+CRDalso enhanced neutrophil uptake of bacteria more so than MBL. Hence, the SP-D N-terminal and/or collagen domains contribute to the enhanced bacterial binding and aggregating activities of SP-D. In prior studies, SP-D/Congneck+CRDand SP-D/MBLneck+CRDhad increased ability to bind to influenza virus compared not only with that of conglutinin or MBL but with that of wild-type SP-D as well. In contrast, the chimeras had either reduced or unchanged ability to bind to or aggregate bacteria compared to that of wild-type SP-D. Hence, although replacement of the neck recognition domains and CRDs of SP-D with those of MBL and conglutinin conferred increased viral binding activity, it did not favorably affect bacterial binding activity, suggesting that requirements for optimal collectin binding to influenza virus and bacteria differ.
Role of Interferon-Stimulated Gene Factor 3γ and Beta Interferon in HLA Class I Enhancement in Synovial Fibroblasts upon Infection withChlamydia trachomatis
Authors: Rödel Jürgen , Vogelsang Heinz , Prager Katrin , Hartmann Matthias , Schmidt Karl-Hermann , Straube Eberhard 
Published: October 2002

ABSTRACTChlamydia trachomatisinfection can cause reactive arthritis that is associated with the persistence of chlamydial organisms in the joint. Fibroblasts of the synovial membrane represent host cells forChlamydiaduring articular infection. In this study we investigated the expression of HLA class I molecules in synovial fibroblasts following infection withC. trachomatisD. The expression of HLA class I heavy chain (HLA-I) was up-regulated in infected cultures as shown by reverse transcription-PCR and immunoblotting. The increase in cell surface expression of HLA-I and β2microglobulin on infected fibroblasts was demonstrated by flow cytometric analysis. Suppression of enhanced production of interferon-stimulated gene factor 3γ (ISGF3γ) in infected cell cultures by antisense oligonucleotide treatment reduced the level of HLA-I. Blocking antibodies to beta interferon (IFN-β) inhibited theChlamydia-induced enhancement of both ISGF3γ and HLA-I. These findings show that the up-regulation of HLA-I in synovial fibroblasts infected withC. trachomatisis caused by the induction of IFN-β, which in turn stimulates the synthesis of ISGF3γ, a transcription factor participating in the regulation of the HLA-I gene. The IFN-β-mediated expression of HLA-I onChlamydia-infected cells may be a regulatory factor in the immune response in chlamydial infections.
Inhibition of Endoplasmic Reticulum-Associated Degradation in CHO Cells Resistant to Cholera Toxin,
Pseudomonas aeruginosa
Exotoxin A, and Ricin
Authors: Teter Ken , Holmes Randall K. 
Published: October 2002

ABSTRACT

Many plant and bacterial toxins act upon cytosolic targets and must therefore penetrate a membrane barrier to function. One such class of toxins enters the cytosol after delivery to the endoplasmic reticulum (ER). These proteins, which include cholera toxin (CT),
Pseudomonas aeruginosa
exotoxin A (ETA), and ricin, move from the plasma membrane to the endosomes, pass through the Golgi apparatus, and travel to the ER. Translocation from the ER to the cytosol is hypothesized to involve the ER-associated degradation (ERAD) pathway. We developed a genetic strategy to assess the role of mammalian ERAD in toxin translocation. Populations of CHO cells were mutagenized and grown in the presence of two lethal toxins, ETA and ricin. Since these toxins bind to different surface receptors and attack distinct cytoplasmic targets, simultaneous acquisition of resistance to both would likely result from the disruption of a shared trafficking or translocation mechanism. Ten ETA- and ricin-resistant cell lines that displayed unselected resistance to CT and continued sensitivity to diphtheria toxin, which enters the cytosol directly from acidified endosomes, were screened for abnormalities in the processing of a known ERAD substrate, the Z form of α1-antitrypsin (α1AT-Z). Compared to the parental CHO cells, the rate of α1AT-Z degradation was decreased in two independent mutant cell lines. Both of these cell lines also exhibited, in comparison to the parental cells, decreased translocation and degradation of a recombinant CTA1 polypeptide. These findings demonstrated that decreased ERAD function was associated with increased cellular resistance to ER-translocating protein toxins in two independently derived mutant CHO cell lines.
Clinical and Immune Impact of
Mycobacterium bovis
BCG Vaccination Scarring
Authors: Jason Janine , Archibald Lennox K. , Nwanyanwu Okey C. , Kazembe Peter N. , Chatt Julie A. , Norton Elizabeth , Dobbie Hamish , Jarvis William R. 
Published: October 2002

ABSTRACT

The World Health Organization recommends
Mycobacterium bovis
BCG vaccination in areas of high tuberculosis prevalence. BCG's clinical and immune effects, not necessarily
Mycobacterium tuberculosis
specific, are unclear. BCG vaccine scarring often is used as a surrogate marker of vaccination or of effective vaccination. We evaluated BCG scarring status in relation to clinical findings and outcome in 700 hospitalized Malawians, of whom 32 had
M. tuberculosis
bloodstream infections (BSI) (10 of whom had cellular immune studies done) and of whom 48 were infants <6 months old and therefore recently vaccinated (19 of whom had immune studies). In the patients ≥6 months old, scarring was not related to the presence of pulmonary symptoms (35 versus 30%), chronic cough or fever, mortality, or
M. tuberculosis
BSI. In
M. tuberculosis
BSI patients, scarring was unrelated to mortality, vital signs, or clinical symptoms but those with scarring had higher proportions of memory and activated T cells and more type 2-skewed cytokine profiles. Infants with either BCG scarring (
n
= 10) or BCG lesional inflammation (
n
= 5) had no symptoms of sepsis, but 18 of 33 infants without BCG vaccination lesions did. Those with BCG lesions had localized infections more often than did those without BCG lesions. These infants also had lower median percentages of lymphocytes spontaneously making interleukin-4 (IL-4) or tumor necrosis factor alpha (TNF-α) and lower ratios of T cells spontaneously making IL-4 to T cells making IL-6. Thus, we found that, in older patients, BCG vaccine scarring was not associated with
M. tuberculosis
-specific or nonspecific clinical protection. Those with
M. tuberculosis
BSI and scarring had immune findings suggesting previous
M. tuberculosis
antigen exposure and induction of a type 2 cytokine pattern with acute reexposure. It is unlikely that this type 2 pattern would be protective against mycobacteria, which require a type 1 response for effective containment. In infants <6 months old, recent BCG vaccination was associated with a non-
M. tuberculosis
-specific, anti-inflammatory cytokine profile. That the vaccinated infants had a greater frequency of localized infections and lesser frequency of sepsis symptoms suggests that this postvaccination cytokine pattern may provide some non-
M. tuberculosis
-specific clinical benefits.
Yersinia pseudotuberculosis
Harbors a Type IV Pilus Gene Cluster That Contributes to Pathogenicity
Authors: Collyn François , Léty Marie-Annick , Nair Shamila , Escuyer Vincent , Ben Younes Amena , Simonet Michel , Marceau Michaël 
Published: October 2002

ABSTRACT

Fimbriae have been shown to play an essential role in the adhesion of pathogenic gram-negative bacteria to host cells. In the enteroinvasive bacterium
Yersinia pseudotuberculosis
, we characterized a previously unknown 11-kb chromosomal locus involved in the synthesis of type IV pili. The locus consists of 11 open reading frames forming a polycistronic unit and encoding putative Pil proteins, PilLMNOPQRSUVW. When introduced into
Escherichia coli
, the
Y. pseudotuberculosis
operon reconstituted bundles of filaments at a pole on the bacterial surface, demonstrating that the
pil
locus was functional in a heterogenous genetic background. Environmental factors regulated transcription of the
Y. pseudotuberculosis
operon; in particular, temperature, osmolarity, and oxygen tension were critical cues. Deletion of the type IV pilus gene cluster was associated with a reduction of
Y. pseudotuberculosis
pathogenicity for mice infected orally. Forty-one percent of
Y. pseudotuberculosis
strains isolated from human or animal sources harbored the type IV pilus locus. Therefore, the
pil
locus of
Y. pseudotuberculosis
might constitute an “adaptation island,” permitting the microorganism to colonize a vast reservoir.