bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detection of Heme-Binding Proteins in Epidemic Strains of
Burkholderia cepacia
Authors: Smalley John W. , Charalabous Panagoula , Birss Andrew J. , Hart C. Anthony 
Published: July 2002

ABSTRACT

A panel of 30 previously characterized strains representing five genomovars from the
Burkholderia cepacia
complex (E. Mahenthiralingam, T. Coenye, J. W. Chung, D. P. Speert, J. R. W. Govan, P. Taylor, and P. Vandamme, J. Clin. Microbiol. 38:910–913, 2000) were examined for their iron protoporphyrin IX-binding ability. These included
B. cepacia
genomovars I and III and
B. stabilis
(formerly
B. cepacia
genomovar IV),
B. multivorans
(formerly
B. cepacia
genomovar II), and
B. vietnamiensis (
formerly
B. cepacia
genomovar V
)
. Cells were exposed to μ-oxo bisheme of iron protoporphyrin IX (μ-oxo dimers) and examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under nonreducing, nondenaturing conditions for the presence of heme-binding proteins using tetramethylbenzidine-H
2
O
2
staining. Seven of the 30 strains, each belonging to
B. cepacia
genomovar III and designated epidemic (in possessing the
B. cepacia
epidemic strain marker), expressed a 96- to 100-kDa heme-binding protein which was located in the outer membrane. The heme-binding protein of
B. cepacia
genomovar III epidemic strain C5424 bound iron(III) protoporphyrin IX in both the monomeric and μ-oxo bisheme forms. Cells of all strains grown on Columbia agar bound iron protoporphyrin IX in the μ-oxo bisheme (dimeric) form. There were no statistical differences between the five genomovars, or those possessing the heme-binding protein, in their μ-oxo bisheme-binding ability. Possession of the outer membrane heme-binding protein may be a pathogenicity trait in enabling the bacterium to withstand oxidative stresses in inflammatory exudates in the lung and may aid identification of invasive epidemic strains of
B. cepacia
.
Role of Nijmegen Breakage Syndrome Protein in Specific T-Lymphocyte Activation Pathways
Authors: Garcı́a-Pérez Miguel Angel , Allende Luis M. , Corell Alfredo , Paz-Artal Estela , Varela Pilar , López-Goyanes Alberto , Garcı́a-Martin Francisco , Vázquez Rosario , Sotoca Amalia , Arnaiz-Villena Antonio 
Published: July 2002

ABSTRACT

Nijmegen breakage syndrome (NBS) is a genetic disorder characterized by immunodeficiency, microcephaly, and “bird-like” facies. NBS shares some clinical features with ataxia telangiectasia (AT), including increased sensitivity to ionizing radiation, increased spontaneous and induced chromosome fragility, and strong predisposition to lymphoid cancers. The mutated gene that results in NBS codes for a novel double-stranded DNA break repair protein, named nibrin. In the present work, a Spanish NBS patient was extensively characterized at the immunological and the molecular DNA levels. He showed low CD3
+
-cell numbers and an abnormal low CD4
+
naive cell/CD4
+
memory cell ratio, previously described in AT patients and also described in the present report in the NBS patient. The proliferative response of peripheral blood lymphocytes in vitro to mitogens is deficient in NBS patients, but the possible link among NBS mutations and the abnormal immune response is still unknown.
Skin Test Reactivity and Cellular Immune Responses to
Mycobacterium avium
Sensitin in AIDS Patients at Risk for Disseminated
M. avium
Infection
Authors: von Reyn C. Fordham , Williams Paige L. , Lederman Howard M. , McCutchan J. Allen , Koletar Susan L. , Murphy Robert L. , Cohn Susan E. , Evans Thomas , Heald Alison E. , Colquhoun Dodi , Bassily Ehab L. , Currier Judith S. 
Published: July 2002

ABSTRACT

Skin tests and lymphocyte proliferation assays (LPA) were performed with
Mycobacterium avium
sensitin on patients with AIDS. Among 139 subjects, 13% had positive skin test results and 32% had positive LPA results. The LPA may be a more sensitive indicator of prior
M. avium
infection in this population.
B-Cell Deficiency Predisposes Mice to Disseminating Anaerobic Infections: Protection by Passive Antibody Transfer
Authors: Hou Linda , Sasakj Hajime , Stashenko Philip 
Published: July 2002

ABSTRACTWe have previously demonstrated that a high proportion of RAG-2 SCID knockout mice, which lack T and B cells, develop orofacial abscesses and disseminated infections following pulpal infection, whereas immunocompetent control mice do not. In the present study, we sought to identify the components of the adaptive immune response which contribute to protection against disseminating anaerobic infections and sepsis. For this purpose, various genetically engineered immunodeficient mice were employed, including RAG-2 SCID, Igh-6 (B-cell deficient), Tcrb Tcrd (T-cell deficient) and Hc0(C5 deficient). For abscess induction, the mandibular first molars were subjected to pulp exposure on day 0. Teeth were infected with a mixture of four anaerobic pathogens, includingPrevotella intermedia,Streptococcus intermedius,Fusobacterium nucleatum, andPeptostreptococcus micros, and teeth were sealed to prevent communication with the oral cavity. The findings demonstrate that both RAG-2 SCID and B-cell-deficient mice, but not T-cell- or C5-deficient mice, have increased susceptibility to the development of disseminating anaerobic infections. Abscess-susceptible RAG-2 SCID and B-cell-deficient mice also showed a significant loss of body weight, splenomegaly, and absent antibacterial antibody production. Furthermore, dissemination was significantly reduced, from 74 to 25%, in susceptible RAG-2 mice by passively transferred antibody, predominantly immunoglobulin G2b (IgG2b) and IgM, against the infecting bacterial innoculum. Fractionated IgG-enriched preparations were more efficient in transferring protection than IgM preparations. We conclude that an antibody-mediated mechanism(s), most likely bacterial opsonization, is of importance in localizing anaerobic root canal infections and in preventing their systemic spread.
Diversity of PspA: Mosaic Genes and Evidence for Past Recombination in
Streptococcus pneumoniae
Authors: Hollingshead Susan K. , Becker Robert , Briles David E. 
Published: July 2002

ABSTRACT

Pneumococcal surface protein A (PspA) is a serologically variable protein of
Streptococcus pneumoniae
. Twenty-four diverse alleles of the
pspA
gene were sequenced to investigate the genetic basis for serologic diversity and to evaluate the potential of diversity to have an impact on PspA's use in human vaccination. The 24
pspA
gene sequences from unrelated strains revealed two major allelic types, termed “families,” subdivided into clades. A highly mosaic gene structure was observed in which individual mosaic sequence blocks in PspAs diverged from each other by over 20% in many cases. This level of divergence exceeds that observed for blocks in the penicillin-binding proteins of
S. pneumoniae
or in many cross-species comparisons of gene loci. Conversely, because the mosaic pattern is so complex, each pair of
pspA
genes also has numerous shared blocks, but the position of conserved blocks differs from gene pair to gene pair. A central region of
pspA
, important for eliciting protective antibodies, was found in six clades, which each diverge from the other clades by >20%. Sequence relationships among the 24 alleles analyzed over three windows were discordant, indicating that intragenic recombination has occurred within this locus. The extensive recombination which generated the mosaic pattern seen in the
pspA
locus suggests that natural selection has operated in the history of this gene locus and underscores the likelihood that PspA may be important in the interaction between the pneumococcus and its human host.
Isolation and Characterization of Mini-Tn
5
Km2 Insertion Mutants of Enterohemorrhagic
Escherichia coli
O157:H7 Deficient in Adherence to Caco-2 Cells
Authors: Tatsuno Ichiro , Kimura Hiroshi , Okutani Akiko , Kanamaru Kyoko , Abe Hiroyuki , Nagai Shinya , Makino Kozo , Shinagawa Hideo , Yoshida Mitsutaka , Sato Katsuhiro , Nakamoto Jyunichi , Tobe Toru , Sasakawa Chihiro 
Published: July 2002

ABSTRACT

Adherence of enterohemorrhagic
Escherichia coli
(EHEC) to intestinal epithelium is essential for initiation of the infection. To identify genes involved in adherence, an EHEC O157:H7 strain (O157Sakai) was mutagenized by mini-Tn
5
Km2, where Km refers to kanamycin resistance, and 4,677 insertion mutants were screened for their ability to form microcolonies (MC) on Caco-2 cells. The less adherent mutants were divided into three groups: those with no adherent ability (designated as class 1 mutants,
n
= 10), those less adherent than the wild type (class 2 mutants,
n
= 16), and those unable to form MC but which adhered in a diffuse manner (class 3 mutants,
n
= 1). The sites of insertion in class 1 mutants were all found within genes of the locus for enterocyte effacement (LEE) thought to be required for type III protein secretion. Indeed, the class 1 mutants failed to secrete type III secreted proteins such as EspA and Tir into the culture medium. The insertions in class 2 mutants were outside the LEE, and all the mutants except one were able to secrete type III proteins into the culture medium. The class 3 mutant had the insertion in the
tir
gene in the LEE and was deficient in Tir and intimin expression, suggesting that in the absence of intimin-Tir, O157Sakai can still adhere to Caco-2 cells but in a diffused manner. This was confirmed by construction of a nonpolar
eae
(encoding intimin) mutant. Examination of the
eae
mutant together with O157Sakai and one of the class 1 mutants for the ability to form MC revealed that EHEC initially adhered diffusely at 1.5 h after infection. Following washing out of the nonadherent bacteria, while wild-type EHEC bacteria developed MC for another 2 to 3 h on Caco-2 cells, the
eae
mutant diffusely adhered throughout the infection without forming MC. MC with O157Sakai but not the diffusely adherent
eae
mutant could evoke F-actin condensation beneath the bacterium. Our results suggest that EHEC encodes additional adherence-associated loci and that the type III secreted proteins are involved in the initial diffuse adherence, while the intimin-Tir interaction is required for the subsequent development of MC.
Saccharomyces boulardiiPreserves the Barrier Function and Modulates the Signal Transduction Pathway Induced in EnteropathogenicEscherichia coli-Infected T84 Cells
Authors: Czerucka Dorota , Dahan Stephanie , Mograbi Baharia , Rossi Bernard , Rampal Patrick 
Published: July 2002

ABSTRACTUse of the nonpathogenic yeastSaccharomyces boulardiiin the treatment of infectious diarrhea has attracted growing interest. The present study designed to investigate the effect of this yeast on enteropathogenicEscherichia coli(EPEC)-associated disease demonstrates thatS. boulardiiabrogated the alterations induced by an EPEC strain on transepithelial resistance, [3H]inulin flux, and ZO-1 distribution in T84 cells. Moreover, EPEC-mediated apoptosis of epithelial cells was delayed in the presence ofS. boulardii. The yeast did not modify the number of adherent bacteria but lowered by 50% the number of intracellular bacteria. Infection by EPEC induced tyrosine phosphorylation of several proteins in T84 cells, including p46 and p52 SHC isoforms, that was attenuated in the presence ofS. boulardii. Similarly, EPEC-induced activation of the ERK1/2 mitogen-activated protein (MAP) kinase pathway was diminished in the presence of the yeast. Interestingly, inhibition of the ERK1/2 pathway with the specific inhibitor PD 98059 decreased EPEC internalization, suggesting that modulation of the ERK1/2 MAP pathway might account for the lowering of the number of intracellular bacteria observed in the presence ofS. boulardii. Altogether, this study demonstrated thatS. boulardiiexerts a protective effect on epithelial cells after EPEC adhesion by modulating the signaling pathway induced by bacterial infection.
Purification and Characterization of a Cytotonic Protein Expressed In Vitro by the Live Cholera Vaccine Candidate CVD 103-HgR
Authors: Sathyamoorthy Venugopal , Hall Robert H. , McCardell Barbara A. , Kothary Mahendra H. , Ahn Susie J. , Ratnayake Shashikala 
Published: July 2002

ABSTRACT

Cholera vaccines developed by the deletion of CTX genes from
Vibrio cholerae
induce a residual reactogenicity in up to 10% of vaccinees. A novel cytotonic agent named secreted CHO cell elongating protein (S-CEP) was purified from culture supernatants of CVD 103-HgR (Levine et al., Lancet ii:467–470, 1988). Five fractionation steps yielded electrophoretically pure S-CEP with an
M
r
of 79,000. A partially purified preparation caused fluid accumulation in the sealed infant mouse model. The amino terminus bore a unique sequence with strong homology to a cytotonic toxin of El Tor
V. cholerae.
Differential Effects of Virulent versus Avirulent
Legionella pneumophila
on Chemokine Gene Expression in Murine Alveolar Macrophages Determined by cDNA Expression Array Technique
Authors: Nakachi Noriya , Matsunaga Kazuto , Klein Thomas W. , Friedman Herman , Yamamoto Yoshimasa 
Published: July 2002

ABSTRACT

The cDNA expression array technique is a powerful tool to determine, at one time from many genes, specific gene messages modulated by infection. In the present study, we identified genes modulated in response to virulent versus avirulent
Legionella pneumophila
infection of the alveolar macrophage cell line MH-S by the cDNA expression array technique. Many macrophage genes were found to be modulated after 5 h of in vitro infection with
L. pneumophila
. In particular, it was found that the monocyte chemotactic protein 3 (MCP-3) gene expression was significantly induced by infection with virulent
L. pneumophila
but not with avirulent
L. pneumophila
. In contrast, other chemokine genes, such as macrophage inflammatory protein (MIP) 1α, were induced by both virulent and avirulent
L. pneumophila
. Reverse transcription (RT)-PCR assay of total RNA isolated from macrophages infected with the bacteria for 5 or 24 h confirmed the differential induction of the chemokine genes by virulent versus avirulent
L. pneumophila
. Thus, the cDNA expression array technique readily revealed differential induction by
L. pneumophila
infection of select chemokine genes of macrophages from more than 1,100 genes. These results also indicate that certain chemokine genes may be selectively induced by virulent bacteria.
B Cells Are Essential for Vaccination-Induced Resistance to VirulentToxoplasma gondii
Authors: Sayles Peter C. , Gibson George W. , Johnson Lawrence L. 
Published: July 2002

ABSTRACTT lymphocytes and gamma interferon (IFN-γ) are known mediators of immune resistance toToxoplasma gondiiinfection, but whether B cells also play an important role is not clear. We have investigated this issue using B-cell-deficient (μMT) mice. If vaccinated with attenuatedT. gondiitachyzoites, μMT mice are susceptible to a challenge intraperitoneal infection with highly virulent tachyzoites that similarly vaccinated B-cell-sufficient mice resist. Susceptibility is evidenced by increased numbers of parasites at the challenge infection site and by extensive mortality. The susceptibility of B-cell-deficient mice does not appear to be caused by deficient T-cell functions or diminished capacity of vaccinated and challenged B-cell-deficient mice to produce IFN-γ. Administration ofToxoplasma-immune serum, but not nonimmune serum, to vaccinated B-cell-deficient mice significantly prolongs their survival after challenge with virulent tachyzoites. Vaccinated mice lacking Fc receptors or the fifth component of complement resist a challenge infection, suggesting that neither Fc-receptor-dependent phagocytosis of antibody-coated tachyzoites nor antibody-dependent cellular cytotoxicity nor antibody-and-complement-dependent lysis of tachyzoites is a crucial mechanism of resistance. However,Toxoplasma-immune serum effectively inhibits the infection of host cells by tachyzoites in vitro. Together, the results support the hypothesis that B cells are required for vaccination-induced resistance to virulent tachyzoites in order to produce antibodies and that antibodies may function protectively in vivo by blocking infection of host cells by tachyzoites.
Salmonella entericaSerovar TyphimuriumsurAMutants Are Attenuated and Effective Live Oral Vaccines
Authors: Sydenham Mark , Douce Gillian , Bowe Frances , Ahmed Saddif , Chatfield Steve , Dougan Gordon 
Published: July 2002

ABSTRACTA previously described attenuated TnphoAmutant (BRD441) ofSalmonella entericaserovar Typhimurium C5 (I. Miller, D. Maskell, C. Hormaeche, K. Johnson, D. Pickard, and G. Dougan, Infect. Immun. 57:2758–2763, 1989) was characterized, and the transposon was shown to be inserted insurA, a gene which encodes a peptidylprolyl-cis,trans-isomerase. A definedsurAdeletion mutation was introduced intoS. entericaserovar Typhimurium C5 and the mutant strain, namedS. entericaserovar Typhimurium BRD1115, was extensively characterized both in vitro and in vivo.S. entericaserovar Typhimurium BRD1115 was found to be defective in the ability to adhere to and invade eukaryotic cells. Furthermore,S. entericaserovar Typhimurium BRD1115 was attenuated by at least 3 log units when administered orally or intravenously to BALB/c mice. Complementation of the mutation with a plasmid carrying the intactsurAgene almost completely restored the virulence of BRD1115. In addition,S. entericaserovar Typhimurium BRD1115 demonstrated potential as a vaccine candidate, since mice immunized with BRD1115 were protected against subsequent challenge withS. entericaserovar Typhimurium C5.S. entericaserovar Typhimurium BRD1115 also showed potential as a vehicle for the effective delivery of heterologous antigens, such as the nontoxic, protective fragment C domain of tetanus toxin, to the murine immune system.
Cytokines inMycoplasma hyorhinis-Induced Arthritis in Pigs Bred Selectively for High and Low Immune Responses
Authors: Jayagopala Reddy N. R. , Wilkie Bruce N. , Borgs Peter , Mallard Bonnie A. 
Published: July 2002

ABSTRACTYorkshire pigs were bred selectively for high and low immune responses (H and L pigs, respectively) based on multiple antibody (Ab) and cell-mediated immune response traits. In a previous experiment, generation 4 (G4) pigs of each line were infected withMycoplasma hyorhinis. High responders had a more rapid and higher Ab response and less polyserositis, but arthritis was more severe in H pigs than in L pigs. To test the hypothesis that line differences were attributable to differential expression of cytokines,M. hyorhinisinfection was induced in pigs of G8. Arthritis was more severe clinically (P, ≤0.05) and postmortem (P, ≤0.001) whenM. hyorhinisCFU were more numerous in synovial fluid (SF) of H pigs than of L pigs (P, ≤0.03). In H pigs but not L pigs, CFU and lesion scores were correlated positively. In H pigs, infection increased the frequency of expression of mRNAs for interleukin-8 (IL-8), IL-10, and tumor necrosis factor alpha (TNF-α) in mononuclear cells from synovial membranes (SM). In L pigs, IL-1α, IL-6, IL-10, and TNF-α mRNAs were increased in frequency of expression. The quantity of the cytokine message for IL-6 was increased in infected H pigs. For L pigs, infection increased the cytokine message for IL-1α, IL-6, IL-10, and TNF-α. IL-6 in SM and gamma interferon (IFN-γ) in SF were produced at a higher copy number in H pigs than in L pigs after infection. For H pigs, there were no positive rank correlations between lesion or CFU scores and cytokines. For L pigs, IL-1α, IL-8, IL-10, and TNF-α in SM correlated with CFU, while IL-6, TNF-β, and IFN-γ in SF correlated with CFU. Lesion score in L pigs correlated with IL-1α in SF. While these results indicate that H and L pigs differ in the cytokine response toM. hyorhinisinfection, they do not confirm a characteristic cytokine response in association with the relative susceptibility to infection and arthritis observed in H pigs.
Phospholipid Synthesis by
Staphylococcus aureus
during (Sub)Lethal Attack by Mammalian 14-Kilodalton Group IIA Phospholipase A2
Authors: Foreman-Wykert Amy K. , Weiss Jerrold , Elsbach Peter 
Published: July 2002

ABSTRACT

Killing of gram-positive bacteria by mammalian group IIA phospholipases A2 (PLA2) requires the catalytic activity of the enzyme. However, nearly complete degradation of the phospholipids can occur with little effect on bacterial viability, suggesting that PLA2-treated bacteria can biosynthetically replace phospholipids that are lost due to PLA2 action. In the presence of albumin, phospholipid degradation products are quantitatively sequestered extracellularly. In the absence of albumin, the bacteria retain and substantially reutilize the phospholipid breakdown products and survive an otherwise lethal dose of PLA2. PLA2-treated bacteria also continue to incorporate sodium [2-
14
C]acetate into phospholipids, suggesting that the bacteria are attempting to repair the damaged membranes by de novo synthesis of phospholipids. To determine whether PLA2 action also triggers activation of bacterial lipolytic enzymes, the effects of nisin and PLA2 on the degradation of
S. aureus
lipids were compared. In contrast to nisin treatment, PLA2 treatment does not stimulate endogenous phospholipase activity in
S. aureus
. These findings show that
S. aureus
responds to PLA2 attack by continued phospholipid (re)synthesis by both de novo and salvage pathways. The fate of PLA2-treated
S. aureus
therefore appears to depend on the relative rates of phospholipid degradation and synthesis.
Molecular and Evolutionary Characterization of the cp32/18 Family of Supercoiled Plasmids in
Borrelia burgdorferi
297
Authors: Caimano Melissa J. , Yang Xiaofeng , Popova Taissia G. , Clawson Michael L. , Akins Darrin R. , Norgard Michael V. , Radolf Justin D. 
Published: July 2002

ABSTRACT

In this study, we characterized seven members of the cp32/18 family of supercoiled plasmids in
Borrelia burgdorferi
297. Complete sequence analysis of a 21-kb plasmid (cp18-2) confirmed that the strain 297 plasmids are similar in overall content and organization to their B31 counterparts. Of the 31 open reading frames (ORFs) in cp18-2, only three showed sequence relatedness to proteins with known functions, and only one, a ParA/SopA ortholog, was related to nonborrelial polypeptides. Besides the lipoproteins, none of the ORFs appeared likely to encode a surface-exposed protein. Comparison with the B31 genomic sequence indicated that paralogs for most of the ORFs in cp18-2 can be identified on other genetic elements. cp18-2 was found to lack a 9- to 10-kb fragment present in the 32-kb homologs which, by extrapolation from the B31 cp32 sequences, contains at least 15 genes presumed to be unnecessary for plasmid maintenance. Sequence analysis of the lipoprotein-encoding variable loci provided evidence that recombinatorial processes within these regions may result in the acquisition of exogenous DNA. Pairwise analysis with random shuffling revealed that the multiple lipoproteins (Mlp; formerly designated 2.9 LPs) fall into two distinct homology groups which appear to have arisen by gene fusion events similar to those recently proposed to have generated the three OspE, OspF, and Elp lipoprotein families (D. R. Akins, M. J. Caimano, X. Yang, F. Cerna, M. V. Norgard, and J. D. Radolf, Infect. Immun. 67:1526–1532, 1999). Comparative analysis of the variable regions also indicated that recombination within the loci of each plasmid may occur independently. Last, comparison of variable loci revealed that the cp32/18 plasmid complements of the B31 and 297 isolates differ substantially, indicating that the two strains have been subject to divergent adaptive pressures. In addition to providing evidence for two different types of recombinatorial events involving cp32/18 plasmids, these findings underscore the need for genetic analysis of diverse borrelial isolates in order to elucidate the Lyme disease spirochete's complex parasitic strategies.