bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression and Immunological Analysis of the Plasmid-BornemlpGenes ofBorrelia burgdorferiStrain B31
Authors: Porcella Stephen F. , Fitzpatrick Cecily A. , Bono James L. 
Published: July 2002

ABSTRACTA lipoprotein gene family first identified inBorrelia burgdorferistrain 297, designated 2.9LPand recently renamedmlp, was found on circular and linear plasmids in the genome sequence ofB. burgdorferistrain B31-M1. Sequence analyses of the B31mlpgenes and physically linked variant gene families indicated thatmlpgene heterogeneity is unique and unrelated to location or linkage to divergent sequences. Evidence of recombination between B31mlpalleles was also detected. Northern blot analysis of cultured strain B31 indicated that themlpgenes were not expressed at a temperature (23°C) characteristic of that of ticks in the environment. In striking contrast, expression of manymlpgenes increased substantially when strain B31 was shifted to 35°C, a temperature change mimicking that occurring in the natural transmission cycle of the spirochete from tick to mammal. Primer extension analysis of themlpmRNA transcripts suggested that sigma 70-like promoters are involved inmlpexpression during temperature shift conditions. Antibodies were made against strain B31 Mlp proteins within the first 4 weeks after experimental mouse infection. Importantly, Lyme disease patients also had serum antibodies reactive with purified recombinant Mlp proteins from strain B31, a result indicating that humans are exposed to Mlp proteins during infection. Taken together, the data indicate that strain B31mlpgenes encode a diverse array of lipoproteins which may participate in early infection processes in the mammalian host.
Suppression of Macrophage Activation with CNI-1493 Increases Survival in Infant Rats with Systemic
Haemophilus influenzae
Infection
Authors: Granert Carl , Abdalla Hana , Lindquist Lars , Diab Asim , Bakhiet Moiz , Tracey Kevin J. , Andersson Jan 
Published: July 2002

ABSTRACT

CNI-1493, a potent macrophage deactivator, was used to treat infant rats systemically infected with
Haemophilus influenzae
type b (Hib). CNI-1493 was injected 1 h prior to bacterial inoculation and 24 h later and resulted in a 75 percent increased rate of survival compared to that for untreated controls. The effect of CNI-1493 on the inflammatory response was studied by immunohistochemical detection of individual tumor necrosis factor alpha (TNF-α)-, interleukin 1 beta (IL-1β)-, and gamma interferon (IFN-γ)-producing cells in the spleen. A significant reduction of the incidence of TNF-α- and IL-1β-expressing cells was found for CNI-1493-treated animals. IFN-γ expression was not suppressed by CNI-1493, indicating that cytokine inhibition was specific in macrophages. CNI-1493 significantly reduced the number of infiltrating granulocytes in the brain from that for controls. This study provides evidence that CNI-1493 protects against lethal Hib infection by deactivating the inflammatory cascade in infant rats.
Clonal Associations amongStaphylococcus aureusIsolates from Various Sites of Infection
Authors: Booth Mary C. , Pence Lisa M. , Mahasreshti Param , Callegan Michelle C. , Gilmore Michael S. 
Published: July 2002

ABSTRACTA molecular epidemiological analysis was undertaken to identify lineages ofStaphylococcus aureusthat may be disproportionately associated with infection. Pulsed-field gel electrophoresis analysis of 405S. aureusclinical isolates collected from various infection types and geographic locations was performed. Five distinctS. aureuslineages (SALs 1, 2, 4, 5, and 6) were identified, which accounted for 19.01, 9.14, 22.72, 10.12, and 4.69% of isolates, respectively. In addition, 85 lineages which occurred with frequencies of <2.5% were identified and were termed “sporadic.” The most prevalent lineage was methicillin-resistantS. aureus(SAL 4). The second most prevalent lineage, SAL 1, was also isolated at a high frequency from the anterior nares of healthy volunteers, suggesting that its prevalence among clinical isolates may be a consequence of high carriage rates in humans. Gene-specific PCR was carried out to detect genes for a number of staphylococcal virulence traits.tstandcnawere found to be significantly associated with prevalent lineages compared to sporadic lineages. When specific infection sites were examined, SAL 4 was significantly associated with respiratory tract infection, while SAL 2 was enriched among blood isolates. SAL 1 and SAL 5 were clonally related to SALs shown by others to be widespread in the clinical isolate population. We conclude from this study that at least five phylogenetic lineages ofS. aureusare highly prevalent and widely distributed among clinical isolates. The traits that confer on these lineages a propensity to infect may suggest novel approaches to antistaphylococcal therapy.
Environmental Signals Controlling Production of Hemagglutinin/Protease in
Vibrio cholerae
Authors: Benitez Jorge A. , Silva Anisia J. , Finkelstein Richard A. 
Published: July 2002

ABSTRACT

Vibrio cholerae
hemagglutinin/protease (Hap) was induced upon nutrient limitation and strongly repressed by glucose. Hap was not produced in a mutant defective in the cyclic AMP (cAMP) receptor protein, suggesting that intracellular cAMP levels mediate Hap expression. No difference was found in Hap production between an
rpoS
deletion mutant and its isogenic wild-type precursor, indicating that the alternate ς
s
factor is not essential for Hap expression. Based on these and previous results, we discuss the role of Hap in the pathogenesis of cholera.
Characterization of a
Brucella
Species 25-Kilobase DNA Fragment Deleted from
Brucella abortus
Reveals a Large Gene Cluster Related to the Synthesis of a Polysaccharide
Authors: Vizcaı́no Nieves , Cloeckaert Axel , Zygmunt Michel S. , Fernández-Lago Luis 
Published: July 2002

ABSTRACT

In the present study we completed the nucleotide sequence of a
Brucella melitensis
16M DNA fragment deleted from
B. abortus
that accounts for 25,064 bp and show that the other
Brucella
spp. contain the entire 25-kb DNA fragment. Two short direct repeats of four nucleotides, detected in the
B. melitensis
16M DNA flanking both sides of the fragment deleted from
B. abortus
, might have been involved in the deletion formation by a strand slippage mechanism during replication. In addition to
omp31
, coding for an immunogenic protein located in the
Brucella
outer membrane, 22 hypothetical genes were identified. Most of the proteins that would be encoded by these genes show significant homology with proteins involved in the biosynthesis of polysacharides from other bacteria, suggesting that they might be involved in the synthesis of a
Brucella
polysaccharide that would be a heteropolymer synthesized by a Wzy-dependent pathway. This polysaccharide would not be synthesized in
B. abortus
and would be a polysaccharide not identified until present in the genus
Brucella
, since all of the known polysaccharides are synthesized in all smooth
Brucella
species. Discovery of a novel polysaccharide not synthesized in
B. abortus
might be interesting for a better understanding of the pathogenicity and host preference differences observed between the
Brucella
species. However, the possibility that the genes detected in the DNA fragment deleted in
B. abortus
no longer lead to the synthesis of a polysaccharide must not be excluded. They might be a remnant of the common ancestor of the alpha-2 subdivision of the class
Proteobacteria
, with some of its members synthesizing extracellular polysaccharides and, as
Brucella
spp., living in association with eukaryotic cells.
Enzyme Degradation and Proinflammatory Activity in Arthritogenic and NonarthritogenicEubacterium aerofaciensCell Walls
Authors: Zhang Xiang , Rimpiläinen Marja , Šimelyte Egle , Toivanen Paavo 
Published: July 2002

ABSTRACTTwo almost-identical strains ofEubacterium aerofaciensisolated from the normal human gut flora were used. The cell wall (CW) of one strain with a peptidoglycan (PG) type A4α induces chronic arthritis in the rat after a single intraperitoneal injection, whereas CW of the other with PG type A4β induces only a transient acute arthritis. The CW of the arthritogenicE. aerofacienswas a twofold-more-potent stimulator of the proinflammatory cytokines tumor necrosis factor alpha (TNF-α) and monocyte chemoattractant protein 1 (MCP-1) than the nonarthritogenic CW. After degradation with mutanolysin, the capacity of the arthritogenic PG to stimulate production of TNF-α and MCP-1 was significantly increased, whereas that of the nonarthritogenic PG was significantly decreased. In other words, after enzyme degradation the arthritogenic PG had a four- to fivefold-stronger stimulatory capacity than that of the enzyme-treated nonarthritogenic PG. These findings indicate that the arthritogenicity of CW or a PG is not dependent on the enzyme resistance alone but also on how the PG fragments released by enzyme degradation stimulate the production of proinflammatory cytokines.
Influence ofMycobacterium bovisBacillus Calmette Guérin on In Vitro Induction of CD1 Molecules in Human Adherent Mononuclear Cells
Authors: Giuliani Anna , Prete Salvatore P. , Graziani Grazia , Aquino Angelo , Balduzzi Alessandra , Sugita Masahiko , Brenner Michael B. , Iona Elena , Fattorini Lanfranco , Orefici Graziella , Porcelli Steven A. , Bonmassar Enzo 
Published: July 2002

ABSTRACTNonpeptide antigens (including glycolipids of microbial origin) can be presented to T cells by CD1 molecules expressed on monocyte-derived dendritic cells. These HLA unrestricted responses appear to play a role in host immunity againstMycobacterium tuberculosisand other pathogenic bacteria. It is known that vaccination withMycobacterium bovisbacillus Calmette-Guérin (BCG) has limited efficacy in many clinical settings, although the reasons for its inadequacy remain unclear. Here we have investigated the influence of BCG on the induction of CD1b on human monocytes by granulocyte-macrophage colony-stimulating factor (GM-CSF), which is believed to be the principal inducer of this antigen-presenting molecule. Although BCG alone led to a slight induction of CD1b expression, this agent reduced markedly the ability of GM-CSF to induce high levels of CD1b that were typically observed in uninfected cells. Inhibition of CD1b expression in BCG-infected monocytes was apparent at both the mRNA transcript and CD1b protein levels. Down-regulation of CD1b expression by BCG was mediated, at least in part,by one or more soluble factors and could not be reversed with high concentrations of GM-CSF or a variety of other cytokines. The present results suggest that BCG could diminish the efficiency of CD1-restricted T-cell responses against nonpeptide mycobacterial antigens by reducing CD1 expression on antigen-presenting cells. These findings have potential implications for understanding the nature of the immune response elicited by BCG in humans and suggest potential strategies that could be important for the development of better vaccines for the prevention of tuberculosis.
Cryptococcus neoformansInduces Macrophage Inflammatory Protein 1α (MIP-1α) and MIP-1β in Human Microglia: Role of Specific Antibody and Soluble Capsular Polysaccharide
Authors: Goldman David , Song Xianyuan , Kitai Ryuhei , Casadevall Arturo , Zhao Meng-Liang , Lee Sunhee C. 
Published: July 2002

ABSTRACTWe characterized the expression of the β-chemokines macrophage inflammatory protein 1α (MIP-1α), MIP-1β, and RANTES by primary human microglia after exposure toCryptococcus neoformans.In the absence of specific antibody,C. neoformansfailed to elicit a chemokine response, while in the presence of specific antibody, microglia produced MIP-1α and MIP-1β in amounts comparable to those induced by lipopolysaccharide. RANTES was also induced but at much lower levels. In addition to MIP-1α and MIP-1β mRNA, we observed a robust induction of monocyte chemoattractant protein 1 and interleukin-8 mRNA following incubation of microglia with opsonizedC. neoformans. In contrast, cryptococcal polysaccharide did not induce a chemokine response even when specific antibody was present and inhibited the MIP-1α induction associated with antibody-mediated phagocytosis ofC. neoformans. The role of the Fc receptor in the observed chemokine induction was explored in several experiments. Treatment of microglia with cytochalasin D inhibited internalization ofC. neoformansbut did not affect MIP-1α induction. In contrast, treatment with herbimycin A, a tyrosine kinase inhibitor, inhibited MIP-1α induction. Microglia stimulated with immobilized murine immunoglobulin also produced MIP-1α and RANTES (MIP-1α > RANTES). Our results show that microglia produce several chemokines when stimulated byC. neoformansin the presence of specific antibody and that this process is likely to be mediated by Fc receptor activation. This response can be down-regulated by cryptococcal capsular polysaccharide. These findings suggest a mechanism by whichC. neoformansinfections fail to induce strong inflammatory responses in patients with cryptococcal meningoencephalitis and have important implications for antibody therapy.
Flagellum of
Legionella pneumophila
Positively Affects the Early Phase of Infection of Eukaryotic Host Cells
Authors: Dietrich Claudia , Heuner Klaus , Brand Bettina C. , Hacker Jörg , Steinert Michael 
Published: July 2002

ABSTRACT

Legionella pneumophila
, the etiologic agent of Legionnaires' disease, contains a single, monopolar flagellum which is composed of one major subunit, the FlaA protein. To evaluate the role of the flagellum in the pathogenesis and ecology of
Legionella
, the
flaA
gene of
L. pneumophila
Corby was mutagenized by introduction of a kanamycin resistance cassette. Immunoblots with antiflagellin-specific polyclonal antiserum, electron microscopy, and motility assays confirmed that the specific flagellar mutant
L. pneumophila
Corby KH3 was nonflagellated. The redelivery of the intact
flaA
gene into the chromosome (
L. pneumophila
Corby CD10) completely restored flagellation and motility. Coculture studies showed that the invasion efficiency of the
flaA
mutant was moderately reduced in amoebae and severely reduced in HL-60 cells. In contrast, adhesion and the intracellular rate of replication remained unaffected. Taking these results together, we have demonstrated that the flagellum of
L. pneumophila
positively affects the establishment of infection by facilitating the encounter of the host cell as well as by enhancing the invasion capacity.
Genetic Regulation of Acquired Immune Responses to Antigens ofMycobacterium tuberculosis:a Study of Twins in West Africa
Authors: Jepson Annette , Fowler Amanda , Banya Winston , Singh Mahavir , Bennett Steve , Whittle Hilton , Hill Adrian V. S. 
Published: July 2002

ABSTRACTThe role of genetic factors in clinical tuberculosis is increasingly recognized; how such factors regulate the immune response toMycobacterium tuberculosisin healthy individuals is unclear. In this study of 255 adult twin pairs residing in The Gambia, West Africa, it is apparent that memory T-cell responses to secreted mycobacterial antigens (85-kDa antigen complex, “short-term culture filtrate,” and peptides from the ESAT-6 protein), as well as to the 65-kDa heat shock protein, are subject to effective genetic regulation. The delayed hypersensitivity response to intradermal tuberculin also demonstrates significant genetic variance, while quantitative T-cell and antibody responses to the 38-kDa cell membrane protein appear to be determined largely by environmental factors. Such findings have implications for vaccine development.
Impact of Genotypic Variation ofBorrelia burgdorferiSensu Stricto on Kinetics of Dissemination and Severity of Disease in C3H/HeJ Mice
Authors: Wang Guiqing , Ojaimi Caroline , Iyer Radha , Saksenberg Victoria , McClain Steve A. , Wormser Gary P. , Schwartz Ira 
Published: July 2002

ABSTRACTVarious genotypes ofBorrelia burgdorferisensu stricto have been previously identified among a large collection of isolates cultured from patients with Lyme disease in the United States. Furthermore, association of specific genotypes with hematogenous dissemination early in the disease course has been observed. The present study assessed kinetics of spirochete dissemination and disease severity in C3H/HeJ mice infected with two different genotypes ofB. burgdorferi. Spirochete load in plasma and ear and other tissue samples of infected mice was measured by quantitative PCR, and these data were compared to those obtained by culture and histopathologic analysis. In mice infected with isolate BL206 (a type 1 strain), the peak number of spirochetes was observed in plasma between day 4 and 7, in heart and ear tissue on day 14, and in joints on day 28 postinoculation. There was a correlation between the peak number of spirochetes in plasma on day 4 or 7 and that in ear biopsy and joint specimens on day 14. By contrast, spirochete burdens in plasma of mice infected with isolate B356 (a type 3 strain) were 16- and 5-fold lower than those of BL206-infected mice on days 7 and 14 of infection, respectively. Similarly, approximately 6- and 13-fold fewer spirochetes were detected in the heart tissues of B356-infected mice compared to BL206-infected mice. Histopathologically, severe arthritis and aortitis were noted only in mice infected with isolate BL206. Spirochete dissemination and disease severity vary significantly in mice infected with distinct genotypes ofB. burgdorferi, suggesting that genotypic differences in the infecting spirochetes play a key role in the pathogenesis and development of clinical disease.
Evidence of Recombination in
Porphyromonas gingivalis
and Random Distribution of Putative Virulence Markers
Authors: Frandsen Ellen V. G. , Poulsen Knud , Curtis Michael A. , Kilian Mogens 
Published: July 2002

ABSTRACT

The association of
Porphyromonas gingivalis
to periodontal disease is not clearly understood. Similar proportions of
P. gingivalis
may be cultivated from both inactive and actively degrading periodontal pockets. Differences in virulence among strains of
P. gingivalis
exist, but the molecular reason for this remains unknown. We examined the population structure of
P. gingivalis
to obtain a framework in which to study pathogenicity in relation to evolution. Phylogenetic trees derived from the sequencing of fragments of four housekeeping genes,
ahp, thy, rmlB
, and
infB
, in 57 strains were completely different with no correlation between clustering of strains in the four dendrograms. Combining the various alleles of the four gene fragments sequenced resulted in 41 different sequence types. The index of association, I
A
, based on a single representative of each sequence type was 0.143 ± 0.202, indicating a population at linkage equilibrium. Inclusion of all isolates for the calculation of I
A
resulted in a value of 0.206 ± 0.171. This suggests an epidemic population structure supported by the finding of genetically identical strains in different parts of the world. We observed a random distribution of two virulence-associated mobile genetic elements, the
ragB
locus and the insertion sequence IS
1598
, among 132 strains tested. In conclusion,
P. gingivalis
has a nonclonal population structure characterized by frequent recombination. Our study suggests that particular genotypes, possibly with increased pathogenic potential, may spread successfully in the human population.
Variation in the Infectivity of
Listeria monocytogenes
Isolates following Intragastric Inoculation of Mice
Authors: Barbour Angela H. , Rampling Anita , Hormaeche Carlos E. 
Published: July 2002

ABSTRACT

The infectivities of 66
Listeria monocytogenes
isolates were assessed by intragastric inoculation of mice. Eight were poorly infective. Serovars 4b and 1/2 were more infective than serovars 3 and 4nonb. A noninfective isolate was cleared more rapidly from the cecum than were infective isolates, suggesting that survival in the gut may relate to infectivity.
Leptospiral Proteins Recognized during the Humoral Immune Response to Leptospirosis in Humans
Authors: Guerreiro Hygia , Croda Júlio , Flannery Brendan , Mazel Mary , Matsunaga James , Reis Mitermayer Galvão , Levett Paul N. , Ko Albert I. , Haake David A. 
Published: July 2002

ABSTRACT

Leptospirosis is an emerging zoonosis caused by pathogenic spirochetes belonging to the genus
Leptospira
. An understanding of leptospiral protein expression regulation is needed to develop new immunoprotective and serodiagnostic strategies. We used the humoral immune response during human leptospirosis as a reporter of protein antigens expressed during infection. Qualitative and quantitative immunoblot analysis was performed using sera from 105 patients from Brazil and Barbados. Sera from patients with other diseases and healthy individuals were evaluated as controls. Seven proteins, p76, p62, p48, p45, p41, p37, and p32, were identified as targets of the humoral response during natural infection. In both acute and convalescent phases of illness, antibodies to lipopolysaccharide were predominantly immunoglobulin M (IgM) while antibodies to proteins were exclusively IgG. Anti-p32 reactivity had the greatest sensitivity and specificity: positive reactions were observed in 37 and 84% of acute- and convalescent-phase sera, respectively, while only 5% of community control individuals demonstrated positive reactions. Six immunodominant antigens were expressed by all pathogenic leptospiral strains tested; only p37 was inconsistently expressed. Two-dimensional immunoblots identified four of the seven infection-associated antigens as being previously characterized proteins: LipL32 (the major outer membrane lipoprotein), LipL41 (a surface-exposed outer membrane lipoprotein), and heat shock proteins GroEL and DnaK. Fractionation studies demonstrated LipL32 and LipL41 reactivity in the outer membrane fraction and GroEL and DnaK in the cytoplasmic fraction, while p37 appeared to be a soluble periplasmic protein. Most of the other immunodominant proteins, including p48 and p45, were localized to the inner membrane. These findings indicate that leptospiral proteins recognized during natural infection are potentially useful for serodiagnosis and may serve as targets for vaccine design.
Construction and Characterization of Genetically Defined
aro omp
Mutants of Enterotoxigenic
Escherichia coli
and Preliminary Studies of Safety and Immunogenicity in Humans
Authors: Turner Arthur K. , Terry Tamsin D. , Sack David A. , Londoño-Arcila Patricia , Darsley Michael J. 
Published: July 2002

ABSTRACT

Enterotoxigenic
Escherichia coli
(ETEC) is a leading cause of diarrhea in travelers to countries where the disease is endemic and causes a major disease burden in the indigenous population, particularly children. We describe here the generation and preclinical characterization of candidate strains of ETEC which are intended to provide the basis of a live attenuated oral vaccine to prevent this disease. It has been shown previously that a spontaneously arising toxin-negative variant ETEC strain, E1392/75-2A, could confer 75% protection against challenge when administered to volunteers. Unfortunately this strain induced mild diarrhea in 15% of recipients. To eliminate the unacceptable reactogenicity of strain E1392/75-2A, it was further attenuated by introducing three different combinations of defined deletion mutations into the chromosome. A mouse intranasal model of immunization was developed and used to show that all of the strains were immunogenic. Immune responses against colonization factor antigens (CFAs) were particularly strong when the bacterial inocula were grown on “CFA agar,” which induces strong expression of these antigens. Two of the strains were selected for a phase I dose escalation safety study with healthy adult volunteers. Freshly grown organisms were harvested from CFA agar plates and administered to volunteers as a suspension containing from 5 × 10
7
to 5 × 10
9
CFU. The vaccine was well tolerated at all doses and induced significant immune responses in all recipients at the highest dose of either strain. The results provide the basis for further clinical evaluation of these vaccine candidates.