bluuebunny/crossref_metadata_2025_split huggingface dataset:
Induction of Necrosis in Human Neutrophils byShigella flexneriRequires Type III Secretion, IpaB and IpaC Invasins, and Actin Polymerization
Authors: François Mathias , Le Cabec Véronique , Dupont Marie-Ange , Sansonetti Philippe J. , Maridonneau-Parini Isabelle 
Published: July 2002

ABSTRACTInfection byShigella flexneriis characterized by infiltration of neutrophils in the intestinal mucosa and by a strong inflammatory reaction. Although neutrophils are constitutively programmed to die by apoptosis, we show that isolated human neutrophils undergo necrosis 2 h after infection with virulentS. flexneristrain M90T but not with the virulence plasmid-cured strain BS176. This was demonstrated by the release of azurophil granule proteins concomitant with the release of lactate dehydrogenase (LDH), disruption of the plasma membrane, and absence of DNA fragmentation. Mutants with themxiD1gene, coding for an essential component of the secretion type III machinery, or the genes coding for IpaB or IpaC invasins deleted were not cytotoxic. Neutrophil necrosis occurred independently of the bacterial ability to leave phagosomes, and it involved actin polymerization, as the addition of cytochalasin D after phagocytosis ofShigellainhibited the release of LDH. In conclusion,Shigellakills neutrophils by necrosis, a process characterized by the release of tissue-injurious granular proteins. This probably contributes to disruption of the epithelial barrier, leading to the dysentery observed in shigellosis and allowingShigellato enter its host cells.
Identification of an Immunodominant ABC Transporter in Methicillin-Resistant
Staphylococcus aureus
Infections
Authors: Burnie James P. , Matthews Ruth C. , Carter Tracey , Beaulieu Elaine , Donohoe Michael , Chapman Caroline , Williamson Peter , Hodgetts Samantha J. 
Published: July 2002

ABSTRACT

Immunoblotting sera from 26 patients with septicemia due to an epidemic strain of methicillin-resistant
Staphylococcus aureus
(EMRSA-15), 6 of whom died, revealed an immunodominant EMRSA-15 antigen at 61 kDa. There was a statistically significant correlate (
P
< 0.001) between survival and immunoglobulin G to the 61-kDa band. The antigen was identified by sequencing positive clones obtained by screening a genomic expression library of EMRSA-15 with pooled sera from patients taken after the septicemic episode. Eluted antibody reacted with the 61-kDa antigen on immunoblots. The amino terminus was obtained by searching the
S. aureus
NCTC 8325 and MRSA strain COL databases, and the whole protein was expressed in
Escherichia coli
TOP 10F′. The derived amino acid sequence showed homology with ABC transporters, with paired Walker A and Walker B motifs and 73% homology to YkpA from
Bacillus subtilis
. Epitope mapping of the derived amino acid sequence with sera from patients who had recovered from EMRSA-15 septicemia delineated seven epitopes. Three of these epitopes, represented by peptides 1 (KIKVYVGNYDFWYQS), 2 (TVIVVSHDRHFLYNNV), and 3 (TETFLRGFLGRMLFS), were synthesized and used to isolate human recombinant antibodies from a phage antibody display library. Recombinant antibodies against peptides 1 and 2 gave logarithmic reductions in organ colony counts, compared with control groups, in a mouse model of the infection. This study suggests the potential role of an ABC transporter as a target for immunotherapy.
Measurement of T-Cell-Derived Antigen Binding Molecules and Immunoglobulin G Specific toCandida albicansMannan in Sera of Patients with Recurrent Vulvovaginal Candidiasis
Authors: Little Colin H. , Georgiou George M. , Marceglia Alex , Ogedgebe Henry , Cone Robert E. , Mazza Danielle 
Published: July 2002

ABSTRACTImmunoglobulin G (IgG) and T-cell-derived antigen binding molecules (TABM) specific to wholeCandidaextract and toCandida-derived mannans prepared by both the cetryltrimethylammonium bromide (CTAB) and alkaline degradation (PEAT) methods were measured in the sera of women with vulvovaginal candidiasis and controls. In the patients there were significantly higher levels of IgG to both CTAB and PEAT mannans and of TABM to CTAB mannan. TABM specific to CTAB mannan was purified from the serum of a patient with a high titer of this TABM. The purified TABM bound specifically to CTAB mannan and to other yeast and mold extracts. This TABM preparation was associated with transforming growth factor β2 (TGF-β2), and on specific binding to mannan there was a marked increase in the level of detectable TGF-β2. This increase in TGF-β2 level was critically dependent on the relative concentrations of the purified TABM and mannan, being smallest when either was in excess. The TABM specific to CTAB mannan was also shown to inhibitCandida-stimulated gamma interferon production. The results suggest that CTAB mannan-specific TABM may increase susceptibility to vulvovaginal candidiasis in association with a shift in the immune response to the Th2 type.
Molecular Characterization of the
Mycoplasma gallisepticum pvpA
Gene Which Encodes a Putative Variable Cytadhesin Protein
Authors: Boguslavsky S. , Menaker D. , Lysnyansky I. , Liu T. , Levisohn S. , Rosengarten R. , García M. , Yogev D. 
Published: July 2002

ABSTRACT

A putative cytadhesin-related protein (PvpA) undergoing variation in its expression was identified in the avian pathogen
Mycoplasma gallisepticum
. The
pvpA
gene was cloned, expressed in
Escherichia coli
, and sequenced. It exhibits 54 and 52% homology with the P30 and P32 cytadhesin proteins of the human pathogens
Mycoplasma pneumoniae
and
Mycoplasma genitalium
, respectively. In addition, 50% homology was found with the MGC2 cytadhesin of
M. gallisepticum
and 49% homology was found with a stretch of 205 amino acids of the cytadherence accessory protein HMW3 of
M. pneumoniae
. The PvpA molecule possesses a proline-rich carboxy-terminal region (28%) containing two identical directly repeated sequences of 52 amino acids and a tetrapeptide motif (Pro-Arg-Pro-X) which is repeated 14 times. Genetic analysis of several clonal isolates representing different expression states of the PvpA product ruled out chromosomal rearrangement as the mechanism for PvpA phase variation. The molecular basis of PvpA variation was revealed in a short tract of repeated GAA codons, encoding five successive glutamate resides, located in the N-terminal region and subject to frequent mutation generating an in-frame UAA stop codon. Size variation of the PvpA protein was observed among
M. gallisepticum
strains, ranging from 48 to 55 kDa and caused by several types of deletions occurring at the PvpA C-terminal end and within the two directly repeated sequences. By immunoelectron microscopy, the PvpA protein was localized on the mycoplasma cell surface, in particular on the terminal tip structure. Collectively, these findings suggest that PvpA is a newly identified variable surface cytadhesin protein of
M. gallisepticum
.
The Putative Proteinase Maturation Protein A of
Streptococcus pneumoniae
Is a Conserved Surface Protein with Potential To Elicit Protective Immune Responses
Authors: Overweg K. , Kerr A. , Sluijter M. , Jackson M. H. , Mitchell T. J. , de Jong A. P. J. M. , de Groot R. , Hermans P. W. M. 
Published: July 2002

ABSTRACT

Surface-exposed proteins often play an important role in the interaction between pathogenic bacteria and their host. We isolated a pool of hydrophobic, surface-associated proteins of
Streptococcus pneumoniae
. The opsonophagocytic activity of hyperimmune serum raised against this protein fraction was high and species specific. Moreover, the opsonophagocytic activity was independent of the capsular type and chromosomal genotype of the pneumococcus. Since the opsonophagocytic activity is presumed to correlate with in vivo protection, these data indicate that the protein fraction has the potential to elicit species-specific immune protection with cross-protection against various pneumococcal strains. Individual proteins in the extract were purified by two-dimensional gel electrophoresis. Antibodies raised against three distinct proteins contributed to the opsonophagocytic activity of the serum. The proteins were identified by mass spectrometry and N-terminal amino acid sequencing. Two proteins were the previously characterized pneumococcal surface protein A and oligopeptide-binding lipoprotein AmiA. The third protein was the recently identified putative proteinase maturation protein A (PpmA), which showed homology to members of the family of peptidyl-prolyl
cis/trans
isomerases. Immunoelectron microscopy demonstrated that PpmA was associated with the pneumococcal surface. In addition, PpmA was shown to elicit species-specific opsonophagocytic antibodies that were cross-reactive with various pneumococcal strains. This antibody cross-reactivity was in line with the limited sequence variation of
ppmA
. The importance of PpmA in pneumococcal pathogenesis was demonstrated in a mouse pneumonia model. Pneumococcal
ppmA
-deficient mutants showed reduced virulence. The properties of PpmA reported here indicate its potential for inclusion in multicomponent protein vaccines.
Central Role of Endogenous Gamma Interferon in Protective Immunity against Blood-StagePlasmodium chabaudiAS Infection
Authors: Su Zhong , Stevenson Mary M. 
Published: July 2002

ABSTRACTThe role of endogenous gamma interferon (IFN-γ) in protective immunity against blood-stagePlasmodium chabaudiAS malaria was studied using IFN-γ gene knockout (GKO) and wild-type (WT) C57BL/6 mice. Following infection with 106parasitized erythrocytes, GKO mice developed significantly higher parasitemia during acute infection than WT mice and had severe mortality. In infected GKO mice, production of interleukin 12 (IL-12) p70 and tumor necrosis factor alpha in vivo and IL-12 p70 in vitro by splenic macrophages was significantly reduced compared to that in WT mice and the enhanced nitric oxide (NO) production observed in infected WT mice was completely absent. WT and GKO mice had comparable numbers of total nucleated spleen cells and B220+and Mac-1+spleen cells both before and after infection. Infected WT mice, however, had significantly more F4/80+, NK1.1+, and F4/80+Ia+spleen cells than infected GKO mice; male WT had more CD3+cells than male GKO mice. In comparison with those from WT mice, splenocytes from infected GKO mice had significantly higher proliferation in vitro in response to parasite antigen or concanavalin A stimulation and produced significantly higher levels of IL-10 in response to parasite antigen. Infected WT mice produced more parasite-specific immunoglobulin M (IgM), IgG2a, and IgG3 and less IgG1 than GKO mice. Significant gender differences in both GKO and WT mice in peak parasitemia levels, mortality, phenotypes of spleen cells, and proliferation of and cytokine production by splenocytes in vitro were apparent during infection. These results thus provide unequivocal evidence for the central role of endogenous IFN-γ in the development of protective immunity against blood-stageP. chabaudiAS.
Differences in Gamma Interferon Production In Vitro Predict the Pace of the In Vivo Response toLeishmania amazonensisin Healthy Volunteers
Authors: Pompeu M. M. L. , Brodskyn C. , Teixeira M. J. , Clarêncio J. , Van Weyenberg J. , Coelho I. C. B. , Cardoso S. A. , Barral A. , Barral-Netto M. 
Published: July 2002

ABSTRACTThe initial encounter ofLeishmaniacells and cells from the immune system is fundamentally important in the outcome of infection and determines disease development or resistance. We evaluated the anti-Leishmania amazonensisresponse of naive volunteers by using an in vitro priming (IVP) system and comparing the responses following in vivo vaccination against the same parasite. In vitro stimulation allowed us to distinguish two groups of individuals, those who produced small amounts of gamma interferon (IFN-γ) (n= 16) (low producers) and those who produced large amounts of this cytokine (n= 16) (high producers). IFN-γ production was proportional to tumor necrosis factor alpha and interleukin 10 (IL-10) levels but did not correlate with IL-5 production. Volunteers who produced small amounts of IFN-γ in vitro remained low producers 40 days after vaccination, whereas high producers exhibited increased IFN-γ production. However, 6 months after vaccination, all individuals tested produced similarly high levels of IFN-γ upon stimulation of their peripheral blood mononuclear cells withLeishmaniapromastigotes, indicating that low in vitro producers respond slowly in vivo to vaccination. In high IFN-γ producers there was an increased frequency of activated CD8+T cells both in vitro and in vivo compared to the frequency in low producers, and such cells were positive for IFN-γ as determined by intracellular staining. Such findings suggest that IVP responses can be used to predict the pace of postvaccination responses of test volunteers. Although all vaccinated individuals eventually have a potent anti-Leishmaniacell-mediated immunity (CMI) response, a delay in mounting the CMI response may influence resistance against leishmaniasis.
Identification and Characterization of a Novel Family of Pneumococcal Proteins That Are Protective against Sepsis
Authors: Adamou John E. , Heinrichs Jon H. , Erwin Alice L. , Walsh William , Gayle Tony , Dormitzer Melissa , Dagan Ron , Brewah Yambasu A. , Barren Philip , Lathigra Raju , Langermann Solomon , Koenig Scott , Johnson Syd 
Published: July 2002

ABSTRACT

Four pneumococcal genes (
phtA, phtB, phtD
, and
phtE
) encoding a novel family of homologous proteins (32 to 87% identity) were identified from the
Streptococcus pneumoniae
genomic sequence. These open reading frames were selected as potential vaccine candidates based upon their possession of hydrophobic leader sequences which presumably target these proteins to the bacterial cell surface. Analysis of the deduced amino acid sequences of these gene products revealed the presence of a histidine triad motif (HxxHxH), termed Pht (pneumococcal histidine triad) that is conserved and repeated several times in each of the four proteins. The four
pht
genes (
phtA, phtB, phtD
, and a truncated version of
phtE
) were expressed in
Escherichia coli
. A flow cytometry-based assay confirmed that PhtA, PhtB, PhtD and, to a lesser extent, PhtE were detectable on the surface of intact bacteria. Recombinant PhtA, PhtB, and PhtD elicited protection against certain pneumococcal capsular types in a mouse model of systemic disease. These novel pneumococcal antigens may serve as effective vaccines against the most prevalent pneumococcal serotypes.
Haemophilus somnusInduces Apoptosis in Bovine Endothelial Cells In Vitro
Authors: Sylte Matt J. , Corbeil Lynette B. , Inzana Thomas J. , Czuprynski Charles J. 
Published: July 2002

ABSTRACTHaemophilus somnuscauses pneumonia, reproductive failure, infectious myocarditis, thrombotic meningoencephalitis, and other diseases in cattle. Although vasculitis is commonly seen as a result of systemicH. somnusinfections, the pathogenesis of vascular damage is poorly characterized. In this study, we demonstrated thatH. somnus(pathogenic isolates 649, 2336, and 8025 and asymptomatic carrier isolates 127P and 129Pt) induce apoptosis of bovine endothelial cells in a time- and dose-dependent manner, as determined by Hoechst 33342 staining, terminal deoxynucleotidyl transferase-mediated dUTP-FITC nick end labeling, DNA fragmentation, and transmission electron microscopy.H. somnusinduced endothelial cell apoptosis in as little as 1 h of incubation and did not require extracellular growth of the bacteria. ViableH. somnusorganisms induced greater endothelial cell apoptosis than heat-killed organisms. Since viableH. somnuscells release membrane fibrils and blebs, which contain lipooligosaccharide (LOS) and immunoglobulin binding proteins, we examined culture filtrates for their ability to induce endothelial cell apoptosis. Culture filtrates induced similar levels of endothelial cell apoptosis, as did viableH. somnusorganisms. Heat inactivation ofH. somnusculture filtrates partially reduced the apoptotic effect on endothelial cells, which suggested the presence of both heat-labile and heat-stable factors. We found thatH. somnusLOS, which is heat stable, induced endothelial cell apoptosis in a time- and dose-dependent manner and was inhibited by the addition of polymyxin B. These data demonstrate thatH. somnusand its LOS induce endothelial cell apoptosis, which may play a role in producing vasculitis in vivo.
Composition and Gene Expression of the
cag
Pathogenicity Island in
Helicobacter pylori
Strains Isolated from Gastric Carcinoma and Gastritis Patients in Costa Rica
Authors: Occhialini Alessandra , Marais Armelle , Urdaci Maria , Sierra Rafaela , Muñoz Nubia , Covacci Antonello , Mégraud Francis 
Published: July 2002

ABSTRACT

The composition and in vitro expression of the
cag
pathogenicity island genes in a group of
Helicobacter pylori
strains obtained from patients suffering from chronic gastritis-associated dyspepsia (
n
= 26) or gastric carcinoma (
n
= 17) were analyzed. No significant difference in the distribution of the 10 studied regions was found between the cases and the controls. Nine strains did not harbor any of the selected regions: eight (30.8%) isolated from patients with gastritis only and one (5.9%) from a patient with gastric carcinoma. No association was found between the number of repeated sequences at the 3′ end of the
cagA
gene or the presence of tyrosine phosphorylation motifs and the clinical origin of the strains. The
virB10
homolog gene was the sole gene studied to be significantly expressed more often in cancer strains than in gastritis strains (
P
= 0.03).
Identification of Stress-Responsive Genes in
Streptococcus mutans
by Differential Display Reverse Transcription-PCR
Authors: Chia Jean-San , Lee Ya-Yu , Huang Peng-Tu , Chen Jen-Yang 
Published: July 2002

ABSTRACT

Streptococcus mutans
, which causes dental caries in the human oral cavity and occasionally causes infective endocarditis in the heart, withstands adverse environmental stress through diverse alterations in protein synthesis. Differential gene expression in response to environmental stress was analyzed by RNA fingerprinting using arbitrarily primed PCR with a panel of 11mer primers designed for differential display in
Enterobacteriaceae
. Dot and Northern blot hybridization confirmed that the transcription of several genes was up- or down-regulated following exposure to acid shock from pH 7.5 to 5.5. RNA of a gene designated AP-185 (acid-stress protein) was induced specifically by acid treatment, while RNA of GSP-781 (general-stress protein) was up-regulated significantly when bacteria were exposed to high osmolarity and temperature, as well as low pH. The deduced amino acid sequence of AP-185 shares homology (78% identity) with branched-chain amino acid aminotransferase. Cloning and sequence analysis of GSP-781 revealed a potential secreted protein of a molecular mass of about 43 kDa and with a pI predicted to be 5.5. Transcriptional levels of another gene, designated AR-186 (acid-repressed protein), which encodes putative aconitase, were repressed by acid treatment but were enhanced by plasma or serum components. Analogous results were identified in
icd
and
citZ
genes, and repression of these genes, along with AR-186, was also observed when they were exposed to high osmolarity and temperature. These results indicate that differential regulation of specific genes at the transcriptional level is triggered by different stress and that genes responsible for glutamate biosynthesis in the citrate pathway are coordinately regulated during the stress response of
S. mutans
.
Elevated Cytokine and Chemokine Levels and Prolonged Pulmonary Airflow Resistance in a Murine
Mycoplasma pneumoniae
Pneumonia Model: a Microbiologic, Histologic, Immunologic, and Respiratory Plethysmographic Profile
Authors: Hardy Robert D. , Jafri Hasan S. , Olsen Kurt , Wordemann Meike , Hatfield Jeanine , Rogers Beverly B. , Patel Padma , Duffy Lynn , Cassell Gail , McCracken George H. , Ramilo Octavio 
Published: July 2002

ABSTRACT

Because
Mycoplasma pneumoniae
is hypothesized to play an important role in reactive airway disease/asthma, a comprehensive murine model of
M. pneumoniae
lower respiratory infection was established. BALB/c mice were intranasally inoculated once with
M. pneumoniae
and sacrificed at 0 to 42 days postinoculation. All mice became infected and developed histologic evidence of acute pulmonary inflammation, which cleared by 28 days postinoculation. By contrast,
M. pneumoniae
persisted in the respiratory tract for the entire 42 days studied. Tumor necrosis factor alpha, gamma interferon, interleukin-6 (IL-6), KC (functional IL-8), MIP-1α, and MCP-1/JE concentrations were significantly elevated in bronchoalveolar lavage samples, whereas IL-4 and IL-10 concentrations were not significantly elevated. Pulmonary airflow resistance, as measured by plethysmography, was detected 1 day postinoculation and persisted even after pulmonary inflammation had resolved at day 28. Serum anti-
M. pneumoniae
immunoglobulin G titers were positive in all mice by 35 days. This mouse model provides a means to investigate the immunopathogenesis of
M. pneumoniae
infection and its possible role in reactive airway disease/asthma.
Analysis of the Capsule Biosynthetic Locus of
Mannheimia
(
Pasteurella
)
haemolytica
A1 and Proposal of a Nomenclature System
Authors: Lo Reggie Y. C. , McKerral Linda J. , Hills Tanya L. , Kostrzynska Magdalena 
Published: July 2002

ABSTRACT

A 16-kbp DNA region that contains genes involved in the biosynthesis of the capsule of
Mannheimia
(
Pasteurella
)
haemolytica
A1 has been characterized. The gene cluster can be divided into three regions like those of the typical group II capsule biosynthetic clusters in gram-negative bacteria. Region 1 contains four genes (
wzt
,
wzm
,
wzf
, and
wza
) which code for an ATP-binding cassette transport apparatus for the secretion of the capsule materials across the membranes. The
M. haemolytica
A1
wzt
and
wzm
genes were able to complement
Escherichia coli kpsT
and
kpsM
mutants, respectively. Further, the ATP binding activity of Wzt was demonstrated by its affinity for ATP-agarose, and the lipoprotein nature of Wza was supported by [
3
H]palmitate labeling. Region 2 contains six genes; four genes (
orf1
/
2
/
3
/
4
) code for unique functions for which no homologues have been identified to date. The remaining two genes (
nmaA
and
nmaB
) code for homologues of UDP–
N
-acetylglucosamine-2-epimerase and UDP–
N
-acetylmannosamine dehydrogenase, respectively. These two proteins are highly homologous to the
E. coli
WecB and WecC proteins (formerly known as RffE and RffD), which are involved in the biosynthesis of enterobacterial common antigen (ECA). Complementation of an
E. coli rffE/D
mutant with the
M. haemolytica
A1
nmaA/B
genes resulted in the restoration of ECA biosynthesis. Region 3 contains two genes (
wbrA
and
wbrB
) which are suggested to be involved in the phospholipid modification of capsular materials.
Normal IncA Expression and Fusogenicity of Inclusions in
Chlamydia trachomatis
Isolates with the
incA
I47T Mutation
Authors: Pannekoek Yvonne , van der Ende Arie , Eijk Paul P. , van Marle Jan , de Witte Moniek A. , Ossewaarde Jacobus M. , van den Brule Adriaan J. C. , Morré Servaas A. , Dankert Jacob 
Published: July 2002

ABSTRACT

To investigate the correlation between the
incA
I47T mutation in
Chlamydia trachomatis
and the nonfusogenic phenotype, the
incA
genes of 25 isolates were sequenced. Four major sequence types were identified. Seven isolates (28%) had the I47T mutation. Isolates representing the four sequence types expressed IncA in the membrane of one large single inclusion. In conclusion, the
incA
I47T mutation is not associated with the nonfusogenic phenotype.