bluuebunny/crossref_metadata_2025_split huggingface dataset:
SdrX, a Serine-Aspartate Repeat Protein Expressed by
Staphylococcus capitis
with Collagen VI Binding Activity
Authors: Liu Yule , Ames Brenda , Gorovits Elena , Prater Bradley D. , Syribeys Peter , Vernachio John H. , Patti Joseph M. 
Published: October 2004

ABSTRACT

Staphylococcus capitis
(
S. capitis
) has been implicated in a large proportion of coagulase-negative staphylococcal infections in very-low-birth-weight infants. To identify potential therapeutic targets, the
S. capitis
genome was probed for the presence of genes encoding microbial surface components recognizing adhesive matrix molecules (MSCRAMM). By using Southern blot analysis, an
S. capitis
gene, designated
sdrX
, that contained sequence motifs consistent with the Sdr family of MSCRAMM proteins was identified. By using monospecific antisera in Western blot and flow cytometry, SdrX was demonstrated to be expressed on the surface of
S. capitis.
Human collagen type VI was found to bind both the recombinant A domain of SdrX and viable
S. capitis
expressing SdrX. SdrX is the first collagen-binding Sdr protein described and is the first MSCRAMM protein identified in
S. capitis
.
Utility of the
Trypanosoma cruzi
Sequence Database for Identification of Potential Vaccine Candidates by In Silico and In Vitro Screening
Authors: Bhatia Vandanajay , Sinha Mala , Luxon Bruce , Garg Nisha 
Published: October 2004

ABSTRACT

Glycosylphosphatidylinositol (GPI)-anchored proteins are abundantly expressed in the infective and intracellular stages of
Trypanosoma cruzi
and are recognized as antigenic targets by both the humoral and cellular arms of the immune system. Previously, we demonstrated the efficacy of genes encoding GPI-anchored proteins in eliciting partially protective immunity to
T. cruzi
infection and disease, suggesting their utility as vaccine candidates. For the identification of additional vaccine targets, in this study we screened the
T. cruzi
expressed sequence tag (EST) and genomic sequence survey (GSS) databases. By applying a variety of web-based genome-mining tools to the analysis of ∼2,500 sequences, we identified 348 (37.6%) EST and 260 (17.4%) GSS sequences encoding novel parasite-specific proteins. Of these, 19 sequences exhibited the characteristics of secreted and/or membrane-associated GPI proteins. Eight of the selected sequences were amplified to obtain genes
TcG1
,
TcG2
,
TcG3
,
TcG4
,
TcG5
,
TcG6
,
TcG7
, and
TcG8
(
TcG1-TcG8
) which are expressed in different developmental stages of the parasite and conserved in the genome of a variety of
T. cruzi
strains. Flow cytometry confirmed the expression of the antigens encoded by the cloned genes as surface proteins in trypomastigote and/or amastigote stages of
T. cruzi
. When delivered as a DNA vaccine, genes
TcG1-TcG6
elicited a parasite-specific antibody response in mice. Except for
TcG5
, antisera to genes
TcG1-TcG6
exhibited trypanolytic activity against the trypomastigote forms of
T. cruzi
, a property known to correlate with the immune control of
T. cruzi
. Taken together, our results validate the applicability of bioinformatics in genome mining, resulting in the identification of
T. cruzi
membrane-associated proteins that are potential vaccine candidates.
Recognition of Mycobacterial Antigens Delivered by Genetically DetoxifiedBordetella pertussisAdenylate Cyclase by T Cells from Cattle with Bovine Tuberculosis
Authors: Vordermeier H. Martin , Simsova Marcela , Wilkinson Katalin A. , Wilkinson Robert J. , Hewinson R. Glyn , Sebo Peter , Leclerc Claude 
Published: October 2004

ABSTRACTThe exponential increase in the incidence of tuberculosis in cattle over the last two decades in the British national herd constitutes a significant economic problem. Therefore, research efforts are under way to develop cattle tuberculosis vaccines and specific diagnostic reagents to allow the distinction of vaccinated from infected animals. Mycobacterial antigens like ESAT-6 and CFP10 allow this distinction. This study investigates whether fusion protein of ESAT-6 or CFP10 with genetically detoxifiedBordetella pertussisadenylate cyclase (CyaA) are recognized byMycobacterium bovis-infected cattle more effectively than conventional recombinant proteins are, thus enhancing sensitivity or reducing the amount of antigens required. By measuring the frequencies of gamma interferon (IFN-γ)-producing cells, we were able to show that the presentation of CFP10 as a CyaA fusion protein enhanced the molecular efficiency of its recognition 20-fold, while the recognition of ESAT-6 was not improved by CyaA delivery. Furthermore, in the whole-blood IFN-γ test currently used in the field, the delivery of CFP10 and ESAT-6 by fusion to CyaA increased the amount of IFN-γ produced and hence the proportion of infected animals responding to CFP10. The improved T-cell recognition of CyaA336/CFP10 was found to be dependent upon interaction with CD11b. In addition, presentation of CyaA336/CFP10 to CD4+T cells was chloroquine sensitive, and CFP10 delivery by CyaA resulted in its accelerated presentation to T cells. In conclusion, the use of CyaA fusion proteins with ESAT-6 and CFP10 has the potential to improve the sensitivity of immunodiagnostic tests detecting bovine tuberculosis in cattle.
Differential Expression of Porins OmpP2A and OmpP2B of
Haemophilus ducreyi
Authors: Prather Derrick T. , Bains Manjeet , Hancock Robert E. W. , Filiatrault Melanie J. , Campagnari Anthony A. 
Published: October 2004

ABSTRACT

Haemophilus ducreyi
is a strict human pathogen and the causative agent of the sexually transmitted disease chancroid. The genome of the human-passaged strain of
H. ducreyi
(35000HP) contains two homologous genes whose protein products have estimated molecular masses of 46 and 43 kDa. A comparative analysis of the deduced amino acid sequences revealed that these proteins share 27 to 33% identity to the outer membrane protein P2 (OmpP2), a major porin of
Haemophilus influenzae
. Therefore, these proteins have been designated OmpP2A and OmpP2B, respectively. The detection of
ompP2A
and
ompP2B
transcripts by reverse transcriptase PCR indicated that these genes were independently transcribed in
H. ducreyi
35000HP. Western blot analysis of outer membrane proteins isolated from a geographically diverse collection of
H. ducreyi
clinical isolates revealed that OmpP2A and OmpP2B were differentially expressed among these strains. Although PCR analysis suggested that
ompP2A
and
ompP2B
were conserved among the strains tested, the differential expression observed was due to nucleotide additions and partial gene deletions. Purified OmpP2A and OmpP2B were isolated under nondenaturing conditions, and subsequent analysis demonstrated that these two proteins exhibited porin activity. OmpP2A and OmpP2B are the first porins described for
H. ducreyi
.
Extracellular Secretion of the
Borrelia burgdorferi
Oms28 Porin and Bgp, a Glycosaminoglycan Binding Protein
Authors: Cluss Robert G. , Silverman Damon A. , Stafford Thomas R. 
Published: October 2004

ABSTRACT

Borrelia burgdorferi
, the Lyme disease pathogen, cycles between its
Ixodes
tick vector and vertebrate hosts, adapting to vastly different biochemical environments. Spirochete gene expression as a function of temperature, pH, growth phase, and host milieu is well studied, and recent work suggests that regulatory networks are involved. Here, we examine the release of
Borrelia burgdorferi
strain B31 proteins into conditioned medium. Spirochetes intrinsically radiolabeled at concentrations ranging from 10
7
to 10
9
cells per ml secreted Oms28, a previously characterized outer membrane porin, into RPMI medium. As determined by immunoblotting, this secretion was not associated with outer membrane blebs or cytoplasmic contamination. A similar profile of secreted proteins was obtained for spirochetes radiolabeled in mixtures of RPMI medium and serum-free Barbour-Stoenner-Kelly (BSK II) medium. Proteomic liquid chromatography-tandem mass spectrometry analysis of tryptic fragments derived from strain B31 culture supernatants confirmed the identity of the 28-kDa species as Oms28 and revealed a 26-kDa protein as 5′-methylthioadenosine/
S
-adenosylhomocysteine nucleosidase (Pfs-2), previously described as Bgp, a glycosaminoglycan-binding protein. The release of Oms28 into the culture medium is more selective when the spirochetes are in logarithmic phase of growth compared to organisms obtained from stationary phase. As determined by immunoblotting, stationary-phase spirochetes released OspA, OspB, and flagellin. Oms28 secreted by strains B31, HB19, and N40 was also recovered by radioimmunoprecipitation. This is the first report of
B. burgdorferi
protein secretion into the extracellular environment. The possible roles of Oms28 and Bgp in the host-pathogen interaction are considered.
Interleukin-10 (IL-10) Counterregulates IL-4-Dependent Effector Mechanisms in Murine Filariasis
Authors: Specht Sabine , Volkmann Lars , Wynn Tom , Hoerauf Achim 
Published: October 2004

ABSTRACTInterleukin-10 (IL-10) was at first described as a Th2-associated cytokine, although more recent reports have shown that immunosuppression applies to both Th1 and Th2 cell responses, e.g., when produced by T regulatory cells. This concept when applied to human filariasis would argue that high parasite loads are associated with IL-10, while bona fide Th2 responses, mediated by IL-4, IL-5, and IL-13, are associated with parasite containment. To prove this relationship in a causal manner, we investigated the roles of IL-4 and IL-10 in a helminth infection model in which mice genetically deficient for IL-4, IL-10, or IL-4 plus IL-10 were infected with the rodent filariaLitomosoides sigmodontis. Compared to C57BL/6 wild-type and IL-10 knockout (KO) mice, IL-4 KO mice remained susceptible, exhibiting a remarkable number of live adult worms. Interestingly however, when the IL-10 gene was knocked out simultaneously with the IL-4 gene, the susceptibility of IL-4 KO mice was reversed. Although production of IFN-γ was increased in IL-4/IL-10 double-knockout mice, depletion of gamma interferon did not affect worm elimination, so it seems unlikely to be the major factor in mediating resistance in IL-4/IL-10 KO mice. Taken together, the results of this study add proof to the concept that has arisen for human filariasis that IL-10-dependent responses, which are associated with patency, are antagonistic to bona fide Th2 responses, which control parasite loads. The finding that knockout of IL-10 reversed a disease phenotype induced by knockout of IL-4 gives the first causal evidence of an antagonistic activity between IL-4 and IL-10 in an infection in vivo.
Respiratory Hydrogen Use by
Salmonella enterica
Serovar Typhimurium Is Essential for Virulence
Authors: Maier R. J. , Olczak A. , Maier S. , Soni S. , Gunn J. 
Published: October 2004

ABSTRACT

Based on available annotated gene sequence information, the enteric pathogen salmonella, like other enteric bacteria, contains three putative membrane-associated H
2
-using hydrogenase enzymes. These enzymes split molecular H
2
, releasing low-potential electrons that are used to reduce quinone or heme-containing components of the respiratory chain. Here we show that each of the three distinct membrane-associated hydrogenases of
Salmonella enterica
serovar Typhimurium is coupled to a respiratory pathway that uses oxygen as the terminal electron acceptor. Cells grown in a blood-based medium expressed four times the amount of hydrogenase (H
2
oxidation) activity that cells grown on Luria Bertani medium did. Cells suspended in phosphate-buffered saline consumed 2 mol of H
2
per mol of O
2
used in the H
2
-O
2
respiratory pathway, and the activity was inhibited by the respiration inhibitor cyanide. Molecular hydrogen levels averaging over 40 μM were measured in organs (i.e., livers and spleens) of live mice, and levels within the intestinal tract (the presumed origin of the gas) were four times greater than this. The half-saturation affinity of
S. enterica
serovar Typhimurium for H
2
is only 2.1 μM, so it is expected that H
2
-utilizing hydrogenase enzymes are saturated with the reducing substrate in vivo. All three hydrogenase enzymes contribute to the virulence of the bacterium in a typhoid fever-mouse model, based on results from strains with mutations in each of the three hydrogenase genes. The introduced mutations are nonpolar, and growth of the mutant strains was like that of the parent strain. The combined removal of all three hydrogenases resulted in a strain that is avirulent and (in contrast to the parent strain) one that is unable to invade liver or spleen tissue. The introduction of one of the hydrogenase genes into the triple mutant strain on a low-copy-number plasmid resulted in a strain that was able to both oxidize H
2
and cause morbidity in mice within 11 days of inoculation; therefore, the avirulent phenotype of the triple mutant is not due to an unknown spurious mutation. We conclude that H
2
utilization in a respiratory fashion is required for energy production to permit salmonella growth and subsequent virulence during infection.
Strain-Specific Humoral Response to a Polymorphic Malaria Vaccine
Authors: Flück Christian , Smith Tom , Beck Hans-Peter , Irion Andrea , Betuela Inoni , Alpers Michael P. , Anders Robin , Saul Allan , Genton Blaise , Felger Ingrid 
Published: October 2004

ABSTRACT

The 3D7 form of the merozoite surface protein 2 (MSP2) of
Plasmodium falciparum
was one of three subunits of the malaria vaccine Combination B that were tested in a phase I/IIb double-blind randomized placebo-controlled trial, which was undertaken with 120 Papua New Guinean children of 5 to 9 years of age. Because only one variant of the highly polymorphic MSP2 was used for vaccination, we examined whether the elicited response was directed against conserved or strain-specific epitopes. Postvaccination (week 12) titers of antibody against recombinantly expressed individual domains of MSP2 were measured by enzyme-linked immunosorbent assay and compared to baseline values. We found that vaccination with the 3D7 form of MSP2 induced a significant strain-specific humoral response directed against the repetitive and semiconserved family-specific part. The conserved N- and C-terminal domains were not immunogenic. Titers of antibody against the alternate FC27 family-specific domain showed a tendency to increase in vaccinated children, but there was no increase in antibodies against FC27-type 32-mer repeats. These results indicate that vaccination with one MSP2 variant mainly induced a strain-specific response, which can explain the selective effect of vaccination with combination B on the genotypes of breakthrough parasites. These findings support the inclusion of both family-specific domains (3D7 and FC27) in an improved vaccine formulation.
Mycobacterium marinum
Strains Can Be Divided into Two Distinct Types Based on Genetic Diversity and Virulence
Authors: van der Sar Astrid M. , Abdallah Abdallah M. , Sparrius Marion , Reinders Erik , Vandenbroucke-Grauls Christina M. J. E. , Bitter Wilbert 
Published: October 2004

ABSTRACT

Mycobacterium marinum
causes a systemic tuberculosis-like disease in a large number of poikilothermic animals and is used as a model for mycobacterial pathogenesis. In the present study, we infected zebra fish (
Danio rerio
) with different strains of
M. marinum
to determine the variation in pathogenicity. Depending on the
M. marinum
isolate, the fish developed an acute or chronic disease. Acute disease was characterized by uncontrolled growth of the pathogen and death of all animals within 16 days, whereas chronic disease was characterized by granuloma formation in different organs and survival of the animals for at least 4 to 8 weeks. Genetic analysis of the isolates by amplified fragment length polymorphism showed that
M. marinum
strains could be divided in two clusters. Cluster I contained predominantly strains isolated from humans with fish tank granuloma, whereas the majority of the cluster II strains were isolated from poikilothermic species. Acute disease progression was noted only with strains belonging to cluster I, whereas all chronic-disease-causing isolates belonged to cluster II. This difference in virulence was also observed in vitro: cluster I isolate Mma20 was able to infect and survive more efficiently in the human macrophage THP-1 and the carp leukocyte CLC cell lines than was the cluster II isolate Mma11. We conclude that strain characteristics play an important role in the pathogenicity of
M. marinum
. In addition, the correlation between genetic variation and host origin suggests that cluster I isolates are more pathogenic for humans.
RNA Encoding the MPT83 Antigen Induces Protective Immune Responses againstMycobacterium tuberculosisInfection
Authors: Xue Tian , Stavropoulos Evangelos , Yang Min , Ragno Silvia , Vordermeier Martin , Chambers Mark , Hewinson Glyn , Lowrie Douglas B. , Colston M. Joseph , Tascon Ricardo E. 
Published: October 2004

ABSTRACTWe have previously demonstrated that vaccination of mice with plasmid DNA vectors expressing immunodominant mycobacterial genes induced cellular immune responses and significant protection against challenge withMycobacterium tuberculosis. We demonstrate here, using in vitro-synthesized RNA, that vaccination with DNA or RNA constructs expressing theM. tuberculosisMPT83 antigen are capable of inducing specific humoral and T-cell immune responses and confer modest but significant protection againstM. tuberculosischallenge in mice. This is the first report of protective immunity conferred against intracellular bacteria by an RNA vaccine. This novel approach avoids some of the drawbacks of DNA vaccines and illustrates the potential for developing new antimycobacterial immunization strategies.
The Infecting Dose ofChlamydia muridarumModulates the Innate Immune Response and Ascending Infection
Authors: Maxion Heather K. , Liu Wei , Chang Mi-Hyang , Kelly Kathleen A. 
Published: October 2004

ABSTRACTMurine vaginal infection with the obligate intracellular bacteriumChlamydia muridarumis commonly used as a model for ascendingChlamydiainfections of the human female genital tract. Gamma interferon-producing Th1 cells, in concert with other mononuclear infiltrates, primarily mediate antichlamydial immunity. However, many factors modify this response, including the bacterial load. To investigate the manner in which the inoculating dose ofC. muridarummodulates a genital infection, we measured innate and adaptive cell numbers, CD4+lymphocyte cytokine profile, chemokine expression, course of infection, and pathological sequelae in genital tracts of BALB/c mice infected with doses ofC. muridarumranging from 104to 107inclusion-forming units. We found that the influx of both innate and adaptive immune cells responded similarly in the lower genital tract (cervical-vaginal tissues) and upper genital tract (oviduct tissues) to increasing inoculating doses. However, cells expressing the innate markers Gr-1 and CD11c were affected to a greater degree by increasing dose than lymphocytes of the adaptive immune response (Th1, CD4+, CD8+, CD19+), resulting in a change in the balance of innate and adaptive cell numbers to favor innate cells at higher infecting doses. Surprisingly, we detected greater numbers of viable chlamydiae in the oviducts at lower inoculating doses, and the number of organisms appeared to directly correlate with hydrosalpinx formation after both primary infection and repeat infection. Taken together, these data suggest that innate immune cells contribute to control of ascending infection.
The Type II Heat-Labile Enterotoxins LT-IIa and LT-IIb and Their Respective B Pentamers Differentially Induce and Regulate Cytokine Production in Human Monocytic Cells
Authors: Hajishengallis George , Nawar Hesham , Tapping Richard I. , Russell Michael W. , Connell Terry D. 
Published: October 2004

ABSTRACTThe type II heat-labile enterotoxins, LT-IIa and LT-IIb, exhibit potent adjuvant properties. However, little is known about their immunomodulatory activities upon interaction with innate immune cells, unlike the widely studied type I enterotoxins that include cholera toxin (CT). We therefore investigated interactions of LT-IIa and LT-IIb with human monocytic THP-1 cells. We found that LT-II enterotoxins were inactive in stimulating cytokine release, whereas CT induced low levels of interleukin-1β (IL-1β) and IL-8. However, all three enterotoxins potently regulated cytokine induction in cells activated by bacterial lipopolysaccharide or fimbriae. Induction of proinflammatory (tumor necrosis factor α [TNF-α]) or chemotactic (IL-8) cytokines was downregulated, whereas induction of cytokines with anti-inflammatory (IL-10) or mucosal adjuvant properties (IL-1β) was upregulated by the enterotoxins. These effects appeared to depend on their A subunits, because isolated B-pentameric subunits lacked regulatory activity. Enterotoxin-mediated inhibition of proinflammatory cytokine induction in activated cells was partially attributable to synergism for endogenous production of IL-10 and to an IL-10-independent inhibition of nuclear factor κB (NF-κB) activation. In sharp contrast to the holotoxins, the B pentamers (LT-IIaB and, to a greater extent, LT-IIbB) stimulated cytokine production, suggesting a link between the absence of the A subunit and increased proinflammatory properties. In this regard, the ability of LT-IIbB to activate NF-κB and induce TNF-α and IL-8 was antagonized by the LT-IIb holotoxin. These findings support distinct immunomodulatory roles for the LT-II holotoxins and their respective B pentamers. Moreover, the anti-inflammatory properties of the holotoxins may serve to suppress innate immunity and promote the survival of the pathogen.
Suppression ofPlasmodium chabaudiParasitemia Is Independent of the Action of Reactive Oxygen Intermediates and/or Nitric Oxide
Authors: Gillman Brad M. , Batchelder Joan , Flaherty Patrick , Weidanz William P. 
Published: October 2004

ABSTRACTThe killing of blood-stage malaria parasites in vivo has been attributed to reactive intermediates of oxygen (ROI) and of nitrogen (RNI). However, in the case of the latter, this contention is challenged by recent observations that parasitemia was not exacerbated in nitric oxide synthase (NOS) knockout (KO) (NOS2−/−or NOS3−/−) mice or in mice treated with NOS inhibitors. We now report that the time course shows thatPlasmodium chabaudiparasitemia in NADPH oxidase KO (p47phox−/−) mice also was not exacerbated, suggesting a minimal role for ROI-mediated killing of blood-stage parasites. It is possible that the production of protective antibodies during malaria may mask the function of ROI and/or RNI. However, parasitemia in B-cell-deficient JH−/−× NOS2−/−or JH−/−× p47phox−/−mice was not exacerbated. In contrast, the magnitude of peak parasitemia was significantly enhanced in p47phox−/−mice treated with the xanthine oxidase inhibitor allopurinol, but the duration of patent parasitemia was not prolonged. Whereas the time course of parasitemia in NOS2−/−× p47phox−/−mice was nearly identical to that seen in normal control mice, allopurinol treatment of these double-KO mice also enhanced the magnitude of peak parasitemia. Thus, ROI generated via the xanthine oxidase pathway contribute to the control of ascendingP. chabaudiparasitemia during acute malaria but alone are insufficient to suppress parasitemia to subpatent levels. Together, these results indicate that ROI or RNI can contribute to, but are not essential for, the suppression of parasitemia during blood-stage malaria.