bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Vitro Studies with RecombinantPlasmodium falciparumApical Membrane Antigen 1 (AMA1): Production and Activity of an AMA1 Vaccine and Generation of a Multiallelic Response
Authors: Kennedy Michael C. , Wang Jin , Zhang Yanling , Miles Aaron P. , Chitsaz Farideh , Saul Allan , Long Carole A. , Miller Louis H. , Stowers Anthony W. 
Published: November 2002

ABSTRACTApical membrane antigen 1 (AMA1) is regarded as a leading malaria blood-stage vaccine candidate. While the overall structure of AMA1 is conserved inPlasmodiumspp., numerous AMA1 allelic variants ofP. falciparumhave been described. The effect of AMA1 allelic diversity on the ability of a recombinant AMA1 vaccine to protect against human infection by differentP. falciparumstrains is unknown. We characterize two allelic forms of AMA1 that were both produced inPichia pastorisat a sufficient economy of scale to be usable for clinical vaccine studies. Both proteins were used to immunize rabbits, singly and in combination, in order to evaluate their immunogenicity and the ability of elicited antibodies to block the growth of differentP. falciparumclones. Both antigens, when used alone, elicited high homologous anti-AMA1 titers, with reduced strain cross-reactivity. Similarly, sera from rabbits immunized with a single antigen were capable of blocking the growth of homologous parasite strains at levels theoretically sufficient to clear parasite infections. However, heterologous inhibition was significantly reduced, providing experimental evidence that AMA1 allelic diversity is a result of immune pressure. Encouragingly, rabbits immunized with a combination of both antigens exhibited titers and levels of parasite inhibition as good as those of the single-antigen-immunized rabbits for each of the homologous parasite lines, and consequently exhibited a broadening of allelic diversity coverage.
Vaccination of Monkeys with RecombinantPlasmodium falciparumApical Membrane Antigen 1 Confers Protection against Blood-Stage Malaria
Authors: Stowers Anthony W. , Kennedy Michael C. , Keegan Brian P. , Saul Allan , Long Carole A. , Miller Louis H. 
Published: November 2002

ABSTRACTA major challenge facing malaria vaccine development programs is identifying efficacious combinations of antigens. To date, merozoite surface protein 1 (MSP1) is regarded as the leading asexual vaccine candidate. Apical membrane antigen 1 (AMA1) has been identified as another leading candidate for an asexual malaria vaccine, but without any direct in vivo evidence that a recombinant form ofPlasmodium falciparumAMA1 would have efficacy. We evaluated the efficacy of a form ofP. falciparumAMA1, produced inPichia pastoris, by vaccinatingAotus vociferansmonkeys and then challenging them withP. falciparumparasites. Significant protection from this otherwise lethal challenge withP. falciparumwas observed. Five of six animals had delayed patency; two of these remained subpatent for the course of the infection, and two controlled parasite growth at <0.75% of red blood cells parasitized. The protection induced by AMA1 was superior to that obtained with a form of MSP1 used in the same trial. The protection induced by a combination vaccine of AMA1 and MSP1 was not superior to the protection obtained with AMA1 alone, although the immunity generated appeared to operate against both vaccine components.
Attenuation of the Virulence of
Porphyromonas gingivalis
by Using a Specific Synthetic Kgp Protease Inhibitor
Authors: Curtis M. A. , Aduse Opoku J. , Rangarajan M. , Gallagher A. , Sterne J. A. C. , Reid C. R. , Evans H. E. A. , Samuelsson B. 
Published: November 2002

ABSTRACT

The Arg- and Lys-gingipains of
Porphyromonas gingivalis
are important virulence determinants in periodontal disease and may correspond to targets for immune- or drug-based treatment strategies. In this investigation we aimed to determine which of these enzymes represents the most promising molecular target for protease inhibitor-based therapy and to examine the effectiveness of the resultant compound in a murine virulence assay. Isogenic mutants with mutations in
rgpA
and
rgpB
(encoding Arg-gingipains) and in
kgp
(encoding Lys-gingipain) and a double mutant with mutations in
rgpA
and
rgpB
were prepared by using
P. gingivalis
W50. The virulence of these mutants indicated that Kgp is a promising drug target. Combinatorial chemistry was used to define the optimal substrate of Kgp, and from this information a specific slowly reversible inhibitor with a nanomolar

K
i

was designed and synthesized. Growth of
P. gingivalis
W50 in the presence of this compound resembled the phenotype of the
kgp
isogenic mutant; in both instances bacterial colonies failed to form pigment on blood agar, and only poor growth was obtained in a defined medium containing albumin as the sole protein source. Furthermore, pretreatment of the wild-type organism with the Kgp inhibitor led to a significant reduction in virulence in the murine assay. These data emphasize the conclusion that Kgp is an important factor for both nutrition and virulence of
P. gingivalis
and that inhibitors of this enzyme may have therapeutic potential for the control of
P. gingivalis
infections. Protease inhibitors may be a potentially novel class of antimicrobial agents with relevance to the control of other bacterial pathogens.
Expression of a Novel
Leishmania
Gene Encoding a Histone H1-Like Protein in
Leishmania major
Modulates Parasite Infectivity In Vitro
Authors: Papageorgiou Fotini T. , Soteriadou Ketty P. 
Published: November 2002

ABSTRACT

We describe identification and characterization of a novel two-copy gene of the parasitic protozoan
Leishmania
that encodes a nuclear protein designated LNP18. This protein is highly conserved in the genus
Leishmania
, and it is developmentally regulated. It is an alanine- and lysine-rich protein with potential bipartite nuclear targeting sequence sites. LNP18 shows sequence similarity to H1 histones of trypanosomatids and of higher eukaryotes and in particular with histone H1 of
Leishmania major
. The nuclear localization of LNP18 was determined by indirect immunofluorescence and Western blot analysis of isolated nuclei by using antibodies raised against the recombinant protein as probes. The antibodies recognized predominantly a 18-kDa band or a 18-kDa-16-kDa doublet. Photochemical cross-linking of intact parasites followed by Western blot analysis provided evidence that LNP18 is indeed a DNA-binding protein. Generation of transfectants overexpressing LNP18 allowed us to determine the role of this protein in
Leishmania
infection of macrophages in vitro. These studies revealed that transfectants overexpressing LNP18 are significantly less infective than transfectants with the vector alone and suggested that the level of LNP18 expression modulates
Leishmania
infectivity, as assessed in vitro.
Cryptosporidium parvum
Genes Containing Thrombospondin Type 1 Domains
Authors: Deng Mingqi , Templeton Thomas J. , London Nicole R. , Bauer Carrey , Schroeder Alison A. , Abrahamsen Mitchell S. 
Published: November 2002

ABSTRACT

Cryptosporidium parvum
is recognized as an enteropathogen of great worldwide medical and veterinary importance, yet understanding of its pathogenesis has been hampered in part by limited knowledge of the invasion machinery of this parasite. Recently, genes containing thrombospondin type 1 (TSP1) domains have been identified in several genera of apicomplexans, including thrombospondin-related adhesive proteins (TRAPs) that have been implicated as key molecules for parasite motility and adhesion onto host cell surfaces. Previously, a large-scale random survey of the
C. parvum
genome conducted in our laboratory revealed the presence of multiple genomic DNA sequences with a high degree of similarity to known apicomplexan TRAP genes. In the present study, TBLASTN screening of available
C. parvum
genomic sequences by using TSP1 domains as queries identified a total of 12 genes possessing TSP1-like domains. All genes have putative signal peptide sequences, one or more TSP1-like domains, plus additional extracellular protein modules such as Kringle, epidermal growth factor, and Apple domains. Two genes, putative paralogs
Cp
TSP8 and
Cp
TSP9, contain predicted introns near their amino termini, which were verified by comparing PCR products from cDNA versus genomic DNA templates. Reverse transcription-PCR analysis of transcript levels reveals that
C. parvum
TSP genes were developmentally regulated with distinct patterns of expression during in vitro infection. TRAPC1,
Cp
TSP3, and
Cp
TSP11 were expressed at high levels during both early and late stages of infection, whereas
Cp
TSP2,
Cp
TSP5,
Cp
TSP6,
Cp
TSP8, and
Cp
TSP9 were maximally expressed during the late stages of infection. Only
Cp
TSP4 was highly expressed solely at an early stage of infection.
Identification of Novel
Mycobacterium tuberculosis
Antigens with Potential as Diagnostic Reagents or Subunit Vaccine Candidates by Comparative Genomics
Authors: Cockle P. J. , Gordon S. V. , Lalvani A. , Buddle B. M. , Hewinson R. G. , Vordermeier H. M. 
Published: November 2002

ABSTRACT

An independent review for the British government has concluded that the development of a cattle vaccine against
Mycobacterium bovis
holds the best long-term prospects for tuberculosis control in British herds. The development of complementary diagnostic tests to differentiate between vaccinated and infected animals is necessary to allow the continuation of test-and-slaughter-based control policies alongside vaccination. Vaccination with
M. bovis
bacillus Calmette-Guérin (BCG), the only available vaccine, results in tuberculin purified protein derivative sensitivity and has shown varying vaccine efficacies in cattle. Thus, identification of more-specific reagents to distinguish between vaccination and infection, as well as the identification of subunit vaccine candidates for improved tuberculosis vaccines, is a research priority. In the present study, we applied comparative genomics to identify
M. bovis-Mycobacterium tuberculosis
antigens whose genes had been deleted in BCG Pasteur. In total, 13 open reading frames (ORFs) from the RD1, RD2, and RD14 regions of the
M. tuberculosis
genome were selected. Pools of overlapping peptides spanning these ORFs were tested in
M. bovis
-infected (
n
= 22), BCG-vaccinated (
n
= 6), and unvaccinated (
n
= 10) control cattle. All were recognized in infected cattle, with responder frequencies varying between 16 and 86%. In particular, eight highly immunogenic antigens were identified whose potentials as diagnostic reagents or as subunit vaccines warrant further study (Rv1983, Rv1986, Rv3872, Rv3873, Rv3878, Rv3879c, Rv1979c, and Rv1769).
Virulence Criteria forBrucella abortusStrains as Determined by Interferon Regulatory Factor 1-Deficient Mice
Authors: Ko Jinkyung , Gendron-Fitzpatrick Annette , Ficht Thomas A. , Splitter Gary A. 
Published: November 2002

ABSTRACTInterferon regulatory factor 1-deficient (IRF-1−/−) mice infected with virulentBrucella abortus2308 at 5 × 105CFU developed acute hepatitis similar to many natural hosts but, unlike natural hosts, IRF-1−/−mice were unable to resolve infection and died. In contrast, IRF-1−/−mice survived when infected at 5 × 105CFU with several attenuatedBrucellastrains (S19, RB51, cbp, and cyd). The survival of infected IRF-1−/−mice is likely a function of the level of virulence of eachBrucellastrain and the extent of retained immunity. Further, these findings suggest that adaptive immunity may be important to the survival of IRF-1−/−mice since attenuatedBrucellastrains can protect IRF-1−/−mice against lethal challenge with virulentBrucella. Using the IRF-1−/−mouse model, the following set of criteria were identified to defineBrucellavirulence: (i) the day of death for 50% of mice infected with 5 × 105CFU ofBrucella, (ii) the extent of liver toxicity, and (iii) the minimum immunizing dose ofBrucellato protect against challenge with virulent S2308. Thus, IRF-1−/−mice are important to determining the level ofBrucellavirulence, to evaluatingBrucellamutants for attenuation, and to investigating adaptive immunity in brucellosis.
Recognition of Variant Rifin Antigens by Human Antibodies Induced during Natural
Plasmodium falciparum
Infections
Authors: Abdel-Latif Mohamed S. , Khattab Ayman , Lindenthal Christoph , Kremsner Peter G. , Klinkert Mo-Quen 
Published: November 2002

ABSTRACT

Antibodies from individuals living in areas where malaria is endemic are known to react with parasite-derived erythrocyte surface proteins. The major immunogenic and clonally variant surface antigen described to date is
Plasmodium falciparum
erythrocyte membrane protein 1 (PfEMP-1), which is encoded by members of the multicopy
var
gene family. We report here that rifin proteins (RIF proteins), belonging to the largest known family of variable infected erythrocyte surface-expressed proteins, are also naturally immunogenic. Recombinant RIF proteins were used to analyze the antibody responses of individuals living in an area of intense malaria transmission. Elevated anti-rifin antibody levels were detected in the majority of the adult population tested, whereas the prevalence of such antibodies was much lower in malaria-exposed children. Despite the high degree of diversity between
rif
sequences and the high gene copy number, it appears that
P. falciparum
infections can induce antibodies that cross-react with several variant rifin molecules in many parasite isolates in a given community, and the immune response is most likely to be stable over time in a hyperendemic area. The protein was localized by fluorescence microscopy on the membrane of ring and young trophozoite-infected erythrocytes with antibodies from human immune sera with specificities for recombinant RIF protein.
Pathological and Therapeutic Significance of Cellular Invasion byProteus mirabilisin an Enterocystoplasty Infection Stone Model
Authors: Mathoera Rejiv B. , Kok Dik J. , Verduin Cees M. , Nijman Rien J. M. 
Published: November 2002

ABSTRACTProteus mirabilisinfection often leads to stone formation. We evaluated how bacterium-mucin adhesion, invasion, and intracellular crystal formation are related to antibiotic sensitivity and may cause frequent stone formation in enterocystoplasties. Five intestinal (Caco-2, HT29, HT29-18N2, HT29-FU, and HT29-MTX) and one ureter cell line (SV-HUC-1) were incubated in artificial urine with fiveProteus mirabilisstrains. Fluorescence-activated cell sorting (FACS), laser scanning microscopy, and electron microscopy evaluated cellular adhesion and/or invasion, pathologic changes to mitochondria, andP. mirabilis-mucin colocalization (MUC2 and MUC5AC). An MTT (thiazolyl blue tetrazolium bromide) assay and FACS analysis of caspase-3 evaluated the cellular response. Infected cells were incubated with antibiotics at dosages representing the expected urinary concentrations in a 10-year-old, 30-kg child to evaluate bacterial invasion and survival. All cell lines showed colocalization ofP. mirabiliswith human colonic mucin (i.e., MUC2) and human gastric mucin (i.e., MUC5AC). The correlation between membrane mucin expression and invasion was significant and opposite for SV-HUC-1 and HT29-MTX. Microscopically, invasion byP. mirabiliswith intracellular crystal formation and mitochondrial damage was found. Double membranes surrounded bacteria in intestinal cells. Relative resistance to cotrimoxazole and augmentin was found in the presence of epithelial cells. Ciprofloxacin and gentamicin remained effective. Membrane mucin expression was correlated with relative antibiotic resistance. Cell invasion byP. mirabilisand mucin- and cell type-related distribution and response differences indicate bacterial tropism that affects crystal formation and mucosal presence. Bacterial invasion seems to have cell type-dependent mechanisms and prolong bacterial survival in antibiotic therapy, giving a new target for therapeutic optimalization of antibiotic treatment.
Environmental Regulation and Differential Production of Members of the Bdr Protein Family of
Borrelia burgdorferi
Authors: Roberts David M. , Caimano Melissa , McDowell John , Theisen Michael , Holm Arne , Orff Edward , Nelson David , Wikel Stephen , Radolf Justin , Marconi Richard T. 
Published: November 2002

ABSTRACT

Borrelia burgdorferi
B31MI carries 18 plasmid-carried genes that form the
bdr
gene family. The
bdr
genes of
B. burgdorferi
encode proteins that form three distinct subfamilies, the BdrD, BdrE, and BdrF subfamilies.
bdr
orthologs have been demonstrated to be carried by all
Borrelia
species analyzed, and their widespread distribution suggests that they play an important genus-wide functional role. The biological rationale for maintaining 18
bdr
alleles has not been defined. It is our hypothesis that specific paralogs function in different environments and are differentially expressed in response to environmental conditions. As a first step in testing this hypothesis, the production patterns of the Bdr proteins in spirochetes grown under a variety of conditions were assessed through immunoblot analyses. The influence of temperature, serum deprivation, tick feeding, and the mammalian environment on Bdr production was evaluated. These analyses revealed that the synthesis of some Bdr paralogs is environmentally regulated. The production of BdrF
2,
BdrF
1
, BdrE
4
, and BdrE
5
were upregulated in host-adapted bacteria, while the production levels of other Bdr paralogs were influenced by temperature and serum starvation. These observations suggest that different Bdr paralogs function in different biological environments and provide insight into the biological basis for maintaining multiple members of this gene family.
Effect of Trimethoprim-Sulfamethoxazole on Recurrent Bacteriuria and Bacterial Persistence in Mice Infected with Uropathogenic
Escherichia coli
Authors: Schilling Joel D. , Lorenz Robin G. , Hultgren Scott J. 
Published: November 2002

ABSTRACT

One of the more perplexing aspects of urinary tract infections (UTIs) is their high propensity to recur. It has been proposed that recurrent infections are a result of the reintroduction of bacteria from the gastrointestinal tract (GIT) to the urinary tract (UT); however, since a significant subset of recurrent UTIs are caused by an identical bacterial strain, it has been challenging to formally prove this hypothesis for same-strain recurrences by using epidemiologic approaches. We present data here obtained by using a mouse model of UTIs in which it was shown that 36% (5 of 14) of mice infected with uropathogenic
Escherichia coli
(UPEC) will have at least one bacteriuric recurrence, with 21% (3 of 14) having more than one recurrence during a 6-week period after an acute UTI. Intraurethrally infected mice develop UPEC reservoirs in both their feces and their bladders. Ten days of trimethoprim-sulfamethoxazole (SXT) therapy reduces urinary recurrences and eradicates fecal colonization, whereas 3 days of SXT treatment has no effect over a twenty-eight-day observation period despite clearing fecal colonization acutely. Interestingly, SXT is unable to eradicate bacteria from the bladder reservoir even after a 10-day treatment regimen, thus demonstrating that the bladder reservoir can persist even in the face of long-term antibiotic therapy.
Lactoferrin Protects Rabbits fromShigella flexneri-Induced Inflammatory Enteritis
Authors: Gomez Henry F. , Ochoa Theresa J. , Herrera-Insua Irene , Carlin Lily G. , Cleary Thomas G. 
Published: November 2002

ABSTRACTShigellaspecies cause bacillary dysentery in humans by invasion, intracellular multiplication, spread to adjacent cells, and induction of brisk inflammatory responses in the intestinal epithelium. In vitro data suggest that lactoferrin, a glycoprotein present in human mucosal secretions, has a role in protection from bacterial enteric infections. We sought to determine the activity of lactoferrin in vivo, using the concentration present in human colostrum, to investigate its effect on the development of clinical and pathological evidence of inflammation in a rabbit model of enteritis. Lactoferrin protected rabbits infected withShigella flexnerifrom developing inflammatory intestinal disease. Typical histological changes in ill animals included villous blunting with sloughing of epithelial cells, submucosal edema, infiltration of leukocytes, venous congestion, and hemorrhage. Lactoferrin at a concentration normally found in human colostrum blocks development ofS. flexneri-induced inflammatory enteritis.
The Bacterial Redox Protein Azurin Induces Apoptosis in J774 Macrophages through Complex Formation and Stabilization of the Tumor Suppressor Protein p53
Authors: Yamada Tohru , Goto Masatoshi , Punj Vasu , Zaborina Olga , Kimbara Kazuhide , Das Gupta T. K. , Chakrabarty A. M. 
Published: November 2002

ABSTRACT

Two redox proteins, azurin and cytochrome
c
551
elaborated by
Pseudomonas aeruginosa
, demonstrate significant cytotoxic activity towards macrophages. Azurin can enter macrophages, localize in the cytosol and nuclear fractions, and induce apoptosis. Two redox-negative mutants of azurin have less cytotoxicity than does wild-type (wt) azurin. Azurin has been shown to form a complex with the tumor suppressor protein p53, a known inducer of apoptosis, thereby stabilizing it and enhancing its intracellular level. A higher level of reactive oxygen species (ROS), generated during treatment of macrophages with wt azurin, correlates with its cytotoxicity. Treatment with some ROS-removing antioxidants greatly reduces azurin-mediated cytotoxicity, thus demonstrating a novel virulence property of this bacterial redox protein.
Comparative Genomics Identifies the Genetic Islands That Distinguish
Neisseria meningitidis
, the Agent of Cerebrospinal Meningitis, from Other
Neisseria
Species
Authors: Perrin Agnès , Bonacorsi Stéphane , Carbonnelle Etienne , Talibi Driss , Dessen Philippe , Nassif Xavier , Tinsley Colin 
Published: November 2002

ABSTRACT

Neisseria meningitidis
colonizes the nasopharynx and, unlike commensal
Neisseria
species, is capable of entering the bloodstream, crossing the blood-brain barrier, and invading the meninges. The other pathogenic
Neisseria
species,
Neisseria gonorrhoeae
, generally causes an infection which is localized to the genitourinary tract. In order to investigate the genetic basis of this difference in disease profiles, we used a strategy of genomic comparison. We used DNA arrays to compare the genome of
N. meningitidis
with those of
N. gonorrhoeae
and
Neisseria lactamica
, a commensal of the nasopharynx. We thus identified sequences conserved among a representative set of virulent strains which are either specific to
N. meningitidis
or shared with
N. gonorrhoeae
but absent from
N. lactamica
. Though these bacteria express dramatically different pathogenicities, these meningococcal sequences were limited and, in contrast to what has been found in other pathogenic bacterial species, they are not organized in large chromosomal islands.