bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Modified Hepatitis B Virus Core Particle Containing Multiple Epitopes of thePlasmodium falciparumCircumsporozoite Protein Provides a Highly Immunogenic Malaria Vaccine in Preclinical Analyses in Rodent and Primate Hosts
Authors: Birkett A. , Lyons K. , Schmidt A. , Boyd D. , Oliveira G. A. , Siddique A. , Nussenzweig R. , Calvo-Calle J. M. , Nardin E. 
Published: November 2002

ABSTRACTDespite extensive public health efforts, there are presently 200 to 400 million malaria infections and 1 to 2 million deaths each year due to thePlasmodiumparasite. A prime target for malaria vaccine development is the circumsporozoite (CS) protein, which is expressed on the extracellular sporozoite and the intracellular hepatic stages of the parasite. Previous studies in rodent malaria models have shown that CS repeat B-cell epitopes expressed in a recombinant hepatitis B virus core (HBc) protein can elicit protective immunity. To design a vaccine for human use, a series of recombinant HBc proteins containing epitopes ofPlasmodium falciparumCS protein were assayed for immunogenicity in mice [A. Birkett, B. Thornton, D. Milich, G. A. Oliveira, A. Siddique, R. Nussenzweig, J. M. Calvo-Calle, and E. H. Nardin, abstract from the 50th Annual Meeting of the American Society of Tropical Medicine and Hygiene 2001, Am. J. Trop. Med. Hyg. 65(Suppl. 3):258, 2001; D. R. Milich, J. Hughes, J. Jones, M. Sallberg, and T. R. Phillips, Vaccine 20:771-788, 2001]. The present paper summarizes preclinical analyses of the optimalP. falciparumHBc vaccine candidate, termed ICC-1132, which contains T- and B-cell epitopes from the repeat region and a universal T-cell epitope from the C terminus of the CS protein. The vaccine was highly immunogenic in mice and inMacaca fascicularis(cynomolgus) monkeys. When formulated in adjuvants suitable for human use, the vaccine elicited antisporozoite antibody titers that were logs higher than those obtained in previous studies. Human malaria-specific CD4+-T-cell clones and T cells of ICC-1132-immunized mice specifically recognized malaria T-cell epitopes contained in the vaccine. In addition to inducing strong malaria-specific immune responses in naïve hosts, ICC-1132 elicited potent anamnestic antibody responses in mice primed withP. falciparumsporozoites, suggesting potential efficacy in enhancing the sporozoite-primed immune responses of individuals living in areas where malaria is endemic.
Genomic Scale Analysis of
Pasteurella multocida
Gene Expression during Growth within the Natural Chicken Host
Authors: Boyce John D. , Wilkie Ian , Harper Marina , Paustian Mike L. , Kapur Vivek , Adler Ben 
Published: November 2002

ABSTRACT

Little is known about the genomic-scale transcriptional responses of bacteria during natural infections. We used whole-genome microarray analysis to assess the transcriptional state of the gram-negative pathogen
Pasteurella multocida
, the causative agent of fowl cholera, during infection in the natural chicken host. We compared the expression profiles of bacteria harvested from the blood of septicemic chickens experiencing late-stage fowl cholera with those from bacteria grown in rich medium. Independent analysis of bacterial expression profiles from the infection of three individual chickens indicated that 40 genes were differentially expressed in all three individuals, 126 were differentially expressed in two of the three individuals, and another 372 were differentially expressed in one individual. Real-time reverse transcription-PCR assays were used to confirm the expression ratios for a number of genes. Of the 40 genes differentially expressed in all three individuals, 17 were up-regulated and 23 were down-regulated in the host compared with those grown in rich medium. The majority (10 of 17) of the up-regulated genes were involved in amino acid transport and metabolism and energy production and conversion, clearly indicating how
P. multocida
alters its biosynthetic and energy production pathways to cope with the host environment. In contrast, the majority (15 of 23) of down-regulated genes were of unknown or poorly characterized functions. There were clear differences in gene expression between the bacteria isolated from each of the three chickens, a finding consistent with individual host variation being an important factor in determining pathogen gene expression. Interestingly, bacteria from only two of the three infected animals had a gene expression profile highly similar to that observed during growth under iron-limiting conditions, suggesting that severe iron starvation may not always occur during
P. multocida
infection.
Opsonophagocytosis-Inhibiting Mac Protein of Group A
Streptococcus
: Identification and Characteristics of Two Genetic Complexes
Authors: Lei Benfang , DeLeo Frank R. , Reid Sean D. , Voyich Jovanka M. , Magoun Loranne , Liu Mengyao , Braughton Kevin R. , Ricklefs Stacy , Hoe Nancy P. , Cole Robert L. , Leong John M. , Musser James M. 
Published: November 2002

ABSTRACT

Recently, it was reported that a streptococcal Mac protein (designated Mac
5005
) made by serotype M1 group A
Streptococcus
(GAS) is a homologue of human CD11b that inhibits opsonophagocytosis and killing of GAS by human polymorphonuclear leukocytes (PMNs) (B. Lei, F. R. DeLeo, N. P. Hoe, M. R. Graham, S. M. Mackie, R. L. Cole, M. Liu, H. R. Hill, D. E. Low, M. J. Federle, J. R. Scott, and J. M. Musser, Nat. Med.
7:
1298-1305, 2001). To study
mac
variation and expression of the Mac protein, the gene in 67 GAS strains representing 36 distinct M protein serotypes was sequenced. Two distinct genetic complexes were identified, and they were designated complex I and complex II. Mac variants in each of the two complexes were closely related, but complex I and complex II variants differed on average at 50.66 ± 5.8 amino acid residues, most of which were located in the middle one-third of the protein. Complex I Mac variants have greater homology with CD11b than complex II variants. GAS strains belonging to serotypes M1 and M3, the most abundant M protein serotypes responsible for human infections in many case series, have complex I Mac variants. The
mac
gene was cloned from representative strains assigned to complexes I and II, and the Mac proteins were purified to apparent homogeneity. Both Mac variants had immunoglobulin G (IgG)-endopeptidase activity. In contrast to Mac
5005
(complex I), Mac
8345
(complex II) underwent autooxidation of its cysteine residues, resulting in the loss of IgG-endopeptidase activity. A Mac
5005
Cys94Ala site-specific mutant protein was unable to cleave IgG but retained the ability to inhibit IgG-mediated phagocytosis by human PMNs. Thus, the IgG-endopeptidase activity was not essential for the key biological function of Mac
5005
. Although Mac
5005
and Mac
8345
each have an Arg-Gly-Asp (RGD) motif, the proteins differed in their interactions with human integrins α
v
β
3
and α
IIb
β
3
. Binding of Mac
5005
to integrins α
v
β
3
and α
IIb
β
3
was mediated primarily by the RGD motif in Mac
5005
, whereas binding of Mac
8345
involved the RGD motif and a region in the middle one-third of the molecule whose sequence is different in Mac
8345
and Mac
5005
. Taken together, the data add to the emerging theme in GAS pathogenesis that allelic variation in virulence genes contributes to fundamental differences in host-pathogen interactions among strains.
Purification and Partial Characterization of a 32-Kilodalton Sialic Acid-Specific Lectin from
Aspergillus fumigatus
Authors: Tronchin Guy , Esnault Karine , Sanchez Myriam , Larcher Gerald , Marot-Leblond Agnes , Bouchara Jean-Philippe 
Published: November 2002

ABSTRACT

Adherence of the opportunistic fungus
Aspergillus fumigatus
to the extracellular matrix components is considered a crucial step in the establishment of the infection. Given the high carbohydrate content of these glycoproteins and the role of carbohydrate-protein interactions in numerous adherence processes, the presence of a lectin in
A. fumigatus
was investigated. Different fungal extracts obtained by sonication or grinding in liquid nitrogen from resting or swollen conidia, as well as from germ tubes and mycelium, were tested by hemagglutination assays using rabbit erythrocytes. A lectin activity was recovered in all the extracts tested. However, sonication of resting conidia resulted in the highest specific activity. Purification of the lectin was achieved by gel filtration followed by ion-exchange and hydrophobic-interaction chromatographies. Analysis of the purified lectin by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed an apparent molecular mass of 32 kDa, which is similar to that of the alkaline protease already identified from different strains of
A. fumigatus
. However, as evidenced by the use of an alkaline protease-deficient mutant, the two activities were supported by distinct proteins. In addition, hemagglutination inhibition experiments using different saccharides and glycoproteins demonstrated the specificity of the lectin for sialic acid residues. Together these results suggest that this lectin may contribute to the attachment of conidia to the extracellular matrix components through the recognition of the numerous terminal sialic acid residues of their carbohydrate chains.
Role of Caspase 1 in Murine Antibacterial Host Defenses and Lethal Endotoxemia
Authors: Joshi Vishwas D. , Kalvakolanu Dhananjaya V. , Hebel John R. , Hasday Jeffrey D. , Cross Alan S. 
Published: November 2002

ABSTRACTSepsis is thought to result from an exaggerated innate immune response to microbial components such as lipopolysaccharide (LPS), but the involvement of a specific mechanism(s) has not been identified. We studied the role of caspase 1 (Cas-1) in the murine innate immune response to infection with gram-negative bacteria and to nonlethal and lethal doses of LPS.cas-1−/−and Cas-1 inhibitor (Ac-YVAD-CHO)-treatedcas-1+/+mice were two- to threefold more susceptible to lethalEscherichia coliinfection thancas-1+/+mice. Administration of Cas-1 products, interleukin-18 (IL-18) or IL-1β, protected three of three and six of seven mice, respectively, from lethal infection withE. colicompared to none of six of untreated mice (P= 0.0082). Therefore,cas-1is essential for antibacterial host defense. Nonlethal (75 μg) and lethal (500 μg) doses of LPS induce different patterns of gamma interferon, IL-1β, and IL-18 expression. Consequently, the role of Cas-1, which cleaves pro-IL-18 and pro-IL-1β to their active forms, was investigated in these disparate conditions by using enzymatic assay and reverse transcription-PCR. At 75 μg, LPS induced a transient increase in IL-1β and IL-18 levels in serum, whereas at 500 μg it induced a 1.5-fold-higher IL-18 level in serum, which increased till death. At 75 μg of LPS, spleniccas-1mRNA expression remained unchanged at all time points, but activity increased transiently at 3 h. In lethally treated mice, Cas-1 activity remained elevated until death; however,cas-1mRNA levels increased at 3 h and decreased to basal levels by 8 h. Treatment with Cas-1 inhibitor protected mice from lethal endotoxemia. Thus, Cas-1 is essential for innate antibacterial host defenses and may represent a mechanism of innate immunity that upon excessive stimulation by microbial components may lead to endotoxic shock.
Arginine-Rich Cationic Polypeptides Amplify Lipopolysaccharide-Induced Monocyte Activation
Authors: Bosshart Herbert , Heinzelmann Michael 
Published: November 2002

ABSTRACTThe human neutrophil-derived cationic protein CAP37, also known as azurocidin or heparin-binding protein, enhances the lipopolysaccharide (LPS)-induced release of tumor necrosis factor alpha (TNF-α) in isolated human monocytes. We measured the release of the proinflammatory cytokine interleukin-8 (IL-8) in human whole blood and found that in addition to CAP37, other arginine-rich cationic polypeptides, such as the small structurally related protamines, enhance LPS-induced monocyte activation. As CAP37 and protamines share high levels of arginine content, we tested different synthetic poly-l-amino acids and found that poly-l-arginine, and to a lesser extent poly-l-lysine, increased IL-8 production in LPS-stimulated human whole blood. Protamine-enhanced LPS responses remained unaffected by the presence of freel-arginine orl-lysine, indicating that basic polypeptides but not basic amino acids act synergistically with LPS. In agreement with observations previously reported for CAP37, the LPS-enhancing effect of poly-l-arginine was completely abolished upon antibody blockade of the human LPS receptor, CD14. Protamines, either immobilized or in solution, bound LPS specifically. Poly-l-arginines, protamines, and CAP37 were equally effective in inhibiting binding of LPS to immobilizedl-arginines. Taken together, our results suggest a CD14-dependent mechanism by which arginine-rich cationic proteins modulate LPS-induced monocyte activation and support the prediction that other strongly basic proteins could act as amplifiers of LPS responses.
B-Cell-Deficient Mice Show an Exacerbated Inflammatory Response in a Model ofChlamydophila abortusInfection
Authors: Buendía Antonio J. , Del Río Laura , Ortega Nieves , Sánchez Joaquín , Gallego María C. , Caro María R. , Navarro Jose A. , Cuello Francisco , Salinas Jesús 
Published: November 2002

ABSTRACTThe resolution ofChlamydophila abortus(Chlamydia psittaciserotype 1) infection is dependent on gamma interferon and CD8+T cells, and classically, B cells have been considered to play a minimal role in host defense. The role of B cells in the immune response was studied by using a model of infection in mice with genetically modified immunoglobulin M transmembrane domains (μMT). In the absence of B cells, infection withC. abortusleads to an acute severe fatal disease that involves a disseminated intravascular coagulation syndrome. μMT mice displayed an increased level of proinflammatory cytokines in serum, and an increased number of neutrophils was observed in the lesions. The possible deleterious role of neutrophils in the pathogenesis of disease in μMT mice was determined by depletion of the neutrophils with the monoclonal antibody RB6-8C5. This led to an enhancement of the bacterial burden and early mortality in both μMT and wild-type mice, while necrotic lesions remained. Analysis of the presence of immunoregulatory cytokines showed significantly lower levels of transforming growth factor β in the sera of μMT mice. However, mice lacking mature B cells were able to establish a specific immune response that protected them from a secondary challenge. Taken together, these data suggest an immunomodulatory role for B cells in the early events ofC. abortusprimary infection that can protect mice against an exaggerated inflammatory response.
Association between the Tumor Necrosis Factor Locus and the Clinical Outcome ofLeishmania chagasiInfection
Authors: Karplus Theresa M. , Jeronimo Selma M. B. , Chang Haeok , Helms Bethany K. , Burns Trudy L. , Murray Jeffrey C. , Mitchell Adele A. , Pugh Elizabeth W. , Braz Regina F. S. , Bezerra Fabiana L. , Wilson Mary E. 
Published: November 2002

ABSTRACTA periurban outbreak of visceral leishmaniasis (VL) caused by the protozoanLeishmania chagasiis ongoing outside Natal, northeast Brazil. Manifestations range from asymptomatic infection to disseminated visceral disease. Literature reports suggest that both genetic and environmental factors influence the outcome of infection. Due to the association of the tumor necrosis factor (TNF) locus with other infectious diseases, we examined whether polymorphic alleles at this locus are associated with the outcome ofL. chagasiinfection. Neighborhoods with ongoing transmission were identified through patients admitted to local hospitals. Altogether, 1,024 individuals from 183 families were classified with the following disease phenotypes: (i) symptomatic VL, (ii) asymptomatic infection (positive delayed-type hypersensitivity [DTH+]), or (iii) no evidence of infection (DTH−). Genotypes were determined at a microsatellite marker (MSM) upstream of theTNFBgene encoding TNF-β and at a restriction fragment length polymorphism (RFLP) at position −307 in the promoter of theTNFAgene encoding TNF-α. Analyses showed that the distribution ofTNFARFLP alleles (TNF1 and TNF2) and the TNF MSM alleles (TNFa1 to TNFa15) differed between individuals with VL and those with DTH+ phenotypes. TNF1 was transmitted more frequently than expected from heterozygous parents to DTH+ offspring (P= 0.0006), and haplotypes containing TNF2 were associated with symptomatic VL (P= 0.0265, transmission disequilibrium test). Resting serum TNF-α levels were higher in TNF1/2 heterozygotes than in TNF1/1 homozygotes (P< 0.05). These data led us to hypothesize that an individual's genotype at the TNF locus may be associated with whether he or she develops asymptomatic or symptomatic disease afterL. chagasiinfection. The results preliminarily suggest that this may be the case, and follow-up with larger populations is needed for verification.
Rapid Translocation of Polarized MDCK Cell Monolayers by
Leptospira interrogans
, an Invasive but Nonintracellular Pathogen
Authors: Barocchi Michele A. , Ko Albert I. , Reis Mitermayer Galvão , McDonald Kent L. , Riley Lee W. 
Published: November 2002

ABSTRACT

Pathogenic spirochetes of the genus
Leptospira
are a major cause of human zoonotic infectious disease worldwide. After gaining entry through the skin, the organism causes disease by hematogenously disseminating to multiple organs. The mechanism by which it penetrates the mammalian cell barriers to disseminate is not well understood. In this study, we used a low-passage-number isolate of
Leptospira interrogans
to elucidate the invasive potential of this spirochete. Quantification of bacteria by dark-field microscopy revealed that pathogenic spirochetes were able to translocate through polarized MDCK cell monolayers at a rate significantly greater than that of nonpathogenic
Leptospira
or a recognized invasive bacterial pathogen,
Salmonella
. In contrast to
Salmonella
,
L. interrogans
did not alter transepithelial electrical resistance during cell translocation. Both transmission and scanning electron microscopy revealed tight association of the extracellular spirochetes with the host cell plasma membrane, without membrane perturbations suggestive of cytoskeletal rearrangement. Spirochetes were not observed within intercellular junctions or membrane-bound compartments inside cells. They were found within the cytoplasm of only 8% of the counted cells. These results indicate that
Leptospira
is an invasive but not a facultative intracellular organism. We propose that the rapid translocation of mammalian cells by pathogenic
Leptospira
is a mechanism designed to evade killing by host cells that permits the organism to quickly reach the bloodstream and disseminate to multiple organs.
The Function of Gamma Interferon-Inducible GTP-Binding Protein IGTP in Host Resistance toToxoplasma gondiiIs Stat1 Dependent and Requires Expression in Both Hematopoietic and Nonhematopoietic Cellular Compartments
Authors: Collazo Carmen M. , Yap George S. , Hieny Sara , Caspar Patricia , Feng Carl G. , Taylor Gregory A. , Sher Alan 
Published: November 2002

ABSTRACTIGTP is a member of the 47-kDa family of gamma interferon (IFN-γ)-induced GTPases. We have previously shown that IGTP is critical for host resistance toToxoplasma gondiiinfection. In the present study, we demonstrate thatT. gondii-induced IGTP expression in vivo and IFN-γ-driven synthesis of the protein in vitro are dependent on Stat1. Consistent with this observation, Stat1-deficient animals succumbed toT. gondiiinfection with the same rapid kinetics as IGTP−/−mice. To ascertain the cellular levels at which IGTP functions in host control of acute infection, we constructed reciprocal bone marrow chimeras between IGTP-deficient and wild-type mice. Resistance to infection was observed only when IGTP was present in both hematopoietic and nonhematopoietic compartments. To assess the possible contribution of IGTP to the maintenance of parasite latency, partial chemotherapy was used to allow the establishment of chronic infection in IGTP-deficient animals. Upon cessation of drug treatment, these animals showed delayed mortality compared with similarly infected and treated IFN-γ-deficient or inducible nitric oxide synthase-deficient mice, which succumbed rapidly. Parallel experiments performed with drug-treated bone marrow chimeras supported a role for the hematopoietic compartment in this NO-dependent, IGTP-independent control of chronic infection. Taken together, our findings demonstrate that host resistance mediated by IGTP is a Stat1-induced function which in the case ofT. gondiiacts predominantly to restrict acute as opposed to chronic infection. This effector mechanism requires expression of IGTP in cells of both hematopoietic and nonhematopoietic origin. In contrast, in latent infection, hematopoietically derived cells mediate resistance by means of a largely NO-dependent pathway.
Contribution of Interleukin-12 (IL-12) and the CD28/B7 and CD40/CD40 Ligand Pathways to the Development of a Pathological T-Cell Response in IL-10-Deficient Mice
Authors: Wille Ulrike , Villegas Eric N. , Craig Linden , Peach Robert , Hunter Christopher A. 
Published: November 2002

ABSTRACTThe ability of interleukin-10 (IL-10) to suppress accessory cell functions required for optimal T-cell activation makes it an important inhibitor of cell-mediated immunity. Thus, after infection with the protozoan parasiteToxoplasma gondii, IL-10 knockout (KO) mice develop a CD4+-T-cell-dependent shock-like reaction with high levels of IL-12 and gamma interferon (IFN-γ) in serum, leading to death of mice during the acute phase of infection. Previous studies from this laboratory have shown that simultaneous blockade of CD28 and CD40 can prevent this lethal reaction by inhibiting the production of IFN-γ. However, the blockade of costimulation did not affect systemic levels of IL-12. To better understand the relationship between IL-12 and the CD28 and CD40 pathways in mediating immune hyperactivity, antagonists of these factors were used to determine their effects on the development of a pathological T-cell response in IL-10 KO mice. Blockade of IL-12 or the CD28/B7 interaction alone did not affect survival; however, the combined blockade of both pathways resulted in decreased production of IFN-γ and the survival of IL-10 KO mice. To assess the role of the two ligands for CD28, B7.1 and B7.2, IL-10 KO mice were treated with αIL-12 plus αB7.1 or αB7.2 or the combination of all three antibodies. These studies revealed that blockade of both B7 molecules is required for decreased production of IFN-γ and survival of infected IL-10 KO mice, suggesting that B7.1 and B7.2 can contribute to the lethal shock-like reaction in IL-10 KO mice. In contrast, neutralization of IL-12 and blockade of the CD40/CD40 ligand (CD40L) interaction in vivo did not alter the production of IFN-γ and only resulted in a small delay in time to death of mice. Together, these data suggest that the CD28/B7 interaction has a central role in the development of a pathological T-cell response in IL-10 KO mice, which is distinct from the role of the CD40/CD40L and IL-12 pathways.