bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interleukin-12 Is Capable of Generating an Antigen-Specific Th1-Type Response in the Presence of an Ongoing Infection-Driven Th2-Type Response
Authors: Schopf Lisa R. , Bliss Judy L. , Lavigne Liz M. , Chung Charles L. , Wolf Stanley F. , Sypek Joseph P. 
Published: December 2019

ABSTRACTPreviously we demonstrated that recombinant murine interleukin-12 (rmIL-12) administration can promote a primary Th1 response while suppressing the Th2 response in mice primed with 2,4,6-trinitrophenyl–keyhole limpet hemocyanin (TNP-KLH). The present studies examined the capacity of rmIL-12 to drive a Th1 response to TNP-KLH in the presence of an ongoing Th2-mediated disease. To establish a distinct Th2 response, we used a murine model of leishmaniasis. Susceptible BALB/c mice produce a strong Th2 response when infected withLeishmania majorand develop progressive visceral disease. On day 26 postinfection, when leishmaniasis was well established, groups of mice were immunized with TNP-KLH in the presence or absence of exogenous rmIL-12. Even in the presence of overt infection, TNP-KLH-plus-rmIL-12-immunized mice were still capable of generating KLH-specific gamma interferon (IFN-γ) as well as corresponding TNP-specific immunoglobulin G2a (IgG2a) titers. In addition, the KLH-specific IL-4 was suppressed in infected mice immunized with rmIL-12. However, parasite-specific IL-4 and IgG1 production with a lack of parasite-specific IFN-γ secretion were maintained in all infected groups of mice including those immunized with rmIL-12. These data show that despite the ongoing infection-driven Th2 response, rmIL-12 was capable of generating an antigen-specific Th1 response to an independent immunogen. Moreover, rmIL-12 administered with TNP-KLH late in infection did not alter the parasite-specific cytokine or antibody responses.
Antibody Response to
Cryptococcus neoformans
Proteins in Rodents and Humans
Authors: Chen Lin-Chi , Goldman David L. , Doering Tamara L. , Pirofski Liise-anne , Casadevall Arturo 
Published: December 2019

ABSTRACT

The prevalence and specificity of serum antibodies to
Cryptococcus neoformans
proteins was studied in mice and rats with experimental infection, in individuals with or without a history of potential laboratory exposure to
C. neoformans
, human immunodeficiency virus (HIV)-positive individuals who developed cryptococcosis, in matched samples from HIV-positive individuals who did not develop cryptococcosis, and in HIV-negative individuals. Rodents had little or no serum antibody reactive with
C. neoformans
proteins prior to infection. The intensity and specificity of the rodent antibody response were dependent on the species, the mouse strain, and the viability of the inoculum. All humans had serum antibodies reactive with
C. neoformans
proteins regardless of the potential exposure, the HIV infection status, or the subsequent development of cryptococcosis. Our results indicate (i) a high prevalence of antibodies reactive with
C. neoformans
proteins in the sera of rodents after cryptococcal infection and in humans with or without HIV infection; (ii) qualitative and quantitative differences in the antibody profiles of HIV-positive individuals; and (iii) similarities and differences between humans, mice, and rats with respect to the specificity of the antibodies reactive with
C. neoformans
proteins. The results are consistent with the view that
C. neoformans
infections are common in human populations, and the results have implications for the development of vaccination strategies against cryptococcosis.
Bovine γδ T-Cell Responses to the Intracellular Protozoan ParasiteTheileria parva
Authors: Daubenberger Claudia A. , Taracha Evans L. N. , Gaidulis Laima , Davis William C. , McKeever Declan J. 
Published: December 2019

ABSTRACTT cells bearing the γδ antigen receptor (γδ T cells) can constitute up to 50% of T cells in the peripheral blood and lymphoid organs of young cattle. We present data showing that γδ T cells are involved in immune responses againstTheileria parva. γδ T cells isolated from peripheral blood mononuclear cells (PBMC) ofT. parva-naive and -immune cattle proliferated in the presence of fixed or unfixed autologousT. parva-infected lymphoblasts (TpL) and heat-stressed concanavalin A (ConA)-induced blasts (ConA blasts) but not untreated ConA blasts. The specificity of response was further evaluated with a panel of γδ T-cell lines and clones. T-cell reactivity was blocked by GB21A, a monoclonal antibody (MAb) specific for the γδ T-cell receptor, but not by MAbs specific for class I and class II major histocompatibility complex (MHC) molecules. In addition, TpL but not ConA blasts from a variety of MHC-mismatched animals induced proliferation of the γδ T-cell lines and clones. These γδ T cells were found to respond to TpL infected with several different parasite stocks and failed to recognize TpL after elimination of the parasite by the theilericidal drug BW 720C. Assays for cytotoxic activity of γδ T cells sorted from bulk cultures of immune PBMC restimulated several times with autologous TpL demonstrated that effector cells whose specificity is similar to that of proliferating cells are generated. These results suggest that bovine γδ T cells are activated by and lyseT. parva-infected cells by recognizing conserved parasite-induced or parasite-derived antigens in an MHC-unrestricted fashion.
Green Fluorescent Protein as a Marker in
Plasmodium berghei
Transformation
Authors: Sultan Ali A. , Thathy Vandana , Nussenzweig Victor , Ménard Robert 
Published: December 2019

ABSTRACT

We present a new marker that confers both resistance to pyrimethamine and green fluorescent protein-based fluorescence on the malarial parasite
Plasmodium berghei
. A single copy of the cassette integrated into the genome is sufficient to direct fluorescence in parasites throughout the life cycle, in both its mosquito and vertebrate hosts. Erythrocyte stages of the parasite that express the marker can be sorted from control parasites by flow cytometry. Pyrimethamine pressure is not necessary for maintaining the cassette in transformed parasites during their sporogonic cycle in mosquitoes, including when it is borne by a plasmid. This tool should thus prove useful in molecular studies of
P. berghei
, both for generating parasite variants and monitoring their behavior.
Suppression of Platelet Aggregation byBordetella pertussisAdenylate Cyclase Toxin
Authors: Iwaki Masaaki , Kamachi Kazunari , Heveker Nikolaus , Konda Toshifumi 
Published: December 2019

ABSTRACTThe effect ofBordetella pertussisadenylate cyclase toxin (ACT) on platelet aggregation was investigated. This cell-invasive adenylate cyclase completely suppressed ADP (10 μM)-induced aggregation of rabbit platelets at 3 μg/ml and strongly suppressed thrombin (0.2 U/ml)-induced aggregation at 10 μg/ml. The suppression was accompanied by marked increase in platelet intracellular cyclic AMP (cAMP) content and was diminished by the anti-ACT monoclonal antibody B7E11. A catalytically inactive point mutant of ACT did not show the suppressive effect. Since an increase of cAMP content is a known cause of platelet dysfunction, these results indicate that the observed platelet inactivation was due to the catalytic activity of ACT through increase of intracellular cAMP.
Platelet-Activating Factor Induces Nitric Oxide Synthesis inTrypanosoma cruzi-Infected Macrophages and Mediates Resistance to Parasite Infection in Mice
Authors: Aliberti Júlio C. S. , Machado Fabiana S. , Gazzinelli Ricardo T. , Teixeira Mauro M. , Silva João S. 
Published: December 2019

ABSTRACTTrypanosoma cruzireplicates in nucleated cells and is susceptible to being killed by gamma interferon-activated macrophages through a mechanism dependent upon NO biosynthesis. In the present study, the role of platelet-activating factor (PAF) in the induction of NO synthesis and in the activation of the trypanocidal activity of macrophages was investigated. In vitro, PAF induced NO secretion byT. cruzi-infected macrophages and the secreted NO inhibited intracellular parasite growth. The addition of a PAF antagonist, WEB 2170, inhibited both NO biosynthesis and trypanocidal activity. The inducible NO synthase/l-arginine pathway mediated trypanocidal activity, since it was inhibited by treatment withl-N-monomethyl arginine (l-NMMA), anl-arginine analog. PAF-mediated NO production in infected macrophages appears to be dependent on tumor necrosis alpha (TNF-α) production, since the addition of a neutralizing anti-TNF-α monoclonal antibody mAb inhibited NO synthesis. To test the role of PAF in mediating resistance or susceptibility toT. cruziinfection, infected mice were treated with WEB 2170, a PAF antagonist. These animals had higher parasitemia and earlier mortality than did vehicle-treated mice. Taken together, our results suggest that PAF belongs to a group of mediators that coordinate the mechanisms of resistance to infections with intracellular parasites.
Resistance toCoccidioides immitisin Mice after Immunization with Recombinant Protein or a DNA Vaccine of a Proline-Rich Antigen
Authors: Abuodeh Raed O. , Shubitz Lisa F. , Siegel Erin , Snyder Shannon , Peng Tao , Orsborn Kris I. , Brummer Elmer , Stevens David A. , Galgiani John N. 
Published: December 2019

ABSTRACTTwo inbred strains of mice (BALB/c and C57BL/6) were vaccinated with either recombinant expression protein of aCoccidioides immitisspherule-derived proline-rich antigen (rPRA) in monophosphoryl lipid A-oil emulsion adjuvant or a DNA vaccine based on the same antigen. Four weeks after vaccination, mice were infected intraperitoneally with arthroconidia. By 2 weeks, groups of mice receiving saline or plasmids with no PRA insert exhibited significant weight loss, and quantitative CFUs in the lungs ranged from 5.9 to 6.4 log10. In contrast, groups of mice immunized with either rPRA or DNA vaccine had significantly smaller pulmonary fungal burdens, ranging from 3.0 to 4.5 log10fewer CFUs. In vitro immunologic markers of lymphocyte proliferation and gamma interferon (IFN-γ) release after splenocytes were stimulated with rPRA correlated with protection. Also, plasma concentrations of rPRA-specific total immunoglobulin G (IgG), IgG1, and IgG2a showed increases in vaccinated mice. These studies expand earlier work by demonstrating protection in mice which differ inH-2background, by using an adjuvant that is potentially applicable to human use, and by achieving comparable protections with a DNA-based vaccine. Our in vitro results substantiate a Th1 response as evidenced by IFN-γ release and increased IgG2a. However, IgG1 was also stimulated, suggesting some Th2 response as well. PRA is a promising vaccine candidate for prevention of coccidioidomycosis and warrants further investigation.
A Longitudinal Study of Human Antibody Responses toPlasmodium falciparumRhoptry-Associated Protein 1 in a Region of Seasonal and Unstable Malaria Transmission
Authors: Fonjungo Peter N. , Elhassan Ibrahim M. , Cavanagh David R. , Theander Thor G. , Hviid Lars , Roper Cally , Arnot David E. , McBride Jana S. 
Published: December 2019

ABSTRACTRhoptry-associated protein 1 (RAP1) ofPlasmodium falciparumis a nonpolymorphic merozoite antigen that is considered a potential candidate for a malaria vaccine against asexual blood stages. In this longitudinal study, recombinant RAP1 (rRAP1) proteins with antigenicity similar to that ofP. falciparum-derived RAP1 were used to analyze antibody responses to RAP1 over a period of 4 years (1991 to 1995) of 53 individuals naturally exposed toP. falciparummalaria. In any 1 year during the study, between 23 and 39% of individuals who had malaria developed immunoglobulin G (IgG) antibodies detectable with at least one rRAP1 protein. However, the anti-RAP1 antibody responses were detected only during or shortly after clinical malarial infections. RAP1 antibody levels declined rapidly (within 1 to 2 months) following drug treatment of the infections. No anti-RAP1 antibodies were usually detected a few months after the end of malaria transmission, during the dry season, or by the start of the next malaria season. Thus, RAP1 IgG responses were very short-lived. The short duration of RAP1 antibody response may explain the apparent lack of response in a surprisingly high proportion of individuals after clinical malarial infections. For some individuals who experienced more than one malarial infection, a higher anti-RAP1 antibody response to subsequent infections than to earlier infections was observed. This suggested secondary responses to RAP1 and thus the development of immunological memory for RAP1.
Effects of Cytotoxic Necrotizing Factor 1 and Lethal Toxin on Actin Cytoskeleton and VE-Cadherin Localization in Human Endothelial Cell Monolayers
Authors: Vouret-Craviari Valérie , Grall Dominique , Flatau Gilles , Pouysségur Jacques , Boquet Patrice , Van Obberghen-Schilling Ellen 
Published: December 2019

ABSTRACTIntegrity of the vascular endothelium is largely dependent on endothelial cell shape and establishment of intercellular junctions. Certain pathogenic bacterial toxins alter the cytoskeletal architecture of intoxicated cells by modulating the GTPase activity of p21 Rho family proteins. In the present study we have analyzed the effect of Rho-directed toxins on the actin cytoskeleton and monolayer integrity of endothelial cells. We report here thatEscherichia colicytotoxic necrotizing factor 1 (CNF1) activates Rho in human umbilical vein endothelial cells (HUVEC). In confluent monolayers, CNF1 treatment induces prominent stress fiber formation without significantly modifying peripheral localization of VE-cadherin, a specific marker of vascular endothelial cell adherens junctions. Further, Rho activation with CNF1 blocks thrombin-induced redistribution of VE-cadherin staining and gap formation in HUVEC monolayers. Inhibition of Rho by prolonged treatment of cells with C3 exoenzyme (Clostridium botulinum) eliminates actin stress fibers without disrupting the continuity of VE-cadherin staining, indicating that Rho-dependent stress fibers are not required for maintaining this adhesion receptor at sites of intercellular contact. Lethal toxin (Clostridium sordellii), an inhibitor of Rac as well as Ras and Rap, potently disrupts the actin microfilament system and monolayer integrity in HUVEC cultures.
Interleukin 5 (IL-5) Is Not Required for Expression of a Th2 Response or Host Resistance Mechanisms during Murine Schistosomiasis Mansoni but Does Play a Role in Development of IL-4-Producing Non-T, Non-B Cells
Authors: Rosa Brunet Laura , Sabin Elizabeth A. , Cheever Allen W. , Kopf Manfred A. , Pearce Edward J. 
Published: December 2019

ABSTRACTDuring schistosomiasis, interleukin-5 (IL-5)-dependent eosinophil responses have been implicated in immunopathology, resistance to superinfection, synergistic interactions with chemotherapeutic agents, and the inductive phase of the egg-induced Th2 response. We examined these issues in IL-5-deficient (IL-5−/−) mice. IL-5−/−and wild-type (WT) mice were indistinguishable in terms of susceptibility to primary infections and the ability to resist secondary infections. Moreover, hepatic pathology was similar in both strains apart from a relative lack of eosinophils and, during chronic infection, a significantly larger mast cell component in the granulomas of IL-5−/−mice. Splenocyte cytokine production in response to soluble egg antigen (SEA) or anti-CD3 revealed no significant differences except for heightened tumor necrosis factor alpha production by cells from chronically infected IL-5−/−mice compared to WT animals. In contrast, ionomycin-stimulated non-B, non-T (NBNT) cells from IL-5−/−mice produced significantly smaller IL-4 amounts than did NBNT cells from WT animals. This difference was not apparent following plate-bound anti-immunoglobulin E or SEA stimulation. The absence of IL-5 failed to affect the induction of Th2 responses in naive mice. Peritoneal exudate cells recovered from egg-injected IL-5−/−or WT mice produced equivalent levels of IL-4 following restimulation with SEA or anti-CD3.
Unanticipated Heterogeneity in Growth Rate and Virulence among
Candida albicans AAF1
Null Mutants
Authors: Rieg Günter , Fu Yue , Ibrahim Ashraf S. , Zhou Xiang , Filler Scott G. , Edwards John E. 
Published: December 2019

ABSTRACT

The disruption of a specific gene in
Candida albicans
is commonly used to determine the function of the gene product. We disrupted
AAF1
, a gene of
C. albicans
that causes
Saccharomyces cerevisiae
to flocculate and adhere to endothelial cells. We then characterized multiple heterozygous and homozygous mutants. These null mutants adhered to endothelial cells to the same extent as did the parent organism. However, mutants with presumably the same genotype revealed significant heterogeneity in their growth rates in vitro. This heterogeneity was not the result of the transformation procedure per se, nor was it caused by differences in the expression or function of URA3, a marker used in the process of gene disruption. The growth rate among the different heterozygous and homozygous null mutants was positively correlated with in vivo virulence in mice. It is possible that the variable phenotypes of
C. albicans
were due to mutations outside of the
AAF1
coding region that were introduced during the gene disruption process. These results indicate that careful phenotypic characterization of mutants of
C. albicans
generated through targeted gene disruption should be performed to exclude the introduction of unexpected mutations that may influence pathogenicity in mice.
Green Fluorescent Protein as a Marker in
Rickettsia typhi
Transformation
Authors: Troyer Jill Michelle , Radulovic Suzana , Azad Abdu F. 
Published: December 2019

ABSTRACT

Transformation of
rickettsiae
is a recent accomplishment, but utility of this technique is limited due to the paucity of selectable markers suitable for use in this intracellular pathogen. We chose a green fluorescent protein variant optimized for fluorescence under UV lights (GFP
UV
) as a fluorometric marker and transformed
Rickettsia typhi
with an
rpoB
-GFP
UV
fusion construct. The rickettsiae were subsequently grown in Vero cells, and cultures were screened by PCR and restriction fragment length polymorphism (RFLP) to confirm incorporation of the
rpoB
-GFP
UV
construct. Cultures were then analyzed by flow cytometry for detection of GFP
UV
expression, and transformed
R. typhi
were isolated in a fluorescence-activated cell sorter. This is the first report of transformation of rickettsiae with a nonrickettsial (GFP
UV
) gene.
A Novel Means of Self-Protection, Unrelated to Toxin Activation, Confers Immunity to the Bactericidal Effects of the
Enterococcus faecalis
Cytolysin
Authors: Coburn Phillip S. , Hancock Lynn E. , Booth Mary C. , Gilmore Michael S. 
Published: December 2019

ABSTRACT

Enterococcus faecalis
has become a pervasive clinical problem due to the emergence of resistance to most antibiotics. The cytolysin of
E. faecalis
is a novel bacterial toxin that contributes to the severity of disease. It consists of two structural subunits, which together possess both hemolytic and bactericidal activity. Both toxin subunits are encoded in a complex operon frequently harbored on pheromone-responsive plasmids.
E. faecalis
strains lacking such plasmids are susceptible to the bactericidal effects of the cytolysin. A novel cytolysin immunity determinant at the 3′ end of the pAD1 cytolysin operon is described in the present study. Deletion analysis and specific mutagenesis isolated the immunity function to a single open reading frame. Specific mutagenesis experiments demonstrate that cytolysin immunity is unrelated to cytolysin activator (CylA) expression as previously proposed. Cytolysin immunity is, however, encoded on the same transcript as and 3′ to CylA, and previous associations between immunity and CylA can be ascribed to the polar behavior of Tn
917
insertion.
Role of Superoxide Dismutase Activity in the Physiology of
Porphyromonas gingivalis
Authors: Lynch Michael C. , Kuramitsu Howard K. 
Published: December 2019

ABSTRACT

Porphyromonas gingivalis
is a gram-negative, obligate anaerobe strongly associated with chronic adult periodontitis. A previous study has demonstrated that this organism requires superoxide dismutase (SOD) for its modest aerotolerance. In this study, we have constructed a mutant deficient in SOD activity by insertional inactivation as well as a
sod
::
lacZ
reporter translational fusion construct to study the regulation of expression of this gene. We have confirmed that SOD is essential for tolerance to atmospheric oxygen but does not appear to be protective against hydrogen peroxide or exogenously generated reactive oxygen species. Furthermore, the
sod
mutant appeared to be no more sensitive to killing by neutrophils than the parental strain 381. SOD appears to be protective against oxygen-dependent DNA damage as measured by increased mutation to rifampin resistance by the
sod
mutant. Use of the
sod
::
lacZ
construct confirmed that SOD expression is maximal at mid-log phase and is influenced by oxygen, temperature, and pH. However, expression does not appear to be significantly affected by iron depletion, osmolarity, or nutrient depletion. The transcription start site of the
sod
gene was determined to be 315 bp upstream of the
sod
start codon and to be within an upstream open reading frame. Our studies demonstrate the essential role that SOD plays in aerotolerance of this organism as well as the selective induction of this enzyme by environmental stimuli.
Mycoplasmal Lipopeptide MALP-2 Induces the Chemoattractant Proteins Macrophage Inflammatory Protein 1α (MIP-1α), Monocyte Chemoattractant Protein 1, and MIP-2 and Promotes Leukocyte Infiltration in Mice
Authors: Deiters Ursula , Mühlradt Peter F. 
Published: December 2019

ABSTRACTNatural as well as experimental infections with pathogenic mycoplasmas lead to cellular responses characterized by early polymorphonuclear leukocyte influx, which in turn is followed by infiltration of macrophages. Since some of the most potent leukocyte chemoattractants are macrophage products, we investigated whether the 2-kDa macrophage-activating lipopeptide (MALP-2) fromMycoplasma fermentanswas capable of inducing chemoattractant chemokines and initiating an in vivo inflammatory effect. MALP-2 was a potent in vitro inducer of the chemokines macrophage inflammatory protein 1α (MIP-1α), monocyte chemoattractant protein 1 (MCP-1), and MIP-2, yielding a maximal response at 0.1 ng/ml (5 × 10−11M). Leukocyte infiltration was determined after intraperitoneal injection of MALP-2, liposome-encapsulated MALP-2, and heat-killed mycoplasmas. There was a steady increase in the number of peritoneal cells over 72 h in response to these agents. Polymorph counts were maximal by 24 to 48 h, decreasing thereafter. Monocytes/macrophages had significantly increased after 3 days. MIP-1α, MCP-1, and MIP-2 levels in serum or peritoneal lavage fluid were determined. MIP-1α and MCP-1 levels were elevated by 2 to 6 h after injection and were still above control values after 24 h. In contrast, MIP-2 levels reached their maximum at 2 h, dropping to control values after 24 h. We conclude that macrophage-stimulating mycoplasmal lipoproteins, exemplified by MALP-2, play an important role in the late phase of phagocyte recruitment at sites of infection and that this is affected by leukoattractive chemokines.