Digital Commons Network^™

Salicylic Acid Attenuates Virulence In Endovascular Infections By Targeting Global Regulatory Pathways In Staphylococcus Aureus, Leon Iri Kupferwasser, Michael R. Yeaman, Cynthia C. Nast, Deborah Kupferwasser, Yan-Qiong Xiong, Marco Palma, Ambrose L. Cheung, Arnold S. Bayer

Dartmouth Scholarship

Aspirin has been previously shown to reduce the in vivo virulence of Staphylococcus aureus in experimental endocarditis, through antiplatelet and antimicrobial mechanisms. In the present study, salicylic acid, the major in vivo metabolite of aspirin, mitigated two important virulence phenotypes in both clinical and laboratory S. aureus strains: α-hemolysin secretion and fibronectin binding in vitro. In addition, salicylic acid reduced the expression of the α-hemolysin gene promoter, hla, and the fibronectin gene promoter, fnbA. Transcriptional analysis, fluorometry, and flow cytometry revealed evidence of salicylic acid–mediated activation of the stress-response gene sigB. Expression of the sigB-repressible global …

G03-1513 Understanding Fungal (Mold) Toxins (Mycotoxins), Michael P. Carlson, Steveb M. Ensley

University of Nebraska-Lincoln Extension: Historical Materials

Mycotoxins are chemicals produced by fungi (molds) under certain conditions. They are not essential for fungal growth or reproduction, and are toxic to animals or humans.

This NebGuide briefly discusses mycotoxins commonly encountered in grains and feeds used in Nebraska and the mycotoxicoses they cause. Mycotoxin sources and clinical signs, lesions, diagnostic aids and treatment for each mycotoxicosis are listed.

Polyadenylation Regulates The Stability Of Trypanosoma Brucei Mitochondrial Rnas, Christopher M. Ryan, Kevin T. Militello, Laurie K. Read

Biology

Polyadenylation of RNAs plays a critical role in modulating rates of RNA turnover and ultimately in controlling gene expression in all systems examined to date. In mitochondria, the precise mechanisms by which RNAs are degraded, including the role of polyadenylation, are not well understood. Our previous in organello pulse-chase experiments suggest that poly(A) tails stimulate degradation of mRNAs in the mitochondria of the protozoan parasite Trypanosoma brucei (Militello, K. T., and Read, L. K. (2000) Mol. Cell. Biol. 21, 731-742). In this report, we developed an in vitro assay to directly examine the effects of specific 3′-sequences on RNA degradation. …

Identification Of The Vibrio Cholerae Enterobactin Receptors Vcta And Irga: Irga Is Not Required For Virulence, Alexandra R. Mey, Elizabeth E. Wyckoff, Amanda G. Oglesby, Eva Rab, Ronald K. Taylor, Shelley M. Payne

Dartmouth Scholarship

The gram-negative enteric pathogen Vibrio cholerae requires iron for growth. V. cholerae has multiple iron acquisition systems, including utilization of heme and hemoglobin, synthesis and transport of the catechol siderophore vibriobactin, and transport of several siderophores that it does not itself make. One siderophore that V. cholerae transports, but does not make, is enterobactin. Enterobactin transport requires TonB and is independent of the vibriobactin receptor ViuA. In this study, two candidate enterobactin receptor genes, irgA (VC0475) and vctA (VCA0232), were identified by analysis of the V. cholerae genomic sequence. A single mutation in either of these genes did not significantly …

Treatment With Soluble Interleukin-15ralpha Exacerbates Intracellular Parasitic Infection By Blocking The Development Of Memory Cd8+ T Cell Response, Imtiaz A. Khan, Magali Moretto, Xiao-Qing Wei, Martha Williams, Joseph D. Schwartzman, F Y. Liew

Dartmouth Scholarship

Interferon (IFN)-γ–producing CD8⁺ T cells are important for the successful resolution of the obligate intracellular parasite Toxoplasma gondii by preventing the reactivation or controlling a repeat infection. Previous reports from our laboratory have shown that exogenous interleukin (IL)-15 treatment augments the CD8⁺ T cell response against the parasite. However, the role of endogenous IL-15 in the proliferation of activated/memory CD8⁺ T cells during toxoplasma or any other infection is unknown. In this study, we treated T. gondii immune mice with soluble IL-15 receptor α (sIL-15Rα) to block the host endogenous IL-15. The treatment markedly reduced the ability …

Cd8+-T-Cell Immunity Against Toxoplasma Gondii Can Be Induced But Not Maintained In Mice Lacking Conventional Cd4+ T Cells, Lori Casciotti, Kenneth H. Ely, Martha E. Williams, Imtiaz A. Khan

Dartmouth Scholarship

T-cell immunity is critical for survival of hosts infected with Toxoplasma gondii. Among the cells in the T-cell population, CD8⁺ T cells are considered the major effector cells against this parasite. It is believed that CD4⁺ T cells may be crucial for induction of the CD8⁺-T-cell response against T. gondii. In the present study, CD4^−/− mice were used to evaluate the role of conventional CD4⁺ T cells in the immune response against T. gondii infection. CD4^−/− mice infected with T. gondii exhibited lower gamma interferon (IFN-γ) messages in the majority of their …

Presented Antigen From Damaged Pancreatic Beta Cells Activates Autoreactive T Cells In Virus-Mediated Autoimmune Diabetes., Marc S. Horwitz, Alex Ilic, Cody Fine, Enrique Rodriguez, Nora Sarvetnick

Journal Articles: Regenerative Medicine

The induction of autoimmunity by viruses has been attributed to numerous mechanisms. In mice, coxsackievirus B4 (CB4) induces insulin-dependent diabetes mellitus (IDDM) resembling the final step of disease progression in humans. The immune response following the viral insult clearly precipitates IDDM. However, the molecular pathway between viral infection and the subsequent activation of T cells specific for islet antigen has not been elucidated. These T cells could become activated through exposure to sequestered antigens released by damaged beta cells, or they could have responded to factors secreted by the inflammatory response itself. To distinguish between these possibilities, we treated mice …

Immune Response Genes Modulate Serologic Responses To Vibrio Cholerae Tcpa Pilin Peptides, Michael D. Meeks, Terri K. Wade, Ronald K. Taylor, William F. Wade

Dartmouth Scholarship

Cholera is an enteric disease caused by Vibrio cholerae. Toxin-coregulated pilus (TCP), a type 4 pilus expressed by V. cholerae, is a cholera virulence factor that is required for host colonization. The TCP polymer is composed of subunits of TcpA pilin. Antibodies directed against TcpA are protective in animal models of cholera. While natural or recombinant forms of TcpA are difficult to purify to homogeneity, it is anticipated that synthesized TcpA peptides might serve as immunogens in a subunit vaccine. We wanted to assess the potential for effects of the immune response (Ir) gene that could complicate a peptide-based …

Evaluation Of A Tetracycline-Inducible Promoter In Staphylococcus Aureus In Vitro And In Vivo And Its Application In Demonstrating The Role Of Sigb In Microcolony Formation, B. T. Bateman, N. P. Donegan, T. M. Jarry, M. Palma

Dartmouth Scholarship

An inducible promoter system provides a powerful tool for studying the genetic basis for virulence. A variety of inducible systems have been used in other organisms, including pXyl-xylR-inducible promoter, the pSpac-lacI system, and the arabinose-inducible P_BAD promoter, but each of these systems has limitations in its application to Staphylococcus aureus. In this study, we demonstrated the efficacy of a tetracycline-inducible promoter system in inducing gene expression in S. aureus in vitro and inside epithelial cells as well as in an animal model of infection. Using the xyl/tetO promoter::gfp_uvr fusion carried on a shuttle …

Anti-Class Ii Monoclonal Antibody-Targeted Vibrio Cholerae Tcpa Pilin: Modulation Of Serologic Response, Epitope Specificity, And Isotype, Jia-Yan Wu, Ronald K. Taylor, William F. Wade

Dartmouth Scholarship

Toxin-coregulated pilus (TCP) is a colonization factor required for cholera infection. It is not a strong immunogen when delivered in the context of whole cells, yet pilus subunits or TcpA derivative synthetic peptides induce protective responses. We examined the efficacy of immunizing mice with TCP conjugated to anti-class II monoclonal antibodies (MAb) with or without the addition of cholera toxin (CT) or anti-CD40 MAb to determine if the serologic response to TcpA could be manipulated. Anti-class II MAb-targeted TCP influenced the anti-TCP peptide serologic response with respect to titer and isotype. Responses to TcpA peptide 4 were induced with class …

Evaluation Of Cholera Vaccines Formulated With Toxin-Coregulated Pilin Peptide Plus Polymer Adjuvant In Mice, Jia-Yan Wu, William F. Wade, Ronald K. Taylor

Dartmouth Scholarship

Cholera is an acute diarrheal disease that is caused by the gram-negative bacterium Vibrio cholerae. The low efficacy of currently available killed-whole-cell vaccines and the reactinogenicity coupled with potential reversion of live vaccines have thus far precluded widespread vaccination for the control of cholera. Recent studies on the molecular nature of the virulence components that contribute to V. cholerae pathogenesis have provided insights into possible approaches for the development of a defined subunit cholera vaccine. Genetic analysis has demonstrated that the toxin-coregulated pilus (TCP) is the major factor that contributes to colonization of the human intestine by V. cholerae. In …

The Toxoplasma Gondii Protein Rop2 Mediates Host Organelle Association With The Parasitophorous Vacuole Membrane, Anthony P. Sinai, Keith A. Joiner

Microbiology, Immunology, and Molecular Genetics Faculty Publications

Toxoplasma gondii replicates within a specialized vacuole surrounded by the parasitophorous vacuole membrane (PVM). The PVM forms intimate interactions with host mitochondria and endoplasmic reticulum (ER) in a process termed PVM–organelle association. In this study we identify a likely mediator of this process, the parasite protein ROP2. ROP2, which is localized to the PVM, is secreted from anterior organelles termed rhoptries during parasite invasion into host cells. The NH₂-terminal domain of ROP2 (ROP2hc) within the PVM is exposed to the host cell cytosol, and has characteristics of a mitochondrial targeting signal. In in vitro assays, ROP2hc is …

The Mannose-Sensitive Hemagglutinin Of Vibrio Cholerae Promotes Adherence To Zooplankton, Deborah A. Chiavelli, Jane W. Marsh, Ronald K. Taylor

Dartmouth Scholarship

The bacterium Vibrio cholerae, the etiological agent of cholera, is often found attached to plankton, a property that is thought to contribute to its environmental persistence in aquatic habitats. The V. cholerae O1 El Tor biotype and V. cholerae O139 strains produce a surface pilus termed the mannose-sensitive hemagglutinin (MSHA), whereas V. cholerae O1 classical biotype strains do not. Although V. cholerae O1 classical does not elaborate MSHA, the gene is present and expressed at a level comparable to that of the other strains. Since V. cholerae O1 El Tor and V. cholerae O139 have displaced V. cholerae O1 classical …

Anti-Gag Cytolytic T Lymphocytes Specific For An Alternative Translational Reading Frame-Derived Epitope And Resistance Versus Susceptibility To Retrovirus-Induced Murine Aids In F1 Mice, Shawn-Marie Mayrand, Patricia A. Healy, Bruce E. Torbett, William R. Green

Dartmouth Scholarship

Murine AIDS (MAIDS) develops in susceptible mouse strains after infection with the LP-BM5 murine leukemia virus complex that contains causative defective, and ecotropic helper, retroviruses. We previously demonstrated that the MAIDSresistant H-2d strains BALB/cByJ and C57BL/KsJ generate MHC class I (Kd ) restricted virus-specific CD81 cytolytic T lymphocytes (CTLs) that lyse cells expressing either defective or ecotropic gag proteins. In contrast, the congenic BALB.B and closely related C57BL/6J MAIDS-susceptible H-2b strains were unable to serve as a source of gag-specific CTLs (Schwarz and Green, 1994), suggesting that anti-gag CTLs might provide a basis for resistance to MAIDS. Although its susceptibility …

Mechanisms Of Immunotherapeutic Intervention By Anti-Cd40l (Cd154) Antibody In An Animal Model Of Multiple Sclerosis, Laurence M. Howard, Amy J. Miga, Carol L. Vanderlugt, Mauro C. Dal Canto, John D. Laman, Randolph J. Noelle, Stephen D. Miller

Dartmouth Scholarship

Relapsing experimental autoimmune encephalomyelitis (R-EAE) in the SJL mouse is a Th1-mediated autoimmune demyelinating disease model for human multiple sclerosis and is characterized by infiltration of the central nervous system (CNS) by Th1 cells and macrophages. Disease relapses are mediated by T cells specific for endogenous myelin epitopes released during acute disease, reflecting a critical role for epitope spreading in the perpetuation of chronic central CNS pathology. We asked whether blockade of the CD40–CD154 (CD40L) costimulatory pathway could suppress relapses in mice with established R-EAE. Anti-CD154 antibody treatment at either the peak of acute disease or during remission effectively blocked …

Resurgence Of Sleeping Sickness In Tambura County, Sudan, Anne Moore, Michaleen Richer, Mario Enrile, Edward Losio, Jacquelin Roberts, Deborah A. Levy

Journal Articles: Epidemiology

Endemic foci of human African trypanosomiasis are present in southern Sudan. In 1996 and 1997, trypanosomiasis increased sharply in Tambura County. To define the magnitude and geographic distribution of the outbreak, we conducted a prevalence survey using population-based cluster sampling in 16 villages: 1,358 participants answered questions about routine activities and tsetse fly contact and received serologic testing. Seroprevalence in the surveyed area was 19.4% (95% confidence interval = 16.9%, 21.8%). We confirmed infection in 66% of seropositive persons who received one parasitologic examination and in 95% of those who had serial examinations of lymph node fluid and blood. Activities …

Development Of A Blocking Enzyme-Linked Immunosorbent Assay For Detection Of Serum Antibodies To O157 Antigen Of Escherichia Coli., W Laegreid, M Hoffman, J Keen, R Elder, J Kwang

Manuscripts, Articles, Book Chapters and Other Papers

The O157 antigen of Escherichia coli shares structural elements with lipopolysaccharide (LPS) antigens of other bacterial species, notably Brucella abortus and Yersinia enterocolitica 09, a fact that confounds the interpretation of assays for anti-O157 antibodies. To address this problem, a blocking enzyme-linked immunosorbent assay (bELISA) was designed with E. coli O157:H7 LPS as the antigen and a monoclonal antibody specific for E. coli O157, designated 13B3, as the competing antibody. The bELISA had equivalent sensitivity to, and significantly higher specificity than, the indirect ELISA (iELISA), detecting anti-O157 antibodies in sera from cattle experimentally inoculated with O157:H7. Only 13% of sera …

Cellular Basis Of Decreased Immune Responses To Pneumococcal Vaccines In Aged Mice, Manju Garg, Wei Luo, Alan M. Kaplan, Subbarao Bondada

Microbiology, Immunology, and Molecular Genetics Faculty Publications

Previously, model systems were developed in our laboratory to study murine immune responses to the 23-valent pneumococcal polysaccharide vaccine Pnu-Imune, both in vivo and in vitro (M. Garg and B. Subbarao, Infect. Immun. 60:2329-2336, 1992; M. Garg, A. M. Kaplan, and S. Bondada, J. Immunol. 152: 1589-1596, 1994). Using these systems, we found that aged mice did not respond to the vaccine in vivo or in vitro. Cell separation studies showed that the unresponsiveness of the aged spleen cells to the vaccine was not due to an intrinsic B-cell defect or to T-cell-mediated immunosuppression but resulted from an accessory cell …

Biochemical And Mutational Analysis Of The Histidine Residues Of Staphylococcal Enterotoxin A., M Hoffman, M Tremaine, J Mansfield, M Betley

Manuscripts, Articles, Book Chapters and Other Papers

The goal of this study was to examine the role of histidine residues in the biological activities of staphylococcal enterotoxin A (SEA). Carboxymethylated SEA was unable to stimulate murine T-cell proliferation but was resistant to monkey stomach lavage fluid degradation, suggesting that native conformation was intact. Site-directed mutagenesis of the histidine residues of SEA was subsequently performed. SEA-H44A (SEA with histidine 44 replaced with alanine), SEA-H44D, SEA-H50A, SEA-H50D, SEA-H114A, SEA-H114D, SEA-H187A, and SEA-H187D retained superantigen and emetic activities, whereas SEA-H225A and SEA-H225D were defective in the ability to stimulate T-cell proliferation. These mutants were unable to compete with SEA for …

Cd40-Cd40 Ligand Interactions In Experimental Allergic Encephalomyelitis And Multiple Sclerosis., Koen Gerritse, Jon D. Laman, Randolph J. Noelle, Alejandro Aruffo

Dartmouth Scholarship

We investigated the role of CD40-CD40 ligand (CD40L) interactions in multiple sclerosis (MS) and experimental allergic encephalomyelitis (EAE). Activated helper T cells expressing CD40L (gp39) surface protein were found in MS patient brain sections, but not in brain tissue sections of normal controls or patients with other neurological disease. CD40L-positive cells were co-localized with CD40-bearing cells in active lesions (perivascular infiltrates). Most of these CD40-bearing cells proved to be of the monocytic lineage (macrophages or microglial cells), and relatively few were B cells. To functionally evaluate CD40-CD40L interactions, EAE was elicited in mice by means of proteolipid-peptide immunization. Treatment with …

Impairment Of The Cellular Immune Response In Acute Murine Toxoplasmosis: Regulation Of Interleukin 2 Production And Macrophage-Mediated Inhibitory Effects., Sakhina Haque, Imtiaz Khan, Azizul Haque, Lloyd Kasper

Dartmouth Scholarship

Depression of the cellular immune response to Toxoplasma gondii has been reported in both mice and humans. The present study was undertaken to determine the kinetics and mechanism of the observed downregulation of interleukin 2 (IL-2) production during experimental murine toxoplasmosis. For these investigations, the cell-mediated immune response to the wild type (PTg) was compared with that to the less-virulent mutant parasite (PTgB), which is deficient in the major surface antigen, p30 (SAG-1). Spleen cells from infected A/J mice failed to proliferate in response to Toxoplasma antigens during the first week of infection. Both PTg- and PTgB-infected A/J mice exhibited …

Induction Of Protective Immunity Against Larval Onchocerca Volvulus In A Mouse Model., A. M. Lange, W. Yutanawiboonchai, J. B. Lok, M. Trpis, D. Abraham

Department of Microbiology and Immunology Faculty Papers

BALB/cBYJ mice were immunized against larval Onchocerca volvulus by subcutaneous injection of normal, irradiated, or freeze-thaw-killed Onchocerca sp. larvae. The mice received challenge infections of O. volvulus third-stage larva (L3) contained in diffusion chambers implanted subcutaneously. At two-weeks postinfection, the diffusion chambers were removed and larval survival was assessed. When mice were immunized a single time with 35-krad-irradiated or normal O. volvulus L3, there was a significant reduction in the survival of challenge parasites. However, there was little or no reduction in challenge worm survival when mice were immunized a single time with freeze-thaw-killed O. volvulus L3 or fourth-stage larva …

Reversal Of Age-Associated Decline In Immune Response To Pnu-Imune Vaccine By Supplementation With The Steroid Hormone Dehydroepiandrosterone, Manju Garg, Subbarao Bondada

Microbiology, Immunology, and Molecular Genetics Faculty Publications

Recently, we reported that murine antibody responses to the 23-valent pneumococcal polysaccharide (Pnu-Imune) vaccine declined with age. Here we present data to support the concept that age-associated immune defects are not only due to intrinsic defects in immune cells but are also due to extrinsic factors emanating from the neuroendocrine system. We found that supplementation with dehydroepiandrosterone, a steroid hormone known to be reduced in the aged, corrects the immune deficiency of aged mice and significantly enhanced their splenic immune responses to the Pnu-Imune vaccine.

Immune Responses Of Systemic And Mucosal Lymphoid Organs To Pnu-Imune Vaccine As A Function Of Age And The Efficacy Of Monophosphoryl Lipid A As An Adjuvant, Manju Garg, Subbarao Bondada

Microbiology, Immunology, and Molecular Genetics Faculty Publications

A murine model system was established to study immune responses to the Pnu-Imune vaccine, which is made up of 23 different pneumococcal capsular polysaccharides. In this animal model, antibody-forming cell responses to 21 of 23 individual polysaccharides in the vaccine were detected. The Pnu-Imune vaccine elicited good antibody responses from the spleens and mesenteric lymph nodes (MLN) of young mice, whereas a variety of other peripheral lymph nodes were unresponsive. The immunoglobulin M plaque-forming cell (PFC) response in the spleen to the Pnu-Imune vaccine (given intraperitoneally or subcutaneously) decreased dramatically with increasing age. However, the spleen and MLN differed in …

Cytolytic T Lymphocytes Specific For Tumors And Infected Cells From Mice With A Retrovirus-Induced Immunodeficiency Syndrome., Jennifer G. Erbe, Kathy A. Green, Karen M. Crassi, Herbert C. Morse, W R. Green

Dartmouth Scholarship

LP-BM5 retrovirus complex-infected C57BL/6 mice develop immunodeficiency, somewhat analogous to AIDS, termed murine AIDS (MAIDS). After secondary stimulation with syngeneic B-cell lymphomas from LP-BM5-infected mice, C57BL/6 mice produced vigorous CD8+ cytotoxic T lymphocytes specific for MAIDS-associated tumors. An anti-LP-BM5 specificity was suggested because spleen and lymph node cells from LP-BM5-infected mice served as target cells in competition assays, and cells from LP-BM5, but not ecotropic, virus-infected mice functioned as secondary in vitro stimulators to generate cytotoxic T lymphocytes to MAIDS tumors.

Primary Antibody Responses To Thymus-Independent Antigens In The Lungs And Hilar Lymph Nodes Of Mice, S. Niranjan Goud, Alan M. Kaplan, Subbarao Bondada

Sanders-Brown Center on Aging Faculty Publications

B lymphocytes from the pulmonary lymphoid tissues were stimulated with a variety of thymus-independent (TI) antigens by intratracheal (i.t.) immunization. Immune responses in the lungs and hilar lymph nodes (HLN), which are part of the localized lymphoid tissue, as well as in the spleen, the systemic lymphoid organ, were studied. Thus, primary i.t. immunization of mice with the TI-1 antigen trinitrophenyl-lipopolysaccharide (TNP-LPS) elicited both antigen-specific and polyclonal plaque-forming cell responses from HLN, lung, and splenic B lymphocytes. These responses appeared as early as 3 days after immunization and declined by day 7. Similar immunization with another TI-1 antigen, TNP-Brucella …

Murine Gamma Interferon Fails To Inhibit Toxoplasma Gondii Growth In Murine Fibroblasts., Joseph D. Schwartzman, Steven L. Gonias, E R. Pfefferkorn

Dartmouth Scholarship

Although treatment of human macrophages or fibroblasts with human gamma interferon results in the inhibition of intracellular Toxoplasma gondii, murine gamma interferon stimulated only murine macrophages, not murine fibroblasts, to inhibit T. gondii. This species difference may be important in understanding the control of acute and chronic toxoplasmosis.

G89-919 Quality Laboratory Samples Necessary For Accurate Disease Diagnosis, Duane Rice, Douglas G. Rogers

University of Nebraska-Lincoln Extension: Historical Materials

This NebGuide discusses the importance of submitting proper specimens to the veterinary diagnostic laboratory as an aid in diagnosing infectious diseases, feed imbalance, or animal poisoning.

To comprehend the reasons for failures in disease diagnosis at veterinary diagnostic laboratories, it is important to understand what disease is, what causes disease, how the animal resists disease (becomes immune), and what happens to the animal if disease develops and the animal does not become immune.

According to Stedmans Dictionary, disease is an interruption, cessation or disorder of body functions, systems or organs. Some diseases may be obvious to the untrained eye, …

Inhibition Of Growth Of Toxoplasma Gondii In Cultured Fibroblasts By Human Recombinant Gamma Interferon., E. R. Pfefferkorn, Paul M. Guyre

Dartmouth Scholarship

The growth of Toxoplasma gondii in cultured human fibroblasts was inhibited by recombinant human gamma interferon at concentrations of 8 to 16 U/ml. The interferon was titrated by observing a total inhibition of parasite plaque formation 7 days after infection. Inhibition of the growth of T. gondii in the early days after infection was measured by marked reductions in the incorporation of radioactive uracil, a precursor that can only be used by the parasites. This assay showed that when cells were pretreated with gamma interferon for 1 day and then infected, inhibition of T. gondii growth could be readily detected …

Lions & Lionesses, Tigers & Tigresses, Bears & Other Animals: Sellers' Liability For Dangerous Animals, Bruce A. Levin, Michael Spak

Notre Dame Law Review

No abstract provided.