bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of staphylococcal enterotoxin B on rodent mast cells
Authors: Komisar J , Rivera J , Vega A , Tseng J
Published: January 2020

Staphylococcal enterotoxin B (SEB) was tested in rodent mast cell cultures for the release of serotonin. Both rat RBL-2H3 mast cells and murine peritoneal cells released serotonin after SEB stimulation in culture. Release of serotonin in RBL-2H3 cells depended on the concentration of SEB; an appreciable release was seen at 50 micrograms/ml. The release of serotonin was not due to cell death. Serotonin release could be enhanced by bradykinin but not by vasoactive intestinal peptide, substance P, lipopolysaccharide from Salmonella typhimurium, the calcium ionophore A23187, acetylcholine, adenosine, 5-hydroxyeicosatetraenoic acid, indomethacin, or phorbol myristate acetate. SEB bound directly to the membrane of RBL-2H3 mast cells, and the SEB-binding site, the presumptive receptor, appeared to be a protein. The SEB receptor could not be capped under membrane-capping conditions, and serotonin release could not be enhanced by attempts to cross-link the receptor. These results suggest that mast cells may be an important cell type involved in SEB toxicosis and that release of serotonin may be enhanced by activation of the kinin-kallikrein system.
Interaction of ruminant transferrins with transferrin receptors in bovine isolates of Pasteurella haemolytica and Haemophilus somnus
Authors: Yu R H , Gray-Owen S D , Ogunnariwo J , Schryvers A B
Published: January 2020

The interactions of ruminant transferrins with receptors on bovine isolates of Pasteurella haemolytica and Haemophilus somnus were compared by growth studies and direct and competitive binding assays. Isolates of P. haemolytica were capable of utilizing and binding transferrin from sheep, goat, or cattle, whereas isolates of H. somnus were capable of utilizing and binding only bovine transferrin.
Phosphate starvation enhances expression of the immunodominant 38-kilodalton protein antigen of Mycobacterium tuberculosis: demonstration by immunogold electron microscopy
Authors: Espitia C , Elinos M , Hernández-Pando R , Mancilla R
Published: January 2020

In this work, we grew Mycobacterium tuberculosis in an enriched Proskauer-Beck-Youmans culture medium in the presence and in the absence of phosphate salts. Immunoblot analysis of sonic extracts showed overexpression of the 38-kDa protein antigen by bacilli grown in the medium without phosphate. These observations were confirmed by immunogold electron microscopy, which showed that the number of gold particles was significantly higher in bacilli grown in medium without phosphate than in bacilli grown in medium with phosphate. The 38-kDa protein was located mainly in the wall and on the cell surface.
Staphylococcal toxic shock syndrome toxin 1-induced tumor necrosis factor alpha and interleukin-1 beta secretion by human peripheral blood monocytes and T lymphocytes is differentially suppressed by protein kinase inhibitors
Authors: See R H , Chow A W
Published: January 2020

The signal transduction pathways by which staphylococcal toxic shock syndrome toxin 1 (TSST-1) induces tumor necrosis factor alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) secretion were examined with various protein kinase inhibitors. TNF-alpha secretion by normal human monocytes and T cells in response to TSST-1 was suppressed by inhibitors of protein kinase C (H7) and tyrosine kinases (genistein). In contrast, the secretion of IL-1 beta was blocked by a cyclic AMP- and cyclic GMP-dependent kinase inhibitor (HA1004) as well as by H7 and genistein. These results suggest that the secretion of TNF-alpha and IL-1 beta may be differentially regulated by TSST-1 and that protein kinases play an important role in mediating cytokine responses to the toxin.
Resistance of severe combined immunodeficient mice to infection with Cryptosporidium parvum: the importance of intestinal microflora
Authors: Harp J A , Chen W , Harmsen A G
Published: January 2020

Cryptosporidium parvum is a protozoan parasite which colonizes intestinal epithelium, causing transient diarrheal illness in immunocompetent hosts and severe chronic disease in immunocompromised hosts. We examined the resistance of severe combined immunodeficient mice, either bearing intestinal flora or germfree, to intestinal infection with C. parvum. Infection was not readily detected in flora-bearing adult severe combined immunodeficient mice until 5 to 7 weeks following oral challenge with C. parvum. In contrast, germfree adult severe combined immunodeficient mice were heavily infected 3 weeks following challenge. These data support the hypothesis that resistance of adult mice to C. parvum infection does not require a specific immune response but can be mediated by nonspecific mechanisms associated with the presence of intestinal flora.
Enterotoxigenicity of Vibrio parahaemolyticus with and without genes encoding thermostable direct hemolysin
Authors: Nishibuchi M , Fasano A , Russell R G , Kaper J B
Published: January 2020

Vibrio parahaemolyticus produces a thermostable direct hemolysin (TDH) that has been implicated in the pathogenesis of diarrheal disease caused by this organism. However, previous studies attempting to demonstrate the contribution of the hemolysin to virulence have been inconclusive. We investigated this putative virulence factor by using an isogenic TDH-negative (TDH-) strain constructed by specifically inactivating the two copies of the tdh gene encoding TDH. The enterotoxigenicities of the parent strain (AQ3815) and the mutant strain were tested by adding sterile culture supernatants to rabbit ileal tissue mounted in Ussing chambers. The culture filtrate of the parent strain produced a significant increase in short-circuit current (Isc), compared with the change induced by the TDH- mutant. The capacity of the culture filtrate of AQ3815 to increase the Isc was reduced by neutralization with anti-TDH serum, and the return of the cloned tdh gene to the TDH- mutant restored the ability to increase the Isc. These results were corroborated by rabbit ileal loop assays in which AQ3815 caused fluid accumulation but the TDH- mutant did not. No microscopic damage was seen in mucosal tissues exposed to the culture filtrate of either strain. These results indicate that TDH has an enterotoxigenic effect on rabbit small intestine and could be responsible for the watery diarrhea seen with V. parahaemolyticus.
Heterogeneity of phenol oxidases in Cryptococcus neoformans
Authors: Ikeda R , Jacobson E S
Published: January 2020

Phenol oxidase enzymes, linked to virulence in Cryptococcus neoformans, were prepared from broken cells. More enzyme activity was found in the ultracentrifugation supernatant; less was found in the membrane fraction. Phenol oxidases were located in acrylamide gel electropherograms by activity staining with L-dihydroxyphenylalanine (DOPA). Mobility differences between soluble and solubilized membrane-bound phenol oxidases were not found. Comparison of enzymes produced at 25 and 37 degrees C revealed that the enzyme had lower activity and lower mobility at 37 degrees C. The mobility of 25 degrees C phenol oxidases from strains of C. neoformans var. gattii was lower than that of those from C. neoformans var. neoformans. Half of the phenol oxidase produced at 25 degrees C was bound by concanavalin A, while that produced at 37 degrees C was not bound. However, glucose starvation of cultures at 25 degrees C overnight resulted in increased amounts of enzyme which did not bind to concanavalin A. A given strain of C. neoformans produces different species of phenol oxidase under different culture conditions.
Cryptdins: antimicrobial defensins of the murine small intestine
Authors: Eisenhauer P B , Harwig S S , Lehrer R I
Published: January 2020

Paneth cells are specialized small intestine epithelial cells that contain lysozyme, possess phagocytic properties, and secrete cytoplasmic granules into the intestinal crypt lumen after the entry of bacteria. Recent studies by Ouellette and associates (A. J. Ouellette, R. M. Greco, M. James, D. Frederick, J. Naftilan, and J. T. Fallon, J. Cell Biol. 108:1687-1695, 1989) indicated that murine Paneth cells produce prodefensin mRNA, but the properties of its peptide product were not reported. We purified two closely related defensins, cryptdin 1 and cryptdin 2, from a subcellular fraction of murine small intestine cells that was enriched in Paneth cells. Both peptides contained 35 amino acid residues, including the characteristic defensin "signature" of six invariantly conserved cysteines. Cryptdins 1 and 2 were approximately 90 to 95% homologous to each other and to the carboxy-terminal domain of the 93-amino-acid defensin precursor, cryptdin A, described by Ouellette and associates (Ouellette et al., J. Cell Biol. 108:1687-1695, 1989). Both cryptdins exerted bactericidal activity against Listeria monocytogenes EGD and Escherichia coli ML-35p in vitro. Their potency exceeded that of human neutrophil defensin HNP-1 but was considerably lower than that of NP-1, a defensin produced by rabbit neutrophils and alveolar macrophages. Both cryptdins killed mouse-avirulent Salmonella typhimurium 7953S (phoP) much more effectively than its phoP+, mouse-virulent, isogenic counterpart, S. typhimurium 14028S. Our data indicate that mouse intestinal prodefensins are processed into 35-amino-acid mature defensins (cryptdins) with broad-spectrum antimicrobial properties. The production of defensins and lysozyme by Paneth cells may enable them to protect the small intestine from bacterial overgrowth by autochthonous flora and from invasion by potential pathogens that cause infection via the peroral route, such as L. monocytogenes and Salmonella species.
Isolation of nonchemotactic mutants of Campylobacter jejuni and their colonization of the mouse intestinal tract
Authors: Takata T , Fujimoto S , Amako K
Published: January 2020

Three nonchemotactic mutants (D54, Y14, and N74) of Campylobacter jejuni were isolated from wild-type strain FUM158432 by either the negative swarming or liquid gradient method with brucella broth as the attractive substance. Strains D54 and Y14 were isolated after mutagenesis with methyl methanesulfonate, and N74 was isolated from a nonmutagenized culture. These mutants all failed to swarm on a semisolid medium and did not show any chemotactic behavior in the hard-agar plus assay method for any of the chemicals which act as attractants for the wild-type strain. They had intact flagella and were actively motile. Swimming behavior examined by a video tracking technique showed that the mutants swim only straight, without any tumbling. When suckling mice were challenged orally with approximately 10(5) CFU of these mutant strains, all of the mutants were cleared from the intestinal tract by 48 h. In contrast, the wild-type strain colonized the intestinal tracts of all mice challenged with 10(2) CFU. We concluded that chemotactic movement is important for colonization of the intestinal tract of suckling mice by C. jejuni.
Borrelia burgdorferi stimulates release of interleukin-1 activity from bovine peripheral blood monocytes
Authors: Kenefick K B , Lederer J A , Schell R F , Czuprynski C J
Published: January 2020

Infection with Borrelia burgdorferi is suspected to be a cause of lameness and arthritis in cattle. Interleukin-1 (IL-1) activity has been detected in joint fluids from human patients affected by various arthritides, including Lyme arthritis. In addition, human monocytes and murine macrophages have been reported to release IL-1 activity when incubated with B. burgdorferi in vitro. To address a possible mechanism by which B. burgdorferi might cause a bovine arthritic syndrome, we determined whether bovine peripheral blood monocytes released IL-1 activity when coincubated with B. burgdorferi in vitro. High-passage and low-passage isolates of B. burgdorferi stimulated release of IL-1 activity from bovine monocytes. The amount of IL-1 activity released was dependent on the number of borreliae added to the monocyte cultures. In addition, live and heat-killed B. burgdorferi cells stimulated release of similar amounts of IL-1. We also obtained no evidence that soluble components released from in vitro-cultured B. burgdorferi stimulated IL-1 release from bovine monocytes. A recombinant IL-1 receptor antagonist blocked the proliferative activity of monocyte-conditioned medium in a thymocyte costimulation assay, thus demonstrating that the costimulatory activity detected was due to IL-1.
Genetic analysis of Pseudomonas aeruginosa adherence: distinct genetic loci control attachment to epithelial cells and mucins
Authors: Simpson D A , Ramphal R , Lory S
Published: January 2020

Infection of mucosal tissues by the opportunistic pathogen Pseudomonas aeruginosa is initiated by attachment of the bacterium to host tissues. To gain a better understanding of this interaction, we used two methods to isolate mutants of P. aeruginosa with altered adherence to cultured A549 cells and to mucins. First, from a population of nonpiliated mutants of P. aeruginosa mutagenized with transposon Tn5G, we have isolated variants that are defective in binding to both A549 cells and respiratory mucins. Using a cloned transposon plus flanking DNA from one such mutant as a DNA probe, we have isolated plasmids from a cosmid bank, which, upon reintroduction to the original mutants, restored adhesion to both A549 cells and mucin. The second strategy to identify genes involved in adhesion used mutagenesis of P. aeruginosa N1G, an rpoN mutant which is unable to bind to either A549 cells or mucin, with transposon Tn5 containing an outward-directed promoter. From this bank of mutagenized P. aeruginosa N1G, two classes of adhesion variants were isolated; one class attached to A549 cells and to mucin, and the other class restored binding of the rpoN mutant to mucin but not to A549 cells. These findings suggest that P. aeruginosa can express at least two adhesins distinct from pili, one recognizing receptors shared by epithelial cells and mucins and the other recognizing mucins alone.
In vivo complement activation and binding of C3 to encapsulated Cryptococcus neoformans
Authors: Truelsen K , Young T , Kozel T R
Published: January 2020

Tissues from mice infected with Cryptococcus neoformans were examined by immunofluorescence to determine the extent of deposition of complement component C3 on encapsulated cryptococci. The relative percentages of cryptococci in each tissue having readily visible C3 were greatest for liver and lung tissues, with the kidney tissue having the next highest percentage and the spleen having the lowest percentage. Binding of C3 fragments to cryptococci in brain tissue was essentially absent.
A conjugated synthetic peptide corresponding to the C-terminal region of Clostridium perfringens type A enterotoxin elicits an enterotoxin-neutralizing antibody response in mice
Authors: Mietzner T A , Kokai-Kun J F , Hanna P C , McClane B A
Published: January 2020

A synthetic peptide homolog corresponding to the C-terminal 30 amino acids of Clostridium perfringens type A enterotoxin (CPE) was conjugated to a thyroglobulin carrier and used to immunize mice. Conjugate-immunized mice produced antibodies which neutralized native CPE cytotoxicity, at least in part, by blocking enterotoxin binding. This peptide may be useful for the development of a vaccine to protect against CPE-mediated disease.
Isolation and partial characterization of glycolipid fractions from Mycobacterium avium serovar 2 (Mycobacterium paratuberculosis 18) that inhibit activated macrophages
Authors: Hines M E , Jaynes J M , Barker S A , Newton J C , Enright F M , Snider T G
Published: January 2020

Glycolipid fractions from Mycobacterium avium serovar 2 (Mycobacterium paratuberculosis 18) inhibited the killing of Candida albicans by activated bovine peripheral-blood-derived macrophages. Fractions were derived by using the matrix solid-phase dispersion technique, which is a new method of simultaneous lysis and partial fractionation of components of bacterial cells. Further purification of active fractions was performed by concanavalin A affinity chromatography, centrifugal filtration, and differing solvent solubility. Three different fractions were isolated and partially characterized. Two of these fractions have characteristics typical of glycolipids, and the third fraction has characteristics compatible with a peptidoglycolipid. This peptidoglycolipid fraction has been purified and named MIF-A3.
Patterns of cytokine production by mycobacterium-reactive human T-cell clones
Authors: Barnes P F , Abrams J S , Lu S , Sieling P A , Rea T H , Modlin R L
Published: January 2020

To gain insight into the functional capacity of human T cells in the immune response against Mycobacterium tuberculosis, we evaluated the spectrum of cytokines produced by mycobacterium-reactive human T-cell clones. Nine of 11 T-cell clones bearing alpha beta or gamma delta T-cell receptors produced both Th1 and Th2 cytokines, a pattern resembling that of murine Th0 clones. The most frequent pattern was secretion of gamma interferon, tumor necrosis factor alpha (TNF), and interleukin-10 (IL-10), in combination with IL-2, IL-5, or both. Two clones produced only Th1 cytokines, and none produced exclusively Th2 cytokines. Although IL-4 was not detected in cell culture supernatants, IL-4 mRNA was detected by polymerase chain reaction amplification in two of six clones. There were no differences between the cytokine profiles of alpha beta and gamma delta T cells. A striking finding was the markedly elevated concentrations of TNF in clone supernatants, independent of the other cytokines produced. Supernatants from mycobacterium-stimulated T-cell clones, in combination with granulocyte-macrophage colony-stimulating factor, induced aggregation of bone-marrow-derived macrophages, and this effect was abrogated by antibodies to TNF. The addition of recombinant TNF to granulocyte-macrophage colony-stimulating factor markedly enhanced macrophage aggregation, indicating that TNF produced by T cells may be an important costimulus for the granulomatous host response to mycobacteria. The cytokines produced by T cells may exert immunoregulatory and immunopathologic effects and thus mediate some of the clinical manifestations of tuberculosis.
Specific T-cell recognition of the merozoite proteins rhoptry-associated protein 1 and erythrocyte-binding antigen 1 of Plasmodium falciparum
Authors: Jakobsen P H , Hviid L , Theander T G , Afare E A , Ridley R G , Heegaard P M , Stuber D , Dalsgaard K , Nkrumah F K
Published: January 2020

The merozoite proteins merozoite surface protein 1 (MSP-1) and rhoptry-associated protein 1 (RAP-1) and synthetic peptides containing sequences of MSP-1, RAP-1, and erythrocyte-binding antigen 1, induced in vitro proliferative responses of lymphocytes collected from Ghanaian blood donors living in an area with a high rate of transmission of malaria. Lymphocytes from a large proportion of the Ghanaian blood donors proliferated in response to the RAP-1 peptide, unlike those of Danish control blood donors, indicating that this sequence contains a malaria-specific T-cell epitope broadly recognized by individuals living in an area with a high transmission rate of malaria. Most of the donor plasma samples tested contained immunoglobulin G (IgG) and IgM antibodies recognizing the merozoite proteins, while only a minority showed high IgG reactivity to the synthetic peptides.
Storage reservoirs of hemin and inorganic iron in Yersinia pestis
Authors: Perry R D , Lucier T S , Sikkema D J , Brubaker R R
Published: January 2020

It is established that a high-frequency chromosomal deletion of ca. 100 kb accounts for the loss of properties making up the pigmented phenotype (Pgm+) of wild-type Yersinia pestis. These determinants are known to include virulence by peripheral routes of injection, sensitivity to the bacteriocin pesticin, adsorption of exogenous hemin or Congo red at 26 degrees C, and growth in iron-sequestered medium at 37 degrees C. We have now identified the outer membrane as the primary site of exogenous hemin storage in Pgm+ cells grown at 26 degrees C. Significant outer membrane storage of hemin did not occur in Pgm- mutants or in Pgm+ cells cultivated at 37 degrees C. However, both Pgm+ and Pgm- organisms grown at 37 degrees C contained a periplasmic reservoir of hemin, which may be associated with a temperature-dependent ca. 70-kDa peptide recently equated with antigen 5. At 37 degrees C, Pgm+ and Pgm- yersiniae also utilized a cytoplasmic ca. 19-kDa bacterioferritin-like peptide for deposition of inorganic iron. Incorporation of [55Fe]hemin into pools at 37 degrees C was not significantly inhibited by competition with excess unlabeled Fe3+. However, excess unlabeled hemin modestly competed with incorporation of label from 55FeCl3. This relative independence of storage pools observed at 37 degrees C is consistent with physiological linkage to in vivo acquisition and transport of Fe3+ from ferritin and of hemin from hemoglobin, myoglobin, or hemopexin.
Transgenic mice expressing C-reactive protein are susceptible to infection with Plasmodium yoelii sporozoites
Authors: Rénia L , Xia D , Samols D , Nussenzweig V
Published: January 2020

Human and rat C-reactive proteins, major acute-phase reactants, bind to sporozoites and inhibit their in vitro development in hepatocytes (A. Nussler, S. Pied, M. Pontet, F. Miltgen, L. Renia, M. Gentilini, and D. Mazier, Exp. Parasitol. 72:1-7, 1991, and S. Pied, A. Nussler, M. Pontet, F. Miltgen, H. Matile, P.-H. Lambert, and D. Mazier, Infect. Immun. 57:278-282, 1989). We show here that rabbit C-reactive protein has identical properties. Nevertheless, infection by Plasmodium yoelii sporozoites was not prevented in transgenic mice engineered to express rabbit C-reactive protein following induction of gluconeogenesis.
Expression and characterization of the eaeA gene product of Escherichia coli serotype O157:H7
Authors: Louie M , de Azavedo J C , Handelsman M Y , Clark C G , Ally B , Dytoc M , Sherman P , Brunton J
Published: January 2020

In enteropathogenic Escherichia coli, the eaeA gene produces a 94-kDa outer membrane protein called intimin which has been shown to be necessary but not sufficient to produce the attaching-and-effacing lesion. The purpose of this study was to characterize the intimin specified by the eaeA allele of the enterohemorrhagic E. coli (EHEC) serotype O157:H7 strain CL8 and to determine its role in adherence. The carboxyl-terminal 266 amino acids of the CL8 intimin were expressed as a protein fusion with glutathione S-transferase, which was used to raise antiserum in rabbits. The antiserum reacted in Western immunoblots with a 97-kDa outer membrane protein of EHEC strains of serogroups O5, O26, O111, and O157 and enteropathogenic E. coli strains of serogroups O55 and O127. Surface labelling of CL8 with 125I showed that intimin was surface exposed. An eaeA insertional inactivation mutant of CL8 was produced and was designated CL8-KO1. Total adherence of CL8-KO1 to HEp-2 cells was not significantly different from that of CL8, but CL8-KO1 gave a negative result in the fluorescent actin staining test. The eaeA gene expressed alone in E. coli HB101 also gave a negative fluorescent actin staining test result. The eaeA gene of CL8 was able to complement the eaeA deletion mutation in CVD206. We conclude that the product of the EHEC eaeA gene is a 97-kDa surface-exposed protein and propose that it be designated intiminO157. Sherman et al. described a 94-kDa outer membrane protein which played an important role in adherence of E. coli O157:H7 (Infect. Immun. 59:890-899, 1991). Western immunoblotting and indirect fluorescent antibody studies showed that the protein described by Sherman et al. is not intimin.
Candida-specific Th1-type responsiveness in mice with experimental vaginal candidiasis
Authors: Fidel P L , Lynch M E , Sobel J D
Published: January 2020

The role of systemic cell-mediated immunity (CMI) as a host defense mechanism in the vagina is poorly understood. Using a murine pseudoestrus model of experimental vaginal candidiasis, we previously found that animals given a vaginal inoculum of viable Candida albicans blastoconidia acquired a persistent vaginal infection and developed Candida-specific delayed-type hypersensitivity (DTH) responses. The present study was designed to characterize the peripheral CMI reactivity generated from the vaginal infection in mice and to determine whether pseudoestrus is a prerequisite for the induction of peripheral CMI reactivity. Mice treated or not treated with estrogen and given a vaginal inoculum of C. albicans blastoconidia were examined for 4 weeks for their vaginal Candida burden and peripheral CMI reactivity, including DTH responsiveness and in vitro Th1 (interleukin-2 [IL-2], gamma interferon [IFN-gamma]/Th2 (IL-4, IL-10)-type lymphokine production in response to Candida antigens. Results showed that although mice not treated with estrogen before being given a vaginal inoculum of C. albicans blastoconidia developed only a short-lived vaginal infection and harbored significantly fewer Candida CFU in the vagina compared with those given estrogen and then infected; DTH reactivity was equivalent in both groups. In vitro measurement of CMI reactivity further showed that lymph node cells from both estrogen- and non-estrogen-treated infected mice produced elevated levels of IL-2 and IFN-gamma in response to Candida antigens during the 4 weeks after vaginal inoculation. In contrast, lymph node cells from the same vaginally infected mice showed no IL-10 production and only small elevations of IL-4 during week 4 of infection. These results suggest that mice with experimental vaginal candidiasis develop predominantly Th1-type Candida-specific peripheral CMI reactivity and that similar patterns of Th1-type reactivity occur in mice regardless of the persistence of infection and the estrogen status of the infected mice.
Pertussis toxin-induced alterations of murine hepatic drug metabolism following administration of diphtheria and tetanus toxoids and pertussis vaccine adsorbed
Authors: Ansher S , Thompson W , Bridgewater J , Snoy P
Published: January 2020

Administration of pertussis toxin (PT) in combination with diphtheria and tetanus toxoids adsorbed (DT vaccine) or with acellular pertussis vaccine adsorbed and diphtheria and tetanus toxoids (APDT) elicits dose- and time-dependent alterations in hepatic drug metabolism in mice. Cytochrome P-450 (P-450) levels were inhibited more than 50% at 7 days following a single injection of PT mixed with either vaccine. When combined with DT vaccine, 125 ng of PT was required to produce this effect, while as little as 16 ng of PT combined with APDT vaccine inhibited P-450 levels. The inhibition of P-450 levels is similar to that observed after a single injection of diphtheria and tetanus toxoids and pertussis vaccine adsorbed (DTP). Alterations of P-450 levels were accompanied by increased activities of quinone reductase but not with changes in plasma interleukin-6 or tumor necrosis factor levels. Other Bordetella pertussis virulence factors, such as filamentous hemagglutinin, fimbriae and pertactin, were also tested but had no significant effect on hepatic drug metabolism. Endotoxin or preparations containing endotoxin caused alterations in hepatic drug metabolism within 24 h, concomitant with increased interleukin-6 and tumor necrosis factor levels, but these effects had resolved by 1 week. DTP vaccine and preparations containing PT caused a marked induction of gamma interferon coincident with the maximal inhibition of P-450 levels. This effect was not present with DT or APDT vaccine alone, nor with endotoxin or any combination of factors that did not contain PT. These results demonstrate that PT is a necessary component for the sustained effects of DTP vaccine on hepatic drug metabolism and suggest a role for gamma interferon in this process.
Vitronectin binds to Pneumocystis carinii and mediates organism attachment to cultured lung epithelial cells
Authors: Limper A H , Standing J E , Hoffman O A , Castro M , Neese L W
Published: January 2020

Pneumocystis carinii attaches to alveolar epithelial cells during the development of pneumonia. Adhesive proteins found within the alveolar space have been proposed to mediate P. carinii adherence to lung cells. Vitronectin (Vn), a 75-kDa glycoprotein present in the lower respiratory tract, has substantial cell-adhesive properties and might participate in the host-parasite interaction during P. carinii pneumonia. To address whether Vn binds to P. carinii, we studied the interaction of radiolabeled Vn with purified P. carinii organisms. Vn bound to P. carinii, occupying an estimated 5.47 x 10(5) binding sites per organism, with an affinity constant, Kd, of 4.24 x 10(-7) M. Interestingly, the interaction of Vn with P. carinii was not mediated through the Arg-Gly-Asp cell-adhesive domain of Vn. Addition of Arg-Gly-Asp-Ser (RGDS) peptides did not inhibit binding. In contrast, Vn binding to P. carinii was substantially inhibited by the addition of heparin or by digesting the organisms with heparitinase, suggesting that P. carinii may interact with the glycosaminoglycan-binding domain of Vn. To determine whether Vn might enhance P. carinii attachment to lung epithelial cells, we studied the binding of 51Cr-labeled P. carinii to cultured A549 lung cells. Addition of Vn resulted in significantly increased binding of P. carinii to A549 cells, whereas a neutralizing anti-Vn serum substantially reduced the binding of P. carinii to A549 cells. These data suggest that Vn binds to P. carinii and that Vn might provide an additional means by which P. carinii attaches to respiratory epithelial cells.
Cation flux studies of the lesion induced in human erythrocyte membranes by the thermostable direct hemolysin of Vibrio parahaemolyticus
Authors: Huntley J S , Hall A C , Sathyamoorthy V , Hall R H
Published: January 2020

Vibrio parahaemolyticus, an important agent of seafood-borne gastroenteritis, expresses several putative virulence factors that could account for the disease symptoms of infected humans, namely, diarrhea, nausea, and abdominal cramps. The pathogenicity of V. parahaemolyticus correlates well with the Kanagawa phenomenon (the hemolytic ability of strains grown on Wagatsuma blood agar), implicating the thermostable direct hemolysin (TDH) as the predominant toxin responsible for pathogenicity. TDH-induced hemolysis could be inhibited by the addition of the osmolyte sorbitol to the extracellular solution, supporting the hypothesis that hemolysis occurs through colloid osmosis secondary to an increase in the cation permeability of the membrane. The effect of TDH on cation permeability was investigated by measuring K+ (congener, 86Rb+) influx into human erythrocytes in which the endogenous cation transporters had been blocked (by use of ouabain, bumetanide, and nitrendipine). TDH increased K+ influx into these cells; this increase was rapid in onset and constant in magnitude, suggesting a direct action by TDH on the membrane. The kinetics of leak generation were examined; the relationship between counts accumulated and hematocrit indicated that the TDH-induced lesion is multihit in nature. TDH-induced K+ influx was sensitive to Zn2+. Time courses of hemolysis in isosmotic solutions of monovalent cation chlorides were used to obtain the selectivity series for the TDH-induced leak: Cs+ > Li+ > K+ > Rb+ > Na+. Both the Zn2+ sensitivity and this selectivity series were obtained for crude culture supernatants, suggesting that TDH is the predominant leak-inducing agent. Thus, we have identified several features of the TDH-induced leak likely to be important in the diarrhetic action of V. parahaemolyticus in the human intestine.
Saliva-binding region of Streptococcus mutans surface protein antigen
Authors: Nakai M , Okahashi N , Ohta H , Koga T
Published: January 2020

A 190-kDa surface protein antigen (PAc) of Streptococcus mutans binds to human salivary components. For detection of specific binding of the PAc protein to human salivary components, a simple sandwich assay was used. Microtiter plates precoated with recombinant PAc (rPAc), PAc fragments, or S. mutans whole cells were allowed to react with human whole saliva and then were incubated with biotinylated rPAc. The biotinylated rPAc bound to salivary components was detected by use of alkaline phosphatase-conjugated streptavidin and p-nitrophenylphosphate. In this assay, the binding of whole cells of S. mutans and purified rPAc to salivary components was confirmed. For determination of a saliva-binding region of the PAc molecule, 14 truncated PAc fragments were constructed by use of the polymerase chain reaction and an expression vector, pAX4a+. The binding of these truncated PAc fragments to human salivary components was determined by the sandwich assay. Among the truncated PAc fragments, fragments corresponding to residues 39 to 864 and residues 39 to 1000 of PAc showed a high ability to bind to salivary components. Shorter recombinant fragments corresponding to residues 39 to 217, residues 200 to 481, residues 470 to 749, and residues 688 to 864 did not exhibit any binding ability. The fragment that corresponds to a proline-rich repeating region (residues 828 to 1000) bound directly to the PAc protein. These results suggest that residues 39 864 of the PAc molecule are important in the binding of the surface protein to human salivary components, and the proline-rich repeating region of the PAc protein may contribute to spontaneous self-aggregation of the PAc protein.
Identification of the Yersinia enterocolitica urease beta subunit as a target antigen for human synovial T lymphocytes in reactive arthritis
Authors: Probst P , Hermann E , Meyer zum Büschenfelde K H , Fleischer B
Published: January 2020

The local T-cell response to bacterial antigens is involved in the pathogenesis of reactive arthritis (ReA). Here, we have identified a 19-kDa antigen of Yersinia enterocolitica O:9 recognized by Yersinia-specific synovial fluid CD4+ T cells in two patients with Yersinia-induced ReA. N-terminal amino acid sequencing of this protein revealed that it was identical to the 19-kDa urease beta subunit of Y. enterocolitica O:9. This protein has previously been shown to be arthritogenic in preimmunized rats after intra-articular injection. Analysis of the T-cell response to this protein showed that it contains several T-cell epitopes, one of which cross-reacts with other enterobacteria not able to induce ReA. This indicates that the arthritogenicity of the 19-kDa antigen is not a property of the 19-kDa protein alone but is dependent on its expression in bacteria able to induce ReA.
Epitope mapping of the Sta58 major outer membrane protein of Rickettsia tsutsugamushi
Authors: Lachumanan R , Devi S , Cheong Y M , Rodda S J , Pang T
Published: January 2020

Binding studies of 160 overlapping, synthetic octapeptides from the hydrophilic regions of the Sta58 major outer membrane protein of Rickettsia tsutsugamushi with sera from patients with scrub typhus revealed 15 immunodominant peptides which are recognized by all the sera tested. Further analysis of the specificity of peptide binding with five of these peptides indicated that the peptides showed significantly stronger binding to scrub typhus patients' sera than they did to sera from patients with other febrile illnesses common in the region, i.e., malaria, dengue fever, typhoid fever, and leptospirosis. The main antibody class binding to these peptides appears to be immunoglobulin M, and there appears to be little correlation between reactivity with peptides and antibody titers measured by the indirect immunoperoxidase test.
Humoral immune response to the class 3 outer membrane protein during the course of meningococcal disease
Authors: Guttormsen H K , Wetzler L M , Naess A
Published: January 2020

We have determined the amounts of specific anti-class 3 outer membrane protein antibodies of immunoglobulin G (IgG), IgM, and IgA isotypes in patient sera during the course of meningococcal disease by using purified class 3 protein as the sensitizing antigen in an enzyme-linked immunosorbent assay. The class 3 protein was obtained from a variant of strain 44/76 (B:15:P1.7,16) lacking class 1 and class 4 outer membrane proteins. Serum samples from 25 patients with systemic meningococcal disease caused by organisms of various serotypes were collected during the course of disease. Seven of these patients had been immunized with a meningococcal outer membrane vesicle vaccine made from strain 44/76 prior to disease. An increase in specific anti-class 3 (type 15) outer membrane protein IgG antibodies was demonstrated in 22 of 25 patients (88%), regardless of the serotype of the infecting strain. This indicates that the specific anti-class 3 antibodies were reacting in part with epitopes not determined by the monoclonal antibodies used for serotyping. A considerable heterogeneity in antibody levels and IgG subclass response was seen. Most patients had low levels of anti-class 3 antibodies during the acute illness, with antibodies peaking during the second week of disease and returning to near baseline in sera collected 6 to 12 months after the onset of the disease. The majority of the specific anti-class 3 IgG antibodies were shown to bind to surface-exposed epitopes on the whole bacteria and to belong to IgG1 and IgG3. The highest anti-class 3 IgG peak levels were seen in patients infected with strains of the homologous serotype after vaccination with the meningococcal outer membrane vesicle vaccine, suggesting an anamnestic response. However, these patients were not protected from meningococcal disease after immunization.
Expression of the murine interleukin-4 gene in an attenuated aroA strain of Salmonella typhimurium: persistence and immune response in BALB/c mice and susceptibility to macrophage killing
Authors: Denich K , Börlin P , O'Hanley P D , Howard M , Heath A W
Published: January 2020

Cytokines are potentially useful in vaccination as adjuvants or modulators of the type of response induced. The work below describes the expression of a cloned cytokine gene for murine interleukin-4 (mIL-4) by a live vaccine vector, an attenuated aroA strain (SL7207) of Salmonella typhimurium, in a murine model system. SL7207 was used as a carrier for two different high-level expression vectors. Both resulting strains, designated SL7207(pOmpAmIL-4) and SL7207(pKKmIL-4), expressed the cloned gene product as monitored by both immunological and biological assays. However, SL7207(pOmpAmIL-4) produced mIL-4 at higher levels and was more stable in vitro than SL7207(pKKmIL-4). When SL7207(pOmpAmIL-4) was used as a live vaccine in BALB/c mice, this strain grew and survived at higher levels than the parental attenuated strain or empty plasmid-carrying strain in spleens, livers, and intestines. This difference in growth and survival did not appear to be caused by alterations in specific lymphocyte-mediated anti-Salmonella immune responses such as delayed-type hypersensitivity or serum antibody as measured by enzyme-linked immunosorbent assay; such alterations have been induced by IL-4 administration in other in vivo systems, and the lack of effect here may reflect the fact that IL-4 is not secreted from the bacteria in large quantities, most of the cytokine being in the cytoplasmic-membrane-bound fraction. Conversely, the ability of mouse macrophages to kill the bacteria in vitro was inhibited by bacterial production of mIL-4. This reduction in macrophage killing activity suggests that bacterial production of mIL-4 may be detrimental to host defense against Salmonella infection and may explain the enhanced bacterial growth and survival in vivo.
T-cell recognition of a cross-reactive antigen(s) in erythrocyte stages of Plasmodium falciparum and Plasmodium yoelii: inhibition of parasitemia by this antigen(s)
Authors: Lucas B , Engels A , Camus D , Haque A
Published: January 2020

In the current study, we investigated the presence of a cross-reactive antigen(s) in the erythrocyte stage from Plasmodium yoelii (265 BY strain) and Plasmodium falciparum through recognition by T cells primed in vivo with antigens from each of these parasites. BALB/c mice are naturally resistant to P. falciparum but are susceptible to P. yoelii infection. Mice that had recovered from P. yoelii primary infection became resistant to a second infection. A higher in vitro proliferative response to a soluble blood stage preparation of P. falciparum was observed in splenic cells from immune animals than in those from mice with a patent P. yoelii infection. The antigen-induced proliferative response was enhanced when animals were exposed to a secondary infection. Animals exposed to a challenge infection were treated with anti-CD4 or anti-CD8 monoclonal antibodies to deplete the corresponding subset of T cells. There was a marked diminution in P. falciparum antigen-induced proliferative response in the total splenic cell populations from CD8-depleted but not from CD4-depleted mice. In CD8-depleted and nondepleted animals, the antigen-induced proliferation in the total cell populations was markedly lower than in the T-cell-rich populations, indicating inhibitory activities of B cells and/or macrophages. There was no such difference in the stimulation between total and T-enriched cell populations from CD4-depleted animals. Flow cytometry analysis demonstrated the presence of an almost equal percentage of CD8+ (59.6%) and CD4+ (64%) T cells in the spleen preparations following in vivo depletion of CD4- and CD8-bearing T cells, respectively. When cultured with P. yoelii blood stage antigen, splenocytes from animals immunized with P. falciparum antigen displayed a significant proliferative response which was markedly diminished by treatment with anti-Thy-1.2 antibody plus complement. Animals immunized with P. falciparum antigen and then challenged with P. yoelii blood stage parasites displayed about a 50% lower level of parasitemia. These results demonstrated the existence of a cross-reactive antigen(s) between a murine and a human Plasmodium species, as determined from both in vivo and in vitro biological assays, and indicated the reactivity of mainly CD8+ T cells with this antigen.
Effect of orally administered monoclonal antibody on persistent Cryptosporidium parvum infection in scid mice
Authors: Perryman L E , Kegerris K A , Mason P H
Published: January 2020

Scid mice, persistently infected after exposure to 10(7) Cryptosporidium parvum oocysts, were treated daily for 14 to 17 days with 0.4 mg of monoclonal antibody (mAb) 17.41 administered by the oral route. Mice receiving mAb 17.41 shed significantly fewer (P < 0.005) C. parvum oocysts than scid mice receiving isotype control mAb. Intestinal (but not gastric) infectivity scores were also reduced for scid mice treated with mAb 17.41 (P < 0.01).
Effect of cholera toxin on vaccine-induced immunity and infection in murine schistosomiasis mansoni
Authors: Akhiani A A , Nilsson L A , Ouchterlony O
Published: January 2020

Intradermal vaccination of mice with soluble adult worm antigen (SWAP) in combination with Mycobacterium bovis BCG (Swedish strain) induced significant protection against subsequent infection with Schistosoma mansoni cercariae. When cholera toxin (CT) was used as an adjuvant in combination with SWAP or fraction A, no significant protection was observed. However, intradermal vaccination in combination with CT triggered a strong anti-SWAP antibody response and induced a strong delayed-type hypersensitivity response to schistosome antigens (SWAP or fraction A), one significantly higher than that in the SWAP-BCG group. In addition, vaccinating mice intranasally with SWAP or cercarial antigen together with CT as adjuvant failed to induce any significant protection. Surprisingly, mice given CT alone intranasally revealed a significantly enhanced worm burden. These findings suggest that mucosal application of CT may modulate the host-parasite relationship in favor of parasite survival.
An Fc gamma RII-, Fc gamma RIII-specific monoclonal antibody (2.4G2) decreases acute Trypanosoma cruzi infection in mice
Authors: Araujo-Jorge T , Rivera M T , el Bouhdidi A , Daëron M , Carlier Y
Published: January 2020

In order to study the role of Fc gamma Rs in Trypanosoma cruzi infection in mice, the 2.4G2 monoclonal antibody (MAb), specific to the extracellular domains of Fc gamma RII and Fc gamma RIII, was injected intraperitoneally into mice. Flow cytometry studies of uninfected mice showed that 2.4G2 MAb bound to peritoneal and lymph node cells, respectively, on days 2 and 6 after injection. Repeating 2.4G2 injections every 3 to 4 days decreased the availability of Fc gamma Rs on peritoneal, lymph node, and spleen cells. Injections of 2.4G2 MAb into T. cruzi-infected mice, at days -1, 3, 7, 11, 16, 20, and 24 relative to infection, reduced mortality in comparison with that in infected animals injected with an unrelated MAb (50 versus 93.3% mortality; P < 0.01). Parasitemia in 2.4G2-treated mice was significantly (three times) lower than in control animals on days 21 and 24 postinfection (P < 0.05), before parasite-specific antibodies were detectable at significant levels. Immunoglobulin and T. cruzi-specific antibody levels were similar in all groups of mice. These results indicate that repeated injections of 2.4G2 MAb administered to acutely infected mice reduce the in vivo infection level, suggesting that Fc gamma Rs play a role in the early host invasion by T. cruzi parasites.
In vivo induction of apoptosis (programmed cell death) in mouse thymus by administration of lipopolysaccharide
Authors: Zhang Y H , Takahashi K , Jiang G Z , Kawai M , Fukada M , Yokochi T
Published: January 2020

In vivo administration of bacterial lipopolysaccharide to mice induced DNA fragmentation in the thymus. Fragmented DNA was confirmed by agarose gel electrophoresis and laser flow cytometry. DNA fragmentation was predominantly detected in the thymus of young mice, while it was undetectable in the spleen, bone marrow, and lymph nodes. DNA fragmentation in the thymus was roughly dependent on the dose of lipopolysaccharide injected and reached the peak about 18 h after the injection. The addition of lipopolysaccharide to in vitro cultures of thymocytes did not cause DNA fragmentation, suggesting that lipopolysaccharide was unable to induce apoptosis of thymocytes directly. The injection of lipopolysaccharide induced no significant DNA fragmentation in adrenalectomized mice. The injection of anti-tumor necrosis factor alpha antibody together with lipopolysaccharide partially inhibited the appearance of DNA fragmentation in the thymus. On the basis of the fact that DNA fragmentation is one of the characteristics typical in apoptotic cell death, it was suggested that lipopolysaccharide could induce apoptosis in the mouse thymus in vivo. This apoptosis in the thymus might be mediated mainly by the adrenal hormones, but it is likely that tumor necrosis factor alpha might also participate in it.