bluuebunny/crossref_metadata_2025 huggingface dataset:
Neutralizing Antibody Responses to Human Herpesviruses 6 and 7 Do Not Cross-React with Each Other, and Maternal Neutralizing Antibodies Contribute to Sequential Infection with These Viruses in Childhood
Authors: Yoshida Mariko , Torigoe Sadayoshi , Ikeue Kumiko , Yamada Masao
Published: July 2002

Seroprevalence of human herpesvirus 6 (HHV-6) and HHV-7 infections is very high throughout the world, and almost all people are exposed first to HHV-6 and second to HHV-7 in their childhood. However, it is not clear whether the neutralizing (NT) antibody response between each virus is cross-reactive or not. To elucidate the NT antibody response between each virus, 55 serum samples from an adult group (subjects 22 to 88 years old) and 60 serum samples from a young group (subjects 2 to 18 years old) were examined by a dot blot method for detecting viral late antigen. Thirty-nine serum samples obtained from cord bloods and a few serum samples obtained from pediatric patients with exanthem subitum were also examined to assess the maternal transferred NT antibodies against each virus. The NT antibody titers against HHV-7 in the adult group remained high throughout all the individuals, and none were negative. Those against HHV-6 were high values in the young group but low values, including negative values (three samples), in the adult group. These results suggested that the NT antibody response to either HHV-6 or HHV-7 in each individual was specific to each virus and did not cross-react with each other. In the adult group, the NT antibody response to HHV-6 decreased, while that to HHV-7 remained high throughout all the individuals. Maternal transferred NT antibody titers against HHV-7 were higher and remained longer after birth than those of HHV-6, and these findings were in accord with the clinical observation that HHV-6 infection usually occurs earlier than HHV-7 infection.
Ross River Virus Transmission, Infection, and Disease: a Cross-Disciplinary Review
Authors: Harley David , Sleigh Adrian , Ritchie Scott
Published: July 2002

Ross River virus (RRV) is a fascinating, important arbovirus that is endemic and enzootic in Australia and Papua New Guinea and was epidemic in the South Pacific in 1979 and 1980. Infection with RRV may cause disease in humans, typically presenting as peripheral polyarthralgia or arthritis, sometimes with fever and rash. RRV disease notifications in Australia average 5,000 per year. The first well-described outbreak occurred in 1928. During World War II there were more outbreaks, and the name epidemic polyarthritis was applied. During a 1956 outbreak, epidemic polyarthritis was linked serologically to a group A arbovirus (Alphavirus). The virus was subsequently isolated from Aedes vigilax mosquitoes in 1963 and then from epidemic polyarthritis patients. We review the literature on the evolutionary biology of RRV, immune response to infection, pathogenesis, serologic diagnosis, disease manifestations, the extraordinary variety of vertebrate hosts, mosquito vectors, and transmission cycles, antibody prevalence, epidemiology of asymptomatic and symptomatic human infection, infection risks, and public health impact. RRV arthritis is due to joint infection, and treatment is currently based on empirical anti-inflammatory regimens. Further research on pathogenesis may improve understanding of the natural history of this disease and lead to new treatment strategies. The burden of morbidity is considerable, and the virus could spread to other countries. To justify and design preventive programs, we need accurate data on economic costs and better understanding of transmission and behavioral and environmental risks.
Campylobacter jejuniCytolethal Distending Toxin Mediates Release of Interleukin-8 from Intestinal Epithelial Cells
Authors: Hickey Thomas E. , McVeigh Annette L. , Scott Daniel A. , Michielutti Ronda E. , Bixby Alyssa , Carroll Shannon A. , Bourgeois A. Louis , Guerry Patricia
Published: July 2002

Live cells ofCampylobacter jejuniandCampylobacter colican induce release of interleukin-8 (IL-8) from INT407 cells. Additionally, membrane fractions ofC. jejuni81-176, but not membrane fractions ofC. colistrains, can also induce release of IL-8. Membrane preparations from 81-176 mutants defective in any of the three membrane-associated protein subunits of cytolethal distending toxin (CDT) were unable to induce IL-8. The presence of the threecdtgenes on a shuttle plasmid intransrestored both CDT activity and the ability to release IL-8 to membrane fractions. However, CDT mutations did not affect the ability of 81-176 to induce IL-8 during adherence to or invasion of INT407 cells. WhenC. jejuni cdtgenes were transferred on a shuttle plasmid into aC. colistrain lacking CDT, membrane preparations became positive in both CDT and IL-8 assays. Growth ofC. jejuniin physiological levels of sodium deoxycholate released all three CDT proteins, as well as CDT activity and IL-8 activity, from membranes into supernatants. Antibodies against recombinant forms of each of the three CDT subunit proteins neutralized both CDT activity and the activity responsible for IL-8 release. The data suggest thatC. jejunican induce IL-8 release from INT407 cells by two independent mechanisms, one of which requires adherence and/or invasion and the second of which requires CDT.
PersistentCryptococcus neoformansPulmonary Infection in the Rat Is Associated with Intracellular Parasitism, Decreased Inducible Nitric Oxide Synthase Expression, and Altered Antibody Responsiveness to Cryptococcal Polysaccharide
Authors: Goldman David L. , Lee Sunhee C. , Mednick Aron J. , Montella Lya , Casadevall Arturo
Published: July 2002

Fungal pathogens are notorious for causing chronic and latent infections, but the mechanism by which they evade the immune response is poorly understood. A major limitation in the study of chronic fungal infection has been the lack of suitable animal models where the infection is controlled and yet persists. PulmonaryCryptococcus neoformansinfection in rats results in a diffuse pneumonitis that resolves without dissemination or scarring except for the persistence of interstitial and subpleural granulomas that harbor viable cryptococci inside macrophages and epithelioid cells. Infected rats are asymptomatic but remain infected for as long as 18 months after inoculation withC. neoformans. Containment of infection is associated with granuloma formation that can be partially abrogated by glucocorticoid administration. Using this model, we identified several features associated with persistent infection in the rat lung, including (i) localization ofC. neoformansto discrete, well-organized granulomas; (ii) intracellular persistence ofC. neoformanswithin macrophages and epithelioid cells; (iii) reduced inducible nitric oxide synthase expression by granulomas harboringC. neoformans; and (iv) reduced antibody responses to cryptococcal polysaccharide. The results show that maintenance of persistent infection is associated with downregulation of both cellular and humoral immune responses.
Lack of a Role of Cytotoxic Necrotizing Factor 1 Toxin fromEscherichia coliin Bacterial Pathogenicity and Host Cytokine Response in Infected Germfree Piglets
Authors: Fournout S. , Dozois C. M. , Odin M. , Desautels C. , Pérès S. , Hérault F. , Daigle F. , Segafredo C. , Laffitte J. , Oswald E. , Fairbrother J. M. , Oswald I. P.
Published: July 2002

SomeEscherichia colistrains isolated from intestinal or extraintestinal infections in pigs produce cytotoxic necrotizing factor 1 (CNF1). In order to analyze the role of CNF1 in the pathogenesis of porcine colibacillosis, newborn colostrum-deprived germfree piglets were orally inoculated with a wild-type CNF1-producing strain (M623) or with an isogeniccnf1mutant (M623ΔCNF1). The two isogenic strains induced a high mortality with similar lung and serosal inflammatory lesions, indicating that both strains were pathogenic in these piglets. Bacterial counts in various organs of inoculated piglets revealed an intestinal predisposition of M623 and M623ΔCNF1 strains for the cecum and colon. Extraintestinal organs (lungs, liver, spleen, and kidney) were also colonized by both strains. Similar colonization of intestinal and extraintestinal tissues in animals inoculated with either strain was observed, except in the ileum, where M623 showed a higher colonization than M623ΔCNF1. Intestinal (ileum and colon), extraintestinal (lung and kidney), and immune (mesenteric lymph nodes and spleen) tissues were sampled at 1 day postinoculation and analyzed for cytokine expression by a reverse transcriptase PCR technique. Inoculation withE. coliM623 induced an enhanced expression of inflammatory cytokines (interleukin-1α [IL-1α], tumor necrosis factor α, and IL-12p40) in the intestinal organs compared to uninoculated piglets or piglets inoculated with nonpathogenic intestinalE. coli862B, which is also able to colonize the intestinal tract. There was little difference in cytokine transcript levels in the intestinal and extraintestinal organs in piglets inoculated withE. colistrains M623 or M623ΔCNF1, except in the ileum, where IL-1α and IL-8 mRNA levels correlated with bacterial colonization. Expression of regulatory cytokines (gamma interferon and IL-4) was weak in immune tissues from piglets inoculated with M623 or M623ΔCNF1. Taken together, our data indicate that the CNF1-producing strain, M623, is pathogenic and induces inflammatory cytokine expression in germfree, colostrum-deprived piglets. Nevertheless, in this model, the CNF1 toxin does not appear to be a major factor for pathogenicity or cytokine response, as demonstrated by the use of an isogeniccnf1mutant.
Transient Loss of Resistance to Pulmonary Tuberculosis in p47phox−/−Mice
Authors: Cooper Andrea M. , Segal Brahm H. , Frank Anthony A. , Holland Steven M. , Orme Ian M.
Published: July 2002

Mycobacterium tuberculosisis an important respiratory pathogen the growth of which is controlled primarily by cytokine-activated macrophages. One of the principal mediators of this control is nitric oxide; however, superoxide has recently been shown to be protective in systemic mycobacterial infections. To determine whether superoxide is important in controllingM. tuberculosisduring primary pulmonary infection, mice lacking the cytosolic p47phoxgene (which is essential for effective superoxide production by the NADPH oxidase) were infected aerogenically. The lack of superoxide during an aerosol infection withM. tuberculosisresulted in a significant increase in bacterial growth over the early period of infection. Once antigen-specific gamma interferon-producing lymphocytes were detected in the draining lymph nodes, however, bacterial growth in the lung stopped. One interesting consequence of the lack of superoxide was an increase in neutrophilic infiltrates within the granuloma. This may be a consequence of increased tissue damage due to more rapid bacterial growth or may reflect a role for superoxide in controlling inflammation.
Identification of a
Haemophilus influenzae
5′-Nucleotidase Protein: Cloning of the
nucA
Gene and Immunogenicity and Characterization of the NucA Protein
Authors: Zagursky Robert J. , Ooi Peggy , Jones Kevin F. , Fiske Michael J. , Smith Robert P. , Green Bruce A.
Published: July 2002

We report on the identification of a surface-exposed, highly conserved, immunogenic nontypeable
Haemophilus influenzae
(NTHi) protein, which elicits cross-reactive bactericidal antibodies against NTHi. The protein was extracted from NTHi strain P860295 with KSCN and purified; it migrated as a single band on a sodium dodecyl sulfate-polyacrylamide gel with an apparent molecular mass of 63 kDa. Mouse antiserum generated against the purified protein was reactive on whole-cell enzyme-linked immunosorbent assay (ELISA) with seven NTHi strains and type b Eagan and Whittier strains and exhibited bactericidal activity to homologous and heterologous NTHi strains. However, the protein is made in small amounts in NTHi as corroborated by immunoelectron microscopy. To further study this protein, we cloned, sequenced, and expressed it recombinantly in
Escherichia coli
. The recombinant protein is localized in the periplasm of
E. coli
and has been purified to homogeneity. Both the recombinant and native proteins possess 5′-nucleotidase activity; hence, the protein has been called NucA. Mouse antiserum directed against the recombinant NucA protein was reactive on Western immunoblots and whole-cell ELISA with all
H. influenzae
strains tested including Eagan and was bactericidal for two heterologous strains tested. The antiserum also resulted in a log reduction in bacteremia, in an infant-rat protection study with
H. influenzae
type b as the challenge strain. These features suggest that NucA is a potential subunit vaccine candidate against NTHi disease.
Interaction ofSalmonella entericaSerotype Typhimurium with Dendritic Cells Is Defined by Targeting to Compartments Lacking Lysosomal Membrane Glycoproteins
Authors: García-Del Portillo Francisco , Jungnitz Heidrun , Rohde Manfred , Guzmán Carlos A.
Published: July 2002

Dendritic cells (DCs) play a central role in the generation of acquired immunity to infections by pathogenic microorganisms.Salmonella entericaserotype Typhimurium is known to survive and proliferate intracellularly within macrophages and nonphagocytic cells, but no data exist on how this pathogen interacts with DCs. In this report, we show the capacity of serotype Typhimurium to survive within the established mouse DC line CB1. In contrast to the case for the macrophage model, the compartments of DCs containing serotype Typhimurium are devoid of lysosomal membrane glycoproteins and the PhoPQ two-component regulatory system is not essential for pathogen intracellular survival.
RgpA-Kgp Peptide-Based Immunogens Provide Protection againstPorphyromonas gingivalisChallenge in a Murine Lesion Model
Authors: O'Brien-Simpson Neil M. , Paolini Rita A. , Reynolds Eric C.
Published: July 2002

Porphyromonas gingivalis, a gram-negative bacterium, has been linked to the onset and progression of periodontitis, a chronic inflammatory disease of the supporting tissues of the teeth. A major virulence factor ofP. gingivalisis an extracellular complex of Arg- and Lys-specific proteinases and adhesins designated the RgpA-Kgp complex (formerly the PrtR-PrtK complex). In this study we show that the RgpA-Kgp complex, when used as an immunogen with incomplete Freund adjuvant (IFA), protects against challenge with invasive and noninvasive strains ofP. gingivalisin the murine lesion model. We identified a variety of peptide vaccine candidates from the RgpA and Kgp polyprotein sequences that involved the putative active site histidine of both proteinases and five repeat motifs in the adhesin domains of both polyproteins implicated in aggregation and binding to host substrates, designated adhesin-binding motif (ABM) peptides. These peptides were synthesized using standard, solid-phase protocols for 9-fluorenylmethoxy carbonyl chemistry withS-acetylmercaptoacetic acid (SAMA) as the N-terminal residue. The SAMA-peptides were then conjugated to diphtheria toxoid and used with IFA to immunize BALB/c mice. Both active-site peptides and three of the five ABM peptides gave protection (P< 0.005) against challenge withP. gingivalisin the murine lesion model. The three ABM peptide sequences that conferred protection exist within a 100-residue span in the RgpA44 and Kgp39 adhesins of the RgpA-Kgp complex. Protective anti-RgpA-Kgp complex mouse antisera recognized the RgpA27, Kgp39, and RgpA44 adhesins in an immunoblot. Epitope mapping of the RgpA27 adhesin using the protective anti-RgpA-Kgp antisera identified a major protective epitope that mapped immediately N terminal to one of the protective ABM peptides in the 100-residue span in RgpA44 and Kgp39. This identified protective epitope contains clusters of basic residues spatially surrounded by hydrophobic amino acids, a finding which is characteristic of a heparin binding motif.
Invasion of Human Epithelial Cells by
Pseudomonas aeruginosa
Involves Src-Like Tyrosine Kinases p60Src and p59Fyn
Authors: Esen Meral , Grassmé Heike , Riethmüller Joachim , Riehle Andrea , Fassbender Klaus , Gulbins Erich
Published: July 2002

Pseudomonas aeruginosa
plays a major role in respiratory tract infections or sepsis in patients with cystic fibrosis or upon suppression of the immune system. Several
P. aeruginosa
strains have been shown to be internalized by human epithelial cells; however, the molecular mechanisms of the invasion process are poorly characterized. Here, we show that the internalization of
P. aeruginosa
into human epithelial cells results in and requires activation of the Src-like tyrosine kinases p59Fyn and p60Src and the consequent tyrosine phosphorylation of several eukaryotic proteins. The significance of Src-like tyrosine kinase activation is shown by an almost complete blockade of
P. aeruginosa
internalization, but not adhesion, upon inhibition of Src-like tyrosine kinases. Likewise, inhibition of
P. aeruginosa
binding to CFTR, which has been shown to block
P. aeruginosa
internalization, prevents Src and Fyn activation, supporting a pivotal role of Src-like tyrosine kinases for invasion by
P. aeruginosa.
Dendritic Cells Phagocytose and Are Activated byTreponema pallidum
Authors: Bouis Deborah A. , Popova Taissia G. , Takashima Akira , Norgard Michael V.
Published: July 2002

Cell-mediated immune processes play a prominent role in the clinical manifestations of syphilis, a sexually transmitted disease of humans caused by spirochetal bacteriumTreponema pallidum. The immune cell type that initiates the early immune response toT. pallidumthus far has not been identified. However, dendritic cells (DCs) are the first immune-competent cells to encounter antigens within skin or mucous membranes, the principal sites of early syphilitic infection. In the present study, immature DC line XS52, derived from murine skin, was utilized to examineT. pallidum-DC interactions and subsequent DC activation (maturation). Electron microscopy revealed thatT. pallidumwas engulfed by DCs via both coiling and conventional phagocytosis and was delivered to membrane-bound vacuoles. The XS52 DC line expressed surface CD14 and mRNA for Toll-like receptors 2 and 4, molecules comprising important signaling components for immune cell activation by bacterial modulins. BothT. pallidumand a synthetic lipopeptide (corresponding to the 47-kDa major membrane lipoprotein) activated the XS52 DC line, as indicated by the secretion of interleukin-12 (IL-12), IL-1β, tumor necrosis factor alpha, and IL-6 and elevated surface expression of CD54. The combined data support the contention that DCs stimulated byT. pallidumand/or its proinflammatory membrane lipoproteins are involved in driving the cellular immune processes that typify syphilis.
Characterization of the Enzymatic Component of the ADP-Ribosyltransferase Toxin CDTa from
Clostridium difficile
Authors: Gülke Irene , Pfeifer Gunther , Liese Jan , Fritz Michaela , Hofmann Fred , Aktories Klaus , Barth Holger
Published: July 2002

Certain strains of
Clostridium difficile
produce the ADP-ribosyltransferase CDT, which is a binary actin ADP-ribosylating toxin. The toxin consists of the binding component CDTb, which mediates receptor binding and cellular uptake, and the enzyme component CDTa. Here we studied the enzyme component (CDTa) of the toxin using the binding component of
Clostridium perfringens
iota toxin (Ib), which is interchangeable with CDTb as a transport component. Ib was used because CDTb was not expressed as a recombinant protein in
Escherichia coli
. Similar to iota toxin, CDTa ADP-ribosylates nonmuscle and skeletal muscle actin. The N-terminal part of CDTa (CDTa
1–240
) competes with full-length CDTa for binding to the iota toxin binding component. The C-terminal part (CDTa
244–263
) harbors the enzyme activity but was much less active than the full-length CDTa. Changes of Glu428 and Glu430 to glutamine, Ser388 to alanine, and Arg345 to lysine blocked ADP-ribosyltransferase activity. Comparison of CDTa with
C. perfringens
iota toxin and
Clostridium botulinum
C2 toxin revealed full enzyme activity of the fragment Ia
208–413
but loss of activity of several N-terminally deleted C2I proteins including C2I
103–431
, C2I
190–431
, and C2I
30–431
. The data indicate that CDTa belongs to the iota toxin subfamily of binary actin ADP-ribosylating toxins with respect to interaction with the binding component and substrate specificity. It shares typical conserved amino acid residues with iota toxin and C2 toxin that are suggested to be involved in NAD-binding and/or catalytic activity. The enzyme components of CDT, iota toxin, and C2 toxin differ with respect to the minimal structural requirement for full enzyme activity.
Regulation of Expression of Major Histocompatibility Antigens by Bovine Macrophages Infected withMycobacterium aviumsubsp.paratuberculosisorMycobacterium aviumsubsp.avium
Authors: Weiss Douglas J. , Evanson Oral A. , McClenahan David J. , Abrahamsen Mitchell S. , Walcheck Bruce K.
Published: July 2002

Mycobacterium aviumsubsp.paratuberculosisandMycobacterium aviumsubsp.aviumare antigenically and genetically very similar organisms; however, they differ markedly in their virulence for cattle. We evaluated the capacity of bovine macrophages infected withM. aviumsubsp.paratuberculosisorM. aviumsubsp.aviumto express major histocompatibility complex (MHC) class I and class II antigens on their surface and to interact with primed autologous lymphocytes. Our results indicate that infection of bovine macrophages withM. aviumsubsp.paratuberculosispromoted the downregulation of MHC class I and class II molecules on the macrophage surface within 24 and 12 h, respectively. Alternatively, MHC class II expression byM. aviumsubsp.avium-infected macrophages was not detected until 24 h after infection, and the magnitude of the decrease was smaller. Decreased MHC class I expression byM. aviumsubsp.avium-infected macrophages was not detected. UnlikeM. aviumsubsp.paratuberculosis-infected macrophages,M. aviumsubsp.avium-infected macrophages upregulated MHC class I and class II expression after activation by gamma interferon or tumor necrosis factor alpha. Further,M. aviumsubsp.avium-infected macrophages were lysed by primed autologous lymphocytes, whereasM. aviumsubsp.paratuberculosis-infected macrophages were not. Overall, the results support the hypothesis that the difference in the virulence ofM. aviumsubsp.paratuberculosisandM. aviumsubsp.aviumfor cattle is dependent on a difference in the capacity of the organisms to suppress mycobacterial antigen presentation to T lymphocytes.
Role of T Cells and Gamma Interferon during Induction of Hypersensitivity to Lipopolysaccharide by Toxic Shock Syndrome Toxin 1 in Mice
Authors: Dinges Martin M. , Schlievert Patrick M.
Published: July 2002

The superantigenic function of toxic shock syndrome toxin 1 (TSST-1) is generally regarded as an important determinant of its lethal effects in humans or experimental animals. This study examined the role of superantigenicity in a BALB/c mouse model of lethal TSST-1-induced hypersensitivity to lipopolysaccharide (LPS). In this model, TSST-1 greatly potentiated both LPS-induced lethality, as well as LPS-induced serum tumor necrosis factor alpha (TNF-α) activity. Although BALB/c-SCID mice were resistant to these LPS enhancement effects of TSST-1, BALB/c-SCID mice reconstituted with T cells were completely susceptible to the enhancement effect of TSST-1 on LPS-induced serum TNF-α. Mice pretreated with cyclosporine (Cs) or neutralizing antibodies against gamma interferon (IFN-γ) did not develop lethal LPS hypersensitivity when injected with TSST-1, and these agents reduced the enhancement effect of TSST-1 on LPS-induced serum TNF-α by 99 and 85%, respectively. Cs pretreatment also completely inhibited the known capacity of TSST-1 to amplify LPS-induced levels of IFN-γ in serum. In contrast, mice given Cs after a priming injection of TSST-1, but before LPS, still exhibited lethal hypersensitivity to LPS. Cs given after TSST-1 also did not inhibit enhancement of LPS-induced serum TNF-α by TSST-1 but inhibited the enhancement effect of TSST-1 on LPS-induced serum IFN-γ by 50%. These experiments support the theory that TSST-1-induced hypersensitivity to LPS is mediated primarily by IFN-γ derived from superantigen-activated T cells.
Nme
SI Restriction-Modification System Identified by Representational Difference Analysis of a Hypervirulent
Neisseria meningitidis
Strain
Authors: Bart Aldert , Pannekoek Yvonne , Dankert Jacob , van der Ende Arie
Published: July 2002

Neisseria meningitidis
is a gram-negative bacterium that may cause meningitis, sepsis, or both. The increase in the incidence of meningococcal disease in various countries in the past 2 decades is mainly due the genotypically related lineage III meningococci. The chromosomal DNA differences between lineage III strains and non-lineage III strains were identified using representational difference analysis. Thus, a 1.8-kb locus that is specific for lineage III meningococci was identified. The locus contains three open reading frames encoding the
Nme
SI restriction-modification system. The methyltransferase gene was cloned and expressed in
Escherichia coli
. Site AGTACT was found to be modified by the enzyme. In conclusion, lineage III strains differ from endemic strains by the presence of a specific restriction-modification system. This restriction-modification system may contribute to the clonal and hypervirulent character of lineage III strains by influencing horizontal gene transfer and transcription.
Acapsular
Pasteurella multocida
B:2 Can Stimulate Protective Immunity against Pasteurellosis
Authors: Boyce John D. , Adler Ben
Published: July 2002

We have previously shown that a
Pasteurella multocida cexA
mutant (PBA875) was impaired in capsule export and highly attenuated in virulence for mice (J. D. Boyce and B. Adler, Infect. Immun. 68:3463–3468, 2000). In this study we show that immunization with high, but not low, doses of PBA875 can confer significant protection against wild-type challenge. We have also constructed a genetically defined acapsular
P. multocida
strain (AL18) by inactivation of
bcbH
, a gene predicted to be involved in polysaccharide biosynthesis. AL18 failed to produce immunoreactive polysaccharide as determined by immunofluorescence and Western immunoblot. Immunization of mice with live AL18 conferred significant protection against wild-type challenge, while immunization with similar doses of either killed wild-type or killed AL18 failed to confer protection.
Chemokine-Dependent Neutrophil Recruitment in a Murine Model ofLegionellaPneumonia: Potential Role of Neutrophils as Immunoregulatory Cells
Authors: Tateda Kazuhiro , Moore Thomas A. , Newstead Michael W. , Tsai Wan C. , Zeng Xianying , Deng Jane C. , Chen Gina , Reddy Raju , Yamaguchi Keizo , Standiford Theodore J.
Published: July 2002

The roles of CXC chemokine-mediated host responses were examined with an A/J mouse model ofLegionella pneumophilapneumonia. After intratracheal inoculation of 106CFU ofL. pneumophila, the bacterial numbers in the lungs increased 10-fold by day 2; this increase was accompanied by the massive accumulation of neutrophils. Reverse transcription-PCR data demonstrated the up-regulation of CXC chemokines, such as keratinocyte-derived chemokine, macrophage inflammatory protein 2 (MIP-2), and lipopolysaccharide-induced CXC chemokine (LIX). Consistent with these data, increased levels of KC, MIP-2, and LIX proteins were observed in the lungs and peaked at days 1, 2, and 2, respectively. Although the administration of anti-KC or anti–MIP-2 antibody resulted in an approximately 20% decrease in neutrophil recruitment on day 2, no increase in mortality was observed. In contrast, the blockade of CXC chemokine receptor 2 (CXCR2), a receptor for CXC chemokines, including KC and MIP-2, strikingly enhanced mortality; this effect coincided with a 67% decrease in neutrophil recruitment. Interestingly, anti-CXCR2 antibody did not affect bacterial burden by day 2, even in the presence of a lethal challenge of bacteria. Moreover, a significant decrease in interleukin-12 (IL-12) levels, in contrast to the increases in KC, MIP-2, and LIX levels, was demonstrated for CXCR2-blocked mice. These data indicated that CXCR2-mediated neutrophil accumulation may play a crucial role in host defense againstL. pneumophilapneumonia in mice. The increase in lethality without a change in early bacterial clearance suggested that neutrophils may exert their protective effect not through direct killing but through more immunomodulatory actions inL. pneumophilapneumonia. We speculate that a decrease in the levels of the protective cytokine IL-12 may explain, at least in part, the high mortality in the setting of reduced neutrophil recruitment.
Fibronectin Attachment Protein Homologue Mediates Fibronectin Binding by
Mycobacterium avium
subsp.
paratuberculosis
Authors: Secott T. E. , Lin T. L. , Wu C. C.
Published: July 2002

Attachment of
Mycobacterium avium
subsp.
paratuberculosis
to host tissue and penetration of mucosal surfaces are pivotal events in the pathogenesis of Johne's disease. Fibronectin (FN) binding is required for attachment and internalization of several mycobacteria by epithelial cells in vitro. The objective of this study was to further characterize the FN binding activity of
M. avium
subsp.
paratuberculosis
. Although the bacteria bound FN poorly at pH above 7, brief acid pretreatment greatly enhanced FN binding within the pH range (3 to 10) studied. A 4.6-kbp fragment from an
M. avium
subsp.
paratuberculosis
genomic library was found to contain a 1,107-bp open reading frame that shows very high nucleotide sequence identity with that of the FN attachment protein (FAP) gene of
M. avium
subsp.
avium
. Pretreatment of FN with an FN-binding peptide from
M. avium
subsp.
avium
FAP abolished FN binding, indicating that
M. avium
subsp.
paratuberculosis
binds FN in a FAP-dependent manner. Pretreatment of
M. avium
subsp.
paratuberculosis
with anti-FAP immunoglobulin G did not abrogate FN binding; blocking occurred only when anti-FAP was added together with FN. FAP was detected by immunofluorescence only in lipid-extracted
M. avium
subsp.
paratuberculosis
. Western blotting and immunoelectron microscopy revealed that FAP is located near the interior of the cell envelope of
M. avium
subsp.
paratuberculosis
. The results indicate that a FAP homologue mediates the attachment of FN to
M. avium
subsp.
paratuberculosis
. Further, given the subcellular location of FAP, it is considered that this protein operates at the terminus of a coordinated FN binding system in the cell envelope of
M. avium
subsp.
paratuberculosis
.
Activation of Endothelium byBorrelia burgdorferiIn Vitro Enhances Transmigration of Specific Subsets of T Lymphocytes
Authors: Gergel Edna I. , Furie Martha B.
Published: July 2002

Lyme disease, caused byBorrelia burgdorferi, is characterized by the accumulation of lymphocytes and monocytes in the affected tissue. Endothelial cells line the blood vessel walls and control the trafficking of inflammatory leukocytes from the blood into the surrounding tissues. A model of the blood vessel wall, consisting of human umbilical vein endothelial cells (HUVEC) grown on amniotic connective tissue, was utilized to examine the effects ofB. burgdorferion the transendothelial migration of T lymphocytes. Maximal migration occurred when the HUVEC-amnion cultures were preincubated withB. burgdorferifor 24 h and T lymphocytes were added for an additional 4 h, yielding a two- to fourfold increase compared to migration across unstimulated cultures. The number of T lymphocytes that migrated was proportional to the number added. The anti-inflammatory cytokine interleukin 10 (IL-10), added during activation of the HUVEC, significantly diminished (by an average of 70% ± 21%) the migration of T lymphocytes across endothelium stimulated for 8 or 24 h withB. burgdorferi, but not IL-1. Compared to the initially added population of T lymphocytes, the population that migrated across untreated endothelium or HUVEC activated withB. burgdorferior IL-1 contained a significantly smaller percentage of CD45RA+RO−(naı̈ve) cells and a greater proportion of CD45RA+RO+cells. The migratory population was also enriched for CD8+T lymphocytes when the endothelium was incubated with either control medium orB. burgdorferi, but not IL-1.B. burgdorferithus activates endothelium in a manner that promotes the transmigration of T lymphocytes, and IL-10 inhibits this activation. These data further suggest that endothelium plays an active role in promoting the recruitment of specific subpopulations of T lymphocytes.
Resolution of SecondaryChlamydia trachomatisGenital Tract Infection in Immune Mice with Depletion of Both CD4+and CD8+T cells
Authors: Morrison Sandra G. , Morrison Richard P.
Published: July 2002

The essential role of T cells in the resolution of primary murineChlamydia trachomatisgenital tract infection is inarguable; however, much less is known about the mechanisms that confer resistance to reinfection. We previously established that CD4+T cells and B cells contribute importantly to resistance to reinfection. In our current studies, we demonstrate that immune mice concurrently depleted of both CD4+T cells and CD8+T cells resisted reinfection as well as immunocompetent wild-type mice. The in vivo depletion of CD4+and CD8+T cells resulted in diminished chlamydia-specific delayed-type hypersensitivity responses, but antichlamydial antibody responses were unaffected. Our data indicate that immunity to chlamydial genital tract reinfection does not rely solely upon immune CD4+or CD8+T cells and further substantiate a predominant role for additional effector immune responses, such as B cells, in resistance to chlamydial genital tract reinfection.
Shigella Infection in a SCID Mouse-Human Intestinal Xenograft Model: Role for Neutrophils in Containing Bacterial Dissemination in Human Intestine
Authors: Zhang Zhi , Jin Lingling , Champion Gretchen , Seydel Karl B. , Stanley Samuel L.
Published: July 2002

Shigellae infect human intestine and cause intense inflammation and destruction of colonic and rectal mucosa. To model the interactions of shigella with human intestine in vivo, we have studied shigella infection in human intestinal xenografts in severe combined immunodeficient mice (SCID-HU-INT mice). Inoculation of shigella into human intestinal xenografts caused severe inflammation and mucosal damage, which was apparent as soon as 4 h following infection. Shigella infection was associated with human intestinal production of interleukin-1B (IL-1B) and IL-8 and a marked neutrophil influx into the graft. Depletion of neutrophils from SCID-HU-INT mice reduced inflammation in the human intestinal xenograft in response to shigella infection but failed to significantly alter tissue damage. However, the number of intracellular bacteria was more than 20-fold higher in the human intestinal xenografts from neutrophil-depleted SCID-HU-INT mice. Infection of human intestinal xenografts with an attenuated vaccine strain of shigella (CVD1203) induced lower levels of IL-1B and IL-8 than wild-type shigella and caused only moderate damage to the intestinal permeability barrier. Our studies establish the SCID-HU-INT mouse as a viable model for studying the interactions between shigella and human intestine and indicate that neutrophils are important for controlling the invasion of human intestine by shigella.
Dissociation of Infectivity and Pathogenicity in
Borrelia burgdorferi
Authors: Thomas Venetta , Anguita Juan , Samanta Swapna , Rosa Patricia A. , Stewart Philip , Barthold Stephen W. , Fikrig Erol
Published: July 2002

Clonal
Borrelia burgdorferi
N40 (cN40) passaged 75 times in vitro (N40-75) infects mice but does not cause disease. N40-75 passaged 45 times further in vitro (N40-120) was no longer infectious and lacked genes encoded on linear plasmids 38 and 28-1, among other differences. These data suggest that
B. burgdorferi
cN40, N40-75, and N40-120 have distinct phenotypes that can be used to dissect the genetic elements responsible for pathogenicity and infectivity.
CD8+T Cells Participate in the Memory Immune Response toMycobacterium tuberculosis
Authors: Serbina Natalya V. , Flynn JoAnne L.
Published: July 2002

The contribution of CD8+T cells to the control of tuberculosis has been studied primarily during acute infection in mouse models. Memory or recall responses in tuberculosis are less well characterized, particularly with respect to the CD8 T-cell subset. In fact, there are published reports that CD8+T cells do not participate in the memory immune response toMycobacterium tuberculosis. We examined the CD8+T-cell memory and local recall response toM. tuberculosis. To establish a memory immunity model, C57BL/6 mice were infected withM. tuberculosis, followed by treatment with anti-mycobacterial drugs and prolonged rest. The lungs of memory immune mice contained CD4+and CD8+T cells with the cell surface phenotype characteristic of memory cells (CD69lowCD25lowCD44high). At 1 week postchallenge withM. tuberculosisvia aerosol, ≥30% of both CD4+and CD8+T cells in the lungs of immune mice expressed the activation marker CD69 and could be restimulated to produce gamma interferon (IFN-γ). In contrast, <6% of T cells in the lungs of naive challenged mice were CD69+at 1 week postchallenge, and IFN-γ production was not observed at this time point. CD8+T cells from the lungs of both naive and memory mice after challenge were cytotoxic towardM. tuberculosis-infected macrophages. Our data indicate that memory and recall immunity toM. tuberculosisis comprised of both CD4+and CD8+T lymphocytes and that there is a rapid response of both subsets in the lungs following challenge.
Salmonella-Induced Cell Death Is Not Required for Enteritis in Calves
Authors: Santos Renato L. , Tsolis Renée M. , Zhang Shuping , Ficht Thomas A. , Bäumler Andreas J. , Adams L. Garry
Published: July 2002

Salmonellaenterica serovar Typhimurium causes cell death in bovine monocyte-derived and murine macrophages in vitro by asipB-dependent mechanism. During this process, SipB binds and activates caspase-1, which in turn activates the proinflammatory cytokine interleukin-1β through cleavage. We used bovine ileal ligated loops to address the role of serovar Typhimurium-induced cell death in induction of fluid accumulation and inflammation in this diarrhea model. Twelve perinatal calves had 6- to 9-cm loops prepared in the terminal ileum. They were divided into three groups: one group received an intralumen injection of Luria-Bertani broth as a control in 12 loops. The other two groups (four calves each) were inoculated with 0.75 × 109CFU of either wild-type serovar Typhimurium (strain IR715) or asopBmutant per loop in 12 loops. Hematoxylin and eosin-stained sections were scored for inflammation, and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL)-positive cells were detected in situ. Fluid accumulation began at 3 h postinfection (PI). Inflammation was detected in all infected loops at 1 h PI. The area of TUNEL-labeled cells in the wild-type infected loops was significantly higher than that of the controls at 12 h PI, when a severe inflammatory response and tissue damage had already developed. ThesopBmutant induced the same amount of TUNEL-positive cells as the wild type, but it was attenuated for induction of fluid secretion and inflammation. Our results indicate that serovar Typhimurium-induced cell death is not required to trigger an early inflammatory response and fluid accumulation in the ileum.
Distribution of Quorum-Sensing Genes in the
Burkholderia cepacia
Complex
Authors: Lutter E. , Lewenza S. , Dennis J. J. , Visser M. B. , Sokol P. A.
Published: July 2002

The distribution of quorum-sensing genes among strains from seven genomovars of the
Burkholderia cepacia
complex was examined by PCR.
cepR
and
cepI
were amplified from
B. cepacia
genomovars I and III,
B. stabilis
, and
B. vietnamiensis. cepR
was also amplified from
B. multivorans
and
B. cepacia
genomovar VI.
bviIR
were amplified from
B. vietnamiensis
. All genomovars produced
N
-octanoyl-
l
-homoserine lactone and
N
-hexanoyl-
l
-homoserine lactone.
B. vietnamiensis
and
B. cepacia
genomovar VII produced additional
N
-acyl-
l
-homoserine lactones.
Susceptibility of Mice to Vaginal Infection withChlamydia trachomatisMouse Pneumonitis Is Dependent on the Age of the Animal
Authors: Pal Sukumar , Peterson Ellena M. , de la Maza Luis M.
Published: July 2002

Mice from three strains, BALB/c (H-2d), C3H (H-2k), and C57BL/6 (H-2b), ranging from 5 to 14 weeks of age, were inoculated intravaginally with different doses of theChlamydia trachomatismouse pneumonitis serovar. Vaginal swabs taken at weekly intervals showed that the percentage of animals with positive cultures and the number of inclusion-forming units recovered per mouse were higher in the younger animals. Furthermore, vaginal shedding lasted longer in the young mice than in the older mice. In addition, following mating higher rates of infertility and a decrease in the number of embryos were observed in the infected young mice. In conclusion, susceptibility to a chlamydial vaginal infection is dependent on the age of the mice, with the older animals being more resistant.
T-Cell Reactivity against Streptococcal Antigens in the Periphery Mirrors Reactivity of Heart-Infiltrating T Lymphocytes in Rheumatic Heart Disease Patients
Authors: Guilherme Luiza , Oshiro Sandra E. , Faé Kellen C. , Cunha-Neto Edécio , Renesto Guilherme , Goldberg Anna C. , Tanaka Ana C. , Pomerantzeff Pablo M. A , Kiss Maria H. , Silva Clóvis , Guzman Fanny , Patarroyo Manuel E. , Southwood Scott , Sette Alessandro , Kalil Jorge
Published: July 2002

T-cell molecular mimicry between streptococcal and heart proteins has been proposed as the triggering factor leading to autoimmunity in rheumatic heart disease (RHD). We searched for immunodominant T-cell M5 epitopes among RHD patients with defined clinical outcomes and compared the T-cell reactivities of peripheral blood and intralesional T cells from patients with severe RHD. The role of HLA class II molecules in the presentation of M5 peptides was also evaluated. We studied the T-cell reactivity against M5 peptides and heart proteins on peripheral blood mononuclear cells (PBMC) from 74 RHD patients grouped according to the severity of disease, along with intralesional and peripheral T-cell clones from RHD patients. Peptides encompassing residues 1 to 25, 81 to 103, 125 to 139, and 163 to 177 were more frequently recognized by PBMC from RHD patients than by those from controls. The M5 peptide encompassing residues 81 to 96 [M5(81–96) peptide] was most frequently recognized by PBMC from HLA-DR7+DR53+patients with severe RHD, and 46.9% (15 of 32) and 43% (3 of 7) of heart-infiltrating and PBMC-derived peptide-reactive T-cell clones, respectively, recognized the M5(81–103) region. Heart proteins were recognized more frequently by PBMC from patients with severe RHD than by those from patients with mild RHD. The similar pattern of T-cell reactivity found with both peripheral blood and heart-infiltrating T cells is consistent with the migration of M-protein-sensitized T cells to the heart tissue. Conversely, the presence of heart-reactive T cells in the PBMC of patients with severe RHD also suggests a spillover of sensitized T cells from the heart lesion.
Rapid Activation of Protein Tyrosine Kinase and Phospholipase C-γ2 and Increase in Cytosolic Free Calcium Are Required byEhrlichia chaffeensisfor Internalization and Growth in THP-1 Cells
Authors: Lin Mingqun , Zhu Michael X. , Rikihisa Yasuko
Published: July 2002

Ehrlichia chaffeensis, a bacterium that cannot survive outside the eukaryotic cell, proliferates exclusively in human monocytes and macrophages. In this study, signaling events required for ehrlichial infection of human monocytic cell line THP-1 were characterized. Entry and proliferation ofE. chaffeensisin THP-1 cells were significantly blocked by various inhibitors that can regulate calcium signaling, including 8-(diethylamino)octyl-3,4,5-trimethoxybenzoate and 2-aminoethoxydiphenyl borate (intracellular calcium mobilization inhibitors), verapamil and 1-{β-[3-(4-methoxyphenyl)propyl]-4-methoxyphenethyl}-1H-imidazole (SKF-96365) (calcium channel inhibitors), neomycin and 1-(6-{[17β-3-methoxyestra-1,3,5(10)-trien-17-yl]amino}hexyl)-1H-pyrrole-2,5-dione (U-73122) (phospholipase C [PLC] inhibitors), monodansylcadaverine (a transglutaminase [TGase] inhibitor), and genistein (a protein tyrosine kinase [PTK] inhibitor). Addition ofE. chaffeensisresulted in rapid increases in the level of inositol 1,4,5-trisphosphate (IP3) and the level of cytosolic free calcium ([Ca2+]i) in THP-1 cells, which were prevented by pretreatment of THP-1 cells with inhibitors of TGase, PTK, and PLC.E. chaffeensisinduced rapid tyrosine phosphorylation of PLC-γ2, and the presence of a PLC-γ2 antisense oligonucleotide in THP-1 cells significantly blocked ehrlichial infection. Furthermore, tyrosine-phosphorylated proteins and PLC-γ2 were colocalized with ehrlichial inclusions, as determined by double-immunofluorescence labeling. The heat-sensitive component of viableE. chaffeensiscells was essential for these signaling events.E. chaffeensis, therefore, can recruit interacting signal-transducing molecules and induce the following signaling events required for the establishment of infection in host cells: protein cross-linking by TGase, tyrosine phosphorylation, PLC-γ2 activation, IP3production, and an increase in [Ca2+]i.
Cross-Reactive Polyclonal Antibodies to the Inner Core of Lipopolysaccharide from
Neisseria meningitidis
Authors: Andersen Svein Rune , Guthrie Terry , Guile Geoffrey R. , Kolberg Jan , Hou Sam , Hyland Lisa , Wong Simon Y. C.
Published: July 2002

Sera from mice immunized with native or detergent-extracted outer membrane vesicles derived from lipopolysaccharide (LPS) mutant 44/76
Mu-4
of
Neisseria meningitidis
were analyzed for antibodies to LPS. The carbohydrate portion of 44/76
Mu-4
LPS consists of the complete inner core, Glcβ1→4[GlcNAc α1→2Hep α1→3]Hep α1→5KDO[4→2αKDO]. Immunoblot analysis revealed that some sera contained antibodies to wild-type LPS which has a fully extended carbohydrate chain of immunotype L3,7, as well as to the homologous LPS. Sera reacted only weakly to LPS from 44/76
Mu-3
, which lacks the terminal glucose of the inner core. No binding to more truncated LPS was observed. Consequently, the cross-reactive epitopes are expressed mainly by the complete inner core. Dephosphorylation of wild-type LPS abolished antibody binding to LPS in all but one serum. Thus, at least two specificities of cross-reactive antibodies exist: one is dependent on phosphoethanolamine groups in LPS, and one is not. Detection of these cross-reactive antibodies strongly supports the notion that epitopes expressed by meningococcal LPS inner core are also accessible to antibodies when the carbohydrate chain is fully extended. Also, these inner core epitopes are sufficiently immunogenic to induce antibody levels detectable in polyclonal antibody responses. Meningococci can escape being killed by antibodies to LPS that bind only to a specific LPS variant, by altering the carbohydrate chain length. Cross-reactive antibodies may prevent such escape. Therefore, inner core LPS structures may be important antigens in future vaccines against meningococcal disease.
Influence of the Alternative σ
28
Factor on Virulence and Flagellum Expression of
Legionella pneumophila
Authors: Heuner Klaus , Dietrich Claudia , Skriwan Carina , Steinert Michael , Hacker Jörg
Published: July 2002

The
fliA
gene of
Legionella pneumophila
encoding the alternative σ
28
factor was inactivated by introducing a kanamycin resistance cassette. Electron microscopy and Western blot analysis revealed that the
fliA
mutant strain is aflagellate and expresses no flagellin. Reporter gene assays indicated that the
flaA
promoter is not active in the
fliA
mutant strain. The
fliA
mutant strain multiplied less effectively in coculture with amoebae than the wild-type strain and was not able to replicate in coculture with
Dictyostelium discoideum
.