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1.
Genome Announc ; 3(5)2015 Sep 24.
Article in English | MEDLINE | ID: mdl-26404594

ABSTRACT

The free-living amoeba Balamuthia mandrillaris is a rare but highly lethal agent of amoebic encephalitis in humans and many other mammalian species. Here, we announce the first draft genome sequence of the original 1990 isolate cultured from the brain of a deceased mandrill baboon.

2.
Eur J Clin Microbiol Infect Dis ; 34(8): 1573-81, 2015 Aug.
Article in English | MEDLINE | ID: mdl-25939803

ABSTRACT

Giardia duodenalis is considered the most common cause of parasitic diarrhea worldwide. Genetic studies revealed that at least eight assemblages (A-H) exist. Of these assemblages, A and B are found primarily in human beings and occasionally in animals. The association between clinical symptoms and G. duodenalis assemblages is controversial. The aim of the present study was to determine the assemblages of G. duodenalis prevalent among Egyptian children with diarrhea. Therefore, 96 positive stool samples for Giardia by light microscopy were subjected to multilocus genotyping targeting the triose phosphate isomerase (tpi), ß-giardin (bg), and glutamate dehydrogenase (gdh) genes. Amplified polymerase chain reaction (PCR) products were then purified, sequenced, and aligned with reference strains to determine the assemblages of the Giardia isolates. Out of the 96 microscopically positive stool samples for Giardia, 77 (80 %) were successfully amplified and sequenced at least at one locus. Of these, 21 (27.3 %) were shown to be assemblage A, 54 (70.1 %) assemblage B, while discordant sequence typing results were observed in 2 (2.6 %) samples. AII was the predominant subassemblage of assemblage A, while it was generally difficult to further classify assemblage B. It was concluded that infection with assemblage B was more common than that with assemblage A. No associations between epidemiological information and assemblage were detected, except with age. Although infections with assemblage B were more frequently associated with abdominal pain and acute diarrhea than with assemblage A, the difference was not statistically significant.


Subject(s)
Diarrhea/epidemiology , Diarrhea/parasitology , Genotype , Giardia lamblia/classification , Giardia lamblia/isolation & purification , Giardiasis/epidemiology , Multilocus Sequence Typing , Adolescent , Animals , Child , Child, Preschool , Egypt/epidemiology , Female , Giardia lamblia/genetics , Humans , Infant , Male , Molecular Epidemiology
3.
Clin Microbiol Infect ; 20(10): O783-5, 2014 Oct.
Article in English | MEDLINE | ID: mdl-24533695

ABSTRACT

We evaluated the performance of an immunochromatographic assay (ICA) in comparison with light microscopy and PCR for the detection of Giardia duodenalis in stool samples from 558 Rwandan children. The association of infection with clinical symptoms was similar for the three diagnostic tools. The ICA equally detected parasites of assemblages A and B and was more sensitive than light microscopy (50.4 versus 29.5% of PCR-positive samples considered true positive; p <0.0001). Hence, the ICA shows superior sensitivity compared with microscopy but still misses half of the G. duodenalis infections detected by PCR in this hyperendemic area.


Subject(s)
Chromatography, Affinity/methods , Giardia lamblia/classification , Giardia lamblia/isolation & purification , Giardiasis/diagnosis , Feces/parasitology , Giardiasis/epidemiology , Humans , Microscopy , Polymerase Chain Reaction , Rwanda/epidemiology , Sensitivity and Specificity
4.
Clin Microbiol Infect ; 17(10): 1462-70, 2011 Oct.
Article in English | MEDLINE | ID: mdl-21851483

ABSTRACT

Human visceral leishmaniasis (HVL) is the most severe clinical form of a spectrum of neglected tropical diseases caused by protozoan parasites of the genus Leishmania. Caused mainly by L. donovani and L. infantum/chagasi, HVL accounts for more than 50 000 deaths every year. Drug therapy is available but costly, and resistance against several drug classes has evolved. Here, we review our current understanding of the immunology of HVL and approaches to and the status of vaccine development against this disease.


Subject(s)
Leishmania/pathogenicity , Leishmaniasis Vaccines/immunology , Leishmaniasis, Visceral/immunology , Animals , Antigens, Protozoan/immunology , Cytokines/immunology , Dogs , Drug Discovery , Epitopes/immunology , Humans , Immunity, Cellular , Leishmania/immunology , Leishmaniasis Vaccines/economics , Leishmaniasis, Visceral/parasitology , Leishmaniasis, Visceral/therapy , Psychodidae/parasitology , Vaccination
5.
Gut ; 57(8): 1065-72, 2008 Aug.
Article in English | MEDLINE | ID: mdl-18417532

ABSTRACT

BACKGROUND: Helicobacter pylori remains a global health hazard, and vaccination would be ideal for its control. Natural infection appears not to induce protective immunity. Thus, the feasibility of a vaccine for humans is doubtful. METHODS: In two prospective, randomised, double-blind, controlled studies (Paul Ehrlich Institute application nos 0802/02 and 1097/01), live vaccines against H pylori were tested in human volunteers seronegative for, and without evidence of, active H pylori infection. Volunteers (n = 58) were immunised orally with Salmonella enterica serovar Typhi Ty21a expressing H pylori urease or HP0231, or solely with Ty21a, and then challenged with 2x10(5) cagPAI(-) H pylori. Adverse events, infection, humoral, cellular and mucosal immune response were monitored. Gastric biopsies were taken before and after vaccination, and postchallenge. Infection was terminated with antibiotics. RESULTS: Vaccines were well tolerated. Challenge infection induced transient, mild to moderate dyspeptic symptoms, and histological and transcriptional changes in the mucosa known from chronic infection. Vaccines did not show satisfactory protection. However, 13 of 58 volunteers, 8 vaccinees and 5 controls, became breath test negative and either cleared H pylori (5/13) completely or reduced the H pylori burden (8/13). H pylori-specific T helper cells were detected in 9 of these 13 (69%), but only in 6 of 45 (13%) breath test-positive volunteers (p = 0.0002; Fisher exact test). T cells were either vaccine induced or pre-existing, depending on the volunteer. CONCLUSION: Challenge infection offers a controlled model for vaccine testing. Importantly, it revealed evidence for T cell-mediated immunity against H pylori infection in humans.


Subject(s)
Bacterial Vaccines/immunology , Helicobacter Infections/prevention & control , Helicobacter pylori/immunology , Salmonella typhi/immunology , T-Lymphocyte Subsets/immunology , Adult , Antigens, Bacterial/immunology , Breath Tests , CD4-Positive T-Lymphocytes/immunology , Double-Blind Method , Gastritis/immunology , Gastritis/microbiology , Gastritis/pathology , Helicobacter Infections/complications , Helicobacter Infections/immunology , Helicobacter Infections/pathology , Helicobacter pylori/enzymology , Helicobacter pylori/isolation & purification , Humans , Immunity, Cellular , Male , Middle Aged , Prospective Studies , Salmonella Vaccines/immunology , Urease/immunology , Vaccination/adverse effects , Vaccines, Synthetic/immunology
6.
Parasite Immunol ; 30(4): 195-201, 2008 Apr.
Article in English | MEDLINE | ID: mdl-18324922

ABSTRACT

Functional analysis of genes from parasitic helminths requires, at the present time, heterologous expression. We have adapted the well-characterized system of transfection in Leishmania protozoal parasites, as a means of analysing the effect of single filarial genes on the mammalian immune system. For example, testing the function of the Brugia malayi abundant larval transcript (ALT) gene-transfected Leishmania mexicana were found to be significantly more virulent in macrophages in vitro. The course of infection in vivo is also aggravated by expression of the ALT gene. Examples are also given of transgenes which reduced in vitro growth within macrophages, as well as others which exert no effect on the protozoal parasitism. Thus, Leishmania transfection provides a tractable system to analyse helminth gene function within the context of the host immune system.


Subject(s)
Genes, Helminth , Helminths/immunology , Leishmania mexicana/genetics , Molecular Biology/methods , Animals , Helminths/genetics , Transfection
7.
Infection ; 33(2): 82-5, 2005 Apr.
Article in English | MEDLINE | ID: mdl-15827876

ABSTRACT

BACKGROUND: Despite intensive research, the etiology of acute anterior uveitis (AAU) remains poorly defined. Infection with gram-negative bacteria such as Yersinia, Salmonella, Shigella, and Chlamydia have already been suggested as a possible trigger event for AAU. Helicobacter pylori is also a gram-negative bacterium, shares the lipopolysaccharides, but did not attract the attention of many ophthalmologists until recently. Having in mind the relatively high incidence of H. pylori infection in the population, we propose that H. pylori may also be a trigger factor for AAU. PATIENTS AND METHODS: The presence of anti-H. pylori antibodies in matching serum and aqueous humor samples of 15 idiopathic AAU patients was determined using a commercial Western blot assay. Control serum and aqueous humor were obtained from five patients undergoing cataract surgery. RESULTS: Six out of 15 AAU patients (40%) were serum-positive for H. pylori, and half of these (n = 3) also had anti-H. pylori antibodies in the aqueous humor. All five aqueous humor and sera controls tested negative for H. pylori infection. CONCLUSION: These are the first results demonstrating anti-H. pylori antibodies in the aqueous humor of AAU patients. Further studies are needed to demonstrate whether this antibody is indeed locally produced. Our data may provide first evidence for a causative link between H. pylori infection and AAU.


Subject(s)
Helicobacter Infections/diagnosis , Helicobacter pylori/pathogenicity , Uveitis, Anterior/microbiology , Adult , Aged , Antibodies, Bacterial/analysis , Antibodies, Bacterial/blood , Antigens, Bacterial/immunology , Aqueous Humor/immunology , Aqueous Humor/microbiology , Bacterial Proteins/immunology , Female , Humans , Male , Middle Aged , Uveitis, Anterior/immunology
8.
Vaccine ; 22(17-18): 2273-7, 2004 Jun 02.
Article in English | MEDLINE | ID: mdl-15149786

ABSTRACT

Orally administered recombinant Salmonella vaccines represent an attractive option for mass vaccination programmes against various infectious diseases. Therefore, it is crucial to gather knowledge about the possible impact of preexisiting immunity to carrier antigens on the immunogenicity of recombinant vaccines. Thirteen volunteers were preimmunized with Salmonella typhi Ty21a in order to evaluate the effects of prior immunization with the carrier strain. Then, they received three doses of 1-2 x 10(10) viable organisms of either the vaccine strain S. typhi Ty21a (pDB1) expressing subunits A and B of recombinant Helicobacter pylori urease (n = 9), or placebo strain S. typhi Ty21a (n = 4). Four volunteers were preimmunized and boosted with the vaccine strain S. typhi Ty21a (pDB1). No serious adverse effects were observed in any of the volunteers. Whereas none of the volunteers primed and boosted with the vaccine strain responded to the recombinant antigen, five of the nine volunteers preimmunized with the carrier strain showed cellular immune responses to H. pylori urease (56%). This supports the results of a previous study in non-preimmunized volunteers where 56% (five of nine) of the volunteers showed a cellular immune response to urease after immunisation with S. typhi Ty21a (pDB1).


Subject(s)
Bacterial Vaccines/immunology , Helicobacter pylori/immunology , Salmonella Vaccines/immunology , Urease/immunology , Adult , Antibodies, Bacterial/blood , Antigens, Bacterial/immunology , Bacterial Vaccines/adverse effects , Bacterial Vaccines/genetics , CD4-Positive T-Lymphocytes/immunology , Female , Helicobacter Infections/prevention & control , Helicobacter pylori/enzymology , Helicobacter pylori/genetics , Humans , Immunity, Cellular , Immunoglobulin G/blood , Interferon-gamma/analysis , Lymphocyte Activation , Male , Plasmids , Recombinant Proteins/genetics , Recombinant Proteins/immunology , Salmonella Vaccines/administration & dosage , Salmonella Vaccines/adverse effects , Salmonella Vaccines/genetics , Salmonella typhi/immunology , Urease/genetics , Vaccines, Attenuated/adverse effects , Vaccines, Attenuated/genetics , Vaccines, Attenuated/immunology , Vaccines, Synthetic/adverse effects , Vaccines, Synthetic/immunology
9.
Vaccine ; 20(5-6): 845-52, 2001 Dec 12.
Article in English | MEDLINE | ID: mdl-11738748

ABSTRACT

Helicobacter pylori urease was expressed in the common live typhoid vaccine Ty21a yielding Ty21a(pDB1). Nine volunteers received Ty21a(pDB1) and three control volunteers received Ty21a. No serious adverse effects were observed in any of the volunteers. Ten out of 12 volunteers developed humoral immune responses to the Salmonella carrier as detected by antigen-specific antibody-secreting cells but only two volunteers seroconverted. A total of five volunteers showed responses in one or two out of three assays for cellular responses to the carrier (proliferation, IFN-gamma-secretion, IFN-gamma-ELISPOT). Three of the volunteers that had received Ty21a(pDB1) showed a weak but significant T-cell response to Helicobacter urease, while no volunteer had detectable humoral responses to urease. Ty21a(pDB1) is a suitable prototype to optimize Salmonella-based vaccination for efficient cellular responses that could mediate protective immunity against Helicobacter.


Subject(s)
Bacterial Vaccines/pharmacology , Helicobacter pylori/enzymology , Helicobacter pylori/immunology , Salmonella typhi/genetics , Urease/genetics , Urease/immunology , Adolescent , Adult , Antibodies, Bacterial/biosynthesis , Antigens, Bacterial/genetics , B-Lymphocytes/immunology , Bacterial Vaccines/adverse effects , Bacterial Vaccines/genetics , Bacterial Vaccines/immunology , Double-Blind Method , Female , Gene Expression , Helicobacter pylori/genetics , Humans , Interferon-gamma/biosynthesis , Lymphocyte Activation , Male , Safety , T-Lymphocytes/immunology , Vaccines, Synthetic/adverse effects , Vaccines, Synthetic/genetics , Vaccines, Synthetic/immunology , Vaccines, Synthetic/pharmacology
10.
Development ; 128(19): 3843-53, 2001 Oct.
Article in English | MEDLINE | ID: mdl-11585809

ABSTRACT

NF-kappaB/Rel transcription factors and IkappaB kinases (IKK) are essential for inflammation and immune responses, but also for bone-morphogenesis, skin proliferation and differentiation. Determining their other functions has previously been impossible, owing to embryonic lethality of NF-kappaB/Rel or IKK-deficient animals. Using a gene targeting approach we have ubiquitously expressed an NF-kappaB super-repressor to investigate NF-kappaB functions in the adult. Mice with suppressed NF-kappaB revealed defective early morphogenesis of hair follicles, exocrine glands and teeth, identical to Eda (tabby) and Edar (downless) mutant mice. These affected epithelial appendices normally display high NF-kappaB activity, suppression of which resulted in increased apoptosis, indicating that NF-kappaB acts as a survival factor downstream of the tumor necrosis factor receptor family member EDAR. Furthermore, NF-kappaB is required for peripheral lymph node formation and macrophage function.


Subject(s)
Epidermis/physiology , Hair Follicle/physiology , Lymphatic System/physiopathology , Macrophages/pathology , NF-kappa B/physiology , Animals , Apoptosis/genetics , Deafness/genetics , Deafness/physiopathology , Eccrine Glands/abnormalities , Ectodysplasins , Edar Receptor , Epidermis/embryology , Exocrine Glands/physiopathology , Hair Follicle/embryology , Hair Follicle/pathology , Hepatocytes/pathology , I-kappa B Proteins/genetics , I-kappa B Proteins/metabolism , Macrophages/physiology , Membrane Proteins/genetics , Membrane Proteins/metabolism , Mice , Mice, Inbred C57BL , Mice, Transgenic , Mutation , Oncogene Proteins v-rel/metabolism , Otitis Media/genetics , Otitis Media/physiopathology , Receptors, Ectodysplasin , Receptors, Tumor Necrosis Factor , Signal Transduction , Tooth/physiopathology
11.
Vaccine ; 20(3-4): 413-20, 2001 Nov 12.
Article in English | MEDLINE | ID: mdl-11672904

ABSTRACT

Previously we described a recombinant attenuated Salmonella typhimurium aroA strain (SL3261[pYZ97]) with constitutive expression of plasmid encoded Helicobacter pylori urease subunits A and B (UreAB). Single dose oral vaccination effectively induced prophylactic immunity against bacterial challenge in BALB/c mice. Here we successfully extended this approach to several mouse strains with allelic differences in NRAMP-1 and H-2 genes. The respective host determinants are known to influence the immune response against S. typhimurium. A comparative analysis of the vaccine efficacy in C57BL/6 and BALB/c mice showed that the live vaccine confers long lasting immunity in both strains (>18 weeks). In C57BL/6 mice, protection was still observed 54 weeks while not all vaccinated BALB/c were immune when challenged after this time. BALB/c mice also needed higher doses of SL3261[pYZ97] for full protection. We also demonstrate a therapeutic potential of SL3261[pYZ97] in H. pylori infected BALB/c and C57BL/6 mice. Urease- and carrier-specific serum antibody responses as well as the level of colonization by the Salmonella were analyzed in both mouse strains after immunization with low (4 x 10(7)CFU) or high (1 x 10(9)CFU) vaccine doses. The results are discussed in the context of inoculum size and the mode of antigen supply required for effective vaccination with recombinant Salmonella.


Subject(s)
Bacterial Vaccines/immunology , Helicobacter pylori/immunology , Salmonella typhimurium/genetics , Urease/immunology , Vaccines, Synthetic/immunology , Animals , CD4-Positive T-Lymphocytes/immunology , Female , Helicobacter pylori/enzymology , Mice , Mice, Inbred Strains , Recombinant Proteins/immunology , Species Specificity , Vaccination
12.
Blood ; 98(5): 1480-8, 2001 Sep 01.
Article in English | MEDLINE | ID: mdl-11520798

ABSTRACT

Transcription factors of the nuclear factor of activated T cells (NFAT) family are thought to regulate the expression of a variety of inducible genes such as interleukin-2 (IL-2), IL-4, and tumor necrosis factor-alpha. However, it remains unresolved whether NFAT proteins play a role in regulating transcription of the interferon- gamma (IFN-gamma) gene. Here it is shown that the transcription factor NFAT1 (NFATc2) is a major regulator of IFN-gamma production in vivo. Compared with T cells expressing NFAT1, T cells lacking NFAT1 display a substantial IL-4-independent defect in expression of IFN-gamma mRNA and protein. Reduced IFN-gamma production by NFAT1(-/-)x IL-4(-/-) T cells is observed after primary in vitro stimulation of naive CD4+ T cells, is conserved through at least 2 rounds of T-helper cell differentiation, and occurs by a cell-intrinsic mechanism that does not depend on overexpression of the Th2-specific factors GATA-3 and c-Maf. Concomitantly, NFAT1(-/-)x IL-4(-/-) mice show increased susceptibility to infection with the intracellular parasite Leishmania major. Moreover, IFN-gamma production in a murine T-cell clone is sensitive to the selective peptide inhibitor of NFAT, VIVIT. These results suggest that IFN-gamma production by T cells is regulated by NFAT1, most likely at the level of gene transcription.


Subject(s)
DNA-Binding Proteins/physiology , Gene Expression Regulation/physiology , Interferon-gamma/biosynthesis , Nuclear Proteins , T-Lymphocyte Subsets/metabolism , Transcription Factors/physiology , Animals , CD4-Positive T-Lymphocytes/metabolism , Cell Differentiation , Cell Line , Culture Media, Serum-Free , DNA-Binding Proteins/antagonists & inhibitors , DNA-Binding Proteins/deficiency , DNA-Binding Proteins/genetics , Immunity, Innate , Interferon-gamma/genetics , Interleukin-4/deficiency , Interleukin-4/genetics , Leishmania major , Leishmaniasis, Cutaneous/genetics , Leishmaniasis, Cutaneous/immunology , Lymphocyte Activation , Mice , Mice, Knockout , NFATC Transcription Factors , Oligopeptides/pharmacology , RNA, Messenger/biosynthesis , Recombinant Fusion Proteins/physiology , Th1 Cells/metabolism , Th2 Cells/metabolism , Transcription Factors/antagonists & inhibitors , Transcription Factors/deficiency , Transcription Factors/genetics , Transcription, Genetic , Transfection
13.
J Immunol ; 167(1): 11-4, 2001 Jul 01.
Article in English | MEDLINE | ID: mdl-11418625

ABSTRACT

The genus Bartonella includes important human-specific and zoonotic pathogens which cause intraerythrocytic bacteremia in their mammalian reservoir host(s). It is accepted that cellular immunity plays a decisive role in the host's defense against most intracellular bacteria. Bartonella sp. infection in the immunocompetent host typically leads to immunity against homologous challenge. The basis of this immunity, be it cellular or humoral, is unclear. In this study, the course of Bartonella grahamii bacteremia in immunocompetent and immunocompromised mice was compared. In immunocompetent hosts, the bacteremia is transient and induces a strong humoral immune response. In contrast, bacteremia persists in immunocompromised B and T cell-deficient mice. Immune serum transfer beginning with day 6 postinfection to B cell-deficient mice unable to produce Igs converted the persistent bacteremia to a transient course indistinguishable from that of immunocompetent animals. These data demonstrate an essential role for specific Abs in abrogating the intraerythrocytic bacteremia of B. grahamii in mice.


Subject(s)
Antibodies, Bacterial/administration & dosage , Bartonella Infections/immunology , Bartonella Infections/prevention & control , Bartonella/immunology , Erythrocytes/microbiology , Adoptive Transfer , Animals , Antibodies, Bacterial/biosynthesis , Antibodies, Bacterial/blood , Bacteremia/genetics , Bacteremia/immunology , Bacteremia/prevention & control , Bartonella/pathogenicity , Bartonella Infections/blood , Bartonella Infections/genetics , Disease Models, Animal , Female , Immune Sera/administration & dosage , Immune Sera/biosynthesis , Immune Sera/blood , Injections, Intravenous , Intracellular Fluid/microbiology , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Knockout
14.
Eur J Immunol ; 31(3): 876-83, 2001 Mar.
Article in English | MEDLINE | ID: mdl-11241293

ABSTRACT

Resolution of infection by Leishmania sp. is critically dependent on activation of CD4(+) T helper cells. Naive CD4(+) T helper cells are primed by dendritic cells which have responded to an activation signal in the periphery. However, the role of Leishmania-infected dendritic cells in the activation of an anti-Leishmania immune response has not been comprehensively addressed. Using the highly controlled model system of bone marrow-derived dendritic cell infection by Leishmania mexicana cultured in vitro, we show that uptake of L. mexicana parasites does not result in activation of immature dendritic cells or secretion of IL-12. Incubation with L. mexicana promastigotes results in the activation of a small percentage of dendritic cells which do not appear to contain whole parasites. Activation of dendritic cells is not suppressed by infection, since infected cells can be fully activated on addition of activating stimuli. Therefore, uptake of intact Leishmania mexicana parasites is not sufficient to activate dendritic cells in vitro. We propose that these data provide a basis for interpreting the interactions between dendritic cells and all Leishmania sp.


Subject(s)
Dendritic Cells/parasitology , Leishmania mexicana/immunology , Animals , Antigens, CD/analysis , Bone Marrow Cells/immunology , Bone Marrow Cells/parasitology , Cells, Cultured , Dendritic Cells/immunology , Dendritic Cells/metabolism , Female , Immunophenotyping , Interleukin-12/biosynthesis , Mice , Mice, Inbred C57BL , Mice, Inbred CBA
15.
Infect Immun ; 69(3): 1714-21, 2001 Mar.
Article in English | MEDLINE | ID: mdl-11179348

ABSTRACT

Protection in the murine model of Helicobacter pylori infection may be mediated by CD4+ T cells, but the mechanism remains unclear. To better understand how protection occurs in this model, we generated and characterized H. pylori urease-specific CD4+ T cells from BALB/c mice immunized with Salmonella enterica serovar Typhimurium expressing H. pylori urease (subunits A and B). The CD4+ T cells were found to be specific for subunit A (UreA). Upon antigen-specific stimulation, expression of interleukin 4 (IL-4), IL-10, gamma interferon (IFN-gamma), and tumor necrosis factor alpha was induced. Immunocytochemical analysis showed that the majority of cells produced IFN-gamma and IL-10. Adoptive transfer of the UreA-specific CD4+ T cells into naive syngeneic recipients led to a threefold reduction in the number of bacteria in the recipient group when compared to that in the nonrecipient group. Stomach colonization was also reduced significantly after transfer of these cells into patently infected mice. Adoptive transfer of UreA-specific CD4+ T cells into IL-4 receptor alpha chain-deficient BALB/c mice indicated that IL-4 and IL-13 were not critical in the control of bacterial load. In addition, synthetic peptides were used to identify three functional T-cell epitopes present in subunit A which were recognized by the UreA-specific T cells. Analysis of H. pylori-specific cellular immune responses in recipient challenged and nonrecipient infected mice indicated a strong local restriction of the response in infected animals. The implications of these findings for the mechanism of protection and the development of peptide-based vaccination are discussed.


Subject(s)
Adoptive Transfer , CD4-Positive T-Lymphocytes/immunology , Helicobacter Infections/therapy , Helicobacter pylori/pathogenicity , Receptors, Interleukin/metabolism , Stomach/microbiology , Urease/immunology , Animals , Antibodies, Bacterial/blood , Antibody Specificity , Female , Helicobacter pylori/immunology , Interleukin-13/metabolism , Interleukin-13 Receptor alpha1 Subunit , Interleukin-4/metabolism , Male , Mice , Mice, Inbred BALB C , Mice, Mutant Strains , Receptors, Interleukin/genetics , Receptors, Interleukin-13 , Receptors, Interleukin-4/genetics , Receptors, Interleukin-4/metabolism , Signal Transduction , Spleen/immunology
16.
Infect Immun ; 69(1): 556-8, 2001 Jan.
Article in English | MEDLINE | ID: mdl-11119552

ABSTRACT

Vaccination of interleukin-4 (IL-4) receptor alpha (IL-4Ralpha) chain-deficient BALB/c mice with Helicobacter pylori urease and cholera toxin or with urease-expressing, live attenuated Salmonella enterica serovar Typhimurium cells revealed that protection against H. pylori infection is independent of IL-4- or IL-13-mediated signals. A comparison of male and female mice suggests a sexual dimorphism in the extent of bacterial colonization that is particularly evident in the absence of the IL-4Ralpha chain.


Subject(s)
Helicobacter Infections/immunology , Helicobacter pylori/immunology , Receptors, Interleukin-4/physiology , Animals , Cholera Toxin/immunology , Female , Gastric Mucosa/microbiology , Interleukin-13/physiology , Interleukin-4/physiology , Male , Mice , Mice, Inbred BALB C , Sex Characteristics , Urease/immunology , Vaccination
17.
J Biotechnol ; 83(1-2): 77-84, 2000 Sep 29.
Article in English | MEDLINE | ID: mdl-11000463

ABSTRACT

Helicobacter pylori is recognised as a causal agent in the pathogenesis of gastritis, gastric and duodenal ulcer disease as well as gastric cancers. Eradication of the bacteria with antibiotics is currently used to treat symptomatic, infected individuals. Theoretically the infection could also be controlled by vaccination. Several immunisation protocols were developed in small animal models and primates in order to validate this approach. Recently making use of mice with defined genetic defects, H. pylori-specific CD4(+) T cells were found to be crucial for protective vaccination. This was unexpected and poses the question of how activation of CD4(+) T cells leads to the elimination of bacteria that reside primarily in the mucin layer behind a barrier of epithelial cells. CD4(+) T cells fulfil their effector function by secreting lymphokines and by engaging specific surface ligands on interacting cells. Here we propose that phagocytes and epithelial cells stimulated either by direct interaction with CD4(+) T cells or by soluble mediators such as cytokines or neuropeptides are the ultimate effector populations in protective immunity induced by vaccination.


Subject(s)
CD4-Positive T-Lymphocytes/immunology , Helicobacter pylori/immunology , Stomach/microbiology , Animals , Bacterial Vaccines/immunology , Disease Models, Animal , Mice
18.
Mol Biochem Parasitol ; 107(2): 251-61, 2000 Apr 15.
Article in English | MEDLINE | ID: mdl-10779601

ABSTRACT

This report describes the construction of a DNA cassette for integration into a genomic small sub-unit rRNA locus of Leishmania mexicana by homologous recombination. Reporter genes encoding beta-galactosidase or green fluorescent protein and the gene conferring hygromycin resistance were integrated downstream of a RNA polymerase I-driven rRNA promoter. To ensure high expression of the marker proteins in the intracellular, amastigote stage, transgene coding sequences were followed by the intergenic region of the L. mexicana cysteine proteinase B 2.8 gene which provides processing signals required for high level expression in this life-cycle stage. Integration of the DNA cassette was also efficiently obtained in L. major. We show that either beta-galactosidase or the green fluorescent protein were abundantly, stably and uniformly expressed in promastigotes and amastigotes of both Leishmania sp. The transgenic lines allow parasite detection at high sensitivity in the tissues of infected mice and will be useful to follow infections in macrophages in culture and in animal hosts.


Subject(s)
Gene Expression , Genes, rRNA , Leishmania major/genetics , Leishmania mexicana/genetics , Transgenes , Animals , Female , Flow Cytometry , Green Fluorescent Proteins , Leishmania major/growth & development , Leishmania major/pathogenicity , Leishmania mexicana/growth & development , Leishmania mexicana/pathogenicity , Leishmaniasis, Cutaneous/parasitology , Luminescent Proteins/metabolism , Macrophages , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , RNA, Protozoan/genetics , RNA, Ribosomal/genetics , Recombination, Genetic , beta-Galactosidase/metabolism
19.
FEMS Immunol Med Microbiol ; 27(4): 357-64, 2000 Apr.
Article in English | MEDLINE | ID: mdl-10727892

ABSTRACT

Live attenuated Salmonella spp. are promising candidates as oral vaccine delivery systems for heterologous antigens. Clinical trials have demonstrated that this approach is feasible for human vaccinations but further optimisation is necessary to obtain a better efficacy. Here, we discuss how existing clinical and pre-clinical data can be used to guide such optimisation efforts.


Subject(s)
Antigens, Bacterial/immunology , Bacterial Infections/prevention & control , Bacterial Vaccines/immunology , Salmonella typhi/genetics , Animals , Antigens, Bacterial/genetics , Antigens, Bacterial/metabolism , Clinical Trials as Topic , Humans , Mice , Recombinant Proteins/immunology , Salmonella typhi/immunology , Salmonella typhi/pathogenicity , Vaccination , Vaccines, Attenuated/immunology , Vaccines, Synthetic/immunology
20.
Infect Immun ; 68(3): 1328-36, 2000 Mar.
Article in English | MEDLINE | ID: mdl-10678945

ABSTRACT

A mixture of well-defined recombinant antigens together with an adjuvant that preferentially stimulates specific gamma interferon (IFN-gamma)-secreting helper type 1 CD4(+) T cells (Th1 cells) presents a rational option for a vaccine against leishmaniasis. The potential of this approach was investigated in murine infections with Leishmania mexicana, which are characterized by the absence of a parasite-specific Th1 response and uncontrolled parasite proliferation. A mixture of three antigens (glycoprotein 63, cysteine proteinases, and a membrane-bound acid phosphatase), which are all expressed in amastigotes, the mammalian stage of the parasite, were used for the immunization of C57BL/6 mice in combination with six adjuvants (interleukin 12 [IL-12], Detox, 4'-monophosphoryl lipid A, QS-21, Mycobacterium bovis BCG, and Corynebacterium parvum). All six vaccine formulations containing the mixture of recombinant antigens were protective against challenge infections with promastigotes, the insect stage of the parasite, in that mice controlled and healed infections but developed transient and, in certain cases, accentuated disease. The most effective adjuvants were IL-12 followed by Detox. Further studies using these two adjuvants showed that a similar protective effect was observed with a mixture of the corresponding native proteins, and mice which had controlled the infection showed a preponderance of IFN-gamma-secreting CD4(+) T cells in the lymph nodes draining the lesion. Using the recombinant proteins individually, it is shown that the relatively abundant cysteine proteinases and glycoprotein 63, but not the acid phosphatase, are able to elicit a protective response. The results are discussed in comparison to previous studies with subunit vaccines and with respect to cell biological aspects of antigen presentation in Leishmania-infected macrophages.


Subject(s)
Adjuvants, Immunologic/pharmacology , Leishmania mexicana/immunology , Leishmaniasis, Cutaneous/prevention & control , Protozoan Proteins/immunology , Protozoan Vaccines/immunology , Vaccines, Synthetic/immunology , Animals , Antigens, Protozoan/immunology , CD4-Positive T-Lymphocytes/metabolism , Female , Interferon-gamma/biosynthesis , Interleukin-12/pharmacology , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Inbred CBA , T-Lymphocytes/immunology , Vaccination
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