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Protective Immune Responses (protective + immune_response)
Selected AbstractsAssessment of in vitro immunity to Mycobacterium tuberculosis in a human peripheral blood infection model using a luciferase reporter construct of M. tuberculosis H37RvCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 3 2006R. Al-Attiyah Summary Protective immune responses to tuberculosis in man are primarily cell-mediated and require the interaction of specific T cells, cytokines and activated macrophages. In the present study, Mycobacterium tuberculosis H37Rv labelled with luciferase reporter enzyme was used to analyse the anti-mycobacterial immunity in man using an in vitro whole blood infection model. Peripheral blood samples obtained from M. bovis bacille Calmette,Guérin (BCG)-vaccinated tuberculin-positive healthy volunteers (n = 23) were cultured with M. tuberculosis H37Rv reporter strain. The growth of bacteria in the whole blood cultures was monitored after 48 and 96 h of infection. The results showed that the growth of M. tuberculosis was significantly inhibited after 96 h (P < 0·029) of culture. Among the cytokines studied, interleukin (IL)-10 and IL-12 were not detected at all, whereas low levels of interferon (IFN)-, after 96 h (0·4 IU/ml) and tumour necrosis factor (TNF)-, after 48 (135 pg/ml) and 96 h (47 pg/ml) of culture were detected in the supernatants of whole blood infected with M. tuberculosis. The magnitude of bacterial growth correlated directly with the concentration of TNF-, detected after 48 h (r = 0·722) and 96 h (r = 0·747) of culture (P , 0·0001 and P , 0·0001, respectively). However, the addition of monoclonal antibodies specific to TNF-, and IFN-, to the blood cultures did not alter mycobacterial growth indicating the role of other mechanisms/factors in restricting the growth of M. tuberculosis in whole blood cultures. [source] IgG2 containing IgM,IgG immune complexes predominate in normal human plasma, but not in plasma of patients with warm autoimmune haemolytic anaemiaEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 3 2006Dorothea Stahl Abstract:, The different physicochemical and sterical properties of IgG subclasses may favour a selective enrichment of defined IgG subclasses in IgM,IgG immune complexes (IC) of human plasma under physiological conditions. Such enrichment of IgG subclasses in IgM,IgG IC of plasma may differ from the normal IgG subclass distribution in plasma itself, and contribute to the physiological functions of IgM,IgG IC. Systematic studies on the IgG subclass distribution in IgM,IgG IC in humans are lacking. Using specific analytical techniques to characterise IgM,IgG IC in human plasma (i.e. fast protein liquid chromatography, enzyme-linked immunosorbent assay, affinity biosensor technology), and taking warm autoimmune haemolytic anaemia (WAIHA) of humans as a disease model, we here demonstrate that: (i) IgG2 is the predominant IgG subclass in IgM,IgG IC under physiological conditions, (ii) the predominance of IgG2 within IgM,IgG IC may get lost in polyclonal IgG-mediated autoimmune disease and (iii) the IgG subclass distribution in IgM,IgG IC influences the interaction between IC and blood cells involved in antigen presentation. The data presented here therefore extend the physiological function of IgG2, which is the protective immune response towards carbohydrate antigens in bacterial infections, and suggest IgG2-dependent regulation of immune responses to self-immunoglobulin in humans. The disturbed IgG subclass distribution in IgM,IgG IC of patients with WAIHA might influence activity of self-reactive B cells involved in the pathophysiology of the disease. [source] Intranasal immunisation with inactivated RSV and bacterial adjuvants induces mucosal protection and abrogates eosinophilia upon challengeEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 5 2006Nathalie Etchart Abstract We have previously shown that following intranasal exposure to influenza virus, specific plasma cells are generated in the nasal-associated lymphoid tissue (NALT) and maintained for the life of the animal. However, we also showed that following infection with respiratory syncytial virus (RSV), specific plasma cells are generated in the NALT but wane quickly and are not maintained even after challenge, even though RSV-specific serum antibody responses remain robust. Only infection with influenza virus generated sterilising immunity, implying a role for these long-lived plasma cells in protection. We show here that the RSV-specific IgA NALT plasma cell population and lung antibody levels can be substantially boosted, both at acute and memory time points, by intranasal immunisation with inactivated RSV (iRSV) in combination with bacterial outer membrane vesicles (OMV) compared to live RSV alone. Finally, challenge with live RSV showed that immunisation with iRSV and OMV protect against both virus replication in the lung and the eosinophil infiltrate generated by either live RSV or iRSV alone. These data show that immunisation with iRSV and OMV maintains a NALT RSV-specific plasma cell population and generates an efficient protective immune response following RSV infection. See accompanying commentary: http://dx.doi.org/10.1002/eji.200636118 [source] Oral vaccination of mice against Helicobacter pylori with recombinant Lactococcus lactis expressing urease subunit BFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 3 2009Qing Gu Abstract To determine whether a protective immune response could be elicited by oral delivery of a recombinant live bacterial vaccine, Helicobacter pylori urease subunit B (UreB) was expressed for extracellular expression in food-grade bacterium Lactococcus lactis. The UreB-producing strains were then administered orally to mice, and the immune response to UreB was examined. Orally vaccinated mice produced a significant UreB-specific serum immunoglobulin G (IgG) response. Specific anti-UreB IgA responses could be detected in the feces of mice immunized with the secreting lactococcal strain. Mice vaccinated orally were significantly protected against gastric Helicobacter infection following a challenge with H. pylori strain SS1. In conclusion, mucosal vaccination with L. lactis expressing UreB produced serum IgG and UreB-specific fecal IgA, and prevented gastric infection with H. pylori. [source] Microbes versus microbes: immune signals generated by probiotic lactobacilli and their role in protection against microbial pathogensFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 4 2002Martin L Cross Abstract Probiotic lactic acid bacteria can signal the immune system through innate cell surface pattern recognition receptors or via direct lymphoid cell activation. In some cases, this action has been shown to be sufficient to modulate local- and systemic-level in vivo immune responses. Practical applications of probiotics include their use in anti-tumour and anti-allergy immunotherapy, but there is also increasing evidence that some probiotics can stimulate a protective immune response sufficiently to enhance resistance to microbial pathogens. This review outlines the experimental and clinical evidence for enhanced anti-microbial immune protection by probiotic lactic acid bacteria, focussing on those studies where a correlative or suggestive link has been shown between immune modulation and enhanced protection. [source] Induction of an antitumour adaptive immune response elicited by tumour cells expressing de novo B7-1 mainly depends on the anatomical site of their delivery: the dose applied regulates the expansion of the responseIMMUNOLOGY, Issue 4 2003Silvia Sartoris Summary De novo expression of costimulatory molecules in tumours generally increases their immunogenicity, but does not always induce a protective response against the parental tumour. This issue was addressed in the mouse Sp6 hybridoma model, comparing different immunization routes (subcutaneous, intraperitoneal and intravenous) and doses (0·5 × 106 and 5 × 106 cells) of Sp6 cells expressing de novo B7-1 (Sp6/B7). The results can be summarized as follows. First, de novo expression of B7-1 rendered Sp6 immunogenic, as it significantly reduced the tumour incidence to ,15% with all delivery routes and doses tested, whereas wild-type Sp6 was invariably tumorigenic (100% tumour incidence). Second, long-lasting protection against wild-type Sp6 was mainly achieved when immunization with Sp6/B7 was subcutaneous: a dose of 0·5 × 106 Sp6/B7 cells elicited protection that was confined to sites in the same anatomical quarter as the immunizing injection. Repeated injections of the same dose extended protection against wild-type Sp6 to other anatomical districts, as well as a single injection of a 10-fold higher dose (5 × 106 cells). Finally, Sp6-specific cytotoxic T-lymphocyte activity was detected in draining lymph nodes, and the splenic expansion of Sp6-specific cytotoxic T-lymphocyte precursors quantitatively correlated with the dose of antigen. We conclude that activation of a protective immune response against Sp6 depends on the local environment where the immunogenic form of the ,whole tumour cell antigen' is delivered. The antigen dose regulates the anatomical extent of the protective response. [source] Phage display particles expressing tumor-specific antigens induce preventive and therapeutic anti-tumor immunity in murine p815 modelINTERNATIONAL JOURNAL OF CANCER, Issue 5 2002Yuzhang Wu Abstract The efficacy of phage display particles expressing tumor antigen P1A35-43 in inducing protective and therapeutic anti-tumor immune responses were studied. A protective immune response against a lethal progressive P815 mastocytoma tumor cell challenge was established after subcutaneous injection of phage display particles. Furthermore, the vaccine suppressed growth of pre-existing tumors. Immunization with the hybrid phage particles elicited P1A35,43 specific CTL responses and a Th1-dominated immune response with phage particle-specific secretion of IFN-, but not IL-4. Our results indicate that phage display particles might be a useful vaccine form for tumor-associated antigen epitopes in tumor immunotherapy. © 2002 Wiley-Liss, Inc. [source] Immunization of rainbow trout, Oncorhynchus mykiss (Walbaum), with a low molecular mass fraction isolated from Flavobacterium psychrophilumJOURNAL OF FISH DISEASES, Issue 12 2008E Högfors Abstract Flavobacterium psychrophilum, the causative agent of rainbow trout fry syndrome has become a widespread fish pathogen in freshwater aquaculture worldwide. In this study, a low molecular mass fraction (P25-33), with an approximate weight of 25,33 kDa, was identified among F. psychrophilum strains in an immunoblotting analysis with anti- F. psychrophilum sera. The immunogenic efficacy of the isolated and extracted P25-33 was investigated in two intraperitoneal immunization trials with rainbow trout, Oncorhynchus mykiss (Walbaum). The first trial included immunizations using P25-33 with Freund's complete adjuvant (FCA) and the second trial included immunizations using P25-33, formalin-inactivated whole and sonicated F. psychrophilum cell preparations without FCA. In both trials, antibody titres against F. psychrophilum were analysed with an enzyme-linked immunosorbent assay and the efficacy of the immunizations was determined by a challenge with F. psychrophilum. The P25-33 was shown to give rise to a protective immune response in rainbow trout after immunization with FCA, but not without FCA when a low concentration of P25-33 was used. Instead formalin-inactivated whole and sonicated cells of F. psychrophilum were able to protect the immunized fish more effectively when immunized without FCA. The results suggest that whole or sonicated F. psychrophilum cells could be better candidates for a cost-effective water-based injection vaccine than the immunogenic fraction. [source] Characterization of serum and mucosal antibody responses and relative per cent survival in rainbow trout, Oncorhynchus mykiss (Walbaum), following immunization and challenge with Flavobacterium psychrophilumJOURNAL OF FISH DISEASES, Issue 12 2002B R LaFrentz Abstract Serum and mucosal antibody responses of juvenile rainbow trout, Oncorhynchus mykiss, were characterized by enzyme-linked immunosorbent assay (ELISA) following immunization with various preparations of formalin-killed Flavobacterium psychrophilum cells. The protective nature of these preparations was then determined by immunizing rainbow trout fry and challenging with the bacterium. Juvenile rainbow trout immunized intraperitoneally (i.p.) with formalin-killed F. psychrophilum emulsified with Freund's complete adjuvant (FCA), and i.p. with formalin-killed F. psychrophilum either with or without culture supernatant generated significant serum antibody responses by 6 and 9 weeks, respectively. Significant mucosal antibody responses were detected by 9 weeks only in fish immunized i.p. with killed F. psychrophilum/FCA. Following immunization and bacterial challenge of rainbow trout fry, protective immunity was conferred in F. psychrophilum/FCA and saline/FCA groups with relative per cent survival values of up to 83 and 51, respectively. Significant protection was not observed in treatment groups immunized by immersion or i.p. without adjuvant at the challenge doses tested. Results suggest that stimulation of non-specific immune factors enhances the ability of fish to mount a protective immune response, but specific antibody appears necessary to provide near complete protection. In this study, an ELISA was developed to monitor anti- F. psychrophilum antibody production in trout. The relationship of such responses to protective immunity suggests that future vaccination strategies against coldwater disease may require stimulation of both the innate and adaptive arms of the immune response. [source] High level serum neutralizing antibody against HIV-1 in Chinese long-term non-progressorsMICROBIOLOGY AND IMMUNOLOGY, Issue 4 2008Qian Wang ABSTRACT NAb have been considered to be an important component of a protective immune response to HIV-1, yet the relationship between the capacity of HIV-1 NAb, the conserved neutralization epitopes and disease progression has been unclear. To gain a better understanding of the protective roles that NAb and conserved neutralization epitopes could play in LTNP, twenty-eight HIV-1-infected subjects were investigated by evaluation of the concentrations of HIV-1 NAb and conserved neutralization epitopes, using single-round PBMC neutralization assay and sequencing. Our study revealed that the concentration of NAb in LTNP was significantly higher than that in subjects with asymptomatic HIV (P < 0.05) and AIDS (P < 0.01). No amino acids substitutions were found in the conserved epitopes of the HIV-1 gp120 region in LTNP, whereas the viruses circulating both in persons with asymptomatic HIV and those with AIDS had amino acid substitutions in their conserved neutralization epitopes. This study suggests that high levels of NAb and stable epitopes in gp120 could play a crucial role in protection against disease progression. [source] Regulation of immune responses to Strongyloides venezuelensis challenge after primary infection with different larvae dosesPARASITE IMMUNOLOGY, Issue 3 2010H. C. SCHILTER Summary Nematode infections are generally followed by high rates of reinfection, leading to elevated prevalence in endemic areas. Therefore, the effective control of nematode infections depends on understanding the induction and regulation of protective mechanisms. However, most experimental models for protective immune response against nematodes use high parasite exposure, not always reflecting what occurs naturally in human populations. In this study, we tested whether infecting mice with different Strongyloides venezuelensis larvae loads would affect protective responses against reinfection. Interestingly, we found that a previous infection with 10,500 larvae conferred high rate of protection against reinfection with S. venezuelensis in mice, by destroying large numbers of migrating larvae. However, low-dose priming did not abolish adult worm maturation, as detected in high-dose primed group. Results also indicated that a previous low-dose infection delayed the development of cellular infiltrate, while a high inoculum rapidly induced these inflammatory features. Cytokine production by splenocyte cultures of challenge infected mice demonstrated that low-dose priming had increased production of IL-4 and IFN-,, while high-dose induced IL-4 production but not IFN-,. Our data support the hypothesis that low-dose nematode infection does not induce a polarized type-2 immune response, allowing adult worm survival. [source] Interferon-,-mediated activation of enterocytes in immunological control of Encephalitozoon intestinalis infectionPARASITE IMMUNOLOGY, Issue 1 2009N. CHOUDHRY SUMMARY The microsporidian Encephalitozoon intestinalis develops within intestinal epithelial cells (enterocytes) and is an important opportunistic diarrhoeal pathogen associated with AIDS. Little is known about the protective immune response against the parasite although in mice IFN-, is involved and is required to prevent dissemination of the infection to other organs. The present study was designed to establish a suitable short-term in vitro culture technique for E. intestinalis that would enable studies of the role of cytokines such as IFN-, in the effector phase of immunity. Encephalitozoon intestinalis reproduced considerably better in the murine enterocyte cell line CMT-93 than in the three human enterocyte cell lines Caco-2, HT29 and HCT-8. Treatment of CMT-93 cells with IFN-, significantly reduced parasite reproduction in a dose- and time-dependent manner. IFN-, also inhibited development of the parasite in Caco-2 cells. Neither production of NO nor Fe deprivation appeared to be involved in IFN-,-mediated parasite killing. However studies suggested that tryptophan catabolism by indoleamine 2,3-dioxygenase played an important part in inactivation of E. intestinalis. [source] CpG-containing ODN has a limited role in the protection against Toxoplasma gondiiPARASITE IMMUNOLOGY, Issue 2 2004R. Saavedra SUMMARY Bacterial DNA containing immunostimulatory motifs (CpG) induces the development of a TH1 immune response. Since protection against Toxoplasma gondii is correlated with this type of response, the aim of this work was to determine if a synthetic oligodeoxynucleotide (ODN) containing CpG sequences could be useful as adjuvant for the induction of a long-lasting protective immune response against T. gondii. BALB/c mice immunized with a total soluble antigen of T. gondii (TSA2) mixed with ODN-containing CpG sequences developed a typical TH1 response, as determined by antibody isotypes and interferon-, (IFN-,) and interleukin-4 (IL-4) production by spleen cells. However, they did not resist a challenge with the virulent RH strain of the parasite. Absence of protection paralleled with lower levels of IFN-,, when compared with mice vaccinated with the live tachyzoites of the attenuated ts.4 strain of the parasite, which resisted this challenge. Intraperitoneal injection of ODN alone to mice induced a high degree of resistance to a lethal challenge inoculated by the same route. Nevertheless, this nonspecific protection was transient. Thus, the use of ODN containing CpG motifs as adjuvant is of limited value for the induction of a protective immune response against T. gondii. [source] Local Applications of GM-CSF Induce the Recruitment of Immune Cells in Cervical Low-Grade Squamous Intraepithelial LesionsAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 2 2010Pascale Hubert Citation Hubert P, Doyen J, Capelle X, Arafa M, Renoux V, Bisig B, Seidel L, Evrard B, Bousarghin L, Gerday C, Boniver J, Foidart J-M, Delvenne P, Jacobs N. Local applications of GM-CSF induce the recruitment of immune cells in cervical low-grade squamous intraepithelial lesions. Am J Reprod Immunol 2010; 64: 126,136 Problem, Quantitative alterations of antigen-presenting cells (APC) in (pre)neoplastic lesions of the uterine cervix associated with human papillomavirus (HPV) infection suggest a diminished capacity to capture viral antigens and to induce a protective immune response. Method of study, To test whether a cervical application of GM-CSF could restore an immune response against HPV in women with cervical low-grade squamous intraepithelial lesions (LSIL), we performed two clinical trials with 11 healthy women and 15 patients with LSIL. Results, GM-CSF applications were well tolerated in all enrolled women, and no difference in toxicity between the treated and placebo groups was observed during the follow-up (until 30 months). Interestingly, in the GM-CSF treated group, a significant increase of APC and cytotoxic T-lymphocyte infiltration was observed in the cervical biopsies with no change in regulatory T cell numbers. All the HPV16+ patients exhibited an immune response against HPV16 after GM-CSF applications, as shown by NK and/or T cells producing IFN-, whereas no cellular immune response was observed before the treatment. Moreover, the anti-virus-like particles antibody titers also increased after the treatment. Conclusion, These encouraging results obtained from a limited number of subjects justify further study on the therapeutic effect of APC in cervical (pre)neoplastic lesions. [source] Tamm-Horsfall protein: a multilayered defence molecule against urinary tract infectionEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 4 2005M. D. Säemann Abstract Urinary tract infection (UTI) is the most common nonepidemic bacterial infection in humans, representing a constant danger for the host. Both innate and adaptive components of the immune system as well as stromal cells including bladder epithelium are involved in the prevention and clearance of UTI. However, the particular properties of the urogenital tract, which does not comprise typical physical barriers like a mucus or ciliated epithelium, necessitate soluble mediators with potent immunomodulatory capabilities. One candidate molecule capable of both mediating direct antimicrobial activity and alerting immune cells is the evolutionary conserved Tamm-Horsfall protein (THP). Tamm-Horsfall protein is exclusively produced by the kidney in the distal loop of Henle; however, its definite physiological function remains elusive. Mounting evidence indicates that beyond a mere direct antimicrobial activity, THP exerts potent immunoregulatory activity. Furthermore, the genetic ablation of the THP gene leads to severe infection and lethal pyelonephritis in an experimental model of UTI. Recent data are provided demonstrating that THP links the innate immune response with specific THP-directed cell-mediated immunity. In light of these novel findings we discuss the particular role of THP as a specialized defence molecule. We propose an integrated model of protective mechanisms against UTI where THP acts by two principle nonmutually exclusive mechanisms involving the capture of potentially dangerous microbes and the ability of this peculiar glycoprotein to induce robust protective immune responses against uropathogenic bacteria. [source] Highly avid, oligoclonal, early-differentiated antigen-specific CD8+ T cells in chronic HIV-2 infectionEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 7 2010Aleksandra Leligdowicz Abstract HIV-1-specific CD8+ T cells are present in most HIV-1-infected people and play an important role in controlling viral replication, but the characteristics of an effective HIV-specific T-cell response are largely unknown. The majority of HIV-2-infected people behave as long-term non-progressors while those who progress to AIDS do so in a manner indistinguishable from HIV-1. A detailed study of HIV-2 infection may identify protective immune responses. Robust gag p26-specific T-cell responses are elicited during HIV-2 infection and correlate with control of viremia. In this study, we analyzed features of an HLA-B*3501-restricted T-cell response to HIV-2 p26 that may contribute to virus control. In contrast to HIV-1, HIV-2-specific T cells are at an early stage of differentiation (CD27+CD28+), a finding that relates directly to CD4+ T-cell levels and inversely to immune activation. The cells demonstrate IFN-, secretion, oligoclonal T-cell receptor V, gene segment usage, exceptional avidity and secretion of pro-inflammatory cytokines. Despite the potentially strong selection pressure imposed on the virus by these cells, there was no evidence of HIV-2 sequence evolution. We propose that in chronic HIV-2 infection, the maintenance of early-differentiated, highly avid CD8+ T cells could account for the non-progressive course of disease. Such responses may be desirable from an HIV vaccine. [source] Accelerating the secondary immune response by inactivating CD4+CD25+ T regulatory cells prior to BCG vaccination does not enhance protection against tuberculosisEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 3 2008Kylie M. Quinn Abstract CD4+CD25+ natural T regulatory cells (Tregs) have been shown to suppress protective immune responses in several different vaccination models. Since the effect of Tregs on vaccination against tuberculosis (Tb) was unknown, we used a murine model to investigate whether natural Tregs suppress the development of protective immunity following Mycobacterium bovis bacille Calmette-Guérin (BCG) vaccination. Using a monoclonal antibody against CD25, natural Tregs were inactivated prior to vaccination with BCG. The primary immune response was evaluated after BCG vaccination and the secondary immune response was assessed after an intranasal BCG challenge 42,days after vaccination. Inactivation of natural Tregs prior to vaccination led to an increased immune response 14,days after vaccination, increased numbers of antigen-responsive lymphocytes immediately prior to secondary challenge and the earlier appearance of IFN-,-producing CD4+ and CD8+ lymphocytes in the draining lymph nodes and lungs after challenge. Despite this, protection from virulent Mycobacterium tuberculosis or M. bovis aerosol challenge was unaffected by natural Treg inactivation prior to BCG vaccination. This suggests that increasing the primary and accelerating the secondary immune responses by inactivating natural Tregs at the time of vaccination, does not affect the development of protective immunity to Tb. [source] IL-23 and the Th17 pathway promote inflammation and impair antifungal immune resistanceEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 10 2007Teresa Zelante Abstract Although inflammation is an essential component of the protective response to fungi, its dysregulation may significantly worsen fungal diseases. We found here that the IL-23/IL-17 developmental pathway acted as a negative regulator of the Th1-mediated immune resistance to fungi and played an inflammatory role previously attributed to uncontrolled Th1 cell responses. Both inflammation and infection were exacerbated by a heightened Th17 response against Candida albicans and Aspergillus fumigatus, two major human fungal pathogens. IL-23 acted as a molecular connection between uncontrolled fungal growth and inflammation, being produced by dendritic cells in response to a high fungal burden and counter-regulating IL-12p70 production. Both IL-23 and IL-17 subverted the inflammatory program of neutrophils, which resulted in severe tissue inflammatory pathology associated with infection. Our data are the first demonstrating that the IL-23/IL-17 pathway promotes inflammation and susceptibility in an infectious disease model. As IL-23-driven inflammation promotes infection and impairs antifungal resistance, modulation of the inflammatory response represents a potential strategy to stimulate protective immune responses to fungi. See accompanying commentary: http://dx.doi.org/10.1002/eji.200737804 [source] Developing live Shigella vaccines using , Red recombineeringFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 3 2006Ryan T. Ranallo Abstract Live attenuated Shigella vaccines have shown promise in inducing protective immune responses in human clinical trials and as carriers of heterologous antigens from other mucosal pathogens. In the past, construction of Shigella vaccine strains relied on classical allelic exchange systems to genetically engineer the bacterial genome. These systems require extensive in vitro engineering of long homologous sequences to create recombinant replication-defective plasmids or phage. Alternatively, the ,red recombination system from bacteriophage facilitates recombination with as little as 40 bp of homologous DNA. The process, referred to as recombineering, typically uses an inducible ,red operon on a temperature-sensitive plasmid and optimal transformation conditions to integrate linear antibiotic resistance cassettes flanked by homologous sequences into a bacterial genome. Recent advances in recombineering have enabled modification of genomic DNA from bacterial pathogens including Salmonella, Yersinia, enteropathogenic Escherichia coli, or enterohemorrhagic E. coli and Shigella. These advances in recombineering have been used to systematically delete virulence-associated genes from Shigella, creating a number of isogenic strains from multiple Shigella serotypes. These strains have been characterized for attenuation using both in vivo and in vitro assays. Based on this data, prototypic Shigella vaccine strains containing multiple deletions in virulence-associated genes have been generated. [source] Migration of naive, effector and memory T cells: implications for the regulation of immune responsesIMMUNOLOGICAL REVIEWS, Issue 1 2001Jürgen Westermann Summary: T cells play an important role in protective immune responses and in the pathogenesis of many diseases. Understanding the mechanisms regulating their distribution in vivo may therefore be of therapeutic value. Reviewing studies that have followed the migration of labelled naive, effector and memory T cells in healthy animals reveals that all T-cell subsets enter all organs investigated. Within the tissue, two principally different migration patterns can be identified. First, naive and memory T cells accumulate in lymphoid organs for about 48 h after injection, as the time needed for migration through lymphoid organs is longer than through non-lymphoid organs. During this time, surface molecule expression is temporarily modified. These changes are reversed before leaving the lymphoid organs and entering the blood to start a new cycle of migration. Second, effector T cells are evenly distributed throughout the body, and most die in the tissues within 24 h. However, depending on the presence of cytokines, some are able to survive and to proliferate, and thereby accumulate in defined microenvironments of the body. Analysing the principles regulating T-cell migration and survival within the tissue may lead to the development of new options for the treatment of disease. [source] Protective immunity of sevenband grouper, Epinephelus septemfasciatus Thunberg, against experimental viral nervous necrosisJOURNAL OF FISH DISEASES, Issue 1 2001S Tanaka This paper describes the protective immune responses of sevenband grouper, Epinephelus septemfasciatus Thunberg, immunized with live piscine nodavirus, the causative agent of viral nervous necrosis (VNN), or the Escherichia coli, expressed recombinant coat protein. Nodavirus-neutralizing antibodies were detected at titres ranging from 1:158 to 1:1257 in serum of sevenband grouper which survived intramuscular injection with the virus, by a cell culture assay system. The virus-neutralizing ability of immune serum was also confirmed by injecting virus previously treated with serum into fish. This indicates establishment of acquired immunity in survivors and thus explains why survivors from natural infection are resistant to recurrence of the disease. Young sevenband grouper were immunized twice by intramuscular injections with the recombinant coat protein. Immunized fish produced neutralizing antibodies at high titres for at least 110 days and showed significantly lower mortalities in virus challenge tests. These results suggest the potential for vaccination against VNN in sevenband grouper, which is susceptible to piscine nodavirus at all life-stages. [source] Nicotinic acetylcholine receptor activation mediates nicotine-induced enhancement of experimental periodontitisJOURNAL OF PERIODONTAL RESEARCH, Issue 3 2009T. Breivik Background and Objective:, Smokers have an increased risk of developing periodontitis as well as showing more rapid progression and resistance to treatment of the disease, but the biological mechanisms are poorly understood. This study was designed to investigate putative biological mechanisms by which nicotine may enhance the susceptibility and thus the course of periodontitis in an animal model. Material and Methods:, Ligature-induced periodontitis was applied in periodontitis-susceptible Fischer 344 rats. The animals were either given daily intraperitoneal injections of the nicotinic acetylcholine receptor antagonist mecamylamine (1 mg/kg) 45 min before subcutaneous injections in the neck skin of nicotine (0.8 mg/kg), or treated with the same amount of saline intraperitoneally and nicotine subcutaneously, or treated with mecamylamine and saline. Control animals received intraperitoneal and subcutaneous injections of saline only. Periodontal bone loss was assessed when the ligatures had been in place for 3 wk. Two hours before decapitation, all rats received lipopolysaccharide (LPS; 100 ,g/kg, intraperitoneally) to induce a robust immune and stress response. Results:, Compared with saline/saline-treated control animals, saline/nicotine-treated rats developed significantly more periodontal bone loss, and LPS provoked a significantly smaller increase in circulating levels of the cytokines tumour necrosis factor-,, transforming growth factor-1, and interleukin-10. Mecamylamine pretreatment of nicotine-treated rats abrogated the increased periodontal bone loss and the LPS-induced decrease in tumour necrosis factor-,, but had no significant effects on the levels of transforming growth factor-1, and interleukin-10, or the stress hormone corticosterone. Conclusion:, The results indicate that nicotine enhances the susceptibility to periodontitis via nicotinic acetylcholine receptors, which may act by suppressing protective immune responses through the cholinergic anti-inflammatory pathway. [source] CD-sens: a biological measure of immunological changes stimulated by ASITALLERGY, Issue 5 2009A. Nopp Background:, Allergen-specific immunotherapy (ASIT) in allergic rhinitis and asthma is the only treatment that effects the long-term development of these diseases. Basophil allergen threshold sensitivity, CD-sens, which is a valuable complement to resource-demanding clinical challenge tests, was used to monitor the initiation of ASIT induced allergen ,blocking activity'. Methods:, Patients IgE-sensitized to timothy (n = 14) or birch (n = 19) pollen were started on conventional (8,16 weeks) or ultra rush ASIT, respectively, and followed by measurements of CD-sens, allergen binding activity (ABA) and serum IgG4- and IgE-antibody concentrations. Results:, CD-sens decreased during the early phase of ASIT-treatment. In parallel, ABA increased and correlated significantly with the increasing levels of IgG4 antibody concentrations. High dosages of allergen were more effective while mode of dosing up did not seem to matter. No change was seen in basophil reactivity. Conclusion:, CD-sens and ABA, in contrast to basophil reactivity, seem to be promising tools to monitor protective immune responses initiated by ASIT. [source] In vitro antigen presenting cell-derived IL-10 and IL-6 correlate with Trichuris muris isolate-specific survivalPARASITE IMMUNOLOGY, Issue 3 2009R. D'ELIA SUMMARY Trichuris muris, the mouse whipworm, is used as a laboratory model of the human parasite T. trichiura. Three laboratory isolates of T. muris exist , the E, J and S isolates. Previous data have shown that the S isolate survives to chronicity in C57BL/6 mice unlike the E and J isolates, which are expelled. The ability of the S isolate to persist is thought to be due to it secreting unique excretory/secretory antigens, which interact with APCs such that protective T cell responses do not develop. To determine whether APCs respond differently to E/S antigens from the three isolates we cultured isolate-specific E/S with bone marrow-derived macrophages (BMM,) and dendritic cells (BMDCs) in vitro. Markers of co-stimulation and levels of MHC-II were analysed by FACS and cytokine levels in supernatants quantified. E/S antigens from the S isolate consistently stimulated significantly higher levels of IL-10 and IL-6 from both macrophages (F4/80+CD11b+CD11c,) and dendritic cells (CD11c+CD11b+F4/80,) compared to J and E isolate E/S. If these in vitro differences in APC-derived cytokines, particularly IL-10, are biologically significant in vivo, they may contribute to the S isolate survival, by creating a regulatory cytokine environment in which protective immune responses are less effective. [source] Comparative efficacy of the Schistosoma mansoni nucleic acid vaccine, Sm23, following microseeding or gene gun deliveryPARASITE IMMUNOLOGY, Issue 4 2002Akram A. Da'dara Summary Sm23 is an integral membrane protein expressed widely in the human parasitic worm Schistosoma mansoni. Sm23 has already been shown to elicit protective immune responses following immunization with peptides or DNA constructs. In this study, we evaluated the immunogenicity and the protective efficacy of the Sm23 DNA vaccine using two different intradermal DNA delivery methods: microseeding and gene gun. Using both techniques, all mice immunized with the Sm23-pcDNA construct generated Sm23-specific immunoglobulin (Ig)G antibody, while mice immunized with the control plasmid, pcDNA, did not. Antibody isotypes analysis revealed that microseeding elicited mainly IgG2a and IgG2b antibodies, with relatively low levels of IgG1 and IgG3. The relative IgG1/IgG2a ratio was 0·03, indicative of a Th1 type immune response. In contrast, gene gun immunization resulted in significantly higher levels of IgG1 and IgG3. The relative IgG1/IgG2a ratio in this case was 11, indicative of a Th2 type immune response. No significant difference in the levels of IgG2b was observed. Coimmunization with plasmid DNA encoding either interleukin (IL)-12 or IL-4 by microseeding did not affect the levels of IgG1, while the levels of IgG2a and IgG2b were reduced. On the other hand, the levels of IgG3 were significantly increased by IL-4, but unchanged by IL-12. Importantly, in all experiments, the Sm23-pcDNA vaccine provided statistically significant levels of protection against challenge infection. Microseeding immunizations resulted in higher levels of protection (31,34% protection) than gene gun immunization (18% protection). This suggests that the Th1 type immune response elicited by microseeding immunization was responsible for the higher protection levels. However, the protective effect of the vaccine was not affected by coadministering plasmids encoding either IL-12 or IL-4 using the microseeding technique. [source] Recommendations for immunizations in stem cell transplantationPEDIATRIC TRANSPLANTATION, Issue 2003Deborah C. Molrine Abstract: Investigations over the past decade have documented that there is a decline in immunity to vaccine preventable diseases in many SCT recipients. The majority of immunization studies conducted in SCT recipients to date support the use of multi-dose regimens for most protein and polysaccharide-conjugate vaccine antigens. The consensus immunization schedule recommended by ACIP/IDSA/ASBMT provides guidance for centers to utilize available vaccines in their SCT populations. With the exception of pneumococcal disease, a schedule beginning at 12 months after SCT is reasonable given the low incidence of disease in HSCT recipients for most of the recommended vaccines and improved immune reconstitution in most recipients by one year post transplant. SCT recipients respond poorly to unconjugated pneumococcal polysaccharide vaccine and the development of polysaccharide-protein conjugate vaccines against S. pneumoniae holds promise to impact potentially on clinical disease in this population. In addition, the strategy of donor immunization may also be effective in eliciting early protective immune responses to vaccine antigens. Future challenges will be the development of safe and effective vaccines against the viral pathogens responsible for considerable morbidity and mortality after SCT. [source] Oral immunization with transgenic rice seeds expressing VP2 protein of infectious bursal disease virus induces protective immune responses in chickensPLANT BIOTECHNOLOGY JOURNAL, Issue 5 2007Jianxiang Wu Summary The expression of infectious bursal disease virus (IBDV) host-protective immunogen VP2 protein in rice seeds, its immunogenicity and protective capability in chickens were investigated. The VP2 cDNA of IBDV strain ZJ2000 was cloned downstream of the Gt1 promoter of the rice glutelin GluA-2 gene in the binary expression vector, pCambia1301-Gt1. Agrobacterium tumefaciens containing the recombinant vector was used to transform rice embryogenic calli, and 121 transgenic lines were obtained and grown to maturity in a greenhouse. The expression level of VP2 protein in transgenic rice seeds varied from 0.678% to 4.521% µg/mg of the total soluble seed protein. Specific pathogen-free chickens orally vaccinated with transgenic rice seeds expressing VP2 protein produced neutralizing antibodies against IBDV and were protected when challenged with a highly virulent IBDV strain, BC6/85. These results demonstrate that transgenic rice seeds expressing IBDV VP2 can be used as an effective, safe and inexpensive vaccine against IBDV. [source] REVIEW ARTICLE: Maternal and Fetal Response to Fetal Persistent Infection with Bovine Viral Diarrhea Virus,AMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 4 2010Thomas R. Hansen Citation Hansen TR, Smirnova NP, Van Campen H, Shoemaker ML, Ptitsyn AA, Bielefeldt-Ohmann H. Maternal and fetal response to fetal persistent infection with bovine viral diarrhea virus. Am J Reprod Immunol 2010 Problem, Infection of naïve pregnant cows with non-cytopathic (ncp) bovine viral diarrhea virus (BVDV) results in transplacental infection of the fetus. Infection of the pregnant cow with ncp BVDV late in gestation (after day 150) results in transient infection (TI), as both the dam and fetus can mount an immune response to the virus. In contrast, if the fetus is infected with ncp BVDV early in gestation (before day 150), the fetal immune system is undeveloped and unable to recognize the virus as foreign. This results in induction of immune tolerance to the infecting BVDV strain and persistent infection (PI). Methods, Infection of naïve pregnant heifers with ncp BVDV2 on day 75 was hypothesized to induce differential gene expression in white blood cells of the dams and their fetuses, adversely affecting development and antiviral immune responses in PI fetuses. Results, Gene expression differed in maternal blood cells in the presence of PI versus uninfected fetuses. PI adversely affected fetal development and antiviral responses, despite protective immune responses in the dam. Conclusion, Fetal PI with BVDV alters maternal immune function, compromises fetal growth and immune responses, and results in expression of maternal blood biomarkers that can be used to identify cows carrying PI fetuses. [source] REVIEW ARTICLE: HIV Infection in the Female Genital Tract: Discrete Influence of the Local Mucosal MicroenvironmentAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 6 2010Charu Kaushic Citation Kaushic C, Ferreira VH, Kafka JK, Nazli A. HIV infection in the female genital tract: discrete influence of the local mucosal microenvironment. Am J Reprod Immunol 2010 Women acquire HIV infections predominantly at the genital mucosa through heterosexual transmission. Therefore, the immune milieu at female genital surfaces is a critical determinant of HIV susceptibility. In this review, we recapitulate the evidence suggesting that several distinctive innate immune mechanisms in the female genital tract (FGT) serve to significantly deter or facilitate HIV-1 infection. Epithelial cells lining the FGT play a key role in forming a primary barrier to HIV entry. These cells express Toll-like receptors and other receptors that recognize and respond directly to pathogens, including HIV-1. In addition, innate biological factors produced by epithelial and other cells in the FGT have anti-HIV activity. Female sex hormones, co-infection with other pathogens and components in semen may also exacerbate or down-modulate HIV transmission. A combination of innate and adaptive immune factors and their interactions with the local microenvironment determine the outcome of HIV transmission. Improving our understanding of the female genital microenvironment will be useful in developing treatments that augment and sustain protective immune responses in the genital mucosa, such as microbicides and vaccines, and will provide greater insight into viral pathogenesis in the FGT. [source] CD40L is Critical for Protection from Demyelinating Disease and Development of Spontaneous Remyelination in a Mouse Model of Multiple SclerosisBRAIN PATHOLOGY, Issue 1 2000Kristen M. Drescher Theiler's murine encephalomyelitis virus (TMEV) induces acute neuronal disease followed by chronic demyelination in susceptible strains of mice. In this study we examined the role of a limited immune defect (deletion or blocking of CD40 ligand [CD40L]) on the extent of brain disease, susceptibility to demyelination, and the ability of demyelinated mice to spontaneously remyelinate following TMEV infection. We demonstrated that CD40L-dependent immune responses participate in pathogenesis in the cerebellum and the spinal cord white matter but protect the striatum of susceptible SJL/J mice. In mice on a background resistant to TMEV-induced demyelination (C57BL/6), the lack of CD40L resulted in increased striatal disease and meningeal inflammation. In addition, CD40L was required to maintain resistance to demyelination and clinical deficits in H-2b mice. CD40L-mediated interactions were also necessary for development of protective H-2b -restricted cytotoxic T cell responses directed against the VP2 region of TMEV as well as for spontaneous remyelination of the spinal cord white matter. The data presented here demonstrated the critical role of this molecule in both antibody- and cell-mediated protective immune responses in distinct phases of TMEV-mediated pathology. [source] | |||||||||||||