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Antigen Processing (antigen + processing)
Selected AbstractsSession 01: Antigen processingIMMUNOLOGY, Issue 2001Article first published online: 28 JUN 200 No abstract is available for this article. [source] Disulfide bonds in merozoite surface protein 1 of the malaria parasite impede efficient antigen processing and affect the in vivo antibody responseEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 3 2004M. Hensmann Vol. 34(3) 2004, DOI 10.1002/eji.200324514 Due to a technical error, the wrong affiliations were given for C. Moss and V. Lindo. These are correct as given above. See original article http://dx.doi.org/10.1002/eji.200324514 [source] The cytoplasmic tail of invariant chain modulates antigen processing and presentationEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 2 2003Abstract The MHC class II-associated invariant chain (Ii) has several important functions in antigen presentation. In this study, we have examined the effect of Iip33 expression on endocytic transport and antigen presentation. We find that degradation of both endocytosed antigen and Ii itself is delayed in cells expressing high levels of Ii, whereas a mutant Ii with an altered charge distributionin the cytoplasmic tail was unable to exert this effect. Furthermore, the Ii mutant did not enhance the presentation of an Ii-dependent MHC class II-restricted epitope to the same extent as the wild type. In a parallel study, we investigated the effect of charge in the cytoplasmic tail of Ii. We find that due to exposed negative charges, it promotes endosome fusion events, and we suggest thatthis causes endosomal retention (Nordeng et al., Mol. Biol. Cell 2002). Together, the data reveal an additional property of the Iip33 cytoplasmic tail that contributes to the modulation of antigen processing and presentation. [source] Disparate peptide-dependent thymic selection outcomes in ,2M-deficient mice versus TAP-1-deficient mice: implications for repertoire formationEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 2 2003Tetsuro Sasada Abstract Fetal thymic organ cultures of N15-transgenic RAG-2,/, H-2b mice on normal, ,-2 microglobulin (,2M),/, or transporter associated with antigen processing (TAP-1),/, MHCI-deficient backgrounds were used to examine differentiation of thymocytes bearing a TCR specific for a viral peptide bound to H-2Kb. Strong agonists mediate negative selection in all mice whereas weak agonists are positively selecting in ,2M,/, mice but negatively selecting on TAP-1,/, or normal backgrounds. Very weak agonists and very weak antagonists are generally without effect in ,2M,/, mice yet foster differentiation in TAP-1,/, animals. The 20,40-fold reduction in ,2M,/, thymic H-2Kb surface expression suggests that the avidity of the TCR for peptide,MHCI accounts for these differences, consistent with effects of TCR density and individual thymic-peptide abundance in peptide,MHC complexes. TCR,self-MHC interaction dominates Kb -based selection, subtly modulated by peptides as revealed by X-ray crystallography. [source] Characterization of HLA DR3/DQ2 transgenic mice: a potential humanized animal model for autoimmune disease studiesEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 1 2003Dan Chen Abstract Linkage studies indicate close associations of certain HLA alleles with autoimmune diseases. To better understand how specific HLA alleles are related to disease pathogenesis, we have generated an HLA DR3/DQ2 transgenic mouse utilizing a 550-kb yeast artificial chromosome (YAC) construct containing the complete DR,, DR,1, DR,3, DQ,, and DQ, regions. The transgenic mouse (4D1/C2D) in an I-A,o background appears healthy with no signs of autoimmune diseases. Lymphoid tissues as well as CD4+ T cells develop normally. Characterization of the transgene expression demonstrates that ,90% of B cells express high levels of DR3 and 50,70% of B cells express DQ2. CD11c+ dendritic cells express high levels of DR and DQ. Approximately12,18% of resting T cells are positive for DR expression, and further up-regulation to 40,50% expression is seen upon activation with anti-CD3/anti-CD28 mAb. These results suggest that the transgenic construct confers a high fidelity to the normal human temporal and spatial expression profile. Analysis of T cell receptor repertoire in transgenic mice confirms that DR3/DQ2 are able to mediate thymic selection. Furthermore, transgenic mice respond to a DR3-restricted antigen, demonstrating antigen processing and presentation by antigen-presenting cells (APC). Purified T cells from ovalbumin (OVA)-immunized 4D1 mice respond to human APC co-cultured with OVA, suggesting appropriate antigen/DR3 or DQ2 recognition by murine T cells. Immunoglobulin isotype switching is also observed, indicating functional T-B cognate interactions. Thus, the DR3/DQ2 transgenic mouse has normal lymphoid development and functionality that are mediated by HLA transgenes and can be used to investigate HLA-associated immunological questions. [source] Regulation of human and mouse procathepsin E gene expressionFEBS JOURNAL, Issue 9 2001Matthew Cook Cathepsin E is an intracellular aspartic proteinase that is considered to have a number of physiological roles including antigen processing. Quantitation of procathepsin E mRNA by LightCyclerÔ technology indicated that the gene was transcribed in lung but not in kidney of both human and mouse origin. In contrast, the transcript was present in mouse spleen and alveolar macrophages but not in the counterpart tissue/cells from humans. Regulation of human and mouse procathepsin E gene expression was shown not to be influenced by the extent of CpG methylation but depended on the recognition of potential binding motifs in each promoter region by transcription factors such as GATA1, PU1 and YY1, as revealed by functional analysis using a series of promoter/luciferase reporter gene fusion constructs. Thus the extent to which the procathepsin E gene is expressed in a particular cell type may depend on the balance between the effects produced by positive-acting, cell-specific transcription factors such as GATA1 and PU1 and the negative influence of the ubiquitous YY1 factor. In this way, the relative abundance and influence of general and cell-specific transcription factors can govern the production of cathepsin E and thereby account for the sporadic cell and tissue distribution of this enzyme in different species. [source] Autophagy and adaptive immunityIMMUNOLOGY, Issue 1 2010Victoria L. Crotzer Summary Autophagy plays an important role in maintaining intracellular homeostasis by promoting the transit of cytoplasmic material, such as proteins, organelles and pathogens, for degradation within acidic organelles. Yet, in immune cells, autophagy pathways serve an additional role in facilitating intracellular surveillance for pathogens and changes in self. Autophagy pathways can modulate key steps in the development of innate and adaptive immunity. In terms of adaptive immunity, autophagy regulates the development and survival of lymphocytes as well as the modulation of antigen processing and presentation. Specialized forms of autophagy may be induced by some viral pathogens, providing a novel route for major histocompatibility complex (MHC) class I antigen presentation and enhanced CD8+ T-cell responses. Autophagy induction in target cells also increases their potential to serve as immunogens for dendritic cell cross-presentation to CD8+ T cells. The requirement for autophagy in MHC class II presentation of cytoplasmic and nuclear antigens is well established, yet recent studies also point to a critical role for autophagy in modulating CD4+ T-cell responses to phagocytosed pathogens. Autophagy pathways can also modulate the selection and survival of some CD4+ T cells in the thymus. However, much still remains to be learned mechanistically with respect to how autophagy and autophagy-linked genes regulate pathogen recognition and antigen presentation, as well as the development and survival of immune cells. [source] Priming of immune responses against transporter associated with antigen processing (TAP)-deficient tumours: tumour direct primingIMMUNOLOGY, Issue 3 2009Xiao-Lin Li Summary We previously showed that introduction of transporter associated with antigen processing (TAP) 1 into TAP-negative CMT.64, a major histocompatibility complex class I (MHC-I) down-regulated mouse lung carcinoma cell line, enhanced T-cell immunity against TAP-deficient tumour cells. Here, we have addressed two questions: (1) whether such immunity can be further augmented by co-expression of TAP1 with B7.1 or H-2Kb genes, and (2) which T-cell priming mechanism (tumour direct priming or dendritic cell cross-priming) plays the major role in inducing an immune response against TAP-deficient tumours. We introduced the B7.1 or H-2Kb gene into TAP1-expressing CMT.64 cells and determined which gene co-expressed with TAP1 was able to provide greater protective immunity against TAP-deficient tumour cells. Our results show that immunization of mice with B7.1 and TAP1 co-expressing but not H-2Kb and TAP1 co-expressing CMT.64 cells dramatically augments T-cell-mediated immunity, as shown by an increase in survival of mice inoculated with live CMT.64 cells. In addition, our results suggest that induction of T-cell-mediated immunity against TAP-deficient tumour cells could be mainly through tumour direct priming rather than dendritic cell cross-priming as they show that T cells generated by tumour cell-lysate-loaded dendritic cells recognized TAP-deficient tumour cells much less than TAP-proficient tumour cells. These data suggest that direct priming by TAP1 and B7.1 co-expressing tumour cells is potentially a major mechanism to facilitate immune responses against TAP-deficient tumour cells. [source] Transcription of major histocompatibility complex class I (Kb) and transporter associated with antigen processing 1 and 2 genes is up-regulated with ageIMMUNOLOGY, Issue 3 2004Alain G. Assounga Summary The transporter associated with antigen processing 1 and 2 (TAP1 and TAP2) genes belong to the ATP-binding cassette family of transporter genes. They provide peptides necessary for the assembly of major histocompatibility complex (MHC) class I molecules by transporting these peptides into the endoplasmic reticulum. As MHC class I protein expression increases with age, we have explored the effect of age on the transcription of MHC class I genes (Kb) and TAP1 and TAP2 genes in C57BL/6 mice. Blood and spleen lymphocytes were isolated from mice aged from 3 months to over 24 months. RNA was extracted and mRNA for Kb, TAP1, TAP2 was quantified using slot-blot hybridization followed by densitometry. There was a parallel age-related increase (1·5-fold) in blood lymphocyte mRNA of these genes from 3 months to 21 months. In mice over 24 months old there was a decrease in Kb and TAP1 mRNA, but an increase in TAP2 mRNA. In spleen lymphocytes an age-related increase in all three mRNA species occurred throughout life. While MHC class I and Tap genes underwent very similar age-related changes, MHC class I mRNA was about 50 times more abundant than either TAP1 or TAP2 mRNA. [source] The MHC class I antigen presentation pathway: strategies for viral immune evasionIMMUNOLOGY, Issue 2 2003Eric W. Hewitt Summary Presumably because of the selective pressure exerted by the immune system, many viruses have evolved proteins that interfere with antigen presentation by major histocompatibility complex (MHC) class I molecules. These viruses utilize a whole variety of ingenious strategies to inhibit the MHC class I pathway. Viral proteins have been characterized that exploit bottlenecks in the MHC class I pathway, such as peptide translocation by the transporter associated with antigen processing. Alternatively, viral proteins can cause the degradation or mislocalization of MHC class I molecules. This is often achieved by the subversion of the host cell's own protein degradation and trafficking pathways. As a consequence elucidation of how these viral proteins act to subvert host cell function will continue to give important insights not only into virus,host interactions but also the function and mechanism of cellular pathways. [source] Mechanism of antigen presentation after hypertonic loading of soluble antigensIMMUNOLOGY, Issue 4 2002Georg A. Enders Summary Hypertonic loading of proteins into cells has been used to introduce soluble proteins into the major histocompatibility complex class I pathway of antigen presentation followed by cytotoxic T-lymphocyte (CTL) induction. The precise mechanism for this pathway is not completely understood. The antigen is either processed and presented by/on the same cell or by professional antigen-presenting cells (APC) after taking up the antigen from damaged or apoptotic cells. After loading labelled ovalbumin (OVA), it could be co-precipitated with the proteasome complex, supporting the role of this pathway for antigen processing. The processing speed however, appeared to be slow since intact OVA could be detected inside the cells even after 18 hr. This corresponded well with the processing of OVA by isolated proteasomes. On the other hand, enough peptides for recognition of target cells by CTLs were generated in this reaction. One reason for the low level of processing might be that hypertonic loading may damage the cells and inhibit direct processing. In fact, at least 50% of the cells became positive for Annexin V binding after hypertonic loading which indicates severe membrane alterations usually associated with the progress of apoptosis. Annexin V binds to phosphatidylserine residues which also serve as ligand for CD36 expressed on monocytes and some immature dendritic cells. This may direct the phagocytic pathway to hypertonically loaded cells and thus enable professional APCs to present OVA-peptides. Therefore, in addition to the direct processing of OVA, CTLs can be primed by professional APC after uptake of apoptotic, OVA-loaded cells. [source] ,, T-cell anergy in human immunodeficiency virus-infected persons with opportunistic infections and recovery after highly active antiretroviral therapyIMMUNOLOGY, Issue 4 2000F. Martini Summary ,, T lymphocytes recognize non-peptidic microbial antigens without antigen processing and major histocompatibility complex (MHC) restriction, representing an early defence mechanism against invading pathogens. As a defective response to non-peptidic antigens was observed in human immunodeficiency virus-positive (HIV+) persons, the aims of this study were twofold: to analyse the incidence of ,, T-cell anergy in HIV+ patients with opportunistic infections/co-infections (HIV-OIC), and to investigate the role of highly active antiretroviral therapy (HAART) on ,, T-cell functions. Peripheral ,, T-cell distribution and in vitro reactivity to a non-peptidic mycobacterial antigen, isopentenyl pyrophosphate (IPP), were analysed. ,, T-cell subset distribution was altered more in HIV-OIC patients than in asymptomatic HIV+ subjects (HIV-ASY). Specifically, the V,2/V,1 ratio was inverted as a consequence of a decrease in V,2 T-cell number. Moreover, IPP-stimulated V,2 T cells from the HIV-OIC group displayed a major defect in interferon-, (IFN-,) production. Interestingly, HAART induced a sustained recovery of naive CD45RA+ and CD62L+ T cells and restored ,, T-cell function. Accordingly, in vitro CD45RA depletion resulted in ,, T-cell hyporesponsiveness. Altogether, the incidence of ,, T-cell anergy was increased in HIV-OIC patients and dependent on CD45RA helper function. Moreover, HAART was able to restore ,, T-cell reactivity, extending the immune recovery to non-peptidic microbial antigens. [source] Association between the TAP2 gene codon 665 polymorphism and Graves' DiseaseJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 3 2006Rong-Hsing Chen Abstract A total of 95 patients with active Graves' disease (GD) and 105 normal healthy subjects were enrolled in this study, which attempted to determine whether single-site polymorphisms of the transporter associated with antigen processing 2 (TAP2) gene contribute to an individual's susceptibility to GD. Such polymorphisms were detected using polymerase chain reaction (PCR)-based restriction analysis. Associations between GD and the three site polymorphisms of the TAP2 gene at codons 379, 565, and 665 were investigated. The results of the genotype analysis revealed that the frequency of the GG homozygote's presence at codon 665 was lower, and that of the AA homozygote's presence was greater in GD patients (15.8% and 36.8%, respectively) compared to normal controls (34.3% and 16.2%, respectively; P<0.001). The OR (OD) for the risk of occurrence for the AA homozygote and AG heterozygote compared to the GG homozygote (as was the case for the GD patients) was respectively 4.941 and 2.117, with respective 95% confidence intervals (CI) of 2.303,10.598 and 1.020,4.369. The allelic analysis also demonstrated reduced G and enhanced A allele frequencies for GD patients compared to controls (respectively 39.5% vs. 59.0% [G allele], and 60.5% vs. 41.0% [A allele]; P=0.0001; OR=2.219, 95% CI: 1.449,3.395). By contrast, the differences between patient and control groups for the frequency of appearance of genotypes and allelic variants at codon 379 (P=0.522 and P=0.306, respectively) and codon 565 (P=0.199 and P=0.157, respectively) did not appear to be significant. These data reveal that the single-site polymorphism of the TAP2 gene at codon 665 may be an indicator for predicting GD development. J. Clin. Lab. Anal. 20:93,97, 2006. © 2006 Wiley-Liss, Inc. [source] TAP1 gene AccI polymorphism is associated with atopic bronchial asthmaJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 2 2003Liang-Wen Hang Abstract Asthma is a hyperresponsive airway disease that may involve inflammation responses. A transporter associated with the antigen processing 1 gene (TAP1) is involved in antigen processing, and is therefore considered to play a role in the pathogenesis of bronchial asthma. The aim of this study was to test whether the polymorphisms of the TAP1 gene are a genetic marker for susceptibility to bronchial asthma. A normal control group comprised of 43 healthy people, and 116 patients with allergic asthma were examined in this study. The polymorphism was detected by polymerase chain reaction (PCR)-based restriction analysis. Associations between atopic bronchial asthma and TAP1 polymorphisms were evaluated. The results revealed no significant differences between normal individuals and asthmatics in regard to the TAP1 gene DpnII polymorphism (P=0.752). However, there was a significant difference between the control and asthma groups as regards the TAP1 gene AccI polymorphism (P=0.020). The odds ratio (OR) of GG homozygotes of the TAP1 AccI polymorphism was 229.8 compared with the AA homozygote group. The results show that the AccI polymorphism may be an indicator for atopic bronchial asthma. J. Clin. Lab. Anal. 17:57,60, 2003. © 2003 Wiley-Liss, Inc. [source] Risk factors of hepatitis C virus-related liver cirrhosis in young adults: Positive family history of liver disease and transporter associated with antigen processing 2 (TAP2) *0201 AlleleJOURNAL OF MEDICAL VIROLOGY, Issue 2 2001Norio Akuta Abstract The aim of this study was to clinically characterize young patients with hepatitis-C-related cirrhosis. We compared 27 patients with liver cirrhosis (Group LC) who were anti-HCV positive, aged 40 years or less at the time of diagnosis, with 323 consecutive patients with HCV-related chronic hepatitis (Group CH) matched for age and gender. Furthermore, Group LC was divided into two arbitrary groups (29,35 years, n,=,8 /36,40 years, n,=,19), based on the age of patients at the time of diagnosis of liver cirrhosis. Patients' characteristics and family history were investigated, and the frequency of transporter associated with antigen processing 2 (TAP2) was determined. A family history of liver disease was present in 40.7% of Group LC but in 18.0% of Group CH (P,<,0.05). The younger the age of diagnosis of cirrhosis in Group LC, the higher the frequency of a positive family history (29,35 years, 87.5%; 36,40 years, 21.1%, P,<,0.05). The frequency of TAP2*0201 was significantly higher in young adult patients with HCV-related liver cirrhosis than in HCV carriers with normal ALT (P,<,0.05), and tended to be higher than in uninfected normal subjects (P,=,0.05). The cumulative survival rate of cirrhosis patients with family history of liver diseases was significantly lower than that of cirrhosis patients without such history (P,<,0.05). Our findings suggest that a positive family history of liver disease and TAP2*0201 polymorphism may be risk factors for HCV-related liver cirrhosis in young adults. J. Med. Virol. 64:109,116, 2001. © 2001 Wiley-Liss, Inc. [source] Viral peptide immunogens: current challenges and opportunitiesJOURNAL OF PEPTIDE SCIENCE, Issue 12 2007Ali Azizi Abstract Synthetic peptide vaccines have potential to control viral infections. Successful experimental models using this approach include the protection of mice against the lethal Sendai virus infection by MHC class I binding CTL peptide epitope. The main benefit of vaccination with peptide epitopes is the ability to minimize the amount and complexity of a well-defined antigen. An appropriate peptide immunogen would also decrease the chance of stimulating a response against self-antigens, thereby providing a safer vaccine by avoiding autoimmunity. In general, the peptide vaccine strategy needs to dissect the specificity of antigen processing, the presence of B-and T-cell epitopes and the MHC restriction of the T-cell responses. This article briefly reviews the implications in the design of peptide vaccines and discusses the various approaches that are applied to improve their immunogenicity. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd. [source] Tannerella forsythia infection-induced calvarial bone and soft tissue transcriptional profilesMOLECULAR ORAL MICROBIOLOGY, Issue 5 2010V. Bakthavatchalu Summary Tannerella forsythia is associated with subgingival biofilms in adult periodontitis, although the molecular mechanisms contributing to chronic inflammation and loss of periodontal bone remain unclear. We examined changes in the host transcriptional profiles during a T. forsythia infection using a murine calvarial model of inflammation and bone resorption. Tannerella forsythia was injected into the subcutaneous soft tissue over calvariae of BALB/c mice for 3 days, after which the soft tissues and calvarial bones were excised. RNA was isolated and Murine GeneChip® (Affymetrix, Santa Clara, CA) array analysis of transcript profiles showed that 3226 genes were differentially expressed in the infected soft tissues (P < 0.05) and 2586 genes were differentially transcribed in calvarial bones after infection. Quantitative real-time reverse transcription-polymerase chain reaction analysis of transcription levels of selected genes corresponded well with the microarray results. Biological pathways significantly impacted by T. forsythia infection in calvarial bone and soft tissue included leukocyte transendothelial migration, cell adhesion molecules (immune system), extracellular matrix,receptor interaction, adherens junction, and antigen processing and presentation. Histologic examination revealed intense inflammation and increased osteoclasts in calvariae compared with controls. In conclusion, localized T. forsythia infection differentially induces transcription of a broad array of host genes, and the profiles differ between inflamed soft tissues and calvarial bone. [source] ORIGINAL ARTICLE: The Transcriptome of the Fetal Inflammatory Response SyndromeAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 1 2010Sally A. Madsen-Bouterse Problem, The fetal inflammatory response syndrome (FIRS) is considered the counterpart of the systemic inflammatory response syndrome (SIRS), but similarities in their regulatory mechanisms are unclear. This study characterizes the fetal mRNA transcriptome of peripheral leukocytes to identify key biological processes and pathways involved in FIRS. Method of study, Umbilical cord blood from preterm neonates with FIRS (funisitis, plasma IL-6 >11 pg/mL; n = 10) and neonates with no evidence of inflammation (n = 10) was collected at birth. Results, Microarray analysis of leukocyte RNA revealed differential expression of 541 unique genes, changes confirmed by qRT-PCR for 41 or 44 genes tested. Similar to SIRS and sepsis, ontological and pathway analyses yielded significant enrichment of biological processes including antigen processing and presentation, immune response, and processes critical to cellular metabolism. Results are comparable with microarray studies of endotoxin challenge models and pediatric sepsis, identifying 25 genes across all studies. Conclusion, This study is the first to profile genome-wide expression in FIRS, which demonstrates a substantial degree of similarity with SIRS despite differences in fetal and adult immune systems. [source] Association of a specific ERAP1/ARTS1 haplotype with disease susceptibility in ankylosing spondylitisARTHRITIS & RHEUMATISM, Issue 5 2009W. P. Maksymowych Objective Alterations in antigen processing have been proposed to play a significant role in the pathogenesis of ankylosing spondylitis (AS). A non,major histocompatibility complex gene encoding an endoplasmic reticulum aminopeptidase, ERAP1, has been implicated recently. This study assessed 13 coding single-nucleotide polymorphisms (SNPs) from 5 genes involved in antigen processing (ERAP1, TAP1, TAP2, LMP2, and LMP7) in 3 Canadian cohorts of patients with AS, to address the possibility of gene interactions in disease susceptibility. Methods The study involved 992 AS cases and 1,437 controls from 3 centers (472 cases and 451 controls from Alberta, 138 cases and 392 controls from Newfoundland, and 382 cases and 594 controls from Toronto). Most of the patients with AS and healthy, unrelated controls were Caucasians of northern European descent. Single-marker and haplotype associations were determined using an allelic likelihood ratio test in UNPHASED, version 3.0.12, and the WHAP program, respectively. P values for significance of haplotype associations were calculated using a permutation test. Results A specific ERAP1 haplotype, rs27044/10050860/30187-CCT, was strongly associated with increased risk of AS in all 3 case,control cohorts (pooled odds ratio [OR] 1.81, 95% confidence interval [95% CI] 1.46,2.24; P = 7 × 10,8), while a second specific ERAP1 haplotype, rs30187/26618/26653-CTG, reduced the disease risk (pooled OR 0.77, 95% CI 0.67,0.88; P = 9 × 10,5). Significant associations were also noted for 3 ERAP1 SNP variants (rs10050860, rs30187, and rs26653), although no significant haplotype interaction between ERAP1 and TAP/LMP loci was evident. Conclusion These data indicate that an AS disease locus may reside on a specific ERAP1 haplotype, and its effect is not multiplicative with contributions from TAP and LMP genes. [source] Bacterial delivery of functional messenger RNA to mammalian cellsCELLULAR MICROBIOLOGY, Issue 5 2005Christoph Schoen Summary The limited access to the nuclear compartment may constitute one of the major barriers after bacteria-mediated expression plasmid DNA delivery to eukaryotic cells. Alternatively, a self-destructing Listeria monocytogenes strain was used to release translation-competent mRNA directly into the cytosol of epithelial cells, macrophages and human dendritic cells. Enhanced green fluorescent protein (EGFP)-encoding mRNA, adapted for translation in mammalian cells by linking an IRES element to the 5,-end of the egfp coding sequence, was produced by T7 RNA polymerase in the carrier bacteria upon entry into the cytosol where the mRNA is efficiently released from the lysed bacteria and immediately translated in eukaryotic host cells. Besides the much earlier expression of EGFP being detectable already 4 h after infection, the number of EGFP expressing mammalian cells obtained with this novel RNA delivery technique is comparable to or , especially in phagocytic cells , even higher than that obtained with the expression plasmid DNA delivery strategy. Accordingly, bacteria-mediated delivery of ovalbumin-encoding mRNA to macrophages resulted in efficient antigen processing and presentation in vitro indicating that this approach may also be adapted for the in vivo delivery of antigen-encoding mRNA leading to a more efficient immune response when applied to vaccine development. [source] | ||||||||||||||||