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Mayr U.B.,Bird C GmbHandCoKG | Kudela P.,Bird C GmbHandCoKG | Atrasheuskaya A.,The Medicines Company | Lubitz W.,Bird C GmbHandCoKG
Microbial Biotechnology | Year: 2012

Bacterial ghosts (BGs) have been applied through oral, aerogenic, intraocular or intranasal routes for mucosal immunization using a wide range of experimental animals. All these applications required a booster after primary immunization to achieve protective immunity against the lethal challenge. Here we report for the first time that a single rectal dose of BGs produced from enterohaemorrhagic Escherichia coli (EHEC) O157:H7 fully protects mice against a 50% lethal challenge with a heterologous EHEC strain given at day 55. BGs from EHEC O157:H7 were prepared by a combination of protein E-mediated cell lysis and expression of staphylococcal nuclease A guaranteeing the complete degradation of pathogen residual DNA. The lack of genetic material in the EHEC BGs vaccine abolished any potential hazard for horizontal gene transfer of plasmid encoded antibiotic resistance genes or pathogenic islands to the recipient's gut flora. Single rectal immunization using EHEC O157:H7 BGs without any addition of adjuvant significantly stimulated efficient humoral and cellular immune responses, and was equally protective as two immunizations, which indicates the possibility to develop a novel efficacious single dose mucosal EHEC O157:H7 BGs vaccine using a simplified immunization regimen. © 2011 The Authors. Microbial Biotechnology © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

Muhammad A.,University of Vienna | Champeimont J.,University of Vienna | Mayr U.B.,BIRD C GmbHandCoKG | Lubitz W.,University of Vienna | And 2 more authors.
Expert Review of Vaccines | Year: 2012

Bacterial ghosts (BGs) represent vaccine delivery systems gifted with outstanding natural adjuvant properties. BGs are empty cell envelopes of Gram-negative bacteria lacking cytoplasmic content yet retaining all unaltered morphological and structural features of their living counterparts. The intact surface make-up of BGs is easily recognized by professional APCs through pattern-recognition receptors, making them ideal for mucosal administration through oral, ocular, intranasal or aerogenic routes, which represent the most desirable methods of application in advanced vaccine use. BGs have been designed to be used as carriers of active substances and foreign antigens (protein and/or DNA) for vaccine development. This review highlights the salient features of the BGs' versatile multipurpose vaccine platform for application in a wide range of human and veterinary medicines. © 2012 Expert Reviews Ltd.

Koller V.J.,University of Vienna | Koller V.J.,Medical University of Vienna | Dirsch V.M.,University of Vienna | Beres H.,University of Vienna | And 4 more authors.
FEBS Journal | Year: 2013

The present study aimed to investigate the capacity of resveratrol (RV) delivered into macrophages by bacterial ghosts (BGs), representing intact empty nonliving envelopes of Gram-negative bacteria, to modulate nitric oxide (NO) production related to the presence of the pathogen-associated molecular patterns on the surface of BGs. Incubation of the murine macrophage cell line RAW 264.7 with BGs leads to a dose-dependent activation of inducible NO synthase. To modify BG-induced NO formation in RAW 264.7 cells by RV; BGs were loaded with RV (RV-BGs) and incubated with murine macrophages in a dose-dependent manner. RV-BGs delivering RV to the target macrophages significantly reduced BG-induced NO production with concentration of RV more than one order of magnitude lower than the amount of RV capable of reducing NO formation when applied directly. Moreover, no cytotoxic impact of BGs on the viability of RAW 264.7 cells added to macrophages alone or loaded with RV was detected after a mutual 24 h incubation, whereas cell viability slightly decreased (~ 10%) when RV concentrations of 30 μm alone were applied. The results obtained in the present study clearly indicate that the intracellular delivery of RV by BGs significantly enhances the total RV effect. The present study demonstrates that NO formation induced after internalization of BGs by macrophages can be effectively modulated by RV loaded inside BGs and delivered directly to the cytosol of target cells. Low doses of RV presented within the BG's envelope significantly decreased generation of NO without having a cytotoxic impact on the viability of phagocytic cells © 2012 The Authors Journal compilation © 2012 FEBS.

Inic-Kanada A.,Medical University of Vienna | Stojanovic M.,Institute of Virology | Schlacher S.,Medical University of Vienna | Stein E.,Medical University of Vienna | And 11 more authors.
PLoS ONE | Year: 2015

Trachoma, caused by the intracellular bacterium Chlamydia trachomatis (Ct), remains the world's leading preventable infectious cause of blindness. Recent attempts to develop effective vaccines rely on modified chlamydial antigen delivery platforms. As the mechanisms engaged in the pathology of the disease are not fully understood, designing a subunit vaccine specific to chlamydial antigens could improve safety for human use.We propose the delivery of chlamydia-specific antigens to the ocular mucosa using particulate carriers, bacterial ghosts (BGs).We therefore characterized humoral and cellular immune responses after conjunctival and subcutaneous immunization with a N-Terminal portion (amino acid 1-893) of the chlamydial polymorphic membrane protein C (PmpC) of Ct serovar B, expressed in probiotic Escherichia coli Nissle 1917 bacterial ghosts (EcN BGs) in BALB/cmice. Three immunizations were performed at two-week intervals, and the immune responses were evaluated two weeks after the final immunization in mice. In a Guinea pig model of ocular infection animals were immunized in the same manner as the mice, and protection against challenge was assessed two weeks after the last immunization. N-PmpC was successfully expressed within BGs and delivery to the ocularmucosa was well tolerated without signs of inflammation. NPmpC-specific mucosal IgA levels in tears yielded significantly increased levels in the group immunized via the conjunctiva compared with the subcutaneously immunized mice. Immunization with N-PmpC EcN BGs via both immunization routes prompted the establishment of an N-PmpC-specific IFNγ immune response. Immunization via the conjunctiva resulted in a decrease in intensity of the transitional inflammatory reaction in conjunctiva of challenged Guinea pigs compared with subcutaneously and non-immunized animals. The delivery of the chlamydial subunit vaccine to the ocular mucosa using a particulate carrier, such as BGs, induced both humoral and cellular immune responses. Further investigations are needed to improve the immunization scheme and dosage. © 2015 Inic-Kanada et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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