Immunogenicity and protective efficacy of Vibrio cholerae  outer membrane vesicles in rabbit model

Cholera toxin (CT), the major virulence factor of Vibrio cholerae, is an AB5 toxin secreted through the type II secretion system (T2SS). Upon secretion, the toxin initiates endocytosis through the interaction of the B pentamer with the GM1 ganglioside receptor on small intestinal cells. In addition to the release of CT in the free form, the bacteria secrete CT in association with outer membrane vesicles (OMVs). Previously, we demonstrated that strain 569B releases OMVs that encapsulate CT and which interact with host cells in a GM1-independent mechanism. Here, we have demonstrated that OMV-encapsulated CT, while biologically active, does not exist in an AB5 form; rather, the OMVs encapsulate two enzymatic A-subunit (CTA) polypeptides. We further investigated the assembly and secretion of the periplasmic CT and found that a major fraction of periplasmic CTA does not participate in the CT assembly process and instead is continuously encapsulated within the OMVs. Additionally, we found that the encapsulation of CTA fragments in OMVs is conserved among several Inaba O1 strains. We further found that under conditions in which the amount of extracellularly secreted CT increases, the concentration of OMV-encapsulated likewise CTA increases. These results point to a secondary mechanism for the secretion of biologically active CT that does not depend on the CTB-GM1 interaction for endocytosis.

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Naturally Occurring IgG Antibodies Provide Innate Protection against Vibrio cholerae Bacteremia by Recognition of the Outer Membrane Protein U

Journal of Innate Immunity ◽

10.1159/000443646 ◽

2016 ◽

Vol 8 (3) ◽

pp. 269-283 ◽

Cited By ~ 17

Author(s):

Kyaw Min Aung ◽

Annika E. Sjöström ◽

Ulrich von Pawel-Rammingen ◽

Kristian Riesbeck ◽

Bernt Eric Uhlin ◽

...

Keyword(s):

Membrane Protein ◽

Outer Membrane ◽

Vibrio Cholerae ◽

Outer Membrane Protein ◽

Membrane Vesicles ◽

Outer Membrane Vesicles ◽

Immune Defense ◽

Dependent Manner ◽

Naturally Occurring ◽

Serum Killing

Cholera epidemics are caused by Vibrio cholerae serogroups O1 and O139, whereas strains collectively known as non-O1/non-O139 V. cholerae are found in cases of extraintestinal infections and bacteremia. The mechanisms and factors influencing the occurrence of bacteremia and survival of V. cholerae in normal human serum have remained unclear. We found that naturally occurring IgG recognizing V. cholerae outer membrane protein U (OmpU) mediates a serum-killing effect in a complement C1q-dependent manner. Moreover, outer membrane vesicles (OMVs) containing OmpU caused enhanced survival of highly serum-sensitive classical V. cholerae in a dose-dependent manner. OMVs from wild-type and ompU mutant V. cholerae thereby provided a novel means to verify by extracellular transcomplementation the involvement of OmpU. Our data conclusively indicate that loss, or reduced expression, of OmpU imparts resistance to V. cholerae towards serum killing. We propose that the difference in OmpU protein levels is a plausible reason for differences in serum resistance and the ability to cause bacteremia observed among V. cholerae biotypes. Our findings provide a new perspective on how naturally occurring antibodies, perhaps induced by members of the microbiome, may play a role in the recognition of pathogens and the provocation of innate immune defense against bacteremia.

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Expression of Heterologous Antigens in Commensal Neisseria spp.: Preservation of Conformational Epitopes with Vaccine Potential

Infection and Immunity ◽

10.1128/iai.72.11.6511-6518.2004 ◽

2004 ◽

Vol 72 (11) ◽

pp. 6511-6518 ◽

Cited By ~ 29

Author(s):

Clíona A. O'Dwyer ◽

Karen Reddin ◽

Denis Martin ◽

Stephen C. Taylor ◽

Andrew R. Gorringe ◽

...

Keyword(s):

Membrane Protein ◽

Outer Membrane ◽

Meningococcal Disease ◽

Protective Efficacy ◽

Membrane Vesicles ◽

Outer Membrane Vesicles ◽

Heterologous Proteins ◽

Protein Vaccine ◽

Native Conformation ◽

Protein Antigens

ABSTRACT Commensal neisseriae share with Neisseria meningitidis (meningococcus) a tendency towards overproduction of the bacterial outer envelope, leading to the formation and release during growth of outer membrane vesicles (OMVs). OMVs from both meningococci and commensal neisseriae have shown promise as vaccines to protect against meningococcal disease. We report here the successful expression at high levels of heterologous proteins in commensal neisseriae and the display, in its native conformation, of one meningococcal outer membrane protein vaccine candidate, NspA, in OMVs prepared from such a recombinant Neisseria flavescens strain. These NspA-containing OMVs conferred protection against otherwise lethal intraperitoneal challenge of mice with N. meningitidis serogroup B, and sera raised against them mediated opsonophagocytosis of meningococcal strains expressing this antigen. This development promises to facilitate the design of novel vaccines containing membrane protein antigens that are otherwise difficult to present in native conformation that provide cross-protective efficacy in the prevention of meningococcal disease.

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Immunization of Mice With Vibrio cholerae Outer-Membrane Vesicles Protects Against Hyperinfectious Challenge and Blocks Transmission

The Journal of Infectious Diseases ◽

10.1093/infdis/jir756 ◽

2011 ◽

Vol 205 (3) ◽

pp. 412-421 ◽

Cited By ~ 27

Author(s):

Anne L. Bishop ◽

Abdullah A. Tarique ◽

Bharathi Patimalla ◽

Stephen B. Calderwood ◽

Firdausi Qadri ◽

...

Keyword(s):

Outer Membrane ◽

Vibrio Cholerae ◽

Membrane Vesicles ◽

Outer Membrane Vesicles

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Faculty Opinions recommendation of Vibrio cholerae Outer Membrane Vesicles Inhibit Bacteriophage Infection.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.733061186.793558877 ◽

2019 ◽

Author(s):

Chris Waters

Keyword(s):

Outer Membrane ◽

Vibrio Cholerae ◽

Membrane Vesicles ◽

Outer Membrane Vesicles ◽

Bacteriophage Infection

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Development of Different Methods for Preparing Acinetobacter baumannii Outer Membrane Vesicles Vaccine: Impact of Preparation Method on Protective Efficacy

Frontiers in Immunology ◽

10.3389/fimmu.2020.01069 ◽

2020 ◽

Vol 11 ◽

Author(s):

Sun Li ◽

Da-Qun Chen ◽

Lu Ji ◽

Si Sun ◽

Zhe Jin ◽

...

Keyword(s):

Acinetobacter Baumannii ◽

Outer Membrane ◽

Preparation Method ◽

Protective Efficacy ◽

Membrane Vesicles ◽

Outer Membrane Vesicles ◽

Vaccine Impact

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Immunization with Vibrio cholerae Outer Membrane Vesicles Induces Protective Immunity in Mice

Infection and Immunity ◽

10.1128/iai.00532-08 ◽

2008 ◽

Vol 76 (10) ◽

pp. 4554-4563 ◽

Cited By ~ 104

Author(s):

Stefan Schild ◽

Eric J. Nelson ◽

Andrew Camilli

Keyword(s):

Immune Responses ◽

Outer Membrane ◽

Vibrio Cholerae ◽

High Titer ◽

Immunoglobulin A ◽

Membrane Vesicles ◽

Oral Route ◽

Outer Membrane Vesicles ◽

Intranasal Route ◽

Female Mice

ABSTRACT The gram-negative bacterium Vibrio cholerae releases outer membrane vesicles (OMVs) during growth. In this study, we immunized female mice by the intranasal, intragastric, or intraperitoneal route with purified OMVs derived from V. cholerae. Independent of the route of immunization, mice induced specific, high-titer immune responses of similar levels against a variety of antigens present in the OMVs. After the last immunization, the half-maximum total immunoglobulin titer was stable over a 3-month period, indicating that the immune response was long lasting. The induction of specific isotypes, however, was dependent on the immunization route. Immunoglobulin A, for example, was induced to a significant level only by mucosal immunization, with the intranasal route generating the highest titers. We challenged the offspring of immunized female mice with V. cholerae via the oral route in two consecutive periods, approximately 30 and 95 days after the last immunization. Regardless of the route of immunization, the offspring was protected against colonization with V. cholerae in both challenge periods. Our results show that mucosal immunizations via both routes with OMVs derived from V. cholerae induce long-term protective immune responses against this gastrointestinal pathogen. These findings may contribute to the development of “nonliving,” OMV-based vaccines against V. cholerae and other enteric pathogens, using the oral or intranasal route of immunization.

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