Exploiting bacterial outer membrane vesicles as a cross-protective vaccine candidate against avian pathogenic Escherichia coli (APEC)

Abstract Background: The well-known fact that avian pathogenic Escherichia coli (APEC) is harder to prevent due to its numerous serogroups has promoted the development of biological immunostimulatory materials as new vaccine candidates in poultry farms. Bacterial outer membrane vesicles (OMVs), known as spherical nanovesicles enriched with various immunostimulants, are naturally secreted by Gram-negative bacteria, and have gained much attention for developing effective vaccine candidates. Recent report has demonstrated that OMVs of APEC O78 can induce protective immunity in chickens. Here, a novel multi-serogroup OMVs (MOMVs) vaccine was developed to achieve cross-protection against APEC infection in broiler chickens.Results: In this study, OMVs produced by three APEC strains were isolated, purified and prepared into MOMVs by mixing these three OMVs. By using SDS-PAGE and LC-MS/MS, 159 proteins were identified in MOMVs and the subcellular location and biological functions of 20 most abundant proteins were analyzed. The immunogenicity of MOMVs was evaluated, and the results showed that MOMVs could elicit innate immune responses, including internalization by chicken macrophage and production of immunomodulatory cytokines. Vaccination with MOMVs induced specific broad-spectrum antibodies as well as Th1 and Th17 immune responses. The animal experiment has confirmed that immunization with an appropriate dose of MOMVs could not cause any adverse effect and was able to reduce bacteria loads and pro-inflammatory cytokines production, thus providing eﬀective cross-protection against lethal infections induced by multi-serogroup APEC strains in chickens. Further experiments indicated that, although vesicular proteins were able to induce stronger protective efficiency than lipopolysaccharide, both vesicular proteins and lipopolysaccharide are crucial in MOMVs-mediated protection. Conclusions: The multi-serogroup nanovesicles produced by APEC strains will open up a new way for the development of next generation vaccines with low toxicity and broad protection in the treatment and control of APEC infection.

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Exploiting bacterial outer membrane vesicles as a cross-protective vaccine candidate against avian pathogenic Escherichia coli

10.21203/rs.2.24454/v1 ◽

2020 ◽

Author(s):

Rujiu Hu ◽

Jing Li ◽

Hua Lin ◽

Liu Liang ◽

Yuezhen Zhao ◽

...

Keyword(s):

Escherichia Coli ◽

Immune Responses ◽

Outer Membrane ◽

Membrane Vesicles ◽

Outer Membrane Vesicles ◽

Cross Protection ◽

Avian Pathogenic Escherichia Coli ◽

Vaccine Candidates ◽

Pathogenic Escherichia Coli ◽

Bacterial Outer Membrane

Abstract Background: The well-known fact that avian pathogenic Escherichia coli (APEC) is harder to prevent due to its numerous serogroups has promoted the development of biological immunostimulatory materials as new vaccine candidates in poultry farms. Bacterial outer membrane vesicles (OMVs), known as spherical nanovesicles enriched with various immunostimulants, are naturally secreted by Gram-negative bacteria, and have gained much attention for developing effective vaccine candidates. Here, a novel multi-serogroup OMVs (MOMVs) vaccine was developed to achieve cross-protection against APEC infection in broiler chickens.Results: In this study, OMVs produced by three APEC strains were isolated, purified and prepared into MOMVs by mixing these three OMVs. By using SDS-PAGE and LC-MS/MS, 159 proteins were identified in MOMVs and the subcellular location and biological functions of 20 most abundant proteins were analyzed. The immunogenicity of MOMVs was evaluated, and the results showed that MOMVs could elicit innate immune responses, including internalization by chicken macrophage and production of immunomodulatory cytokines. Vaccination with MOMVs induced specific broad-spectrum antibodies as well as Th1 and Th17 immune responses. The animal experiment has confirmed that immunization with an appropriate dose of MOMVs could not cause any adverse effect and was able to reduce bacteria loads and pro-inflammatory cytokines production, thus providing eﬀective cross-protection against lethal infections induced by multi-serogroup APEC in chickens. Further experiments indicated that, although vesicular proteins were able to induce stronger protective efficiency than lipopolysaccharide, both vesicular proteins and lipopolysaccharide are crucial in MOMVs-mediated protection.Conclusions: The multi-serogroup nanovesicles produced by APEC strains will open up a new way for the development of next generation vaccines with low toxicity and broad protection in the treatment and control of APEC infection.

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Naturally secreted bacterial outer membrane vesicles: potential platform for a vaccine against Campylobacter jejuni

10.1101/2020.10.16.342261 ◽

2020 ◽

Author(s):

Ankita Singh ◽

Afruja Khan ◽

Tamal Ghosh ◽

Samiran Mondal ◽

Amirul Islam Mallick

Keyword(s):

Immune Responses ◽

Outer Membrane ◽

Membrane Vesicles ◽

Outer Membrane Vesicles ◽

Mucosal Vaccine ◽

Secretory Iga ◽

Effective Vaccine ◽

Vaccine Strategy ◽

Mucosal Delivery ◽

Bacterial Outer Membrane

AbstractAcute diarrheal illness and gastroenteritis caused by Campylobacter jejuni (C. jejuni) infection remain significant public health risks in developing countries with substantial mortality and morbidity in humans, particularly in children under the age of five. Despite improved global awareness in sanitation and hygiene practices, including food safety measures, C. jejuni infections continue to rise even across the developed nations and no vaccine is currently available for humans. Genetic diversities among C. jejuni strains as well as limited understanding of immunological correlates of host protection remain primary impediments for developing an effective vaccine against C. jejuni. Given the role of bacterial outer membrane-associated proteins in intestinal adherence and invasion as well as modulating dynamic interplay between host and pathogens, bacterial outer membrane vesicles (OMVs) have emerged as potential vaccine platforms against a number of enteric pathogens, including C. jejuni. In the present study, we describe a mucosal vaccine strategy using chitosan (CS) coated OMVs (CS-OMVs) to induce specific immune responses against C. jejuni in mice. However, considering the challenges of mucosal delivery of OMVs in terms of exposure to variable pH, risk of enzymatic degradation, rapid gut transit, and low permeability across the intestinal epithelium, we preferentially used CS as a non-toxic, mucoadhesive polymer to coat OMVs. Mucosal administration of CS-OMVs induced high titre of systemic (IgG) and local (secretory IgA) antibodies in mice. The neutralizing ability of secretory IgA (sIgA) produced in the intestine was confirmed by in vitro inhibition of cell adherence and invasion of C. jejuni while in vivo challenge study in OMVs immunized mice showed a significant reduction in cecal colonization of C. jejuni. Moreover, to investigate the immunological correlates of the observed protection, present data suggest OMVs driven T cell proliferation with an increased population of CD4+ and CD8+ T cells. In addition to antibody isotype profile, significant upregulation of IFN-γ and IL-6 gene expression in mesenteric lymph nodes collected from OMVs immunized mice further suggests that mucosal delivery of OMVs promotes a Th1/Th2 mixed type immune responses. Together, we provide strong experimental evidence that as an acellular and non-replicating canonical end product of bacterial secretion, mucosal delivery of OMVs may represent a promising platform for developing an effective vaccine against C. jejuni.Author SummaryDespite the loss of 7.5 million disability-adjusted life years, which is over and above any other globally prevalent enteric or enterotoxigenic pathogens, C. jejuni remains a neglected foodborne pathogen, particularly in tropical countries. Even with the improved global awareness in sanitation and hygiene practices, including food safety measures C. jejuni infections continue to rise globally and no vaccine is currently available for humans. In light of the importance of the diverse cargo selection by bacterial OMVs, the present study describes a mucosal vaccine strategy using chitosan-coated OMVs to induce specific immune responses against C. jejuni in mice. We provide here strong experimental evidence that as a non-replicating canonical end product of bacterial secretion, mucosal delivery of OMVs represents an attractive vaccine platform against C. jejuni.

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Yersinia Outer Membrane Vesicles as Potential Vaccine Candidates in Protecting against Plague

Biomolecules ◽

10.3390/biom10121694 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1694

Author(s):

Andrey A. Byvalov ◽

Ilya V. Konyshev ◽

Vladimir N. Uversky ◽

Svetlana V. Dentovskaya ◽

Andrey P. Anisimov

Keyword(s):

Outer Membrane ◽

Membrane Vesicles ◽

Outer Membrane Vesicles ◽

Vaccine Candidates ◽

Lethal Infection ◽

Potential Vaccine ◽

Bacterial Outer Membrane ◽

Vaccine Prophylaxis ◽

Low Incidence ◽

Plague Vaccine

Despite the relatively low incidence of plague, its etiological agent, Yersinia pestis, is an exceptional epidemic danger due to the high infectivity and mortality of this infectious disease. Reports on the isolation of drug-resistant Y. pestis strains indicate the advisability of using asymmetric responses, such as phage therapy and vaccine prophylaxis in the fight against this problem. The current relatively effective live plague vaccine is not approved for use in most countries because of its ability to cause heavy local and system reactions and even a generalized infectious process in people with a repressed immune status or metabolic disorders, as well as lethal infection in some species of nonhuman primates. Therefore, developing alternative vaccines is of high priority and importance. However, until now, work on the development of plague vaccines has mainly focused on screening for the potential immunogens. Several investigators have identified the protective potency of bacterial outer membrane vesicles (OMVs) as a promising basis for bacterial vaccine candidates. This review is aimed at presenting these candidates of plague vaccine and the results of their analysis in animal models.

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Immunization With Outer Membrane Vesicles Derived From Major Outer Membrane Protein-Deficient Salmonella Typhimurium Mutants for Cross Protection Against Salmonella Enteritidis and Avian Pathogenic Escherichia coli O78 Infection in Chickens

Frontiers in Microbiology ◽

10.3389/fmicb.2020.588952 ◽

2020 ◽

Vol 11 ◽

Author(s):

Yuxuan Chen ◽

Kaiwen Jie ◽

Biaoxian Li ◽

Haiyan Yu ◽

Huan Ruan ◽

...

Keyword(s):

Escherichia Coli ◽

Membrane Protein ◽

Outer Membrane ◽

Broad Spectrum ◽

Outer Membrane Protein ◽

Salmonella Enteritidis ◽

Membrane Vesicles ◽

Outer Membrane Vesicles ◽

Major Outer Membrane Protein ◽

Cross Protection

Colibacillosis is an economically important infectious disease in poultry, caused by avian pathogenic Escherichia coli (APEC). Salmonella enterica serovar Enteritidis (S. Enteritidis) is a major cause of food-borne diseases in human circulated through poultry-derived products, including meat and chicken eggs. Vaccine control is the mainstream approach for combating these infections, but it is difficult to create a vaccine for the broad-spectrum protection of poultry due to multiple serotypes of these pathogens. Our previous studies have shown that outer membrane vesicles (OMVs) derived from S. enterica serovar Typhimurium mutants with a remodeled outer membrane could induce cross-protection against heteroserotypic Salmonella infection. Therefore, in this study, we further evaluated the potential of broad-spectrum vaccines based on major outer membrane protein (OMP)-deficient OMVs, including ΔompA, ΔompC, and ΔompD, and determined the protection effectiveness of these candidate vaccines in murine and chicken infection models. The results showed that ΔompA led to an increase in the production of OMVs. Notably, ΔompAΔompCΔompD OMVs showed significantly better cross-protection against S. enterica serovar Choleraesuis, S. Enteritidis, APEC O78, and Shigella flexneri 2a than did other omp-deficient OMVs, with the exception of ΔompA OMVs. Subsequently, we verified the results in the chicken model, in which ΔompAΔompCΔompD OMVs elicited significant cross-protection against S. Enteritidis and APEC O78 infections. These findings further confirmed the feasibility of improving the immunogenicity of OMVs by remodeling the outer membrane and provide a new perspective for the development of broad-spectrum vaccines based on OMVs.

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Protective Plant Immune Responses are Elicited by Bacterial Outer Membrane Vesicles

10.1101/2020.07.24.220160 ◽

2020 ◽

Author(s):

Hannah M. McMillan ◽

Sophia G. Zebell ◽

Jean B. Ristaino ◽

Xinnian Dong ◽

Meta J. Kuehn

Keyword(s):

Immune Responses ◽

Outer Membrane ◽

Pseudomonas Syringae ◽

Membrane Vesicles ◽

Outer Membrane Vesicles ◽

Plant Responses ◽

Bacterial Survival ◽

Microbe Interactions ◽

Bacterial Outer Membrane ◽

Host Microbe Interactions

SummaryBacterial outer membrane vesicles (OMVs) perform a variety of functions in bacterial survival and virulence. In mammalian systems, OMVs activate immune responses and have been exploited as vaccines. However, little work has focused on the role that OMVs play during interactions with plant hosts. Here we report that OMVs from the pathogenic Pseudomonas syringae and the beneficial Pseudomonas fluorescens activate plant immune responses that protect against bacterial and oomycete pathogens. OMVs from these two species display different sensitivity to biochemical stressors, which could indicate differences in OMV cargo packaging. Furthermore, our study shows that OMV-induced protective immune responses are T3SS- and protein-independent, while OMV-mediated seedling growth inhibition largely depends on protein cargo. Importantly, OMV-mediated plant responses are distinct from those triggered by PAMP/MAMPs or effector molecules alone. OMVs provide a unique opportunity to study virulence factors in combination and add a new layer of interaction and complexity to host-microbe interactions.

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