Next Article in Journal
Hemopexin and Cancer
Next Article in Special Issue
Preclinical In Vitro Model to Assess the Changes in Permeability and Cytotoxicity of Polarized Intestinal Epithelial Cells during Exposure Mimicking Oral or Intravenous Routes: An Example of Arsenite Exposure
Previous Article in Journal
Biallelic Variants in PYROXD2 Cause a Severe Infantile Metabolic Disorder Affecting Mitochondrial Function
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
IJMS
Volume 23
Issue 2
10.3390/ijms23020994
ijms-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Review

Shigella Outer Membrane Vesicles as Promising Targets for Vaccination

by
Muhammad Qasim
1,
Marius Wrage
2,
Björn Nüse
2 and
Jochen Mattner
2,*
1
Department of Microbiology, Kohat University of Science and Technology, Kohat 26000, Pakistan
2
Mikrobiologisches Institut-Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen and Friedrich-Alexander Universität (FAU) Erlangen-Nürnberg, 91054 Erlangen, Germany
*
Author to whom correspondence should be addressed.
Int. J. Mol. Sci. 2022, 23(2), 994; https://doi.org/10.3390/ijms23020994
Submission received: 28 December 2021 / Revised: 11 January 2022 / Accepted: 14 January 2022 / Published: 17 January 2022
(This article belongs to the Special Issue Inflammatory Bowel Disease: From Pre-clinial Models into Translation)
Browse Figures
Review Reports Versions Notes

Abstract

:
The clinical symptoms of shigellosis, a gastrointestinal infection caused by Shigella spp. range from watery diarrhea to fulminant dysentery. Endemic infections, particularly among children in developing countries, represent the majority of clinical cases. The situation is aggravated due to the high mortality rate of shigellosis, the rapid dissemination of multi-resistant Shigella strains and the induction of only serotype-specific immunity. Thus, infection prevention due to vaccination, encompassing as many of the circulating serotypes as possible, has become a topic of interest. However, vaccines have turned out to be ineffective so far. Outer membrane vesicles (OMVs) are promising novel targets for vaccination. OMVs are constitutively secreted by Gram-negative bacteria including Shigella during growth. They are composed of soluble luminal portions and an insoluble membrane and can contain toxins, bioactive periplasmic and cytoplasmic (lipo-) proteins, (phospho-) lipids, nucleic acids and/or lipopolysaccharides. Thus, OMVs play an important role in bacterial cell–cell communication, growth, survival and pathogenesis. Furthermore, they modulate the secretion and transport of biomolecules, the stress response, antibiotic resistance and immune responses of the host. Thus, OMVs serve as novel secretion machinery. Here, we discuss the current literature and highlight the properties of OMVs as potent vaccine candidates because of their immunomodulatory, antigenic and adjuvant properties.

1. Introduction

Shigella species invade the gut-lining epithelium and cause shigellosis, also known as bacillary dysentery. Infections with Shigella are among the leading causes of bacterial diarrhea world-wide, [1] and the mortality rate of shigellosis can be high, particularly in epidemic infections with Shigella (S.) dysenteriae serotype 1 or endemic S. flexneri infections in children living in areas with a high prevalence of malnutrition [2]. Although shigellosis is a global health problem in all age groups, endemic infections in children, particularly in developing countries with poor sanitation and/or with poor personal hygiene, constitute the main disease burden [3].
Shigellae are transmitted via water, food or via the fecal–oral route. The infectious inoculum is low, which further facilitates the spread of this very contagious bacterium from one person to another. Even after diarrhea stops, an individual person can shed and transmit Shigellae for several weeks. Thus, low hygiene and sanitation standards facilitate the person-to-person spread of Shigella spp. Furthermore, therapeutic options become increasingly limited, as Shigella strains rapidly develop resistance to commonly used frontline antibiotics including beta-lactame antibiotics, fluoroquinolones, tetracyclines, and aminoglycosides, and even become multi-drug resistant (MDR) [4,5]. As there are multiple serotypes associated with illness, repeated infections in one individual are common. However, the decrease in the incidence of disease with increasing age suggests that protective immunity develops [2,6,7]. Thus, vaccination might be an adequate tool to restrain the person-to-person spread of Shigellae and/or the severity of shigellosis in any one individual.

2. Shigella spp. and Shigellosis

Shigella spp. are Gram-negative, non-motile, and facultative anaerobic rods belonging to the family of Enterobacteriaceae. Based on 16S rRNA sequence analyses [8,9], we know nowadays that Shigella spp. are closely related to Escherichia (E.) coli strains. Indeed, today’s commensal and pathogenic E. coli and Shigella variants share common progenitor strains [10]. Thus, Shigellae are considered as E. coli strains that have acquired a specific set of genes that contribute to their specific pathogenesis and clinical pathology [9,11]. However, historically, Shigella spp. and E. coli strains have been classified as separate species based on their biochemical characteristics, serological typing, and clinical relevance [12,13,14].
The genus Shigella itself is sub-divided into four species: S. dysentriae, S. flexneri, S. boydii, and S. sonnei. Each species is composed of different serotypes based on the structure of their lipopolysaccharide (LPS) antigen, the so-called O antigen, repeats [15]. At least 50 different serotypes exist [15,16]. The identification of their distribution is pivotal for the success of vaccination strategies as acquired antibody responses to Shigellae are serotype-specific [6].
Shigellosis can present with versatile symptoms ranging from acute watery diarrhea to fulminant dysentery, accompanied by fever and abdominal cramps. While S. boydii and S. sonnei usually cause a relatively mild illness, which includes watery or bloody diarrhea, S. flexneri and S. dysenteriae are predominantly responsible for endemic and epidemic shigellosis in developing countries, with high transmission rates and significant fatality case rates. Particularly, S. dysenteriae serotype 1 causes severe disease and might be associated with life-threatening complications [2].
The ability of Shigella spp. to cause this wide range of symptoms has been linked to different virulence factors, which are encoded on chromosomal pathogenicity islands and the virulence plasmid [17]. These virulence factors include the type III secretion system, lipopolysaccharide (LPS) or the Shiga-toxins among others and mediate inflammation and enterotoxic effects, subvert the host cell structure and function, and suppress protective immune responses [17].
The distribution of Shigella species varies among geographical regions. S. dysenteriae is a major causative agent of severe epidemic disease in less developed areas while S. flexneri and S. sonnei occur primarily in developing and developed countries [18,19].
Indeed, the persistent colonization of local areas by sub-lineages of S. flexneri may have contributed to the species’ long-term success [20]. S. boydii is confined to the Indian subcontinent, and S. sonnei occurs in both transitional and developed countries [17,18]. Stratified analyses indicated a decrease in the prevalence of S. flexneri cases and an increase in the prevalence of S. sonnei cases concurrent with the rapid economic growth experienced by China in recent years [21], as observed in many other emerging countries [22,23,24]. Thus, as acquired immune responses are serotype-specific [6], the local circulating Shigella strains and serotypes need to be identified in order to develop successful vaccine candidates.

3. Vaccination Approaches

Several approaches have been employed to obtain effective vaccine candidates against shigellosis. These included (sub-) cellular vaccines, formalin-inactivated whole S. sonnei, glycoconjugates, subunit candidates, live attenuated deletion mutants, conjugated detoxified polysaccharide parenteral vaccines or conjugated synthetic carbohydrates among others [6,25,26]. Unfortunately, despite the broad variety of strategies applied and the number of potential candidates identified, there is not yet a convincing or licenced vaccine against shigellosis available. Although some vaccines have been evaluated in clinical settings, further pre-clinical and clinical studies are urgently required once the safety, immunogenicity, and protection of promising vaccine candidates have been confirmed in challenge models. Owing to the wide range of Shigella serotypes and subtypes, there is a need for the development of a multivalent vaccine that represents the prevalent species and serotypes [27]. Due to their characteristic assembly of antigenic structures and virulence factors, the outer membrane vesicles (OMVs) of Shigella are promising targets for vaccination in this context. Furthermore, the possibility of mixing OMVs from multiple serotypes presumably allows the induction of a multi-serotype immunity. Last, OMV-based vaccines can be applied orally, and thus, might overcome the ineffectiveness of parenteral vaccines to stimulate a mucosal immune response.

4. Outer Membrane Vesicles (OMVs) as Targets for Vaccination

Outer membrane vesicles (OMVs) are approximately 50–300 nm large vesicles released by Gram-negative bacteria during growth in vivo as well as in liquid and solid culture in vitro [28,29]. They consist of many potential antigenic structures including proteins, lipoproteins, lipopolysaccharides (LPS), toxins, nucleic acids, lipids, and phospholipids derived from the periplasm and from the outer bacterial membrane [28,29] (Figure 1). Thus, they are promising targets for vaccination.
OMVs presumably contribute to the stress response of bacteria, the removal of misfolded proteins, inter-bacterial communication, the transmission of virulence factors, and the delivery of molecules and toxins [30]. Furthermore, they facilitate horizontal gene transfer, the acquisition of nutrients, and the formation of biofilms. In addition, they help in the establishment of a colonization niche, protection against antibiotics, and neutralize anti-microbial peptides [29,31]. Thus, OMVs improve bacterial survival on the one hand, while on the other, they also enhance immune responses in host cells, communicate with epithelial and immune cells, and modulate host-pathogen interactions, making them attractive targets for an immune attack (Figure 2).
Shigella OMVs contain virulence factors that facilitate the adhesion of Shigella to colonic epithelial cells, the inter- and intra-cellular spread, biofilm formation, and immune evasion. Thus, OMV-based vaccines not only ameliorate the severity of disease, but also inhibit the person-to-person spread.
Thus, OMVs represent promising tools for various biomedical applications including vaccination, immunotherapy, drug delivery and as vehicle for infection control. Indeed, due to their immunogenic nature, stability in various chemical and physical conditions, and low cellular toxicity, OMVs are excellent vaccine targets [32]. Thus, OMV-based vaccines against many bacteria including E. coli, Salmonella, Vibrio and Campylobacter spp., Helicobacter pylori as well as Neisseria and Shigella spp. have been intensively studied [33,34,35,36,37]. Although OMVs are considered as cost-effective, non-living vaccine candidates against Shigella [38], detailed knowledge about the biology of OMVs on immune-modulation and bacterial pathogenesis is missing. Thus, the objective of this review is to summarize the current knowledge on the structure and chemical composition of OMVs as well as on their biological role. Furthermore, we discuss the virulence factors of Shigellae, and in particular, of S. flexneri and their interaction with the immune system of the host. Last, we describe OMV production methods in order to obtain sufficient amounts of antigens.

5. Immunological Responses Triggered by Shigella OMVs in Infection Models

A number of studies have investigated the immunogenic properties of OMVs from Shigella species in animal models (Table 1).
In one study, an intranasal immunization with OMVs protected 100% of nine-week old, female BALB/c mice against an infection with 1 × 107 CFUs S. flexneri 2a 35 days later [39]. The OMVs from S. flexneri 2a thereby induced serotype-specific protective IgG1 and IgG2a antibodies. In another study, about 50% of OMV-immunized female BALB/c mice survived a lethal dose of 4 × 106 CFUs of S. flexneri 2a [40]. Importantly, however, OMV vaccination did not only induce sero-type specific protection; for example, the oral administration of an OMV mixture from S. dysenteriae 1, S. flexneri 2a, S. flexneri 3a, S. flexneri 6 and S. sonnei to 7-week female Swiss mice elicited the secretion of protective cross-reactive IgA, IgG, IgG1, IgG2a, IgG2b, IgG3, and IgM antibodies [41]. OMVs of multiple serotypes (MOMVs) including S. dysenteriae 1 Δstx, S. flexneri 2a, 3a and 6, S. boydii type 4 and S. sonnei triggered Th1/Th2 cell-mediated immunity in BALB/c mice and provided cross-reactive protection following infection with each individual serotype [42].
Single-serotype outer membrane vesicles (SMOVs) and MOMVs of S. dysenteriae 1, S. flexneri 2a, 3a and 6, S. boydii type 4, and S. sonnei induced the release of TNF-α, IL-1β, IFN-γ, IL-6, IL-10, and IL-4 [50]. Indeed, MOMVs induced immune responses more efficiently compared to SOMVs [50]. OMVs of S. flexneri coupled to nanoparticles (NPs) provided also protection against shigellosis in BALB/c mice. The oral and the nasal application of these NP-OMVs enhanced the release of IL-12p40 and of IL-10, and in particular, the oral vaccination protected against a lethal dose of S. flexneri [43]. Furthermore, individual components of OMVs such as OmpA enhanced the production of IFN-γ and TNF-α. When coupled to histaq as an adjuvant, the intranasal administration of OmpA also protected 100% of the challenged mice against shigellosis [44]. Further analyses indicated that the combination of OmpA from S. flexneri 2a with Freund’s complete adjuvant also protected mice against a lethal dose of S. flexneri 2a [45]. Next to TNF-α and IFN-γ, OmpA also enhanced the production of IL-6 and MIP-2α in this study. Furthermore, the intraperitoneal or subcutaneous application of OmpC from the S. flexneri serotype 3a coupled with monophosphoryl-lipid [51] as adjuvant provided variable protection against a lethal dose of S. flexneri [46].
Genetic modifications of individual OMV components represent another important strategy to enhance OMV-specific immune responses. For example, the subcutaneous administration of generalized modules of membrane antigens (GMMAs) along with Freund’s adjuvant (FA) or with aluminum hydroxide (alum) elicited the production of specific IgG antibodies in outbred CD1 mice [47]. A subsequent study confirmed the immunogenic potential of GMMAs in mice [48]. OMVs obtained from S. boydii strains with a tol-A mutation, one of the genes of the Shigella membrane, also induced the production of mucosal IgG and IgA antibodies and of inflammatory cytokines including TNF-α, IL-6, and IFN-γ. Importantly, these OMVs also elicited 100% protection against shigellosis in neonatal Swiss mice [41]. The Pan-Shigella surface protein 1 (PSSP-1) of the S. flexneri serotypes 2a and 6 as well as of S. dysenteriae serotype 1 strain is known as a potent immune-modulating agent. It enhanced the production of several cytokines including IL-17A, IL-2, IL-6, IL-4, TNF-α, and IFN-γ, and protected against shigellosis in murine infection models. Furthermore, the application of PSSP-1 along with the cholera toxin (CT) and a double mutant (R192G/L211A) of the heat-labile E.coli toxin (dmLT) triggered IgG-specific antibody responses [49].

6. Immunoreactive Proteins in OMVs

The outer membrane proteins (OMPs) of OMVs derived from Gram-negative bacteria induce potent immune responses. Thus, they are important targets for the development of vaccines. Indeed, several proteins obtained from Shigella OMVs have been identified and characterized. We have summarized the findings on the immune-reactive properties of some of the outer membrane proteins (Table 2) as well as on surface proteins and polysaccharides.
A 34 kDa major outer membrane protein (MOMP) of the S. flexneri serotype 2a enhances bacterial attachment to macrophages. It also augments the production and the release of nitric oxide and of various cytokines and chemokines including granulocyte-colony stimulating factor (G-CSF), IL-12p70, TNF-α, IL-6, MIP-1α, MIP-1β, and RANTES [52,53]. Furthermore, the 34 kDa MOMP promotes the expression of the Toll-like receptor (TLR2) as well as of MHC class II and CD80 molecules on macrophages, and thus, increases their stimulatory capacity. MOMP also activates p38 MAP kinase signaling and promotes the translocation of NF-κB to the nucleus, affecting the transcription and expression of other genes [53]. Similarly, the 24 kDa and 57 kDa MOMPs of S. flexneri also enhance the production of nitric oxide, TNF-α, and IL-12 in mouse macrophages, and thus, promote Th1 responses [54,59].
OmpA plays a pivotal role in the pathogenesis of Shigellae as described above. Furthermore, OmpA is highly immunoreactive. Thus, OmpA increases the secretion of IgG and IgA, and induces Th1 cells in mice. OmpA also activates macrophages and B cells, and enhances the expression of MHC class II, CD80, and CD40 molecules on both cell subsets. Furthermore, it augments the production of Th1 cytokines. Importantly, OmpA protects mice against a lethal dose of S. flexneri [44]. Similar as described for the 34 kDA MOMP, TLR2 engagement mainly mediates these immunological effects of OmpA [45]. In contrast to the 34 kDA MOMP, OmpA engages protein tyrosine kinase, ERK, and NF-κB as signaling pathways [56].
Human umbilical cord sera react to OmpC, a 38-kDa outer membrane protein of the S. flexneri serotype 3a. This reactivity has been associated with protective activity [46].
Interestingly, the Omps of one Shigella species can elicit cross-reactive immune responses against other Shigella species, as shown, for example, for OmpA and OmpC of S. dysentariae serotype 1 [60]. However, Omps do not only provide cross-species protection, but can also elicit immune responses across genera. Thus, the recombinant LacVax® OmpA of Lactococcus lactis (L. lactis) induced antibody- and immune cell-mediated protection against Shigella infections [61].
EpiMix®, the chemically synthesized conserved epitopes of OmpA and of OmpC of S. flexneri, exhibit epitope-specific antibody responses following intramuscular administration in mice. Specifically, EpiMix® stimulated the secretion of specific IgA and IgG antibodies in the blood, and the release of IL-4, IL-2, and IFN-γ in the feces [58].
Pan-Shigella surface protein 1 (PSSP-1), a conserved Shigella protein, also provides immunological protection against various Shigella species including S. flexneri serotypes 2a, 5a, and 6 as well as against S. boydii, S. sonnei, and S. dysenteriae serotype 1. Specifically, PSSP-1 induces local and systemic antibody responses as well as the production of IL-17A and IFN-γ [49].
Furthermore, polysaccharides might be interesting targets for vaccination as they are often the main components of the outer cell wall in various Gram-negative bacteria. Indeed, the mucosal delivery of polysaccharide antigens via OMVs induced protection against S. flexneri infection in mice [43]. The LPS of Shigella flexneri is a hexa-acylated isoform that can trigger optimal inflammatory activity. However, Shigellae drastically change the degree of acylation of the lipid A component of LPS during invasion into the host cell. The purified hypo-acylated LPS exhibits a reduced inflammatory potential, which allows the bacteria to lower the sensory activity of the immune system and to escape the downstream anti-bacterial effector mechanisms [62]. Serum IgG antibodies against LPS antigens also correlate with effective protection against shigellosis [63]. This is the reason why LPS or parts of LPS are utilized as components in conjugate compounds [64].
However, the structure of LPS, especially the O antigen, is diverse between individual Shigella serovars. Thus, the cross-reactivity of existing antibodies is likely to be limited. However, LPS from locally endemic circulating strains can trigger cross-reactivity in sera of patients infected with non-local Shigella spp. (unpublished observations). Interestingly, the O-specific polysaccharides with their preserved heptosis or Kdo residuals presumably preserve cross-reactivity to other Shigella spp. [65].

7. Virulence Factors of Shigella OMVs

Shigella species, like other Gram-negative bacteria, secrete OMVs during growth in vitro and in vivo. OMVs help to establish bacterial pathogenesis. They also deliver virulence factors including toxins into host cells [30]. We have summarized several virulence factors and toxins that Shigella spp. release in Table 3.
In detail, MxiD, a 64 KDa outer membrane protein (membrane-associated ring-forming protein, MxiD), for example, perpetuates the secretion of the Ipa invasins (IpaA, IpaB, and IpaC) of S. flexneri, which are pivotal for bacterial invasion into epithelial cells of the host [66]. MxiD is also an important component of the needle complex of the type III secretory machine of Shigellae [74,85].
Furthermore, the outer membrane lipoprotein, MxiM, plays a pivotal role in the invasion of Shigellae. Similar to MxiD, MxiM also acts though the type III secretion system [74,76]. MxiM also stabilizes MxiD in its location and both MxiD and MxiM contribute to the assembly of the type III secretion system machinery and the needle complex [74]. Another lipoprotein, MxiJ, plays a key role in the invasion process due to the secretion of the Ipa invasins, IpaA, IpaB, and IpaC of Shigellae [75].
A 35 KDa outer membrane protein A [55] is involved in IcsA exposition, cell-to-cell-spread, and protrusion formation [67]. OmpA plays also a vital role in other aspects of bacterial pathogenesis such as biofilm formation, host cell invasion, intracellular spread, the evasion of immune defences, and the mediation of cytokine production. In addition, it modifies host cell survival and mitochondrial fragmentation. Furthermore, OmpA serves as a receptor for bacteriophages [86,87,88,89].
The outer membrane protein IcsA (VirG) is an adhesin-like autotransporter protein of Shigella that is regulated by the type III secretion system. It is required for the pathogenesis of Shigella [90]. IcsA promotes the polymerization of actin. Thus, it is involved in the actin-mediated intra- and intercellular transmission of Shigella spp. in the host [69,70,71]. Furthermore, IcsA mediates biofilm formation and bacterial cell–cell communication [72].
SopA, the outer membrane protease of Shigella, is required for the polar localization of IcsA and the actin-based motility inside infected cells [68]. SopA, along with other effector proteins of the pathogenicity islands of Shigella is also responsible for the invasion of epithelial cells [91] and the induction of diarrhea [92].
YaeT (Omp85) is required for the secretion and the expression of the autotransporters IcsA and SepA of S. flexneri [77]. It acts as a Stx phage recognition site, mediates the dissemination of Shiga toxins, and the insertion of proteins in the outer membranes of Enterobacteriaceae [93,94,95].
The outer membrane protease (IcsP) cleaves the IcsA protein, and thus, controls the quantity and the distribution of IcsA. It also has an important role in the actin-based spread of Shigella in host tissues [68,80,81,82,83,84].
Cardiolipins are acidic diphosphatidylglycerols encoded by the synthase ClsA. They are involved in the surface localization of IcsA and the spread of Shigella [78]. Cardiolipins also promote the transportation of LPS to the outer membrane in Gram-negative bacteria [96].
Furthermore, the outer membrane phospholipase A (OMPLA), PldA and the β-barrel proteins in the outer membrane are responsible for the structural stability of Shigella membranes and type III secretion [79,97].
Thus, in summary, multiple virulence factors of Shigella spp. accumulate in OMVs. Thus, OMVs are presumably even more immunogenic compared to whole bacteria themselves.

8. Methods for Enhancing Shigella OMV Release and Yield

Bacteria produce OMVs during growth or infection in vitro and in vivo. The main hurdle in the isolation of OMVs is their low yield, as bacteria release only small quantities of OMVs. To tackle this problem, different approaches to increase the production and release of OMVs have been described. These include genetic manipulation, nutrient depletion [36,37,48,98,99,100,101,102], oxidative stress [103], heat shock exposure [104,105] or induction by detergents [106,107], antibiotics [108,109,110], peptides [31,111] or sonication [112,113,114]. Although these approaches are effective and enhance the induction and release of OMVs, they influence the size and the chemical composition of OMVs, and subsequently, the cellular interaction and immune response [31,105,107,110,112,115,116,117,118,119,120].
With respect to genetic manipulations, the release of OMVs in S. boydii serotype 4 strains was enhanced by about 60% due to a disruption of the tolA gene in the outer membrane. The released OMVs stimulated the secretion of mucosal IgG and IgA and of TNF-α, IL-6, and IFN-γ in immunized mice [38]. Disruption of the Tol-Pal system in S. flexneri ΔtolR mutants even resulted in an 8-times increase in the release of OMVs. The produced OMVs still induced specific antibodies and the expression of MHC-II or CD40 [121].
The evolution of generalized modules for membrane antigens (GMMA) due to the deletion of the tolR gene has been utilized to increase the release of OMVs in S. sonnei. GMMA are strongly immunogenic, but less toxic; thus, they appear to be suitable for use in human trials [48]. Another study also showed that mutations in tolR and galU enhanced the production of GMMA [47]. Mutations in the virK gene of S. flexneri also increased the production of OMVs in a temperature-dependent manner [122].

9. Augmenting OMV Immune-Reactivity

To utilize OMVs as targets for vaccination, their immunological properties can be enhanced due to the application of different methods (Table 4).
One way is to mix OMVs from various Shigella species, which results in multi-serotype outer membrane vesicles (MOMVs). MOMVs have been generated from a mixture of OMVs from S. dysenteriae 1 Δstx, S. flexneri 2a, 3a and 6, S. boydii type 4 and S. sonnei. In mice, an immunization with MOMVs increased antibody responses, and subsequently, protection against several Shigella serotypes. In addition, mice exhibited a consistent broad-spectrum antibody response, and thus showed protection against all tested serotypes [42]. Similarly, MOMVs produced from several serotypes significantly enhanced cytokine production in rabbits following immunization [50].
Chemical tools can also be utilized to increase the immunological activation potential of OMVs. A treatment of S. flexneri 2a with binary ethylenimine [123] led to the production of OMVs with increased immunological properties. Due to the inactivation of S. flexneri, it can be used as safe OMV-based vaccine [39,124,125].
Coating OMVs with various agents also enhances their immunological potential, stability, and safety. OMVs from S. flexneri were formulated in nano-capsules and applied to mice, which resulted in high and long-lasting immune protection [39]. In another study, Chitosan-TPP coated with an enteric polymer (NP-OMVs) from S. sonnei were highly efficient in triggering persistent immunological responses in mice [126].

10. Conclusions

OMVs exhibit a broad range of functions that are fundamental for the biology and the ecology of Gram-negative bacteria. These functions include, for example, bacterial cell–cell communication, growth, survival, and pathogenesis as well as the transmission of virulence factors, horizontal gene transfer or the delivery of toxins. Furthermore, due to the assembly of various antigenic structures, OMVs are also key factors for the induction of inflammatory responses in the host, and thus, they are attractive targets for vaccination. Furthermore, due to mixing OMVs from different Shigella serotypes, cross-reactive immunity can be induced. Therefore, the characterization of the biological role of OMVs and an understanding of their bio-generation as well as the identification of local circulating Shigella strains and serotypes is essential to establish them as essential tools to combat bacterial pathogens.

Author Contributions

M.Q. reviewed the literature, prepared the figures and wrote the first draft. J.M. conceptualized, reviewed, edited and wrote the manuscript. M.W. and B.N. organized the tables, edited the figures and the manuscript, and contributed to the review of the literature. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the German Academic Exchange Service (DAAD- 91646398) and the German Research Foundation (DFG—CRC1181-project number C04; DFG—MA 2621/4-1 and DFG—MA 2621/5-1.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Akhondi, H.; Simonsen, K.A. Bacterial Diarrhea. In StatPearls; StatPearls Publishing: Treasure Island, FL, USA, 2021. [Google Scholar]
  2. Khalil, I.A.; Troeger, C.; Blacker, B.F.; Rao, P.C.; Brown, A.; Atherly, D.E.; Brewer, T.G.; Engmann, C.M.; Houpt, E.R.; Kang, G.; et al. Morbidity and mortality due to shigella and enterotoxigenic Escherichia coli diarrhoea: The Global Burden of Disease Study 1990–2016. Lancet Infect. Dis. 2018, 18, 1229–1240. [Google Scholar] [CrossRef] [Green Version]
  3. Kotloff, K.L.; Riddle, M.S.; Platts-Mills, J.A.; Pavlinac, P.; Zaidi, A.K.M. Shigellosis. Lancet 2018, 391, 801–812. [Google Scholar] [CrossRef]
  4. Taneja, N.; Tiewsoh, J.B.A.; Gupta, S.; Mohan, B.; Verma, R.; Shankar, P.; Narayan, C.; Yadav, V.K.; Jayashree, M.; Singh, S. Antimicrobial resistance in Shigella species: Our five years (2015–2019) experience in a tertiary care center in north India. Indian J. Med. Microbiol. 2021, 39, 489–494. [Google Scholar] [CrossRef]
  5. Guglielmino, C.J.D.; Kakkanat, A.; Forde, B.M.; Rubenach, S.; Merone, L.; Stafford, R.; Graham, R.M.A.; Beatson, S.A.; Jennison, A.V. Outbreak of multi-drug-resistant (MDR) Shigella flexneri in northern Australia due to an endemic regional clone acquiring an IncFII plasmid. Eur. J. Clin. Microbiol. Infect Dis. 2021, 40, 279–286. [Google Scholar] [CrossRef]
  6. Mani, S.; Wierzba, T.; Walker, R.I. Status of vaccine research and development for Shigella. Vaccine 2016, 34, 2887–2894. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  7. Chakraborty, S.; Harro, C.; DeNearing, B.; Bream, J.; Bauers, N.; Dally, L.; Flores, J.; Van de Verg, L.; Sack, D.A.; Walker, R. Evaluation of the Safety, Tolerability, and Immunogenicity of an Oral, Inactivated Whole-Cell Shigella flexneri 2a Vaccine in Healthy Adult Subjects. Clin. Vaccine Immunol. 2016, 23, 315–325. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  8. Christensen, H.; Nordentoft, S.; Olsen, J.E. Phylogenetic relationships of Salmonella based on rRNA sequences. Int. J. Syst. Bacteriol. 1998, 48, 605–610. [Google Scholar] [CrossRef] [Green Version]
  9. Sims, G.E.; Kim, S.H. Whole-genome phylogeny of Escherichia coli/Shigella group by feature frequency profiles (FFPs). Proc. Natl. Acad Sci. USA 2011, 108, 8329–8334. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  10. Lecointre, G.; Rachdi, L.; Darlu, P.; Denamur, E. Escherichia coli molecular phylogeny using the incongruence length difference test. Mol. Biol. Evol. 1998, 15, 1685–1695. [Google Scholar] [CrossRef] [Green Version]
  11. Hale, T.L. Genetic basis of virulence in Shigella species. Microbiol. Rev. 1991, 55, 206–224. [Google Scholar] [CrossRef]
  12. Khot, P.D.; Fisher, M.A. Novel approach for differentiating Shigella species and Escherichia coli by matrix-assisted laser desorption ionization-time of flight mass spectrometry. J. Clin. Microbiol. 2013, 51, 3711–3716. [Google Scholar] [CrossRef] [Green Version]
  13. Paauw, A.; Jonker, D.; Roeselers, G.; Heng, J.M.; Mars-Groenendijk, R.H.; Trip, H.; Molhoek, E.M.; Jansen, H.J.; van der Plas, J.; de Jong, A.L.; et al. Rapid and reliable discrimination between Shigella species and Escherichia coli using MALDI-TOF mass spectrometry. Int. J. Med. Microbiol. 2015, 305, 446–452. [Google Scholar] [CrossRef] [PubMed]
  14. Devanga Ragupathi, N.K.; Muthuirulandi Sethuvel, D.P.; Inbanathan, F.Y.; Veeraraghavan, B. Accurate differentiation of Escherichia coli and Shigella serogroups: Challenges and strategies. New Microbes New Infect. 2018, 21, 58–62. [Google Scholar] [CrossRef] [PubMed]
  15. Liu, J.; Pholwat, S.; Zhang, J.; Taniuchi, M.; Haque, R.; Alam, M.; Ochieng, J.B.; Jones, J.A.; Platts-Mills, J.A.; Tennant, S.M.; et al. Evaluation of Molecular Serotyping Assays for Shigella flexneri Directly on Stool Samples. J. Clin. Microbiol. 2021, 59, e02455-20. [Google Scholar] [CrossRef] [PubMed]
  16. Anderson, M.; Sansonetti, P.J.; Marteyn, B.S. Shigella Diversity and Changing Landscape: Insights for the Twenty-First Century. Front. Cell Infect. Microbiol. 2016, 6, 45. [Google Scholar] [CrossRef]
  17. Mattock, E.; Blocker, A.J. How Do the Virulence Factors of Shigella Work Together to Cause Disease? Front. Cell Infect. Microbiol. 2017, 7, 64. [Google Scholar] [CrossRef] [PubMed]
  18. Levine, M.M.; Kotloff, K.L.; Barry, E.M.; Pasetti, M.F.; Sztein, M.B. Clinical trials of Shigella vaccines: Two steps forward and one step back on a long, hard road. Nat. Rev. Microbiol. 2007, 5, 540–553. [Google Scholar] [CrossRef] [Green Version]
  19. Kotloff, K.L. Shigella infection in children and adults: A formidable foe. Lancet Glob. Health 2017, 5, e1166–e1167. [Google Scholar] [CrossRef] [Green Version]
  20. Connor, T.R.; Barker, C.R.; Baker, K.S.; Weill, F.X.; Talukder, K.A.; Smith, A.M.; Baker, S.; Gouali, M.; Pham Thanh, D.; Jahan Azmi, I.; et al. Species-wide whole genome sequencing reveals historical global spread and recent local persistence in Shigella flexneri. Elife 2015, 4, e07335. [Google Scholar] [CrossRef]
  21. Chang, Z.; Lu, S.; Chen, L.; Jin, Q.; Yang, J. Causative species and serotypes of shigellosis in mainland China: Systematic review and meta-analysis. PLoS ONE 2012, 7, e52515. [Google Scholar] [CrossRef]
  22. von Seidlein, L.; Kim, D.R.; Ali, M.; Lee, H.; Wang, X.; Thiem, V.D.; Canh, D.G.; Chaicumpa, W.; Agtini, M.D.; Hossain, A.; et al. A multicentre study of Shigella diarrhoea in six Asian countries: Disease burden, clinical manifestations, and microbiology. PLoS Med. 2006, 3, e353. [Google Scholar] [CrossRef] [PubMed]
  23. Seol, S.Y.; Kim, Y.T.; Jeong, Y.S.; Oh, J.Y.; Kang, H.Y.; Moon, D.C.; Kim, J.; Lee, Y.C.; Cho, D.T.; Lee, J.C. Molecular characterization of antimicrobial resistance in Shigella sonnei isolates in Korea. J. Med. Microbiol. 2006, 55, 871–877. [Google Scholar] [CrossRef] [Green Version]
  24. Wei, H.L.; Wang, Y.W.; Li, C.C.; Tung, S.K.; Chiou, C.S. Epidemiology and evolution of genotype and antimicrobial resistance of an imported Shigella sonnei clone circulating in central Taiwan. Diagn. Microbiol. Infect. Dis. 2007, 58, 469–475. [Google Scholar] [CrossRef]
  25. Rahman, K.M.; Arifeen, S.E.; Zaman, K.; Rahman, M.; Raqib, R.; Yunus, M.; Begum, N.; Islam, M.S.; Sohel, B.M.; Rahman, M.; et al. Safety, dose, immunogenicity, and transmissibility of an oral live attenuated Shigella flexneri 2a vaccine candidate (SC602) among healthy adults and school children in Matlab, Bangladesh. Vaccine 2011, 29, 1347–1354. [Google Scholar] [CrossRef] [PubMed]
  26. Frenck, R.W., Jr.; Baqar, S.; Alexander, W.; Dickey, M.; McNeal, M.; El-Khorazaty, J.; Baughman, H.; Hoeper, A.; Barnoy, S.; Suvarnapunya, A.E.; et al. A Phase I trial to evaluate the safety and immunogenicity of WRSs2 and WRSs3; two live oral candidate vaccines against Shigella sonnei. Vaccine 2018, 36, 4880–4889. [Google Scholar] [CrossRef] [PubMed]
  27. Kweon, M.N. Shigellosis: The current status of vaccine development. Curr. Opin. Infect. Dis. 2008, 21, 313–318. [Google Scholar] [CrossRef] [PubMed]
  28. Furuyama, N.; Sircili, M.P. Outer Membrane Vesicles (OMVs) Produced by Gram-Negative Bacteria: Structure, Functions, Biogenesis, and Vaccine Application. Biomed. Res. Int. 2021, 2021, 1490732. [Google Scholar] [CrossRef] [PubMed]
  29. Schwechheimer, C.; Kuehn, M.J. Outer-membrane vesicles from Gram-negative bacteria: Biogenesis and functions. Nat. Rev. Microbiol. 2015, 13, 605–619. [Google Scholar] [CrossRef] [Green Version]
  30. Bittel, M.; Reichert, P.; Sarfati, I.; Dressel, A.; Leikam, S.; Uderhardt, S.; Stolzer, I.; Phu, T.A.; Ng, M.; Vu, N.K.; et al. Visualizing transfer of microbial biomolecules by outer membrane vesicles in microbe-host-communication in vivo. J. Extracell. Vesicles 2021, 10, e12159. [Google Scholar] [CrossRef]
  31. Balhuizen, M.D.; Veldhuizen, E.J.A.; Haagsman, H.P. Outer Membrane Vesicle Induction and Isolation for Vaccine Development. Front. Microbiol. 2021, 12, 629090. [Google Scholar] [CrossRef]
  32. Cai, W.; Kesavan, D.K.; Wan, J.; Abdelaziz, M.H.; Su, Z.; Xu, H. Bacterial outer membrane vesicles, a potential vaccine candidate in interactions with host cells based. Diagn. Pathol. 2018, 13, 95. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  33. Lee, J.; Yoon, Y.J.; Kim, J.H.; Dinh, N.T.H.; Go, G.; Tae, S.; Park, K.S.; Park, H.T.; Lee, C.; Roh, T.Y.; et al. Outer Membrane Vesicles Derived From Escherichia coli Regulate Neutrophil Migration by Induction of Endothelial IL-8. Front. Microbiol. 2018, 9, 2268. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  34. Zanella, I.; Konig, E.; Tomasi, M.; Gagliardi, A.; Frattini, L.; Fantappie, L.; Irene, C.; Zerbini, F.; Caproni, E.; Isaac, S.J.; et al. Proteome-minimized outer membrane vesicles from Escherichia coli as a generalized vaccine platform. J. Extracell. Vesicles 2021, 10, e12066. [Google Scholar] [CrossRef] [PubMed]
  35. Adriani, R.; Mousavi Gargari, S.L.; Nazarian, S.; Sarvary, S.; Noroozi, N. Immunogenicity of Vibrio cholerae outer membrane vesicles secreted at various environmental conditions. Vaccine 2018, 36, 322–330. [Google Scholar] [CrossRef]
  36. Gerritzen, M.J.H.; Martens, D.E.; Uittenbogaard, J.P.; Wijffels, R.H.; Stork, M. Sulfate depletion triggers overproduction of phospholipids and the release of outer membrane vesicles by Neisseria meningitidis. Sci. Rep. 2019, 9, 4716. [Google Scholar] [CrossRef]
  37. Gerritzen, M.J.H.; Salverda, M.L.M.; Martens, D.E.; Wijffels, R.H.; Stork, M. Spontaneously released Neisseria meningitidis outer membrane vesicles as vaccine platform: Production and purification. Vaccine 2019, 37, 6978–6986. [Google Scholar] [CrossRef]
  38. Mitra, S.; Sinha, R.; Mitobe, J.; Koley, H. Development of a cost-effective vaccine candidate with outer membrane vesicles of a tolA-disrupted Shigella boydii strain. Vaccine 2016, 34, 1839–1846. [Google Scholar] [CrossRef]
  39. Camacho, A.I.; Irache, J.M.; de Souza, J.; Sanchez-Gomez, S.; Gamazo, C. Nanoparticle-based vaccine for mucosal protection against Shigella flexneri in mice. Vaccine 2013, 31, 3288–3294. [Google Scholar] [CrossRef]
  40. Pastor, Y.; Camacho, A.; Gil, A.G.; Ramos, R.; Cerain, A.L.; Penuelas, I.; Irache, J.M.; Gamazo, C. Effective protection of mice against Shigella flexneri with a new self-adjuvant multicomponent vaccine. J. Med. Microbiol. 2017, 66, 946–958. [Google Scholar] [CrossRef]
  41. Mitra, S.; Barman, S.; Nag, D.; Sinha, R.; Saha, D.R.; Koley, H. Outer membrane vesicles of Shigella boydii type 4 induce passive immunity in neonatal mice. FEMS Immunol. Med. Microbiol. 2012, 66, 240–250. [Google Scholar] [CrossRef] [Green Version]
  42. Mitra, S.; Chakrabarti, M.K.; Koley, H. Multi-serotype outer membrane vesicles of Shigellae confer passive protection to the neonatal mice against shigellosis. Vaccine 2013, 31, 3163–3173. [Google Scholar] [CrossRef] [PubMed]
  43. Nag, D.; Sinha, R.; Mitra, S.; Barman, S.; Takeda, Y.; Shinoda, S.; Chakrabarti, M.K.; Koley, H. Heat killed multi-serotype Shigella immunogens induced humoral immunity and protection against heterologous challenge in rabbit model. Immunobiology 2015, 220, 1275–1283. [Google Scholar] [CrossRef]
  44. Camacho, A.I.; de Souza, J.; Sanchez-Gomez, S.; Pardo-Ros, M.; Irache, J.M.; Gamazo, C. Mucosal immunization with Shigella flexneri outer membrane vesicles induced protection in mice. Vaccine 2011, 29, 8222–8229. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  45. Pore, D.; Mahata, N.; Pal, A.; Chakrabarti, M.K. Outer membrane protein A (OmpA) of Shigella flexneri 2a, induces protective immune response in a mouse model. PLoS ONE 2011, 6, e22663. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  46. Pore, D.; Chakrabarti, M.K. Outer membrane protein A (OmpA) from Shigella flexneri 2a: A promising subunit vaccine candidate. Vaccine 2013, 31, 3644–3650. [Google Scholar] [CrossRef] [PubMed]
  47. Wolf, M.; Schimpl, A.; Hunig, T. Control of T cell hyperactivation in IL-2-deficient mice by CD4(+)CD25(-) and CD4(+)CD25(+) T cells: Evidence for two distinct regulatory mechanisms. Eur. J. Immunol. 2001, 31, 1637–1645. [Google Scholar] [CrossRef]
  48. Jarzab, A.; Witkowska, D.; Ziomek, E.; Dabrowska, A.; Szewczuk, Z.; Gamian, A. Shigella flexneri 3a outer membrane protein C epitope is recognized by human umbilical cord sera and associated with protective activity. PLoS ONE 2013, 8, e70539. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  49. Berlanda Scorza, F.; Colucci, A.M.; Maggiore, L.; Sanzone, S.; Rossi, O.; Ferlenghi, I.; Pesce, I.; Caboni, M.; Norais, N.; Di Cioccio, V.; et al. High yield production process for Shigella outer membrane particles. PLoS ONE 2012, 7, e35616. [Google Scholar] [CrossRef] [Green Version]
  50. Gerke, C.; Colucci, A.M.; Giannelli, C.; Sanzone, S.; Vitali, C.G.; Sollai, L.; Rossi, O.; Martin, L.B.; Auerbach, J.; Di Cioccio, V.; et al. Production of a Shigella sonnei Vaccine Based on Generalized Modules for Membrane Antigens (GMMA), 1790GAHB. PLoS ONE 2015, 10, e0134478. [Google Scholar] [CrossRef]
  51. Kim, J.O.; Rho, S.; Kim, S.H.; Kim, H.; Song, H.J.; Kim, E.J.; Kim, R.Y.; Kim, E.H.; Sinha, A.; Dey, A.; et al. Shigella outer membrane protein PSSP-1 is broadly protective against Shigella infection. Clin. Vaccine Immunol. 2015, 22, 381–388. [Google Scholar] [CrossRef]
  52. Pore, D.; Chowdhury, P.; Mahata, N.; Pal, A.; Yamasaki, S.; Mahalanabis, D.; Chakrabarti, M.K. Purification and characterization of an immunogenic outer membrane protein of Shigella flexneri 2a. Vaccine 2009, 27, 5855–5864. [Google Scholar] [CrossRef]
  53. Pore, D.; Mahata, N.; Pal, A.; Chakrabarti, M.K. 34 kDa MOMP of Shigella flexneri promotes TLR2 mediated macrophage activation with the engagement of NF-kappaB and p38 MAP kinase signaling. Mol. Immunol. 2010, 47, 1739–1746. [Google Scholar] [CrossRef] [PubMed]
  54. Mukhopadhaya, A.; Mahalanabis, D.; Chakrabarti, M.K. Role of Shigella flexneri 2a 34 kDa outer membrane protein in induction of protective immune response. Vaccine 2006, 24, 6028–6036. [Google Scholar] [CrossRef]
  55. Bagchi, A.K.; Sinha, A.K. Role of 57 kDa major antigenic component of Shigella dysenteriae outer membrane proteins in induction of major histocompatibility complex II-restricted T-cell response. Arch. Med. Res. 2004, 35, 427–434. [Google Scholar] [CrossRef]
  56. Bhowmick, R.; Pore, D.; Chakrabarti, M.K. Outer membrane protein A (OmpA) of Shigella flexneri 2a induces TLR2-mediated activation of B cells: Involvement of protein tyrosine kinase, ERK and NF-kappaB. PLoS ONE 2014, 9, e109107. [Google Scholar] [CrossRef] [Green Version]
  57. Sharma, D.; Yagnik, B.; Baksi, R.; Desai, N.; Padh, H.; Desai, P. Shigellosis murine model established by intraperitoneal and intranasal route of administration: A comparative comprehension overview. Microbes Infect. 2017, 19, 47–54. [Google Scholar] [CrossRef] [PubMed]
  58. Yagnik, B.; Sharma, D.; Padh, H.; Desai, P. Oral immunization with LacVax(R) OmpA induces protective immune response against Shigella flexneri 2a ATCC 12022 in a murine model. Vaccine 2019, 37, 3097–3105. [Google Scholar] [CrossRef] [PubMed]
  59. Padh, H.; Yagnik, B.; Sharma, D.; Desai, P. EpiMix Based Novel Vaccine Candidate for Shigella: Evidence of Prophylactic Immunity in Balb/c Mice. Int. J. Pept. Res. Ther. 2021, 27, 1095–1110. [Google Scholar] [CrossRef]
  60. Paciello, I.; Silipo, A.; Lembo-Fazio, L.; Curcuru, L.; Zumsteg, A.; Noel, G.; Ciancarella, V.; Sturiale, L.; Molinaro, A.; Bernardini, M.L. Intracellular Shigella remodels its LPS to dampen the innate immune recognition and evade inflammasome activation. Proc. Natl. Acad. Sci. USA 2013, 110, E4345–E4354. [Google Scholar] [CrossRef] [Green Version]
  61. Cohen, D.; Meron-Sudai, S.; Bialik, A.; Asato, V.; Goren, S.; Ariel-Cohen, O.; Reizis, A.; Hochberg, A.; Ashkenazi, S. Serum IgG antibodies to Shigella lipopolysaccharide antigens—A correlate of protection against shigellosis. Hum. Vaccin Immunother. 2019, 15, 1401–1408. [Google Scholar] [CrossRef] [Green Version]
  62. Barel, L.A.; Mulard, L.A. Classical and novel strategies to develop a Shigella glycoconjugate vaccine: From concept to efficacy in human. Hum. Vaccin Immunother. 2019, 15, 1338–1356. [Google Scholar] [CrossRef]
  63. Silipo, A.; Molinaro, A. The diversity of the core oligosaccharide in lipopolysaccharides. Subcell. Biochem. 2010, 53, 69–99. [Google Scholar] [CrossRef]
  64. Akesson, K.; Tompa, A.; Ryden, A.; Faresjo, M. Low expression of CD39(+) /CD45RA(+) on regulatory T cells (Treg) cells in type 1 diabetic children in contrast to high expression of CD101(+) /CD129(+) on Treg cells in children with coeliac disease. Clin. Exp. Immunol. 2015, 180, 70–82. [Google Scholar] [CrossRef] [Green Version]
  65. Pore, D.; Mahata, N.; Chakrabarti, M.K. Outer membrane protein A (OmpA) of Shigella flexneri 2a links innate and adaptive immunity in a TLR2-dependent manner and involvement of IL-12 and nitric oxide. J. Biol. Chem. 2012, 287, 12589–12601. [Google Scholar] [CrossRef] [Green Version]
  66. Allaoui, A.; Sansonetti, P.J.; Parsot, C. MxiD, an outer membrane protein necessary for the secretion of the Shigella flexneri lpa invasins. Mol. Microbiol. 1993, 7, 59–68. [Google Scholar] [CrossRef]
  67. Schuch, R.; Maurelli, A.T. MxiM and MxiJ, base elements of the Mxi-Spa type III secretion system of Shigella, interact with and stabilize the MxiD secretin in the cell envelope. J. Bacteriol. 2001, 183, 6991–6998. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  68. Schroeder, G.N.; Hilbi, H. Molecular pathogenesis of Shigella spp.: Controlling host cell signaling, invasion, and death by type III secretion. Clin. Microbiol. Rev. 2008, 21, 134–156. [Google Scholar] [CrossRef] [Green Version]
  69. Bernardini, M.L.; Sanna, M.G.; Fontaine, A.; Sansonetti, P.J. OmpC is involved in invasion of epithelial cells by Shigella flexneri. Infect. Immun. 1993, 61, 3625–3635. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  70. Allaoui, A.; Sansonetti, P.J.; Parsot, C. MxiJ, a lipoprotein involved in secretion of Shigella Ipa invasins, is homologous to YscJ, a secretion factor of the Yersinia Yop proteins. J. Bacteriol. 1992, 174, 7661–7669. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  71. Ambrosi, C.; Pompili, M.; Scribano, D.; Zagaglia, C.; Ripa, S.; Nicoletti, M. Outer membrane protein A (OmpA): A new player in shigella flexneri protrusion formation and inter-cellular spreading. PLoS ONE 2012, 7, e49625. [Google Scholar] [CrossRef] [Green Version]
  72. Tiku, V.; Kofoed, E.M.; Yan, D.; Kang, J.; Xu, M.; Reichelt, M.; Dikic, I.; Tan, M.W. Outer membrane vesicles containing OmpA induce mitochondrial fragmentation to promote pathogenesis of Acinetobacter baumannii. Sci. Rep. 2021, 11, 618. [Google Scholar] [CrossRef]
  73. Murphy, E.R.; Rossmanith, J.; Sieg, J.; Fris, M.E.; Hussein, H.; Kouse, A.B.; Gross, K.; Zeng, C.; Hines, J.V.; Narberhaus, F.; et al. Regulation of OmpA Translation and Shigella dysenteriae Virulence by an RNA Thermometer. Infect. Immun. 2020, 88, e00871-19. [Google Scholar] [CrossRef]
  74. Confer, A.W.; Ayalew, S. The OmpA family of proteins: Roles in bacterial pathogenesis and immunity. Vet. Microbiol. 2013, 163, 207–222. [Google Scholar] [CrossRef] [PubMed]
  75. Smith, S.G.; Mahon, V.; Lambert, M.A.; Fagan, R.P. A molecular Swiss army knife: OmpA structure, function and expression. FEMS Microbiol. Lett. 2007, 273, 1–11. [Google Scholar] [CrossRef]
  76. Brotcke Zumsteg, A.; Goosmann, C.; Brinkmann, V.; Morona, R.; Zychlinsky, A. IcsA is a Shigella flexneri adhesin regulated by the type III secretion system and required for pathogenesis. Cell Host Microbe. 2014, 15, 435–445. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  77. Robbins, J.R.; Monack, D.; McCallum, S.J.; Vegas, A.; Pham, E.; Goldberg, M.B.; Theriot, J.A. The making of a gradient: IcsA (VirG) polarity in Shigella flexneri. Mol. Microbiol. 2001, 41, 861–872. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  78. Goldberg, M.B.; Theriot, J.A. Shigella flexneri surface protein IcsA is sufficient to direct actin-based motility. Proc. Natl. Acad. Sci. USA 1995, 92, 6572–6576. [Google Scholar] [CrossRef] [Green Version]
  79. d’Hauteville, H.; Sansonetti, P.J. Phosphorylation of IcsA by cAMP-dependent protein kinase and its effect on intracellular spread of Shigella flexneri. Mol. Microbiol. 1992, 6, 833–841. [Google Scholar] [CrossRef]
  80. Koseoglu, V.K.; Hall, C.P.; Rodriguez-Lopez, E.M.; Agaisse, H. The Autotransporter IcsA Promotes Shigella flexneri Biofilm Formation in the Presence of Bile Salts. Infect. Immun. 2019, 87, e00861-18. [Google Scholar] [CrossRef] [Green Version]
  81. Egile, C.; d’Hauteville, H.; Parsot, C.; Sansonetti, P.J. SopA, the outer membrane protease responsible for polar localization of IcsA in Shigella flexneri. Mol. Microbiol. 1997, 23, 1063–1073. [Google Scholar] [CrossRef]
  82. Raffatellu, M.; Wilson, R.P.; Chessa, D.; Andrews-Polymenis, H.; Tran, Q.T.; Lawhon, S.; Khare, S.; Adams, L.G.; Baumler, A.J. SipA, SopA, SopB, SopD, and SopE2 contribute to Salmonella enterica serotype typhimurium invasion of epithelial cells. Infect. Immun. 2005, 73, 146–154. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  83. Zhang, S.; Santos, R.L.; Tsolis, R.M.; Stender, S.; Hardt, W.D.; Baumler, A.J.; Adams, L.G. The Salmonella enterica serotype typhimurium effector proteins SipA, SopA, SopB, SopD, and SopE2 act in concert to induce diarrhea in calves. Infect. Immun. 2002, 70, 3843–3855. [Google Scholar] [CrossRef] [Green Version]
  84. Jain, S.; Goldberg, M.B. Requirement for YaeT in the outer membrane assembly of autotransporter proteins. J. Bacteriol. 2007, 189, 5393–5398. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  85. Doerrler, W.T.; Raetz, C.R. Loss of outer membrane proteins without inhibition of lipid export in an Escherichia coli YaeT mutant. J. Biol. Chem. 2005, 280, 27679–27687. [Google Scholar] [CrossRef] [Green Version]
  86. Smith, D.L.; James, C.E.; Sergeant, M.J.; Yaxian, Y.; Saunders, J.R.; McCarthy, A.J.; Allison, H.E. Short-tailed stx phages exploit the conserved YaeT protein to disseminate Shiga toxin genes among enterobacteria. J. Bacteriol. 2007, 189, 7223–7233. [Google Scholar] [CrossRef] [Green Version]
  87. Werner, J.; Misra, R. YaeT (Omp85) affects the assembly of lipid-dependent and lipid-independent outer membrane proteins of Escherichia coli. Mol. Microbiol. 2005, 57, 1450–1459. [Google Scholar] [CrossRef]
  88. Shere, K.D.; Sallustio, S.; Manessis, A.; D’Aversa, T.G.; Goldberg, M.B. Disruption of IcsP, the major Shigella protease that cleaves IcsA, accelerates actin-based motility. Mol. Microbiol. 1997, 25, 451–462. [Google Scholar] [CrossRef]
  89. Steinhauer, J.; Agha, R.; Pham, T.; Varga, A.W.; Goldberg, M.B. The unipolar Shigella surface protein IcsA is targeted directly to the bacterial old pole: IcsP cleavage of IcsA occurs over the entire bacterial surface. Mol. Microbiol. 1999, 32, 367–377. [Google Scholar] [CrossRef] [PubMed]
  90. Wing, H.J.; Goldman, S.R.; Ally, S.; Goldberg, M.B. Modulation of an outer membrane protease contributes to the virulence defect of Shigella flexneri strains carrying a mutation in the virK locus. Infect. Immun. 2005, 73, 1217–1220. [Google Scholar] [CrossRef] [Green Version]
  91. Hensley, C.T.; Kamneva, O.K.; Levy, K.M.; Labahn, S.K.; Africa, L.A.; Wing, H.J. Two promoters and two translation start sites control the expression of the Shigella flexneri outer membrane protease IcsP. Arch. Microbiol. 2011, 193, 263–274. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  92. Africa, L.A.; Murphy, E.R.; Egan, N.R.; Wigley, A.F.; Wing, H.J. The iron-responsive Fur/RyhB regulatory cascade modulates the Shigella outer membrane protease IcsP. Infect. Immun. 2011, 79, 4543–4549. [Google Scholar] [CrossRef] [Green Version]
  93. Rossi, R.M.; Yum, L.; Agaisse, H.; Payne, S.M. Cardiolipin Synthesis and Outer Membrane Localization Are Required for Shigella flexneri Virulence. MBio 2017, 8, e01199-17. [Google Scholar] [CrossRef] [Green Version]
  94. Douglass, M.V.; Cleon, F.; Trent, M.S. Cardiolipin aids in lipopolysaccharide transport to the gram-negative outer membrane. Proc. Natl. Acad. Sci. USA 2021, 118, e2018329118. [Google Scholar] [CrossRef]
  95. Wang, X.; Jiang, F.; Zheng, J.; Chen, L.; Dong, J.; Sun, L.; Zhu, Y.; Liu, B.; Yang, J.; Yang, G.; et al. The outer membrane phospholipase A is essential for membrane integrity and type III secretion in Shigella flexneri. Open Biol. 2016, 6, 160073. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  96. Wu, E.L.; Fleming, P.J.; Yeom, M.S.; Widmalm, G.; Klauda, J.B.; Fleming, K.G.; Im, W.E. coli outer membrane and interactions with OmpLA. Biophys. J. 2014, 106, 2493–2502. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  97. Schuch, R.; Maurelli, A.T. The mxi-Spa type III secretory pathway of Shigella flexneri requires an outer membrane lipoprotein, MxiM, for invasin translocation. Infect. Immun. 1999, 67, 1982–1991. [Google Scholar] [CrossRef] [PubMed]
  98. Ojima, Y.; Sawabe, T.; Konami, K.; Azuma, M. Construction of hypervesiculation Escherichia coli strains and application for secretory protein production. Biotechnol. Bioeng. 2020, 117, 701–709. [Google Scholar] [CrossRef]
  99. Micoli, F.; Alfini, R.; Di Benedetto, R.; Necchi, F.; Schiavo, F.; Mancini, F.; Carducci, M.; Palmieri, E.; Balocchi, C.; Gasperini, G.; et al. GMMA Is a Versatile Platform to Design Effective Multivalent Combination Vaccines. Vaccines 2020, 8, 540. [Google Scholar] [CrossRef]
  100. Chen, L.; Valentine, J.L.; Huang, C.J.; Endicott, C.E.; Moeller, T.D.; Rasmussen, J.A.; Fletcher, J.R.; Boll, J.M.; Rosenthal, J.A.; Dobruchowska, J.; et al. Outer membrane vesicles displaying engineered glycotopes elicit protective antibodies. Proc. Natl. Acad. Sci. USA 2016, 113, E3609–E3618. [Google Scholar] [CrossRef] [Green Version]
  101. Ferrari, G.; Garaguso, I.; Adu-Bobie, J.; Doro, F.; Taddei, A.R.; Biolchi, A.; Brunelli, B.; Giuliani, M.M.; Pizza, M.; Norais, N.; et al. Outer membrane vesicles from group B Neisseria meningitidis delta gna33 mutant: Proteomic and immunological comparison with detergent-derived outer membrane vesicles. Proteomics 2006, 6, 1856–1866. [Google Scholar] [CrossRef] [PubMed]
  102. Elhenawy, W.; Bording-Jorgensen, M.; Valguarnera, E.; Haurat, M.F.; Wine, E.; Feldman, M.F. LPS Remodeling Triggers Formation of Outer Membrane Vesicles in Salmonella. MBio 2016, 7, e00940-16. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  103. Gerritzen, M.J.H.; Maas, R.H.W.; van den Ijssel, J.; van Keulen, L.; Martens, D.E.; Wijffels, R.H.; Stork, M. High dissolved oxygen tension triggers outer membrane vesicle formation by Neisseria meningitidis. Microb. Cell Fact. 2018, 17, 157. [Google Scholar] [CrossRef] [PubMed]
  104. Baumgarten, T.; Sperling, S.; Seifert, J.; von Bergen, M.; Steiniger, F.; Wick, L.Y.; Heipieper, H.J. Membrane vesicle formation as a multiple-stress response mechanism enhances Pseudomonas putida DOT-T1E cell surface hydrophobicity and biofilm formation. Appl. Environ. Microbiol. 2012, 78, 6217–6224. [Google Scholar] [CrossRef] [Green Version]
  105. Eberlein, C.; Baumgarten, T.; Starke, S.; Heipieper, H.J. Immediate response mechanisms of Gram-negative solvent-tolerant bacteria to cope with environmental stress: Cis-trans isomerization of unsaturated fatty acids and outer membrane vesicle secretion. Appl. Microbiol. Biotechnol. 2018, 102, 2583–2593. [Google Scholar] [CrossRef] [Green Version]
  106. Acevedo, R.; Fernandez, S.; Zayas, C.; Acosta, A.; Sarmiento, M.E.; Ferro, V.A.; Rosenqvist, E.; Campa, C.; Cardoso, D.; Garcia, L.; et al. Bacterial outer membrane vesicles and vaccine applications. Front. Immunol. 2014, 5, 121. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  107. Van der Pol, L.; Stork, M.; van der Ley, P. Outer membrane vesicles as platform vaccine technology. Biotechnol. J. 2015, 10, 1689–1706. [Google Scholar] [CrossRef] [PubMed]
  108. Schertzer, J.W.; Whiteley, M. A bilayer-couple model of bacterial outer membrane vesicle biogenesis. MBio 2012, 3, e00297-11. [Google Scholar] [CrossRef] [Green Version]
  109. Kuerban, K.; Gao, X.; Zhang, H.; Liu, J.; Dong, M.; Wu, L.; Ye, R.; Feng, M.; Ye, L. Doxorubicin-loaded bacterial outer-membrane vesicles exert enhanced anti-tumor efficacy in non-small-cell lung cancer. Acta Pharm. Sin. B 2020, 10, 1534–1548. [Google Scholar] [CrossRef]
  110. Chan, K.W.; Shone, C.; Hesp, J.R. Antibiotics and iron-limiting conditions and their effect on the production and composition of outer membrane vesicles secreted from clinical isolates of extraintestinal pathogenic E. coli. Proteom. Clin. Appl. 2017, 11, 1600091. [Google Scholar] [CrossRef]
  111. Manning, A.J.; Kuehn, M.J. Contribution of bacterial outer membrane vesicles to innate bacterial defense. BMC Microbiol. 2011, 11, 258. [Google Scholar] [CrossRef] [Green Version]
  112. Roberts, R.; Moreno, G.; Bottero, D.; Gaillard, M.E.; Fingermann, M.; Graieb, A.; Rumbo, M.; Hozbor, D. Outer membrane vesicles as acellular vaccine against pertussis. Vaccine 2008, 26, 4639–4646. [Google Scholar] [CrossRef]
  113. Asensio, C.J.; Gaillard, M.E.; Moreno, G.; Bottero, D.; Zurita, E.; Rumbo, M.; van der Ley, P.; van der Ark, A.; Hozbor, D. Outer membrane vesicles obtained from Bordetella pertussis Tohama expressing the lipid A deacylase PagL as a novel acellular vaccine candidate. Vaccine 2011, 29, 1649–1656. [Google Scholar] [CrossRef]
  114. Bottero, D.; Zurita, M.E.; Gaillard, M.E.; Bartel, E.; Vercellini, C.; Hozbor, D. Membrane Vesicles Derived from Bordetella bronchiseptica: Active Constituent of a New Vaccine against Infections Caused by This Pathogen. Appl. Environ. Microbiol. 2018, 84, e01877-17. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  115. Schwechheimer, C.; Kuehn, M.J. Synthetic effect between envelope stress and lack of outer membrane vesicle production in Escherichia coli. J. Bacteriol. 2013, 195, 4161–4173. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  116. Takaki, K.; Tahara, Y.O.; Nakamichi, N.; Hasegawa, Y.; Shintani, M.; Ohkuma, M.; Miyata, M.; Futamata, H.; Tashiro, Y. Multilamellar and Multivesicular Outer Membrane Vesicles Produced by a Buttiauxella agrestis tolB Mutant. Appl. Environ. Microbiol. 2020, 86, e01131-20. [Google Scholar] [CrossRef] [PubMed]
  117. Perez-Cruz, C.; Canas, M.A.; Gimenez, R.; Badia, J.; Mercade, E.; Baldoma, L.; Aguilera, L. Membrane Vesicles Released by a hypervesiculating Escherichia coli Nissle 1917 tolR Mutant Are Highly Heterogeneous and Show Reduced Capacity for Epithelial Cell Interaction and Entry. PLoS ONE 2016, 11, e0169186. [Google Scholar] [CrossRef] [Green Version]
  118. Michel, L.V.; Gallardo, L.; Konovalova, A.; Bauer, M.; Jackson, N.; Zavorin, M.; McNamara, C.; Pierce, J.; Cheng, S.; Snyder, E.; et al. Ampicillin triggers the release of Pal in toxic vesicles from Escherichia coli. Int. J. Antimicrob. Agents 2020, 56, 106163. [Google Scholar] [CrossRef]
  119. Yun, S.H.; Park, E.C.; Lee, S.Y.; Lee, H.; Choi, C.W.; Yi, Y.S.; Ro, H.J.; Lee, J.C.; Jun, S.; Kim, H.Y.; et al. Antibiotic treatment modulates protein components of cytotoxic outer membrane vesicles of multidrug-resistant clinical strain, Acinetobacter baumannii DU202. Clin. Proteom. 2018, 15, 28. [Google Scholar] [CrossRef]
  120. Kesavan, D.; Vasudevan, A.; Wu, L.; Chen, J.; Su, Z.; Wang, S.; Xu, H. Integrative analysis of outer membrane vesicles proteomics and whole-cell transcriptome analysis of eravacycline induced Acinetobacter baumannii strains. BMC Microbiol. 2020, 20, 31. [Google Scholar] [CrossRef] [Green Version]
  121. Pastor, Y.; Camacho, A.I.; Zuniga-Ripa, A.; Merchan, A.; Rosas, P.; Irache, J.M.; Gamazo, C. Towards a subunit vaccine from a Shigella flexneri DeltatolR mutant. Vaccine 2018, 36, 7509–7519. [Google Scholar] [CrossRef]
  122. Sidik, S.; Kottwitz, H.; Benjamin, J.; Ryu, J.; Jarrar, A.; Garduno, R.; Rohde, J.R. A Shigella flexneri virulence plasmid encoded factor controls production of outer membrane vesicles. G3 2014, 4, 2493–2503. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  123. Fernandez, I.; Zeiser, R.; Karsunky, H.; Kambham, N.; Beilhack, A.; Soderstrom, K.; Negrin, R.S.; Engleman, E. CD101 surface expression discriminates potency among murine FoxP3+ regulatory T cells. J. Immunol. 2007, 179, 2808–2814. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  124. Camacho, A.I.; Irache, J.M.; Gamazo, C. Recent progress towards development of a Shigella vaccine. Expert Rev. Vaccines 2013, 12, 43–55. [Google Scholar] [CrossRef] [PubMed]
  125. Camacho, A.I.; Souza-Reboucas, J.; Irache, J.M.; Gamazo, C. Towards a non-living vaccine against Shigella flexneri: From the inactivation procedure to protection studies. Methods 2013, 60, 264–268. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  126. Mohammed, M.A.; Syeda, J.T.M.; Wasan, K.M.; Wasan, E.K. An Overview of Chitosan Nanoparticles and Its Application in Non-Parenteral Drug Delivery. Pharmaceutics 2017, 9, 53. [Google Scholar] [CrossRef] [Green Version]
Ijms 23 00994 g001 550
Figure 1. OMVs originate from the outer membranes of Gram-negative bacteria. They are 50–300 nm large vesicles that contain lipids, proteins, phospholipids, peptidoglycan, toxins, enzymes, LPS, DNA, and RNA derived from the periplasm between the inner membrane and the outer membrane as well as from the inner and outer membranes themselves.
Figure 1. OMVs originate from the outer membranes of Gram-negative bacteria. They are 50–300 nm large vesicles that contain lipids, proteins, phospholipids, peptidoglycan, toxins, enzymes, LPS, DNA, and RNA derived from the periplasm between the inner membrane and the outer membrane as well as from the inner and outer membranes themselves.
Ijms 23 00994 g001
Ijms 23 00994 g002 550
Figure 2. Shigella OMVs induce the release of different cytokines, chemokines, and specific antibodies by different immune cells, including macrophages, B and T lymphocytes. Their immune-stimulatory properties make OMVs attractive targets for vaccination against shigellosis.
Figure 2. Shigella OMVs induce the release of different cytokines, chemokines, and specific antibodies by different immune cells, including macrophages, B and T lymphocytes. Their immune-stimulatory properties make OMVs attractive targets for vaccination against shigellosis.
Ijms 23 00994 g002
Table
Table 1. Evaluations of immunological response triggered by Shigella OMVs in infection models.
Table 1. Evaluations of immunological response triggered by Shigella OMVs in infection models.
Shigella SpeciesDose and Route of OMVsInfection after Immunization Duration of
Protection 		ProtectionRef
S. flexneri 2a20 µg OMVs i.n.35 days0–15 days100%[39]
S. flexneri 2a20 μg OMVs i.n./p.o.28 days0–9 days50%[40]
S. dysenteriae 1, S. fle-neri 2a, 3a and 6, S. sonnei. 32 μg OMVs
p.o.		21 days0–120 daysVariable [41]
S. dysenteriae 1 Δstx, S. flexneri 2a, 3a and 6, S. boydii type 4, S. sonnei50 μg MOMVs p.o.
 100% [42]
S. flexneri20–100 μg OMVs i.d. or p.o.35 days 20–100%[43]
S. flexneri 2a (N.Y-962/92) 3 μg recombinant his-tag OmpA i.n. 28 days14 days100% [44]
S. flexneri 2a1 μg OmpA i.p.28 days0–14 days100% [45]
S. flexneri 3a1.6–20 μg OmpC s.c.0–21 days
 Variable[46]
Genetically modified S. sonnei0.2–2 µg
GM-MA s.c.		0–35 days0–49 days [47]
S. sonnei 1790GAHB29–238 µg
GM-MA i.p.		21 days [48]
S. boydii25 μg
tolA-disrupted OMVs p.o.		54 days 100%[38]
S. flexneri 2a and 6,
S. dysenteriae 1 		20 μg PSSP1
i.n.		28 days0–10 daysVariable [49]
Note: ND, not determined; MOMVs: Multi-serotype outer membrane vesicles; SMOVs: Single-serotype outer membrane vesicles; GMMA: Generalized modules of membrane antigens; PSSP-1: pan-Shigella surface protein 1; NP: Nanoparticle; FA: Freund’s adjuvant; Alum: aluminum hydroxide; LD50: Infectious dose 50; LD: Lethal dose; MPL: Monophosphoryl lipid A; CT: cholera toxin; dmLT: double mutant (R192G/L211A) of heat-labile toxin of E.coli; i.n.: intranasal; i.p.: intraperitoneal; s.c.: subcutaneous; p.o.: per os/oral; i.d.: intradermal
Table
Table 2. Immune-reactive proteins in OMVs from Shigella.
Table 2. Immune-reactive proteins in OMVs from Shigella.
Immune-Reactive ProteinShigella SpeciesPotential Role/FunctionRef
34 kDa major outer membrane protein (MOMP)S. flexneri 2a(i) Promotes binding to macrophages
(ii) Increases the production of nitric oxide
(iii) Enhances cytokine production 		[52]
34 kDa MOMPS. flexneri 2a(i) Enhances TLR2 expression on macrophages.
(ii) Increases the translocation of NF-κB to the nucleus
(iii) Triggers the expression of p38 MAP kinases
(iv) Augments the production of MyD88 and TRAF6
(v) Pormotes cytokine and chemokine production		[53]
OmpAS. flexneri 2a(i) Enhances the secretion of IgG and IgA
(ii) Activates Th1 cells & macrophages
(iii) Induces the expression of MHCII, CD80, CD40
(iv) Promotes the production of cytokines		[45]
34 kDa outer membrane proteinS. flexneri 2a(i) Enhances production of nitric oxide,
(ii) Increases TNF-α and interleukin-12 production		[54]
Outer membrane protein A [55]S. flexneri 2a(i) Enhances protective immunity (mucosal and systemic) by protein specific IgG and IgA responses.
(ii) Increases the production of IgA secreting cells		[44]
Pan-Shigella surface protein 1 (PSSP-1)S. flexneri 2a and 6; S. dysenteriae 1 (i) Enhances local and systemic antibody responses
(ii) Increases the production of interleukin 17A and gamma interferon.		[49]
38-kDa OmpC S. flexneri 3a Increases B-cell specific antigenic epitopes (based on modelling)[46]
Outer membrane protein A [55] S. flexneri 2a(i) Enhances the production of IgG and IgA
(ii) Induces IL-6 and IL-10 production
(iii) Increases MHC II and CD86 expression on B cells
(iv) Promotes the differentiation of B cells into antibody secreting plasma cells 		[56]
Outer membrane protein A [55] S. flexneri 2a(i) Activates NF-κB
(ii) Enhances the production of cytokines and of NO
(iii) Stimulates the T cells to release IFN-γ and IL-2 		[57]
EpiMix®S. flexneri(i) Increases the secretion of specific serum IgG
(ii) Enhances IgA, IL-4, IL-2and IFN-γ levels in feces		[58]
Table
Table 3. Virulence factors of Shigella OMVs.
Table 3. Virulence factors of Shigella OMVs.
Shigella SpeciesVirulence Factors Putative Function(s)Ref
S. flexneriMxiD, an outer membrane protein (omp)Secretion of the Ipa invasins (IpaA, IpaB, and IpaC,) of S. flexneri. MxiD is an essential component of the Ipa secretion apparatus.[66]
Outer membrane proteinA [55]IcsA exposition, cell-to-cell-spread and protrusion formation[67]
SopA, outer mem-brane proteaseRequired for the polar localization of IcsA and the actin-based motility inside infected cells[68]
Outer membrane protein IcsA (VirG)Promotes bacterial transmission from host cell to host cell, mediates actin filament nucleation and unidirectional actin-based motility of Shigellae[69]
Outer membrane protein IcsA (VirG)Involved in the actin-based motility required for intra- and intercellular Shigella spread[70]
Outer membrane protein IcsA (VirG)Intracellular and cell-to-cell spread through polymerization of actin. Phosphoryation of IcsA and subsequent modulation of LcsA function[71]
Outer membrane protein IcsA (VirG)Responsible for biofilm formation and bacterial cell to cell contact[72]
Outer Membrane Lipoprotein, MxiMPlays a role in Shigella invasion and in the type III secretion system[73]
Outer Membrane Lipoprotein, MxiMSupports the stability and localization of MxiD, it is required for the assembly in cells[74]
MxiJ, a lipoproteinMediates the secretion of Shigella Ipa invasins (IpaA, IpaB, and IpaC)[75]
Outer membrane protein C (ompC)Involved in the spread of Shigella in epithelial cells[76]
YaeT (Omp85)Required for the secretion and expression of Shigella auto-transporters IcsA and SepA.[77]
Cardiolipin
(Gene encoded on synthase ClsA)		Involved in the surface localization of IcsA and spread of Shigella
[78]
Outer membrane phospholipase A (OMPLA)-PldAEssential for membrane stability and integrity, and type III secretion[79]
S. dys-enteriae,
S. flexneri		Outer membrane protease IcsPModulates the quantity and distribution of IcsA; role in actin-based motility-based Shigella spread[68,80,81,82,83,84]
Table
Table 4. Methods for enhancing the release, the immunological efficiency and the safety of Shigella OMVs.
Table 4. Methods for enhancing the release, the immunological efficiency and the safety of Shigella OMVs.
Method MechanismIncrease in OMV ReleaseImmunological EfficiencyRef
Enhancing OMV releaseDisruption of tolA, one of the genes of the Tol–Pal system of membrane60%Mucosal IgG and IgA, pro-inflammatory cytokines (TNF-α, IL-6, IFN-γ)[38]
Distruption in Tol-Pal system in outer membraneMore than 8-timesEnhanced production of anti-bodies and expression of MHC II and costimulatory molecules[121]
Development of GMMA by deletion of tolREconomic and high yieldHighly immunogenic[48]
Null mutants of tolR
and galU 		High yield, increased production of GMMAHighly immunogenic[47]
virK mutant enhance the High yield, OMV over- productionND[122]
Enhancing efficiencyMixing of OMVs from multiple Shigella species to obtain MOMVs NDConsistent broad spectrum antibody response and protection against all tested serotypes[42]
Mixing of OMVs from multiple Shigella species → MOMVs NDSignificantly enhanced cytokine production compared to SOMVs [38]
Binary ethylenimine [123] treatment NDGood immunogenic properties of OMVs[124,125]
Nanoencap-sulation of the OMVsNDLong-term protection[39]
Heat-induced (HT) outer-membrane vesicles developmentNDHigher contents of some antigenic structures than classical OMVs[40]
Note: ND. not determined.
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Qasim, M.; Wrage, M.; Nüse, B.; Mattner, J. Shigella Outer Membrane Vesicles as Promising Targets for Vaccination. Int. J. Mol. Sci. 2022, 23, 994. https://doi.org/10.3390/ijms23020994

AMA Style

Qasim M, Wrage M, Nüse B, Mattner J. Shigella Outer Membrane Vesicles as Promising Targets for Vaccination. International Journal of Molecular Sciences. 2022; 23(2):994. https://doi.org/10.3390/ijms23020994

Chicago/Turabian Style

Qasim, Muhammad, Marius Wrage, Björn Nüse, and Jochen Mattner. 2022. "Shigella Outer Membrane Vesicles as Promising Targets for Vaccination" International Journal of Molecular Sciences 23, no. 2: 994. https://doi.org/10.3390/ijms23020994

APA Style

Qasim, M., Wrage, M., Nüse, B., & Mattner, J. (2022). Shigella Outer Membrane Vesicles as Promising Targets for Vaccination. International Journal of Molecular Sciences, 23(2), 994. https://doi.org/10.3390/ijms23020994

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop