Effect of O-Antigen Chain Length Regulation on the Immunogenicity of Shigella and Salmonella Generalized Modules for Membrane Antigens (GMMA)

Gasperini, Gianmarco; Raso, Maria Michelina; Arato, Vanessa; Aruta, Maria Grazia; Cescutti, Paola; Necchi, Francesca; Micoli, Francesca

doi:10.3390/ijms22031309

Cited by 19 publications

(26 citation statements)

References 43 publications

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“…One of these features is the saccharide length, a well-known parameter that can modulate the intensity and quality of immune response elicited by glycoconjugate vaccines. In contrast with what observed for traditional glycoconjugates, O-antigen length did not result to be a critical parameter for GMMA immunogenicity, independently by the pathogen and by the sugar structural characteristics (11). Moreover, we demonstrated that exposure of GMMA to high-temperature (100°C for 40 min) did not impact GMMA stability and immunogenicity in mice, whereas milder temperatures for a longer period of time did (37°C or 50°C for 4 weeks).…”

Section: Future Directionscontrasting

confidence: 88%

“…Indeed, the entire production process from fermentation to final purified GMMA lasts 3 days and thus, depending on the size of the vaccine dose, a relatively small manufacture facility with a 500 L fermenter could produce 100 000 000 doses of vaccines per year at a manufacturing cost of approximately $1 per dose (10). GMMA from Shigella (4,5,7,9,(11)(12)(13), Salmonella (8,14,15), and Neisseria (16,18) species have been already generated using this approach, which is shown to be flexible enough to be potentially extended with minimal adjustments to any Gram-negative bacterial species. Indeed multiple industrial (17)(18)(19) and research (20)(21)(22) approaches based on genetic engineering of bacteria for hyper-vesiculating and surface-expression of a variety of homologous and heterologous antigens, including bacterial (20)(21)(22), viral (23), parasitic (24) and even cancer antigens (25) have been described.…”

Section: Introductionmentioning

confidence: 99%

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GMMA-Based Vaccines: The Known and The Unknown

et al. 2021

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Generalized Modules for Membrane Antigens (GMMA) are outer membrane vesicles derived from Gram-negative bacteria engineered to provide an over-vesiculating phenotype, which represent an attractive platform for the design of affordable vaccines. GMMA can be further genetically manipulated to modulate the risk of systemic reactogenicity and to act as delivery system for heterologous polysaccharide or protein antigens. GMMA are able to induce strong immunogenicity and protection in animal challenge models, and to be well-tolerated and immunogenic in clinical studies. The high immunogenicity could be ascribed to their particulate size, to their ability to present to the immune system multiple antigens in a natural conformation which mimics the bacterial environment, as well as to their intrinsic self-adjuvanticity. However, GMMA mechanism of action and the role in adjuvanticity are still unclear and need further investigation. In this review, we discuss progresses in the development of the GMMA vaccine platform, highlighting successful applications and identifying knowledge gaps and potential challenges.

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Section: Future Directionscontrasting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

GMMA-Based Vaccines: The Known and The Unknown

et al. 2021

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“…Indeed, GMMA-producing strains can be easily mutated to display OAg with the desired features and resulting GMMA can be rapidly tested in animal studies. Here we have generated GMMA displaying S. flexneri 2a and 1b OAg with different O-acetylation patterns by knocking-out the responsible genes, similarly to what has already been reported to obtain different OAg size [43].…”

Section: Discussionmentioning

confidence: 91%

Impact of O-Acetylation on S. flexneri 1b and 2a O-Antigen Immunogenicity in Mice

et al. 2021

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Shigellosis is a diarrheal disease caused prevalently by Shigella flexneri and S. sonnei and representing a major global health risk, particularly in developing countries. Bacterial O-antigen (OAg) is the primary target of the host immune response and modifications of its oligosaccharide units, including O-acetylation, are responsible for the variability among the circulating S. flexneri serotypes. No vaccines are widely available against shigellosis and the understanding of the immunogenicity induced by the OAg is fundamental for the design of a vaccine that could cover the most prevalent Shigella serotypes. To understand whether a different O-acetylation pattern could influence the immune response elicited by S. flexneri OAg, we employed as a vaccine technology GMMA purified from S. flexneri 2a and 1b strains that were easily engineered to obtain differently O-acetylated OAg. Resulting GMMA were tested in mice, demonstrating not only no major impact of O-acetyl decorations on the immune response elicited by the two OAg against the homologous strains, but also that the O-acetylation of the Rhamnose III residue (O-factor 9), shared among serotypes 1b, 2a and 6, does not induce cross-reactive antibodies against these serotypes. This work contributes to the optimization of vaccine design against Shigella, providing indication about the ability of shared epitopes to elicit broad protection against S. flexneri serotypes and supporting the identification of critical quality attributes of OAg-based vaccines.

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“…The serum samples used were polyclonal sera raised in mice or rabbits immunized with glycoconjugates (Vi-CRM197 [32,33] and O:2-CRM197 [34]), or with GMMA-based vaccines obtained from S. flexneri 1b, 2a, 3a, S. sonnei, S. Typhimurium and S. Enteritidis GMMA-producing strains [11,[24][25][26]31,35].…”

Section: Serum Samplesmentioning

confidence: 99%

Increasing the High Throughput of a Luminescence-Based Serum Bactericidal Assay (L-SBA)

Aruta

Carducci

Micoli

et al. 2021

BioTech

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Serum bactericidal assay (SBA) is the method to investigate in vitro complement-mediated bactericidal activity of sera raised upon vaccination. The assay is based on incubating the target bacteria and exogenous complement with sera at different dilutions and the result of the assay is represented by the sera dilution being able to kill 50% of bacteria present in the inoculum. The traditional readout of the assay is based on measurement of colony-forming units (CFU) obtained after plating different reaction mixes on agar. This readout is at low throughput and time consuming, even when automated counting is used. We previously described a novel assay with a luminescence readout (L-SBA) based on measurement of ATP released by live bacteria, which allowed to substantially increase the throughput as well as to reduce the time necessary to perform the assay when compared to traditional methods. Here we present a further improvement of the assay by moving from a 96-well to a 384-well format, which allowed us to further increase the throughput and substantially reduce costs while maintaining the high performance of the previously described L-SBA method. The method has been successfully applied to a variety of different pathogens.

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Effect of O-Antigen Chain Length Regulation on the Immunogenicity of Shigella and Salmonella Generalized Modules for Membrane Antigens (GMMA)

Cited by 19 publications

References 43 publications

GMMA-Based Vaccines: The Known and The Unknown

GMMA-Based Vaccines: The Known and The Unknown

Impact of O-Acetylation on S. flexneri 1b and 2a O-Antigen Immunogenicity in Mice

Increasing the High Throughput of a Luminescence-Based Serum Bactericidal Assay (L-SBA)

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