scholarly journals GMMA and Glycoconjugate Approaches Compared in Mice for the Development of a Vaccine against Shigella flexneri Serotype 6

Vaccines ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 160 ◽  
Author(s):  
Maria Michelina Raso ◽  
Gianmarco Gasperini ◽  
Renzo Alfini ◽  
Fabiola Schiavo ◽  
Maria Grazia Aruta ◽  
...  
Keyword(s):  
Vaccine Development ◽  
Shigella Flexneri ◽  
Antigen Delivery ◽  
O Antigen ◽  
Alternative Approach ◽  
Large Panel ◽  
Membrane Antigens ◽  
Glycoconjugate Vaccines ◽  
Vaccine Approach ◽  
Immunogenicity Study

Shigella infections are one of the top causes of diarrhea throughout the world, with Shigella flexneri being predominant in developing countries. Currently, no vaccines are widely available and increasing levels of multidrug-resistance make Shigella a high priority for vaccine development. The serotype-specific O-antigen moiety of Shigella lipopolysaccharide has been recognized as a key target for protective immunity, and many O-antigen based candidate vaccines are in development. Recently, the Generalized Modules for Membrane Antigens (GMMA) technology has been proposed as an alternative approach to traditional glycoconjugate vaccines for O-antigen delivery. Here, these two technologies are compared for a vaccine against S. flexneri serotype 6. Genetic strategies for GMMA production, conjugation approaches for linkage of the O-antigen to CRM197 carrier protein, and a large panel of analytical methods for full vaccine characterization have been put in place. In a head-to-head immunogenicity study in mice, GMMA induced higher anti-O-antigen IgG than glycoconjugate administered without Alhydrogel. When formulated on Alhydrogel, GMMA and glycoconjugate elicited similar levels of persistent anti-O-antigen IgG with bactericidal activity. Glycoconjugates are a well-established bacterial vaccine approach, but can be costly, particularly when multicomponent preparations are required. With similar immunogenicity and a simpler manufacturing process, GMMA are a promising strategy for the development of a vaccine against Shigella.

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

2021 ◽  
Vol 22 (3) ◽  
pp. 1309
Author(s):  
Gianmarco Gasperini ◽  
Maria Michelina Raso ◽  
Vanessa Arato ◽  
Maria Grazia Aruta ◽  
Paola Cescutti ◽  
...  
Keyword(s):  
Immune Response ◽  
Structural Characteristics ◽  
Antigen Delivery ◽  
Critical Quality Attributes ◽  
O Antigen ◽  
Alternative Approach ◽  
Length Regulation ◽  
Membrane Antigens ◽  
Glycoconjugate Vaccines ◽  
Work Supports

Recently, generalized modules for membrane antigens (GMMA) technology has been proposed as an alternative approach to traditional glycoconjugate vaccines for O-antigen delivery. Saccharide length is a well-known parameter that can impact the immune response induced by glycoconjugates both in terms of magnitude and quality. However, the criticality of O-antigen length on the immune response induced by GMMA-based vaccines has not been fully elucidated. Here, Shigella and Salmonella GMMA-producing strains were further mutated in order to display homogeneous polysaccharide populations of different sizes on a GMMA surface. Resulting GMMA were compared in mice immunization studies. Athymic nude mice were also used to investigate the involvement of T-cells in the immune response elicited. In contrast with what has been reported for traditional glycoconjugate vaccines and independent of the pathogen and the sugar structural characteristics, O-antigen length did not result in being a critical parameter for GMMA immunogenicity. This work supports the identification of critical quality attributes to optimize GMMA vaccine design and improve vaccine efficacy and gives insights on the nature of the immune response induced by GMMA.

scholarly journals Comparison and Optimization of Quantification Methods for Shigella flexneri Serotype 6 O-antigen Containing Galacturonic Acid and Methyl-Pentose

2021 ◽  
Vol 22 (22) ◽  
pp. 12160
Author(s):  
Maria Michelina Raso ◽  
Oscar Vassallo ◽  
Francesca Micoli ◽  
Carlo Giannelli
Keyword(s):  
Galacturonic Acid ◽  
Vaccine Development ◽  
Shigella Flexneri ◽  
Colorimetric Method ◽  
Original Method ◽  
Fast Analysis ◽  
Middle Income ◽  
Middle Income Countries ◽  
O Antigen

Shigella is a leading diarrheal cause of morbidity and mortality worldwide, especially in low- and middle-income countries and in children under five years of age. Increasing levels of antimicrobial resistance make vaccine development an even higher global health priority. S. flexneri serotype 6 is one of the targets of many multicomponent vaccines in development to ensure broad protection against Shigella. The O-antigen (OAg) is a key active ingredient and its content is a critical quality attribute for vaccine release in order to monitor their stability and to ensure appropriate immune response. Here, the optimization of two methods to quantify S. flexneri 6 OAg is reported together with the characterization of their performances. The optimized Dische colorimetric method allows a tenfold increment of the sensitivity with respect to the original method and is useful for fast analysis detecting selectively methyl-pentoses, as rhamnose in S. flexneri 6 OAg. Also, a more specific HPAEC-PAD method was developed, detecting the dimer galacturonic acid-galactosamine (GalA-GalN) coming from S. flexneri 6 OAg acid hydrolysis. These methods will facilitate characterization of S. flexneri 6 OAg based vaccines. The colorimetric method can be used for quantification of other polysaccharide containing methyl-pentoses, and the HPAEC-PAD could be extended to other polysaccharides containing uronic acids.

Outer membrane vesicles derived from Salmonella Typhimurium can deliver Shigella flexneri 2a O-polysaccharide antigen to prevent Shigella flexneri 2a infection in mice

2021 ◽  
Author(s):  
Huizhen Tian ◽  
Biaoxian Li ◽  
Tian Xu ◽  
Haolin Yu ◽  
Jingxuan Chen ◽  
...  
Keyword(s):  
Developing Countries ◽  
Outer Membrane ◽  
Shigella Flexneri ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Effective Vaccine ◽  
Antigen Delivery ◽  
Polysaccharide Antigen ◽  
O Antigen ◽  
Shigella Flexneri 2A

Abstract: Shigellosis has become a serious threat to health in many developing countries due to the severe diarrhea it causes. Shigella flexneri 2a ( S. flexneri 2a) is the principal species responsible for this endemic disease. Despite multiple attempts to design a vaccine against shigellosis, no effective vaccine has not yet been developed. Lipopolysaccharide (LPS) is both an essential virulence factor and an antigen protective against Shigella , due to its outer domain, termed O-polysaccharide antigen. In the present study, S. flexneri 2a O-polysaccharide antigen was innovatively bio-synthesized in Salmonella and attached to core-lipid A via the ligase WaaL, with purified outer membrane vesicles (OMVs) utilized as vaccine vectors. Here, we identified the expression of the heterologous O-antigen and have described the isolation, characterization, and immune protection efficiency of the OMV vaccine. Furthermore, the results of animal experiments indicated that immunization of mice with the OMV vaccine both intranasally and intraperitoneally induced significant specific anti-Shigella LPS antibodies in the serum, with a similar trend IgA levels from vaginal secretions and fluid from bronchopulmonary lavage. The OMV vaccine derived from both routes of administration provided significant protection against virulent S. flexneri 2a infection, as judged by a serum bactericidal assay (SBA), opsonization assay, and challenge test. This vaccination strategy represents a novel and improved approach to control shigellosis by the combination of Salmonella glycosyl carrier lipid bioconjugation with OMVs. Importance: Shigella , the cause of shigellosis or bacillary dysentery, is a major public health concern, especially for children in developing countries. An effective vaccine would control the spread of the disease to some extent. However, no licensed vaccine against Shigella infection in humans has so far been developed. The Shigella O-antigen polysaccharide is effective in stimulating the production of protective antibodies and so could represent a vaccine antigen candidate. Additionally, bacterial outer membrane vesicles (OMVs) have been used as antigen delivery platforms due to their nanoscale properties and ease of antigen delivery to trigger an immune response. Therefore, the present study provides a new strategy for vaccine design, combining a glycoconjugated vaccine with OMVs. The design concept of this strategy is the expression of Shigella O-antigen via the LPS synthesis pathway in recombinant Salmonella , from which the OMV vaccine is then isolated. Based on these findings, we believe that the novel vaccine design strategy in which polysaccharide antigens are delivered via bacterial OMVs will be effective for the development and clinical application of an effective Shigella vaccine.

scholarly journals Conformational and Immunogenicity Studies of the Shigella flexneri Serogroup 6 O-Antigen: The Effect of O-Acetylation

Vaccines ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 432
Author(s):  
Nicole Inge Richardson ◽  
Neil Ravenscroft ◽  
Vanessa Arato ◽  
Davide Oldrini ◽  
Francesca Micoli ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Low Income ◽  
Diarrheal Disease ◽  
Repeat Unit ◽  
Shigella Flexneri ◽  
Low Income Countries ◽  
Effective Vaccine ◽  
Antigen Delivery ◽  
O Antigen

The pathogenic bacterium Shigella is a leading cause of diarrheal disease and mortality, disproportionately affecting young children in low-income countries. The increasing prevalence of antibiotic resistance in Shigella necessitates an effective vaccine, for which the bacterial lipopolysaccharide O-antigen is the primary target. S. flexneri serotype 6 has been proposed as a multivalent vaccine component to ensure broad protection against Shigella. We have previously explored the conformations of S. flexneri O-antigens from serogroups Y, 2, 3, and 5 that share a common saccharide backbone (serotype Y). Here we consider serogroup 6, which is of particular interest because of an altered backbone repeat unit with non-stoichiometric O-acetylation, the antigenic and immunogenic importance of which have yet to be established. Our simulations show significant conformational changes in serogroup 6 relative to the serotype Y backbone. We further find that O-acetylation has little effect on conformation and hence may not be essential for the antigenicity of serotype 6. This is corroborated by an in vivo study in mice, using Generalized Modules for Membrane Antigens (GMMA) as O-antigen delivery systems, that shows that O-acetylation does not have an impact on the immune response elicited by the S. flexneri serotype 6 O-antigen.

scholarly journals Sequence analysis of Plasmodium vivax Duffy binding proteins reveals the presence of unique haplotypes and diversifying selection in Ethiopian isolates

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Lemu Golassa ◽  
Alebachew Messele ◽  
Eniyou Cheryll Oriero ◽  
Alfred Amambua-Ngwa
Keyword(s):  
Vaccine Development ◽  
Haplotype Diversity ◽  
Sri Lankan ◽  
Duffy Binding Protein ◽  
Synonymous Mutations ◽  
South Korean ◽  
Blood Stage Infection ◽  
Vaccine Approach ◽  
Papua New Guinean ◽  
Reference Haplotype

Abstract Background Red blood cell invasion by the Plasmodium vivax merozoite requires interaction between the Duffy antigen receptor for chemokines (DARC) and the P. vivax Duffy-binding protein II (PvDBPII). Given that the disruption of this interaction prevents P. vivax blood-stage infection, a PvDBP-based vaccine development has been well recognized. However, the polymorphic nature of PvDBPII prevents a strain transcending immune response and complicates attempts to design a vaccine. Methods Twenty-three P. vivax clinical isolates collected from three areas of Ethiopia were sequenced at the pvdbpII locus. A total of 392 global pvdbpII sequences from seven P. vivax endemic countries were also retrieved from the NCBI archive for comparative analysis of genetic diversity, departure from neutrality, linkage disequilibrium, genetic differentiation, PvDBP polymorphisms, recombination and population structure of the parasite population. To establish a haplotype relationship a network was constructed using the median joining algorithm. Results A total of 110 variable sites were found, of which 44 were parsimony informative. For Ethiopian isolates there were 12 variable sites of which 10 were parsimony informative. These parsimony informative variants resulted in 10 nonsynonymous mutations. The overall haplotype diversity for global isolates was 0.9596; however, the haplotype diversity was 0.874 for Ethiopia. Fst values for genetic revealed Ethiopian isolates were closest to Indian isolates as well as to Sri Lankan and Sudanese isolates but further away from Mexican, Papua New Guinean and South Korean isolates. There was a total of 136 haplotypes from the 415 global isolates included for this study. Haplotype prevalence ranged from 36.76% to 0.7%, from this 74.2% were represented by single parasite isolates. None of the Ethiopian isolates grouped with the Sal I reference haplotype. From the total observed nonsynonymous mutations 13 mapped to experimentally verified epitope sequences. Including 10 non-synonymous mutations from Ethiopia. However, all the polymorphic regions in Ethiopian isolates were located away from DARC, responsible for junction formation. Conclusion The results of this study are concurrent with the multivalent vaccine approach to design an effective treatment. However, the presence of novel haplotypes in Ethiopian isolates that were not shared by other global sequences warrant further investigation.

scholarly journals Dissecting the contribution of O-Antigen and proteins to the immunogenicity of Shigella sonnei generalized modules for membrane antigens (GMMA)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Francesca Mancini ◽  
Gianmarco Gasperini ◽  
Omar Rossi ◽  
Maria Grazia Aruta ◽  
Maria Michelina Raso ◽  
...  
Keyword(s):  
Protective Immunity ◽  
Critical Role ◽  
Shigella Sonnei ◽  
Added Value ◽  
Protein Antigens ◽  
Outer Membranes ◽  
O Antigen ◽  
Membrane Antigens ◽  
Specific Igg

AbstractGMMA are exosomes released from engineered Gram-negative bacteria resembling the composition of outer membranes. We applied the GMMA technology for the development of an O-Antigen (OAg) based vaccine against Shigella sonnei, the most epidemiologically relevant cause of shigellosis. S. sonnei OAg has been identified as a key antigen for protective immunity, and GMMA are able to induce anti-OAg-specific IgG response in animal models and healthy adults. The contribution of protein-specific antibodies induced upon vaccination with GMMA has never been fully elucidated. Anti-protein antibodies are induced in mice upon immunization with either OAg-negative and OAg-positive GMMA. Here we demonstrated that OAg chains shield the bacteria from anti-protein antibody binding and therefore anti-OAg antibodies were the main drivers of bactericidal activity against OAg-positive bacteria. Interestingly, antibodies that are not targeting the OAg are functional against OAg-negative bacteria. The immunodominant protein antigens were identified by proteomic analysis. Our study confirms a critical role of the OAg on the immune response induced by S. sonnei GMMA. However, little is known about OAg length and density regulation during infection and, therefore, protein exposure. Hence, the presence of protein antigens on S. sonnei GMMA represents an added value for GMMA vaccines compared to other OAg-based formulations.

scholarly journals Molecular Modeling of the Shigella flexneri Serogroup 3 and 5 O-Antigens and Conformational Relationships for a Vaccine Containing Serotypes 2a and 3a

Vaccines ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 643
Author(s):  
Jason Hlozek ◽  
Sara Owen ◽  
Neil Ravenscroft ◽  
Michelle M. Kuttel
Keyword(s):  
Diarrheal Disease ◽  
Shigella Flexneri ◽  
Quadrivalent Vaccine ◽  
Slight Effect ◽  
Work Support ◽  
O Antigen ◽  
The Common ◽  
O Antigens ◽  
Chain Conformations ◽  
Shared Epitopes

The pathogenic bacterium Shigella flexneri is a leading global cause of diarrheal disease. The O-antigen is the primary vaccine target and distinguishes the 30 serotypes reported. Except for serotype 6, all S. flexneri serotypes have a common backbone repeating unit (serotype Y), with variations in substitution creating the various serotypes. A quadrivalent vaccine containing serotypes 2a and 3a (as well as 6 and Shigella sonnei) is proposed to provide broad protection against non-vaccine S. flexneri serotypes through shared epitopes and conformations. Here we model the O-antigen (O-Ag) conformations of serogroups 3 and 5: a continuation of our ongoing systematic study of the S. flexneri O-antigens that began with serogroup 2. Our simulations show that S. flexneri serogroups 2, 3, and 5 all have flexible O-Ags, with substitutions of the backbone altering the chain conformations in different ways. Our analysis suggests three general heuristics for the effects of substitution on the Shigella O-Ag conformations: (1) substitution on rhamnose C reduces the extension of the O-Ag chain; (2) substitution at O-3 of rhamnose A restricts the O-Ags to predominantly helical conformations, (3) substitution at O-3 of rhamnose B has only a slight effect on conformation. The common O-Ag conformations across serotypes identified in this work support the assumption that a quadrivalent vaccine containing serotypes 2a and 3a could provide coverage against S. flexneri serotype 3b and serogroup 5.

scholarly journals A GMMA-CPS-Based Vaccine for Non-Typhoidal Salmonella

Vaccines ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 165
Author(s):  
Akosiererem S. Sokaribo ◽  
Sumudu R. Perera ◽  
Zoe Sereggela ◽  
Ryan Krochak ◽  
Lindsay R. Balezantis ◽  
...  
Keyword(s):  
Vaccine Development ◽  
Random Mutagenesis ◽  
Bloodstream Infections ◽  
Sub Saharan Africa ◽  
Colanic Acid ◽  
High Fatality Rate ◽  
Current Vaccine ◽  
Membrane Antigens ◽  
Human Use ◽  
Sub Saharan

Non-typhoidal Salmonella are a major cause of gastroenteritis worldwide, as well as causing bloodstream infections in sub-Saharan Africa with a high fatality rate. No vaccine is currently available for human use. Current vaccine development strategies are focused on capsular polysaccharides (CPS) present on the surface of non-typhoidal Salmonella. This study aimed to boost the amount of CPS purified from S. Typhimurium for immunization trials. Random mutagenesis with Tn10 transposon increased the production of CPS colanic acid, by 10-fold compared to wildtype. Immunization with colanic acid or colanic acid conjugated to truncated glycoprotein D or inactivated diphtheria toxin did not induce a protective immune response in mice. However, immunization with Generalized Modules for Membrane Antigens (GMMAs) isolated from colanic acid overproducing isolates reduced Salmonella colonization in mice. Our results support the development of a GMMA-CPS-based vaccine against non-typhoidal Salmonella.

scholarly journals Two Complex, Adenovirus-Based Vaccines That Together Induce Immune Responses to All Four Dengue Virus Serotypes

2006 ◽  
Vol 14 (2) ◽  
pp. 182-189 ◽  
Author(s):  
David H. Holman ◽  
Danher Wang ◽  
Kanakatte Raviprakash ◽  
Nicholas U. Raja ◽  
Min Luo ◽  
...  
Keyword(s):  
Immune Responses ◽  
Dengue Virus ◽  
Vaccine Development ◽  
De Novo ◽  
Natural Infection ◽  
Hemorrhagic Fever ◽  
Virus Infections ◽  
Dengue Vaccine ◽  
Membrane Antigens ◽  
Dengue Virus Serotypes

ABSTRACT Dengue virus infections can cause hemorrhagic fever, shock, encephalitis, and even death. Worldwide, approximately 2.5 billion people live in dengue-infested regions with about 100 million new cases each year, although many of these infections are believed to be silent. There are four antigenically distinct serotypes of dengue virus; thus, immunity from one serotype will not cross-protect from infection with the other three. The difficulties that hamper vaccine development include requirements of the natural conformation of the envelope glycoprotein to induce neutralizing immune responses and the necessity of presenting antigens of all four serotypes. Currently, the only way to meet these requirements is to use a mixture of four serotypes of live attenuated dengue viruses, but safety remains a major problem. In this study, we have developed the basis for a tetravalent dengue vaccine using a novel complex adenovirus platform that is capable of expressing multiple antigens de novo. This dengue vaccine is constructed as a pair of vectors that each expresses the premembrane and envelope genes of two different dengue virus serotypes. Upon vaccination, the vaccine expressed high levels of the dengue virus antigens in cells to mimic a natural infection and induced both humoral and cellular immune responses against multiple serotypes of dengue virus in an animal model. Further analyses show the humoral responses were indeed neutralizing against all four serotypes. Our studies demonstrate the concept of mimicking infections to induce immune responses by synthesizing dengue virus membrane antigens de novo and the feasibility of developing an effective tetravalent dengue vaccine by vector-mediated expression of glycoproteins of the four serotypes.

scholarly journals A Novel Glucosyltransferase Involved in O-Antigen Modification of Shigella flexneri Serotype 1c

2009 ◽  
Vol 191 (21) ◽  
pp. 6612-6617 ◽  
Author(s):  
Robert M. Stagg ◽  
Swee-Seong Tang ◽  
Nils I. A. Carlin ◽  
Kaisar A. Talukder ◽  
Phung D. Cam ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Shigella Flexneri ◽  
Functional Expression ◽  
Transposon Mutagenesis ◽  
The Other ◽  
Bacterial Chromosome ◽  
Gene Encoding ◽  
O Antigen ◽  
Species Analysis

ABSTRACT The O antigen of serotype 1c differs from the unmodified O antigen of serotype Y by the addition of a disaccharide (two glucosyl groups) to the tetrasaccharide repeating unit. It was shown here that addition of the first glucosyl group is mediated by the previously characterized gtrI cluster, which is found within a cryptic prophage at the proA locus in the bacterial chromosome. Transposon mutagenesis was performed to disrupt the gene responsible for addition of the second glucosyl group, causing reversion to serotype 1a. Colony immunoblotting was used to identify the desired revertants, and subsequent sequencing, cloning, and functional expression successfully identified the gene encoding serotype 1c-specific O-antigen modification. This gene (designated gtrIC) was present as part of a three-gene cluster, similar to other S. flexneri glucosyltransferase genes. Relative to the other S. flexneri gtr clusters, the gtrIC cluster is more distantly related and appears to have arrived in S. flexneri from outside the species. Analysis of surrounding sequence suggests that the gtrIC cluster arrived via a novel bacteriophage that was subsequently rendered nonfunctional by a series of insertion events.

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