Conjugation of Different Immunogenic Enterococcal Vaccine Target Antigens Leads to Extended Strain Coverage

Romero-Saavedra, Felipe; Laverde, Diana; Kalfopoulou, Ermioni; Martini, Cécilia; Torelli, Riccardo; Martínez-Matamoros, Diana; Sanguinetti, Maurizio; Hüebner, Johannes

doi:10.1093/infdis/jiz357

Cited by 16 publications

(23 citation statements)

References 46 publications

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“…Our results support the utilization of this in vitro assay for the selection of mother-wells producing opsonic and specific antibodies and could be applied to the identification of other MAbs against different antigens and/or pathogens. In addition, the development of these two opsonic MAbs upon immunization with DHG-SagA supports our previous findings that this glycoconjugate is a good vaccine candidate against prevalent enterococcal species and that SagA could serve as a carrier protein (56).…”

Section: Discussionsupporting

confidence: 83%

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Development of Opsonic Mouse Monoclonal Antibodies against Multidrug-Resistant Enterococci

et al. 2019

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Multidrug-resistant enterococci are major causes of hospital-acquired infections. Immunotherapy with monoclonal antibodies (MAbs) targeting bacterial antigens would be a valuable treatment option in this setting. Here, we describe the development of two MAbs through hybridoma technology that target antigens from the most clinically relevant enterococcal species. Diheteroglycan (DHG), a well-characterized capsular polysaccharide of Enterococcus faecalis, and the secreted antigen A (SagA), an immunogenic protein from Enterococcus faecium, are both immunogens that have been proven to raise opsonic and cross-reactive antibodies against enterococcal strains. For this purpose, a conjugated form of the native DHG with SagA was used to raise the antibodies in mice, while enzyme-linked immunosorbent assay and opsonophagocytic assay were combined in the selection process of hybridoma cells producing immunoreactive and opsonic antibodies targeting the selected antigens. From this process, two highly specific IgG1(κ) MAbs were obtained, one against the polysaccharide (DHG.01) and one against the protein (SagA.01). Both MAbs exhibited good opsonic killing against the target bacterial strains: DHG.01 showed 90% killing against E. faecalis type 2, and SagA.01 showed 40% killing against E. faecium 11231/6. In addition, both MAbs showed cross-reactivity toward other E. faecalis and E. faecium strains. The sequences from the variable regions of the heavy and light chains were reconstructed in expression vectors, and the activity of the MAbs upon expression in eukaryotic cells was confirmed with the same immunological assays. In summary, we identified two opsonic MAbs against enterococci which could be used for therapeutic or prophylactic approaches against enterococcal infections.

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Section: Discussionsupporting

confidence: 83%

“…In addition, our results support the use of SagA as a vaccine target against nosocomial E. faecium strains and potentially as a carrier protein in glycoconjugated vaccine formulations (12, 14, 56).…”

Section: Introductionsupporting

confidence: 72%

Development of Opsonic Mouse Monoclonal Antibodies against Multidrug-Resistant Enterococci

et al. 2019

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“…DHG of E. faecalis was isolated as previously described. 60 Briefly, a bacterial strain was used to inoculate Columbia broth (Becton-Dickinson) supplemented with 2% glucose and incubated at 37°C without agitation until an optical density at 600 nm of 0.8 was reached. Bacterial cells were pelleted by centrifugation at 8000 rpm for 30 min at 4 °C and were resuspended with Tris-sucrose buffer (10 mM Tris-HCl, 25% sucrose, pH 8.0).…”

Section: ■ Methodsmentioning

confidence: 99%

“…DHG of E. faecalis was isolated as previously described . Briefly, a bacterial strain was used to inoculate Columbia broth (Becton-Dickinson) supplemented with 2% glucose and incubated at 37°C without agitation until an optical density at 600 nm of 0.8 was reached.…”

Section: Methodsmentioning

confidence: 99%

Synthetic Oligomers Mimicking Capsular Polysaccharide Diheteroglycan are Potential Vaccine Candidates against Encapsulated Enterococcal Infections

et al. 2020

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Infections caused by Enterococcus spp. are a major concern in the clinical setting. In Enterococcus faecalis, the capsular polysaccharide diheteroglycan (DHG), composed of ß-D-galactofuranose-(1 → 3)-ß-D-glucopyranose repeats, has been described as an important virulence factor and as a potential vaccine candidate against encapsulated strains. Synthetic structures emulating immunogenic polysaccharides present many advantages over native polysaccharides for vaccine development. In this work, we described the synthesis of a library of DHG oligomers, differing in length and order of the monosaccharide constituents. Using suitably protected thioglycoside building blocks, oligosaccharides up to 8-mer in length built up from either Galf-Glcp or Glcp-Galf dimers were generated, and we evaluated their immunoreactivity with antibodies raised against DHG. After the screening, we selected two octasaccharides, having either a galactofuranose or glucopyranose terminus, which were conjugated to a carrier protein for the production of polyclonal antibodies. The resulting antibodies were specific toward the synthetic structures and mediated in vitro opsonophagocytic killing of different encapsulated E. feacalis strains. The evaluated oligosaccharides are the first synthetic structures described to elicit antibodies that target encapsulated E. faecalis strains and are, therefore, promising candidates for the development of a well-defined enterococcal glycoconjugate vaccine.

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“…For this purpose, in our recent study, we evaluated the two enterococcal proteins, SagA and PpiC, as antigens and carrier proteins for the enterococcal polysaccharide DHG in order to elicit a cross-species immunoresponse against enterococci. The evaluated glycoconjugates exhibited crossreactivity in ELISA and opsonophagocytic assay against several enterococcal strains, as well as protective efficacy in a mouse sepsis model [124].…”

Section: Prospects and Pitfalls In The Development Of Immunotherapiesmentioning

confidence: 97%

Advances and Prospects in Vaccine Development against Enterococci

Kalfopoulou

Hüebner

2020

Cells

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Enterococci are the second most common Gram-positive pathogen responsible for nosocomial infections. Due to the limited number of new antibiotics that reach the medical practice and the resistance of enterococci to the current antibiotic options, passive and active immunotherapies have emerged as a potential prevention and/or treatment strategy against this opportunistic pathogen. In this review, we explore the pathogenicity of these bacteria and their interaction with the host immune response. We provide an overview of the capsular polysaccharides and surface-associated proteins that have been described as potential antigens in anti-enterococcal vaccine formulations. In addition, we describe the current status in vaccine development against enterococci and address the importance and the current advances toward the development of well-defined vaccines with broad coverage against enterococci.

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Conjugation of Different Immunogenic Enterococcal Vaccine Target Antigens Leads to Extended Strain Coverage

Cited by 16 publications

References 46 publications

Development of Opsonic Mouse Monoclonal Antibodies against Multidrug-Resistant Enterococci

Development of Opsonic Mouse Monoclonal Antibodies against Multidrug-Resistant Enterococci

Synthetic Oligomers Mimicking Capsular Polysaccharide Diheteroglycan are Potential Vaccine Candidates against Encapsulated Enterococcal Infections

Advances and Prospects in Vaccine Development against Enterococci

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