Boosting Vaccine Research: The 16-Year Journey of TRANSVAC Vaccine Infrastructure.

TRANSVAC represents a long-running effort to accelerate the development of novel vaccines by integrating institutions from across Europe under a single collaborative framework. This initiative has empowered the global vaccine community since 2009 including contributing toward the development and optimization of vaccine candidates as well as the provision of new adjuvants, research protocols, and technologies. Scientific services were provided in support of 88 different vaccine development projects, and 400 professionals attended TRANSVAC training events on various vaccine-related topics.

Outer membrane vesicle-based intranasal vaccines.

Delivery of vaccines via the mucosal route is regarded as the most effective mode of immunization to counteract infectious diseases that enter via mucosal tissues, including oral, nasal, pulmonary, intestinal, and urogenital surfaces. Mucosal vaccines not only induce local immune effector elements, such as secretory Immunoglobulin A (IgA) reaching the luminal site of the mucosa, but also systemic immunity. Moreover, mucosal vaccines may trigger immunity in distant mucosal tissues because of the homing of primed antigen-specific immune cells toward local and distant mucosal tissue via the common mucosal immune system.

Lipid A heterogeneity and its role in the host interactions with pathogenic and commensal bacteria.

Lipopolysaccharide (LPS) is for most but not all Gram-negative bacteria an essential component of the outer leaflet of the outer membrane. LPS contributes to the integrity of the outer membrane, which acts as an effective permeability barrier to antimicrobial agents and protects against complement-mediated lysis. In commensal and pathogenic bacteria LPS interacts with pattern recognition receptors (e.

An Intranasal OMV-Based Vaccine Induces High Mucosal and Systemic Protecting Immunity Against a SARS-CoV-2 Infection.

The development of more effective, accessible, and easy to administer COVID-19 vaccines next to the currently marketed mRNA, viral vector, and whole inactivated virus vaccines is essential to curtailing the SARS-CoV-2 pandemic. A major concern is reduced vaccine-induced immune protection to emerging variants, and therefore booster vaccinations to broaden and strengthen the immune response might be required. Currently, all registered COVID-19 vaccines and the majority of COVID-19 vaccines in development are intramuscularly administered, targeting the induction of systemic immunity.

Nanoflow LC-MS Method Allowing In-Depth Characterization of Natural Heterogeneity of Complex Bacterial Lipopolysaccharides.

The variable modification of the outer membrane lipopolysaccharide (LPS) in Gram-negative bacteria contributes to bacterial pathogenesis through various mechanisms, including the development of antibiotic resistance and evasion of the immune response of the host. Characterizing the natural structural repertoire of LPS is challenging due to the high heterogeneity, branched architecture, and strong amphipathic character of these glycolipids. To address this problem, we have developed a method enabling the separation and structural profiling of complex intact LPS mixtures by using nanoflow reversed-phase high-performance liquid chromatography (nLC) coupled to electrospray ionization Fourier transform mass spectrometry (ESI-FT-MS).

Rational Vaccine Design in Times of Emerging Diseases: The Critical Choices of Immunological Correlates of Protection, Vaccine Antigen and Immunomodulation.

Vaccines are the most effective medical intervention due to their continual success in preventing infections and improving mortality worldwide. Early vaccines were developed empirically however, rational design of vaccines can allow us to optimise their efficacy, by tailoring the immune response. Establishing the immune correlates of protection greatly informs the rational design of vaccines.

Shortening the Lipid A Acyl Chains of Enables Depletion of Lipopolysaccharide Endotoxic Activity.

Whooping cough, or pertussis, is an acute respiratory infectious disease caused by the Gram-negative bacterium Whole-cell vaccines, which were introduced in the fifties of the previous century and proved to be effective, showed considerable reactogenicity and were replaced by subunit vaccines around the turn of the century. However, there is a considerable increase in the number of cases in industrialized countries. A possible strategy to improve vaccine-induced protection is the development of new, non-toxic, whole-cell pertussis vaccines.

Substrate specificity of the pyrophosphohydrolase LpxH determines the asymmetry of lipid A.

Lipopolysaccharides are anchored to the outer membrane of Gram-negative bacteria by a hydrophobic moiety known as lipid A, which potently activates the host innate immune response. Lipid A of , the causative agent of whooping cough, displays unusual structural asymmetry with respect to the length of the acyl chains at the 3 and 3' positions, which are 3OH-C10 and 3OH-C14 chains, respectively. Both chains are attached by the acyltransferase LpxA, the first enzyme in the lipid A biosynthesis pathway, which, in , has limited chain length specificity.

Th17-Mediated Cross Protection against Pneumococcal Carriage by Vaccination with a Variable Antigen.

Serotype-specific protection against is an important limitation of the current polysaccharide-based vaccines. To prevent serotype replacement, reduce transmission, and limit the emergence of new variants, it is essential to induce broad protection and restrict pneumococcal colonization. In this study, we used a prototype vaccine formulation consisting of lipopolysaccharide (LPS)-detoxified outer membrane vesicles (OMVs) from serovar Typhimurium displaying the variable N terminus of PspA (α1α2) for intranasal vaccination, which induced strong Th17 immunity associated with a substantial reduction of pneumococcal colonization.

Modulating endotoxin activity by combinatorial bioengineering of meningococcal lipopolysaccharide.

Neisseria meningitidis contains a very potent hexa-acylated LPS that is too toxic for therapeutic applications. We used systematic molecular bioengineering of meningococcal LPS through deletion of biosynthetic enzymes in combination with induction of LPS modifying enzymes to yield a variety of novel LPS mutants with changes in both lipid A acylation and phosphorylation. Mass spectrometry was used for detailed compositional determination of the LPS molecular species, and stimulation of immune cells was done to correlate this with endotoxic activity.

Meningococcal Outer Membrane Vesicle Composition-Dependent Activation of the Innate Immune Response.

Meningococcal outer membrane vesicles (OMVs) have been extensively investigated and successfully implemented as vaccines. They contain pathogen-associated molecular patterns, including lipopolysaccharide (LPS), capable of triggering innate immunity. However, Neisseria meningitidis contains an extremely potent hexa-acylated LPS, leading to adverse effects when its OMVs are applied as vaccines.

Phase variation of Opa proteins of Neisseria meningitidis and the effects of bacterial transformation.

Opa proteins are major proteins involved in meningococcal colonization of the nasopharynx and immune interactions. Opa proteins undergo phase variation (PV) due to the presence of the 5'-CTCTT-3' coding repeat (CR) sequence. The dynamics of PV of meningococcal Opa proteins is unknown.

Outer membrane vesicles as platform vaccine technology.

Outer membrane vesicles (OMVs) are released spontaneously during growth by many Gram-negative bacteria. They present a range of surface antigens in a native conformation and have natural properties like immunogenicity, self-adjuvation and uptake by immune cells which make them attractive for application as vaccines against pathogenic bacteria. In particular with Neisseria meningitidis, they have been investigated extensively and an OMV-containing meningococcal vaccine has recently been approved by regulatory agencies.

Surface display of a borrelial lipoprotein on meningococcal outer membrane vesicles.

Outer Membrane Vesicles (OMVs) are gaining attention as vaccine candidates. The successful expression of heterologous antigens in OMVs, with the OMV functioning both as adjuvant and delivery vehicle, has greatly enhanced their vaccine potential. Since there are indications that surface exposed antigens might induce a superior immune response, targeting of heterologous antigens to the OMV surface is of special interest.

Biosynthetically engineered lipopolysaccharide as vaccine adjuvant.

Lipopolysaccharide (LPS), a dominant component of the Gram-negative bacterial outer membrane, is a strong activator of the innate immune system, and thereby an important determinant in the adaptive immune response following bacterial infection. This adjuvant activity can be harnessed following immunization with bacteria-derived vaccines that naturally contain LPS, and when LPS or molecules derived from it are added to purified vaccine antigens. However, the downside of the strong biological activity of LPS is its ability to contribute to vaccine reactogenicity.

Modulation of the CD4(+) T cell response after acellular pertussis vaccination in the presence of TLR4 ligation.

Whole cell pertussis (wP) vaccines are gradually being replaced by aluminum salt-adjuvanted acellular pertussis (aP) vaccines. These promote CD4(+) T cell responses with a non-protective Th2 component, while protective immune mechanisms to B. pertussis may rather involve long-lived Th1/Th17 type CD4(+) T cells.

Bordetella pertussis naturally occurring isolates with altered lipooligosaccharide structure fail to fully mature human dendritic cells.

Bordetella pertussis is a Gram-negative bacterium and the causative agent of whooping cough. Despite high vaccination coverage, outbreaks are being increasingly reported worldwide. Possible explanations include adaptation of this pathogen, which may interfere with recognition by the innate immune system.

Meningitis caused by a lipopolysaccharide deficient Neisseria meningitidis.

Objective: Lipopolysaccharide (LPS) is a major component of the Neisseria meningitidis outer membrane. Here we report a patient with meningococcal meningitis of which the causative isolate lacked LPS. Thus far, no naturally occurring LPS-deficient meningococcal isolate has been known to cause clinical disease.

Lipopolysaccharide engineering in Neisseria meningitidis: structural analysis of different pentaacyl lipid A mutants and comparison of their modified agonist properties.

Engineering the lipopolysaccharide (LPS) biosynthetic pathway offers the potential to obtain modified derivatives with optimized adjuvant properties. Neisseria meningitidis strain H44/76 was modified by expression of the pagL gene encoding lipid A 3-O-deacylase from Bordetella bronchiseptica and by inactivation of the lgtB gene encoding the terminal oligosaccharide galactosyltransferase. Mass spectrometry analysis of purified mutant LPS was used for detailed compositional analysis of all present molecular species.

Acellular pertussis vaccine based on outer membrane vesicles capable of conferring both long-lasting immunity and protection against different strain genotypes.

Despite high vaccination coverage rates, pertussis continues to be a global concern, with increased incidence widely noted. The current pertussis epidemiologic situation has been mainly attributed to waning immunity and pathogen adaptation. To improve the disease control, a new generation of vaccines capable to overcome those weaknesses associated to the current vaccines need to be developed.

Meningococcal serogroup Y lpxL1 variants from South Africa are associated with clonal complex 23 among young adults.

Objectives: To determine the genotypes of serogroup Y meningococcus (MenY), and to determine the prevalence of and identify factors associated with MenY lpxL1 variants.

Methods: Isolates, collected from 2003 to 2007 through national surveillance for invasive meningococcal disease, were characterized by multilocus sequence typing and screened for interleukin-6 induction. LpxL1 genes were sequenced from low IL-6 inducers.

LOS oligosaccharide modification enhances dendritic cell responses to meningococcal native outer membrane vesicles expressing a non-toxic lipid A.

Outer membrane vesicles (OMV) are released by many bacteria, and contain immunogenic antigens in addition to harmful inflammatory factors, like lipopolysaccharides. Chemically detoxified OMV have been used in vaccines against Neisseria meningitidis (Nm); however, little is known about their interaction with antigen presenting cells. In this study, we investigated the interaction of Nm OMV with human dendritic cells (DC) to gain further understanding of their biological activity.

Expression of human CEACAM1 in transgenic mice limits the Opa-specific immune response against meningococcal outer membrane vesicles.

Outer membrane vesicles (OMVs) have been extensively investigated as meningococcal vaccine candidates. Among their major components are the opacity (Opa) proteins, a family of surface-exposed outer membrane proteins important for bacterial adherence and entry into host cells. Many Opa-dependent interactions are mediated through the carcinoembryonic antigen-related cell adhesion molecule (CEACAM) family of receptors.

Cysteine depletion causes oxidative stress and triggers outer membrane vesicle release by Neisseria meningitidis; implications for vaccine development.

Outer membrane vesicles (OMV) contain immunogenic proteins and contribute to in vivo survival and virulence of bacterial pathogens. The first OMV vaccines successfully stopped Neisseria meningitidis serogroup B outbreaks but required detergent-extraction for endotoxin removal. Current vaccines use attenuated endotoxin, to preserve immunological properties and allow a detergent-free process.

Antigen sparing with adjuvanted inactivated polio vaccine based on Sabin strains.

Six different adjuvants, each in combination with inactivated polio vaccine (IPV) produced with attenuated Sabin strains (sIPV), were evaluated for their ability to enhance virus neutralizing antibody titres (VNTs) in the rat potency model. The increase of VNTs was on average 3-, 15-, 24-fold with adjuvants after one immunization (serotypes 1, 2, and 3, respectively). Also after a boost immunization the VNTs of adjuvanted sIPV were on average another 7-20-27 times higher than after two inoculations of sIPV without adjuvant.