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A Meningococcal Outer Membrane Vesicle Vaccine Incorporating Genetically Attenuated Endotoxin Dissociates Inflammation from Immunogenicity.

ABSTRACT: Group B Neisseria meningitidis, an endotoxin-producing Gram-negative bacterium, causes the highest incidence of group B meningococcus (MenB) disease in the first year of life. The Bexsero vaccine is indicated in Europe from 8?weeks of age. Endotoxin components of outer membrane vesicles (OMVs) or soluble lipopolysaccharide (LPS) represent a potential source of inflammation and residual reactogenicity. The purpose of this study was to compare novel candidate MenB vaccine formulations with licensed vaccines, including Bexsero, using age-specific human in vitro culture systems.OMVs from wild type- and inactivated lpxL1 gene mutant-N. meningitidis strains were characterized in human neonatal and adult in vitro whole blood assays and dendritic cell (DC) arrays. OMVs were benchmarked against licensed vaccines, including Bexsero and whole cell pertussis formulations, with respect to Th-polarizing cytokine and prostaglandin E2 production, as well as cell surface activation markers (HLA-DR, CD86, and CCR7). OMV immunogenicity was assessed in mice.?lpxLI native OMVs (nOMVs) demonstrated significantly less cytokine induction in human blood and DCs than Bexsero and most of the other pediatric vaccines (e.g., PedvaxHib, EasyFive, and bacillus Calmette-Guérin) tested. Despite a much lower inflammatory profile in vitro than Bexsero, ?lpxLI nOMVs still had moderate DC maturing ability and induced robust anti-N. meningitidis antibody responses after murine immunization.A meningococcal vaccine comprised of attenuated LPS-based OMVs with a limited inflammatory profile in vitro induces robust antigen-specific immunogenicity in vivo.

SUBMITTER: Dowling DJ

PROVIDER: S-EPMC5143884 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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A Meningococcal Outer Membrane Vesicle Vaccine Incorporating Genetically Attenuated Endotoxin Dissociates Inflammation from Immunogenicity.

Dowling David J DJ Sanders Holly H Cheng Wing Ki WK Joshi Sweta S Brightman Spencer S Bergelson Ilana I Pietrasanta Carlo C van Haren Simon D SD van Amsterdam Sandra S Fernandez Jeffrey J van den Dobbelsteen Germie P J M GP Levy Ofer O

Frontiers in immunology 20161208

<h4>Background</h4>Group B <i>Neisseria meningitidis</i>, an endotoxin-producing Gram-negative bacterium, causes the highest incidence of group B meningococcus (MenB) disease in the first year of life. The Bexsero vaccine is indicated in Europe from 8 weeks of age. Endotoxin components of outer membrane vesicles (OMVs) or soluble lipopolysaccharide (LPS) represent a potential source of inflammation and residual reactogenicity. The purpose of this study was to compare novel candidate MenB vaccine ...[more]

PMID: 28008331

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Project description:BackgroundThere is a clear need for novel approaches to malaria vaccine development. We aimed to develop a genetically attenuated blood-stage vaccine and test its safety, infectivity, and immunogenicity in healthy volunteers. Our approach was to target the gene encoding the knob-associated histidine-rich protein (KAHRP), which is responsible for the assembly of knob structures at the infected erythrocyte surface. Knobs are required for correct display of the polymorphic adhesion ligand P. falciparum erythrocyte membrane protein 1 (PfEMP1), a key virulence determinant encoded by a repertoire of var genes.MethodsThe gene encoding KAHRP was deleted from P. falciparum 3D7 and a master cell bank was produced in accordance with Good Manufacturing Practice. Eight malaria naïve males were intravenously inoculated (day 0) with 1800 (2 subjects), 1.8 × 105 (2 subjects), or 3 × 106 viable parasites (4 subjects). Parasitemia was measured using qPCR; immunogenicity was determined using standard assays. Parasites were rescued into culture for in vitro analyses (genome sequencing, cytoadhesion assays, scanning electron microscopy, var gene expression).ResultsNone of the subjects who were administered with 1800 or 1.8 × 105 parasites developed parasitemia; 3/4 subjects administered 3× 106 parasites developed significant parasitemia, first detected on days 13, 18, and 22. One of these three subjects developed symptoms of malaria simultaneously with influenza B (day 17; 14,022 parasites/mL); one subject developed mild symptoms on day 28 (19,956 parasites/mL); and one subject remained asymptomatic up to day 35 (5046 parasites/mL). Parasitemia rapidly cleared with artemether/lumefantrine. Parasitemia induced a parasite-specific antibody and cell-mediated immune response. Parasites cultured ex vivo exhibited genotypic and phenotypic properties similar to inoculated parasites, although the var gene expression profile changed during growth in vivo.ConclusionsThis study represents the first clinical investigation of a genetically attenuated blood-stage human malaria vaccine. A P. falciparum 3D7 kahrp- strain was tested in vivo and found to be immunogenic but can lead to patent parasitemia at high doses.Trial registrationAustralian New Zealand Clinical Trials Registry (number: ACTRN12617000824369 ; date: 06 June 2017).

Project description:BackgroundDeclining antimicrobial susceptibility to current gonorrhoea antibiotic treatment and inadequate treatment options have raised the possibility of untreatable gonorrhoea. New prevention approaches, such as vaccination, are needed. Outer membrane vesicle meningococcal serogroup B vaccines might be protective against gonorrhoea. We evaluated the effectiveness of a serogroup B meningococcal outer membrane vesicle vaccine (MenB-4C) against gonorrhoea in individuals aged 16-23 years in two US cities.MethodsWe identified laboratory-confirmed gonorrhoea and chlamydia infections among individuals aged 16-23 years from sexually transmitted infection surveillance records in New York City and Philadelphia from 2016 to 2018. We linked gonorrhoea and chlamydia case records to immunisation registry records to determine MenB-4C vaccination status at infection, defined as complete vaccination (two MenB-4C doses administered 30-180 days apart), partial vaccination (single MenB-4C vaccine dose), or no vaccination (serogroup B meningococcal vaccine naive). Using log-binomial regression with generalised estimating equations to account for correlations between multiple infections per patient, we calculated adjusted prevalence ratios (APR) and 95% CIs to determine if vaccination was protective against gonorrhoea. We used individual-level data for descriptive analyses and infection-level data for regression analyses.FindingsBetween Jan 1, 2016, and Dec 31, 2018, we identified 167 706 infections (18 099 gonococcal infections, 124 876 chlamydial infections, and 24 731 gonococcal and chlamydial co-infections) among 109 737 individuals linked to the immunisation registries. 7692 individuals were vaccinated, of whom 4032 (52·4%) had received one dose, 3596 (46·7%) two doses, and 64 (<1·0%) at least three doses. Compared with no vaccination, complete vaccination series (APR 0·60, 95% CI 0·47-0·77; p<0·0001) and partial vaccination series (0·74, 0·63-0·88; p=0·0012) were protective against gonorrhoea. Complete MenB-4C vaccination series was 40% (95% CI 23-53) effective against gonorrhoea and partial MenB-4C vaccination series was 26% (12-37) effective.InterpretationMenB-4C vaccination was associated with a reduced gonorrhoea prevalence. MenB-4C could offer cross-protection against Neisseria gonorrhoeae. Development of an effective gonococcal vaccine might be feasible with implications for gonorrhoea prevention and control.FundingNone.

Project description:There is a pressing need for a gonorrhea vaccine due to the high disease burden associated with gonococcal infections globally and the rapid evolution of antibiotic resistance in Neisseria gonorrhoeae (Ng). Current gonorrhea vaccine research is in the stages of antigen discovery and the identification of protective immune responses, and no vaccine has been tested in clinical trials in over 30 years. Recently, however, it was reported in a retrospective case-control study that vaccination of humans with a serogroup B Neisseria meningitidis (Nm) outer membrane vesicle (OMV) vaccine (MeNZB) was associated with reduced rates of gonorrhea. Here we directly tested the hypothesis that Nm OMVs induce cross-protection against gonorrhea in a well-characterized female mouse model of Ng genital tract infection. We found that immunization with the licensed Nm OMV-based vaccine 4CMenB (Bexsero) significantly accelerated clearance and reduced the Ng bacterial burden compared to administration of alum or PBS. Serum IgG and vaginal IgA and IgG that cross-reacted with Ng OMVs were induced by 4CMenB vaccination by either the subcutaneous or intraperitoneal routes. Antibodies from vaccinated mice recognized several Ng surface proteins, including PilQ, BamA, MtrE, NHBA (known to be recognized by humans), PorB, and Opa. Immune sera from both mice and humans recognized Ng PilQ and several proteins of similar apparent molecular weight, but MtrE was only recognized by mouse serum. Pooled sera from 4CMenB-immunized mice showed a 4-fold increase in serum bactericidal50 titers against the challenge strain; in contrast, no significant difference in bactericidal activity was detected when sera from 4CMenB-immunized and unimmunized subjects were compared. Our findings directly support epidemiological evidence that Nm OMVs confer cross-species protection against gonorrhea, and implicate several Ng surface antigens as potentially protective targets. Additionally, this study further defines the usefulness of murine infection model as a relevant experimental system for gonorrhea vaccine development.

Project description:Outer membrane vesicles (OMVs) are spontaneously released by many gram-negative bacteria during their growth and constitute an important virulence factor for bacteria, helping them to survive through harsh environmental conditions. Native OMVs, naturally-released from bacteria, are produced at a level too low for vaccine manufacturing, requiring chemical treatment (detergent-extracted) or genetic manipulation, resulting in generalized modules for membrane antigens (GMMAs). Over the years, the nature and properties of OMVs have made them a viable platform for vaccine development. There are a few licensed OMV vaccines mainly for the prevention of meningitis caused by Neisseria meningitidis serogroup B (MenB) and Haemophilus influenzae type b (Hib). There are several candidates in clinical development against other gram-negative organisms from which the OMVs are derived, but also against heterologous targets in which the OMVs are used as carriers (e.g. coronavirus disease 2019 [COVID-19]). The use of OMVs for targets other than those from which they are derived is a major advancement in OMV technology, improving its versatility by being able to deliver protein or polysaccharide antigens. Other advances include the range of genetic modifications that can be made to improve their safety, reduce reactogenicity, and increase immunogenicity and protective efficacy. However, significant challenges remain, such as identification of general tools for high-content surface expression of heterologous proteins on the OMV surface. Here, we outline the progress of OMV vaccines to date, particularly discussing licensed OMV-based vaccines and candidates in clinical development. Recent trends in preclinical research are described, mainly focused on genetic manipulation and chemical conjugation for the use of OMVs as carriers for heterologous protein and polysaccharide antigens. Remaining challenges with the use of OMVs and directions for future research are also discussed.

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A Meningococcal Outer Membrane Vesicle Vaccine Incorporating Genetically Attenuated Endotoxin Dissociates Inflammation from Immunogenicity.

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A Meningococcal Outer Membrane Vesicle Vaccine Incorporating Genetically Attenuated Endotoxin Dissociates Inflammation from Immunogenicity.

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