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Experimental vaccine induces Th1-driven immune responses and resistance to Neisseria gonorrhoeae infection in a murine model.

ABSTRACT: Female mice were immunized intravaginally with gonococcal outer membrane vesicles (OMVs) plus microencapsulated interleukin-12 (IL-12), and challenged using an established model of genital infection with Neisseria gonorrhoeae. Whereas sham-immunized and control animals cleared the infection in 10-13 days, those immunized with OMV plus IL-12 cleared infection with homologous gonococcal strains in 6-9 days. Significant protection was also seen after challenge with antigenically distinct strains of N. gonorrhoeae, and protective anamnestic immunity persisted for at least 6 months after immunization. Serum and vaginal immunoglobulin G (IgG) and IgA antibodies were generated against antigens expressed by homologous and heterologous strains. Iliac lymph node CD4+ T cells secreted interferon-? (IFN?), but not IL-4, in response to immunization, and produced IL-17 in response to challenge regardless of immunization. Antigens recognized by immunized mouse serum included several shared between gonococcal strains, including two identified by immunoproteomics approaches as elongation factor-Tu (EF-Tu) and PotF3. Experiments with immunodeficient mice showed that protective immunity depended upon IFN? and B cells, presumably to generate antibodies. The results demonstrated that immunity to gonococcal infection can be induced by immunization with a nonliving gonococcal antigen, and suggest that efforts to develop a human vaccine should focus on strategies to generate type 1 T helper cell (Th1)-driven immune responses in the genital tract.

SUBMITTER: Liu Y

PROVIDER: S-EPMC5591041 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

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Experimental vaccine induces Th1-driven immune responses and resistance to Neisseria gonorrhoeae infection in a murine model.

Liu Y Y Hammer L A LA Liu W W Hobbs M M MM Zielke R A RA Sikora A E AE Jerse A E AE Egilmez N K NK Russell M W MW

Mucosal immunology 20170301 6

Female mice were immunized intravaginally with gonococcal outer membrane vesicles (OMVs) plus microencapsulated interleukin-12 (IL-12), and challenged using an established model of genital infection with Neisseria gonorrhoeae. Whereas sham-immunized and control animals cleared the infection in 10-13 days, those immunized with OMV plus IL-12 cleared infection with homologous gonococcal strains in 6-9 days. Significant protection was also seen after challenge with antigenically distinct strains of ...[more]

PMID: 28272393

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Project description:BackgroundVaccination against tuberculosis (TB) should provide long-term protective immunity against Mycobacterium tuberculosis (M.tb). The current TB vaccine, Bacille Calmette-Guerin (BCG), protects against disseminated childhood TB, but protection against lung TB in adolescents and adults is variable and mostly poor. One potential reason for the limited durability of protection may be waning of immunity through gradual attrition of BCG-induced T cells. We determined if a MVA85A viral-vector boost could enhance the durability of mycobacteria-specific T cell responses above those induced by BCG alone.MethodsWe describe a long-term follow-up study of persons previously vaccinated with MVA85A. We performed a medical history and clinical examination, a tuberculin skin test and measured vaccine-specific T cell responses in persons previously enrolled as adults, adolescents, children or infants into three different Phase II trials, between 2005 and 2011.ResultsOf 252 potential participants, 183 (72.6%) consented and completed the study visit. Vaccine-induced Ag85A-specific CD4+ T cell responses were remarkably persistent in healthy, HIV-uninfected adults, adolescents, children and infants, up to 6 years after MVA85A vaccination. Specific CD4+ T cells expressed surface markers consistent with either CD45RA-CCR7+ central memory or CD45RA-CCR7- effector memory T cells. Similarly durable Ag85A-specific CD4+ T cell responses were detected in HIV-infected persons who were on successful antiretroviral therapy when MVA85A was administered. By contrast, Ag85A-specific CD4+ T cell frequencies in untreated MVA85A-vaccinated HIV-infected persons were mostly undetectable 3-5 years after vaccination.ConclusionMVA85A induces remarkably durable T cell responses in immunocompetent persons. However, results from a recent phase IIb trial of MVA85A, conducted in infants from the same geographic area and study population, showed no vaccine efficacy, suggesting that these durable T cell responses do not enhance BCG-induced protection against TB in infants.

Project description:The immune response to Neisseria gonorrhoeae is poorly understood, but its extensive antigenic variability and resistance to complement are thought to allow it to evade destruction by the host’s immune defenses. We propose that N. gonorrhoeae also avoids inducing protective immune responses in the first place. We previously found that N. gonorrhoeae induces IL-17-dependent innate responses in mice and suppresses Th1/Th2-dependent adaptive responses in murine cells in vitro through the induction of TGF-β. In this study using a murine model of vaginal gonococcal infection, mice treated with anti-TGF-β antibody during primary infection showed accelerated clearance of N. gonorrhoeae with incipient development of Th1 and Th2 responses and diminished Th17 responses in genital tract tissue. Upon secondary reinfection, mice that had been treated with anti-TGF-β during primary infection showed anamnestic recall of both Th1 and Th2 responses, with the development of anti-gonococcal antibodies in serum and secretions, and enhanced resistance to reinfection. In knockout mouse strains defective in Th1 or Th2 responses, accelerated clearance of primary infection due to anti-TGF-β treatment was dependent on Th1 but not Th2 activity, whereas resistance to secondary infection resulting from anti-TGF-β treatment during primary infection was due to both Th1- and Th2-dependent memory responses. We propose that N. gonorrhoeae proactively elicits Th-17-driven innate responses that it can resist, and suppresses Th1/Th2-driven specific adaptive immunity that would protect the host. Blockade of TGF-β reverses this pattern of host immune responsiveness and facilitates the emergence of protective anti-gonococcal immunity. We only did microarray assay for wild-type mice with or without anti-TGF-b treatment. Experiment A: Totally there are three groups: Sham-infected mice without treatment; N.gonorrhoeae-infected with control IgG treatment; N.gonorrhoeae-infected with anti-TGF-β treatment. For each group, two mice were studied. Total RNA from mouse vagina were analysed. Experiment B: Totally there are three groups: Sham-reinfected mice without treatment; N.gonorrhoeae-reinfected with control IgG treatment; N.gonorrhoeae-reinfected with anti-TGF-β treatment. For each group, two mice were studied. Total RNA from mouse vagina were analysed.

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.

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Experimental vaccine induces Th1-driven immune responses and resistance to Neisseria gonorrhoeae infection in a murine model.

Publications

Experimental vaccine induces Th1-driven immune responses and resistance to Neisseria gonorrhoeae infection in a murine model.

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