1724. A Lipidated Pneumococcal Fusion Protein Confers Toll-like Receptor 2-Dependent IL-17A Responses and Protection Against Nasopharyngeal Carriage in Mice
Session: Poster Abstract Session: Studies of the Interface of Host-Microbial Interaction
Saturday, October 5, 2013
Room: The Moscone Center: Poster Hall C
Posters
  • MOFFITT IDWeek Poster.pdf (1.8 MB)
  • Background: Development of affordable pneumococcal vaccines, particularly those that target invasive disease and mucosal colonization, is a global health priority. We have previously identified several pneumococcal proteins that protect mice from colonization in a CD4+ T cell and IL-17A-dependent manner; one of these (SP2108, MalX) is a lipidated substrate-binding protein of an ABC transporter. Studies of non-lipidated SP2108 demonstrated the requirement for lipidation for TH17 priming and protection against carriage. We hypothesized that this immunogenicity was Toll-like receptor (TLR) 2-dependent. To test this hypothesis, we investigated the role of TLR2 in SP2108-induced pro-inflammatory cytokine release and priming of TH17 responses.

    Methods: Lipidated or non-lipidated SP2108 was used to stimulate macrophages from wild-type (WT) and TLR2-/- C57BL/6 mice; pro-inflammatory cytokine secretion was compared. A vaccine containing SP2108 fused to a non-lipidated antigen and adsorbed onto alum was given subcutaneously to WT and TLR2-/- mice. Following immunization, peripheral blood cells were stimulated with a pneumococcal whole cell antigen to measure IL-17A responses. Mice were intranasally challenged with live type 6B pneumococcus and bacterial burden from nasal washes was determined.

    Results: TLR2-/- macrophages had ~10-100x lower pro-inflammatory (TNFa, IL-1b, and G-CSF) cytokine release compared with WT macrophages following stimulation with lipidated SP2108 while neither WT nor TLR2-/- macrophages responded to non-lipidated SP2108.  Immunized WT animals demonstrated robust systemic IL-17A responses while immunized TLR2-/- animals had no detectable IL-17A response. In WT mice, the vaccine significantly reduced colonization burden (p < 0.0001), whereas no reduction was noted in TLR2-/- mice; there was no difference in colonization burden of alum-immunized WT vs. TLR2-/- mice. Studies of the mucosal vaccine-induced recall T cell responses are underway.

    Conclusion: A parenteral subunit vaccine containing a lipidated TH17 antigen is immunogenic and protective against nasal carriage in mice in a TLR2-dependent manner. We believe this vaccine candidate may advance the development of a next-generation pneumococcal vaccine.

    Kristin Moffitt, MD1, Mojca Skoberne, PhD2, Angela Howard, AB1, L. Cristina Gavrilescu, PhD2, Jessica B. Flechtner, PhD2 and Richard Malley, MD1, (1)Division of Infectious Diseases, Boston Children's Hospital/Harvard Medical School, Boston, MA, (2)Genocea Biosciences, Cambridge, MA

    Disclosures:

    K. Moffitt, None

    M. Skoberne, Genocea Biosciences: Employee, Salary

    A. Howard, None

    L. C. Gavrilescu, Genocea Biosciences: Employee, Salary

    J. B. Flechtner, Genocea Biosciences: Employee, Salary

    R. Malley, None

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