Our laboratory has been investigating the immunobiology of the Neisserial porin PorB for the last two decades. We first began by investigating the use of this protein as a potential anti-Neisserial candidate, but through this work we found that this protein had unique immune stimulatory abilities above and beyond its own potential use as a vaccine. We found that PorB can be used as an immune adjuvant for vaccines and that this ability was directly related to its ability to stimulate antigen presenting cells (APC) and increase expression of the costimulatory molecule CD86 and class II MHC. Moreover, we found that the ability of PorB to stimulate and activate antigen presenting cells was directly due to an interaction with the pattern recognition receptor, TOLL-like Receptor 2 (TLR2) and requires the TLR adaptor protein MyD88. We have further shown, as described in the preliminary data section and in that TLR2 needs to heterodimerize with TLR1 (and not TLR6) in order for PorB to stimulate these APCs. Utilizing this body of information, the next logical step for studying the immune stimulating adjuvant activity of PorB is to compare this activity to other known vaccine adjuvants. This will allow for the better use of PorB as adjuvant, by understanding what type of immune response it induces as compared to these other adjuvants. Moreover, we believe it is essential to continue to investigate the adjuvant potential of PorB, as it is currently the only TLR2 ligand being investigated as a vaccine adjuvant. We shall compare the immune stimulation by PorB to panel of other adjuvants, including the only licensed adjuvant, Alum (inflammasomes mediated immune activation, other TLR ligands, including CpG DNA (TLR9), and monophosphoryl lipid A (MPL)(TLR4), and QS-21. We shall examine the ability of these adjuvants to induce immune responses to a test antigen, ovalbumin, which we have used previously as described in the Preliminary Data section. We shall measure antibody levels induced, isotypes and IgG subtypes induced, antibody affinity, CD4 T cell response and ability to induce APC migration and lymph node specific T cell stimulation. Moreover, we shall compare the ability of these different adjuvants to protect mice from infection with Listeria which secretes OVA. This is a well characterized model and has been used previously to demonstrate that the presence of OVA specific CD4 and CD8 T cells are necessary for protection of mice from infection with this pathogen when it is constructed to secrete OVA. We shall obtain this strain from Dr. Darren Higgins in the Dept. of Microbiology at the Harvard Medical School, who has significant expertise in this model and will act as a consultant on this proposal. Even though the protection induced by most licensed vaccines are due to the induction of neutralizing or functional antibodies, we feel it would extremely important to begin to definitively compare the ability of these adjuvants, including PorB, to not only induce functional antibodies, but to potentially induce a protective CD8 CTL response.

Public Health Relevance

We have shown that the Neisserial porin, PorB, is a potent immune adjuvant and works via recognition by TLR2 and induction of antigen presenting cell activation. This proposal will examine the adjuvant activity of PorB and compare this activity to other currently investigated adjuvants (including Alum, CpG DNA, MPL and QS-21). We shall examine induction of both humoral responses and CD8 T cell responses and the ability of the vaccines to prevent Listeria infection in mice. Moreover, we shall further examine the mechanism of PorB adjuvant activity via the use of MyD88 floxed mice bred with mice expressing cell specific cre recombinase.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Vaccines Against Microbial Diseases (VMD)
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Leitner, Wolfgang W
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Boston Medical Center
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Mosaheb, Munir; Wetzler, Lee M (2018) Meningococcal PorB induces a robust and diverse antigen specific T cell response as a vaccine adjuvant. Vaccine 36:7689-7699
Mosaheb, Munir M; Reiser, Michael L; Wetzler, Lee M (2017) Toll-Like Receptor Ligand-Based Vaccine Adjuvants Require Intact MyD88 Signaling in Antigen-Presenting Cells for Germinal Center Formation and Antibody Production. Front Immunol 8:225
Reiser, Michael L; Mosaheb, Munir M; Lisk, Christina et al. (2017) The TLR2 Binding Neisserial Porin PorB Enhances Antigen Presenting Cell Trafficking and Cross-presentation. Sci Rep 7:736
Toussi, Deana N; Wetzler, Lee M; Liu, Xiuping et al. (2016) Neisseriae internalization by epithelial cells is enhanced by TLR2 stimulation. Microbes Infect 18:627-638
Kattner, Christof; Pfennig, Sabrina; Massari, Paola et al. (2015) One-step purification and porin transport activity of the major outer membrane proteins P2 from Haemophilus influenzae, FomA from Fusobacterium nucleatum and PorB from Neisseria meningitidis. Appl Biochem Biotechnol 175:2907-15
Kattner, Christof; Toussi, Deana N; Zaucha, Jan et al. (2014) Crystallographic analysis of Neisseria meningitidis PorB extracellular loops potentially implicated in TLR2 recognition. J Struct Biol 185:440-7
Platt, Andrew; MacLeod, Heather; Massari, Paola et al. (2013) In vivo and in vitro characterization of the immune stimulating activity of the Neisserial porin PorB. PLoS One 8:e82171
Massari, Paola; Wetzler, Lee M (2012) Analysis of parameters associated with prevention of cellular apoptosis by pathogenic Neisseriae and purified porins. Methods Mol Biol 799:319-41
Toussi, Deana N; Carraway, Margaretha; Wetzler, Lee M et al. (2012) The amino acid sequence of Neisseria lactamica PorB surface-exposed loops influences Toll-like receptor 2-dependent cell activation. Infect Immun 80:3417-28
Arjunaraja, Swadhinya; Massari, Paola; Wetzler, Lee M et al. (2012) The nature of an in vivo anti-capsular polysaccharide response is markedly influenced by the composition and/or architecture of the bacterial subcapsular domain. J Immunol 188:569-77

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