UC Irvine

Vaccines have employed many designs to eradicate numerous infectious diseases. Influenza, the respiratory specific virus that causes flu, is a pathogen that readily mutates every year to avoid immune system detection. Due to this characteristic, new vaccine development is required each year and the demand for a universal flu vaccine has become very relevant. Coxiella burnetii, the causative agent of Q fever and a potential bioterrorism agent with no approved vaccine, is a bacterial pathogen that infects and resides internally in host cells. For this reason, a T lymphocyte response, in addition to an adequate antibody response, is likely necessary for eradication of the pathogen. Our previous studies, utilizing the E2 protein nanoparticle (E2) in a viral-mimetic strategy for cancer immunotherapy, resulted in formulations that elicited strong T cell responses against tumors. Our current studies aim to integrate immunodominant protein and peptide antigens of influenza and C. burnetii onto the surface of E2, to develop improved prophylactic vaccine formulations against these infectious diseases.We explored the modularity, scope, and effectiveness of loading protein antigens onto protein nanoparticles (NPs). Multiple approaches for conjugation of the immunodominant C. burnetii protein antigen CBU1910 to the E2 nanoparticle were investigated including direct genetic fusion, a newly-synthesized high-affinity tris-NTA-Ni conjugation to polyhistidine-tagged CBU1910, and the SpyTag/SpyCatcher (ST/SC) system. Application of the ST/SC approach yielded the most stable nanoparticles that could simultaneously co-deliver the protein antigen CBU1910 and adjuvant CpG1826 (CpG) on one nanoparticle. Evaluating the prophylactic immune responses elicited by these formulations showed that displaying antigen on nanoparticles significantly increased antigen-specific antibody responses than soluble antigen and delivering adjuvant CpG in nanoparticles increased its immune response skewing potency. In addition, E2 nanoparticles formulated with T cell epitope antigen peptides from CBU1910 generated elevated T cell responses to the whole CBU1910 protein. Integration of protein antigen hemagglutinin (HA) from H1N1 influenza with tris-NTA-Ni also revealed a synergistic effect from the combination of H1 display on the E2 NP and soluble adjuvant that generated broader homo- and heterosubtypic cross-reactivity, which is valuable when developing a universal flu vaccine. Many NP-based vaccines build upon a pathogen-mimetic strategy to achieve sizes and structures comparable to that of viral or bacterial pathogens with antigens and adjuvants. However, the addition of a second, different adjuvant to the same protein NP scaffold has yet to be explored. We engineered NPs capable of co-delivering two adjuvants (i.e., flagellin and CpG) with protein antigen hemagglutinin from the potentially pandemic H5N1 avian influenza virus on a single NP. Displaying antigen and adjuvant elicited greater antigen-antibody responses and broader homosubtypic cross-reactivity. Skewing of the immune responses could be modulated by adjuvant type and NP attachment. Animals immunized with E2-based NPs and subsequently challenged with H5N1 influenza showed 100% survival. In all, these investigations highlight that NP-based delivery of antigen and adjuvants can effectively modulate the strength, breadth, and bias of an immune response against infectious disease.