routes showed balanced reactions in terms of IL-4 (Number 3A) and IFN- (Number 3B) production. The higher level of immunogenicity exhibited from the rMSP1-QDs was accomplished without further addition of additional adjuvant components. Bone Rabbit Polyclonal to HSF2 marrow derived dendritic cells were shown to efficiently occupy the nanoparticles leading to their activation and the manifestation/secretion of important cytokines, suggesting that this may be a mode of action for the enhanced immunogenicity. This study provides encouraging results for the use of water soluble, inorganic nanoparticles (<15nm) as potent vehicles/platforms to enhance the immunogenicity of polypeptide antigens in adjuvant-free immunizations. Keywords: Adjuvant, Malaria Vaccine, Nanoparticles, Dendritic Cells, Inhibitory Antibodies Intro A major obstacle in the development of subunit recombinant and peptide vaccines is the availability of adjuvants that can induce robust immune responses. The development of human being blood stage malaria vaccines is a good example. One such vaccine is the Merozoite Surface Protein 1C42 (MSP1-42) [1C5]. MSP1-42 is a surface protein found on the invading merozoites of the erythrocytic stage [6, 7]. Vaccinations with MSP1-42 in animal models have shown strong safety with the use of strong oil-water emulsion adjuvants such as Freunds Total Adjuvant [1, 3C5, 8]. Parasite inhibitory antibodies specific for MSP1-42 are protecting and correlate with medical immunity [3, 4, 9C13]. Despite obvious demonstration of protecting immunity in animal models, a medical trial using MSP1-42 showed no significant effectiveness [14]. The inability of the MSP1-42 vaccine formulations to induce safety in medical trials could be attributed to very low levels (titers) of parasite inhibitory antibodies [14, 15]. Two Phase 1 tests of MSP1-42 using Alum and Alum+CPG adjuvants also induced low levels of inhibitory antibodies [16, 17]. The failure to elicit protecting immunity and/or high levels of parasite inhibitory antibodies in these medical trials may be attributed partially to the choice of adjuvants (ASO2A, CPG, and Alum) [14, 16C18]. Currently, there are limited numbers of adjuvant formulations suitable for medical testing; not only for malaria vaccines but also for vaccines against additional infectious diseases. Alternate strategies need to be explored and developed to enhance vaccine immunogenicity. One such strategy is the use of particle-mediated delivery systems such as micro- or nanoparticles [19C23]. The types TNP-470 of particles currently being evaluated are lipid polymers (eg. PLGA, PGA, PLA) particles [24C27]; Virus-Like Particles (VLPs) [28, 29]; Immune Revitalizing Complexes (ISCOMS) [30, 31]; chitosans [32C34]; and inorganic particles [35]. More recently, Self-Assembling, Polypeptide-based Nanoparticles (SAPN) have also been tested like a delivery platform for TNP-470 any peptide sporozoite malaria vaccine [36]. In this study, we focused on the use of the semiconductor nanoparticles, Quantum Dots (QDs) as an alternative vaccine delivery platform. QDs are small (<15nm) inorganic nanoparticles having a crystal shell of alternating cationic and anionic layers, which in this case is definitely CdSe/ZnS [37C39]. QDs are non-immunogenic, stable, and when coated with an organic layer allow for an array of proteins, DNA, along with other biomolecules to be conjugated to their surfaces [37C39]. Because of their small size and surface changes, QDs are TNP-470 highly soluble and behave as a true remedy [40]. These characteristics may allow the particles to be rapidly dispersed in vivo, therefore readily reaching immunological sites and organs. Despite these advantages, the effectiveness of nanoparticles below 15 nm as vaccine delivery vehicles has not been thoroughly investigated. We used the recombinant malaria vaccine antigen, MSP1-42 (referred hereon as rMSP1) like a model immunogen to evaluate nanoparticles below 15 nm like a vaccine delivery platform in adjuvant-free immunizations. Results showed that rMSP1 conjugated to QDs (rMSP1-QD) was much superior to rMSP1 given with CFA or having a clinically acceptable adjuvant, Montanide ISA51 in enhancing immunogenicity and effectiveness. Our data provides encouraging proof-of-concept for the development of solid inorganic nanoparticles (<15 nm) as adjuvant-free vaccine delivery platforms. Material and Methods Mouse Strain Outbred Swiss Webster (SW) mice and C57Bl/6 mice (female, 6C8 weeks older) were from Charles River Laboratory (Wilmington, MA). The use of mice was authorized by the University or college of Hawaiis Institutional Animal Care and Use Committee. Recombinant MSP1-42 (rMSP1) A truncated version of MSP1-42 was indicated in Drosophila cells [41] and purified by affinity chromatography [42]. Number 1A shows SDS-PAGE profile of the purified TNP-470 protein. This recombinant MSP1-42 (rMSP1) offers been shown to induce parasite.