Nanoparticular vaccines: spatial and temporal control of Toll-like receptor (TLR) agonist and antigen delivery

• Applicant: Professorin Dr. Miriam Breunig
• Subject Area: Pharmacy
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 546598635

Immunization seems a captivating easy concept, but launching an effective vaccine remains for pathogens like HIV-1 a challenge. Thus, many research efforts are pursued to enhance the immunogenicity of HIV-1´s envelope (Env) protein like using nanoparticles that present the monovalent antigen in a polyvalent, repetitive array on the nanoparticular surface. We have successfully demonstrated the principle for the covalent and oriented immobilization of Env on the surface of silica nanoparticles (Env-SiNPs). For this project, we identified Toll-like receptor (TLR) agonists as an additional adjusting screw to increase immunogenicity of Env because an orchestrated and joint action of TLRs and B cell receptors (BCRs) may qualitatively and quantitatively change humoral immune response of B cells. To follow up this goal, we will design a nanoparticular platform to control of the presentation of the Env antigen in combination with the costimulatory effect of TLR agonists on B cells in a spatial and temporal manner. We will fabricate and characterize SiNPs that are decorated with Env and TLR agonists either on different (Env-SiNP, TLR-SiNP) or on the same surface (Env-TLR-SiNP). The SiNPs will be tested in TLR reporter and human B cells to make sure that they have the required functionality. We will carefully pay attention to the following points: 1. Temporal control: The first major focus will be to find out if it is necessary to keep a specific order for the presentation of the Env antigen and TLR agonist to B cells. This will be realized by either a time-delayed or simultaneous addition of Env-SiNPs and TLR-SiNPs to B cells. In addition, it will also be elucidated if a prolonged presence of the TLR agonist will be of advantage for the quality of B cell response. Thus, in a first step, TLR-SiNPs will be in repeatedly added at varying time intervals, and in a second step, a sustained release of TLR-SiNPs from a hydrogel will be realized. 2. Spatial control: The second major focus will be to investigate the co-delivery of Env and TLR agonist on the same particle (Env-TLR-SiNPs). In addition, the prolonged presence of Env-TLR-SiNPs on B cells will be investigated by repeated administration at varying time intervals and alternatively, by release from hydrogel. 3. Beyond these essential questions we will fine-tune SiNP formulations according to the following parameters: - the ratio of the Env antigen and the TLR agonist, - the selection of the optimal TLR agonist in combination with the Env antigen, and - a combination of two different TLR agonists. In the second phase of the project (second three years), we will use these findings to fine-tune the composition of hydrogels regarding the release duration and kinetics of the nanoparticles and investigate the release and immunogenicity of the developed nanoparticles in vivo. Because the developed platform can be used as building blocks, principles will be transferred to other pathogens like influenza in future.

• DFG Programme: Research Grants
• Co-Investigators: Professor Dr. Achim Goepferich; Professor Dr. Lutz Nuhn; Professor Dr. Ralf Wagner