Fast-Track Proposals will be accepted. Direct-to-Phase II will not be accepted. Number of anticipated awards: 2-4 Budget (total costs): Phase I: $300,000 for up to 1 year; Phase II: $2,000,000 for up to 3 years. Background Efforts towards the development of an efficacious HIV vaccine have focused on improvements in the design of the HIV envelope (Env) immunogen for induction and generation of broadly neutralizing antibody (bNAb) responses and novel platforms for immunogen delivery. One major hurdle for the induction of bnAbs is that the B cell lineages for these antibodies are found at extremely low frequencies; further, the naïve B cell receptors of these lineages may only recognize an HIV envelope from the transmitted infecting virus. Therefore, considerable efforts have focused on HIV envelope design to target these rare germline B-cells receptors including minimal epitopes and modified stabilized Env trimers. Once these naïve, germline B-cell receptors have been triggered, more native-like HIV Env immunogens may be designed to drive B cell maturation and evolution towards Ab breadth. Additionally, effective activation of rare B cell lineages will probably require an alternative delivery platform of immunogens compared to vaccination with just soluble Env immunogens. Improvements to the delivery system of these next-generation HIV Env immunogens could include multivalent antigen presentation, targeted delivery to lymph nodes, sustained antigen release, coupled co-delivery of adjuvants, etc. It is expected that the improvements to Env design coupled to improved delivery methods may increase the probability of engaging rare bNAb B cell precursors, enhance affinity maturation, and improve antibody magnitude and durability. This topic will selectively focus on the development of platforms for the delivery of HIV immunogens; immunogens may be either based on protein or nucleic acid-based design. Co-delivery of adjuvants can be included with the vaccine delivery platform. Project Goal The goal of this project is to develop an HIV vaccine platform for delivery of HIV Env immunogens that induce bnAbs. The platforms may include, but not be limited to: lipid- or polymer-based nanoparticles (NP) or equivalent multimeric antigen display platform and may contain immune-stimulators, such as adjuvants; the immunogen may either be recombinant protein (minimal epitopes, optimized trimers, etc.) or nucleic acids (RNA or DNA) expressing HIV Env proteins and/or Env proteins covalently linked to NP or multimerization domains. The goal will be to demonstrate that the vaccine platform/immunogen proposed will elicit a strong and durable NAb HIV Env response. Phase I activities may include, but are not limited to: • Engineering and fabricating nanoparticle platforms/systems and approaches (such as synthetic, self-assembling particles, conjugating technologies to attach HIV antigen to nanoparticles, lipid encapsulating technologies, etc.) for delivering existing and/or novel HIV Env immunogens (minimal epitope, native and/or native-like trimers either as a recombinant protein or expressed by nucleic acids/mRNA/self-amplifying RNAs). Page 104 • Developing and evaluating particulate systems (described above) that can facilitate co-delivery and/or co-formulation of HIV antigens (described above) with adjuvants (such as existing, licensed, biosimilar novel adjuvants/TLR agonists). • Developing optimal parameters/conditions for incorporation of HIV Env antigen(s) into nanoparticulate formulation. • Developing assays and test methods to analyze and characterize molecular properties of the particulate-antigen formulations through in vitro (biophysical, physicochemical, binding assays) and/or in vivo testing (small animal studies). • Studying conditions for controlling particle size and size distribution, charge, composition, and aggregation. • Evaluating particulated formulation technologies for fabrication and development of HIV vaccine development. • Developing an efficient process for early-stage/pre-clinical studies, which could be adapted to scale-up studies and which can subsequently lead to the production of clinical-grade material in conformance with the Current Good Manufacturing Practice (cGMP) regulations. • Evaluating the delivery, immunogenicity, and effectiveness of particle-based HIV vector platforms in small animal models. • Investigating the effects of route of immunization, dose, dosage form, and dose-sparing capacity of particulate formulations on the particle distribution and kinetics of the immune response to the immunogen. Phase II activities may include, but are not limited to: • Developing lead vaccine formulation into an efficient, stable, and reproducible process. • Generating a pilot lot and/or scale-up studies based on optimized conditions that can subsequently lead to the production of clinical-grade material in conformance with the cGMP regulation. • Developing cGMP manufacturing processes for developing nanoparticle formulations. • Translating in vitro studies into proof-of-concept studies in nonhuman primates, as warranted. • Developing methods to evaluate compositional quality on critical components in nanoparticles, for example, but not limited to, quality, manufacturability, and stability/degradation of lipids and related components. • Evaluating the performance, effectiveness, and toxicity of particulated HIV vaccine candidates compared to soluble antigen in small animal models. • Establishing quality assurance and quality control, methodology, and development protocols for the generation of HIV antigen-adjuvanted formulations for codelivery.