Design of single-shot sequential immunization regimens for HIV using atomic layer deposition technology. - Project Title: Design of single-shot sequential immunization regimens for HIV using atomic layer deposition technology Project Summary/Abstract 30 lines or less: Preclinical studies and early stage human trials evaluating passively transferred broadly neutralizing antibodies (bnAbs) suggest that a vaccine capable of eliciting bnAbs would provide effective protection from HIV infection. However, bnAb induction through vaccination is a major challenge. We have developed an immunogen series targeting the CD4 binding site bnAb epitope on HIV Env using germline targeting to prime appropriate B cell precursors, and then shepherd the BCR mutations of these recruited B cells through a series of booster vaccinations, where each engineered immunogen promotes key mutations along the path to bnAb development. In a rigorous humanized mouse model, a near-complete vaccine regimen has been demonstrated, leading to epitope-specific mAbs capable of binding to heterologous wildtype HIV Env trimers. However, this regimen involves up to 5 or 6 shots, which would be challenging to implement in global vaccination campaigns. To overcome this hurdle, we have developed a vaccine formulation strategy that can deliver multiple boosts over time from a single injection. Atomic layer deposition (ALD) is used to “cap” spray-dried microparticle vaccine formulations with a thin layer of alumina. On injection, the vaccine undergoes a rapid release from the ALD particle once the alumina coating dissolves, and the timing of vaccine release can be precisely determined by the thickness of the ALD coating. By injecting ALD particles containing a series of booster immunogens capped by alumina coatings of distinct thickness, a series of immunogen (and adjuvant) exposures can be pre- programmed from a single immunization. Here we propose to carry out systematic studies to apply this technology to sequential immunization regimens targeting the development of bnAbs against the CD4 binding site, establish the limits of such single-shot formulations, and develop a mechanistic understanding of immune responses elicited by ALD vaccine formulations. Our specific aims are to (1) Characterize key process parameters governing ALD vaccine formulation function, (2) Apply ALD technology for single-shot sequential immunizations in a humanized mouse model targeting the CD4bs, and (3) Optimize ALD technology for sequential delivery of mRNA vaccines. These studies will provide important insights into the immunology and practical potential of ALD vaccines for enabling sequential immunization regimens that may be critical for a successful HIV vaccine. This technology is being commercially developed for cGMP vaccine manufacturing, and these studies will provide important preclinical data to support translation to human HIV vaccine trials.
