Friday, May 9, 2025
5/9/2025
Engineering Bacteriophage T4 as a Targeted Gene Therapy Drug for in vivo HIV Cure - This proposal aims to establish a new category of safe and affordable in vivo HIV cure “drugs” that would transform the health of substance users who are disproportionately affected by HIV-1 (HIV) disease. Substance users suffer from high rates of HIV acquisition and transmission, poor adherence to antiretrovirals and drug resistance, and high prevalence of neurodegenerative and mental health problems. It will also be broadly transformative to more than 40 million people across the globe who are living with HIV today. Using a unique bacteriophage (phage) T4 artificial viral vector (T4-AVV) technology we have recently developed, we will engineer the 120 x 86 nm T4 capsid nanoparticle to target patient's hematopoietic stem cells (HSCs) in vivo and deliver a payload of genome modification molecules. These will introduce a delta-32 deletion mutation into the CCR5 HIV co-receptor gene, which will make the HSCs and the cells derived from it, HIV- resistant. This is the only known HIV cure option today, as evident from at least five independent HIV cure cases worldwide, all remarkably involving transplanted HSCs containing the naturally present delta-32 mutation. Our experimental path involves three milestones. First, we will identify targeting ligands that have high affinity and binding specificity to HSCs from human umbilical cord blood (UCB). These will be selected from libraries of nanobodies, darpins, and ScFvs displayed on phage T4 capsid through fusion at the tip of the 180Å-long, flexible, outer fibers known as Hoc. Next, HSC-targeting, lipid-coated, T4-AVVs will be assembled in the test tube by incorporating all the HIV cure molecules into one nanoparticle by sequential assembly and DNA packaging. These include combinations of genome editing enzymes, gRNAs, and donor DNAs. The T4-AVVs that exhibit maximum delta-32 genome conversion will be optimized using an ex vivo UCB-HSC model. Finally, the HSC-targeted T4-AVVs will be tested in vivo in a humanized DRAGA mouse model reconstituted with the same UCB-HSCs, using a protocol that mimics HIV cure in humans. Various parameters will be optimized such that the T4-AVVs will enter HSCs in minutes, deliver payload in hours, and modify genome in 1-2 days. The T4-AVV in vivo HIV-cure would be a safe, affordable, outpatient protocol that can be easily administered to substance users. Since it is targeted, a small dose of T4-AVVs (~10E12 particles) would be sufficient to capture the HSCs mobilized into patient's blood, while minimizing host immune responses and off-target events. The delta-32 converted HSCs will then repopulate the body with HIV-resistant blood cells including CD4+ T cells, which would replace the HIV reservoir and result in functional HIV cure. A single dose of T4-AVVs might be sufficient, however a second dose may be needed to maximize HSC delta-32 conversion for permanent HIV cure. Currently, T4-AVV is the only technology that has the capacity and engineering capability to create such HIV cure delivery vehicles. Furthermore, this plug-and-play drug model can be adapted to many other blood cell diseases and cancer, potentially transforming future gene therapies and precision medicine.
HHS’ Tracking Accountability in Government Grants System (TAGGS) website provides access to detailed descriptions of grants, loans, aggregated direct payments and other types of financial assistance awarded by the HHS Operating Divisions (OPDIVs) and the Office of the Secretary Staff Divisions (STAFFDIVs).