Use of Focused ultrasound stimulated blood brain barrier opening for CNS HIV/SIV reservoir reduction - Abstract The advent of combination anti-retroviral therapy (cART) has prolonged the lifespans of people living with HIV. However, upon cessation of ART treatment the virus quickly rebounds. One of the likely causes for this rebound is the rapid seeding and establishment of viral reservoirs in multiple tissue compartments including the central nervous system (CNS). The CNS is a sanctuary site for HIV due to the presence of barriers such as the blood brain barrier (BBB) and choroid plexus. These structures significantly limit the CNS delivery of ART drugs which prevents control of viral replication and the associated negative effects on cognition. Therefore, novel strategies need to be developed for both treatment and viral reservoir clearance in the brain. We recently optimized a novel technique called focused ultrasound induced blood brain barrier opening (FUSS-BBBO) to overcome BBB permeability constraints. FUS-BBBO has been safely and successfully used to deliver anticancer chemotherapy drugs directly into brain tumors in human patients and target large brain regions in rodents and nonhuman primates for gene delivery. FUS-BBBO uses low-intensity ultrasound with systemically administered microbubbles, which oscillate in blood vessels at the ultrasound focus, resulting in safe, localized, temporary (6- 24 h), and reversible opening of the BBB. FUS-BBBO has been successfully used to deliver proteins, small molecules, and viral vectors without inflicting detectable tissue damage in both rodents and nonhuman primates. Therefore, in the present study, we will use FUS-BBBO to deliver long-acting cART (Cabotegravir and Islatravir) drugs in conjunction with an anti-inflammatory delta-9-tetrahydrocannabinol treatment to two specific areas of the brain (basal ganglia and hippocampus) known to be targeted by HIV/SIV for better control of viral replication and persistence. In addition, we will use Adeno-Associated vector particles to deliver a gene therapeutic blocking SIV infection (anti-SIV glycosylphosphatidylinositol-anchored single chain variable fragments (scFvs) to brain resident macrophages and microglia for durable suppression of viral replication in the brain following cART interruption. These new technologies will be tested in the SIV-infected rhesus macaque model that shows consistent CNS infection, and neuroinflammation under suppressive cART. While both Cabotegravir and Islatravir have been independently demonstrated to reduce plasma viremia in the human and rhesus macaques, our studies will for the first time directly test the efficacy of these drugs administered using subdermal nanofluidic implants on HIV/SIV replication in brain resident perivascular macrophages and microglia. The proposed studies will help establish the FUS-BBBO method to increase cART drug delivery to the brain for reduction of neuro- HIV/SIV infection and its adverse effects on brain function. Finally, these studies will also help evaluate the safety and efficacy of FUS-BBBO delivery of long-acting cARTs and novel AAV-delivered anti-HIV/SIV inhibitors to the brain.
