Cellular Mechanism of Oxysterol-Binding Protein (OSBP) in Viral Proliferation: A Chemical Biology Approach

The current COVID-19 crisis starkly illustrates the need to develop new modalities for the
therapeutic treatment of pathogenic single-stranded RNA (ssRNA) viruses, including against
novel viruses that have yet to emerge. Human oxysterol-binding protein (OSBP) has recently
been determined to be a critical mediator in the replication of a broad spectrum of ssRNA viral
human pathogens, including the enteroviruses, rhinovirus, hepatitis C, Zika virus, Dengue fever
viruses, and coronaviruses. OSBP is an ER-located, non-enzymatic protein reported to function
as an important lipid sensor and lipid transporter in eukaryotic cells. Published research, including
our own recent publications, has established the antiviral activity of structurally-diverse OSBP-
targeting small molecules against multiple RNA pathogenic viruses. These discoveries present
the opportunity for a paradigm shift in antiviral drug development: potentially drug targeting a
human host protein, OSBP, that is required for viral proliferation of a broad-spectrum of RNA
viruses, as opposed to targeting viral proteins present in individual viruses. We have discovered
that transient, low dose treatment with the OSBP-targeting compound OSW-1-compound induces
a longterm, multigenerational repression of OSBP, and the cells with repressed OSBP show a
pronounced inhibition of ssRNA viral replication. Our preliminary results show that the OSW-1-
compound has prophylactic antiviral activity at low nanomolar concentrations against several
ssRNA viruses, including against one coronavirus tested. The longterm repression of OSBP,
triggered by OSW-1, has no effect on cellular division, viability, or morphology.
The purpose of this proposal is to understand the cellular role of OSBP in innate antiviral
response. Our preliminary results show that OSBP: 1) regulates mTORC1 activity, 2) induces
autophagy; 3) slows global protein translation; and 4) activates alternative splicing nonsense-
mediated decay (AS-NMD) process, which is an RNA regulatory process. All of these OSBP-
involved cellular processes would limit ssRNA viral replication individually, but there is little insight
into the organization of these systems to establish a coordinated antiviral response.Our overall
hypothesis is that OSBP serves in a major regulatory role to coordinate a multifaceted innate
antiviral response to ssRNA infection. We propose a complete model of how OSBP senses early-
stage viral infection and then triggers a multisystem response to block viral replication in cells,
including through modulating mTOR1C activity and the AS-NMD system.

Grant Number: 5R01AI154274-05
NIH Institute/Center: NIH
Principal Investigator: Anthony Burgett