Targeting Nuclear HSF1 as a Novel Anti-HCMV Strategy

Project Summary
Human cytomegalovirus (HCMV) infects the majority of people in the world and can cause serious disease in
immunocompromised patients and neonates. The virus establishes life-long latency in bone marrow cells and
disseminates to peripheral organs in quiescently infected monocytes. Antiviral therapy delays virus replication,
but does not eliminate infected cells. Virus rebound, resistance, and drug toxicity complicate treatment and
create a strong demand for improved therapeutics. We advocate that the suppression of HCMV replication must
be in combination with the killing of infected monocytes. We found that HCMV infection of fibroblasts and
monocytes rapidly stimulated the activity of heat shock factor (HSF) 1, a stress-responsive transcription factor,
in a distinct fashion from canonical activation induced by heat shock (HS). Using a novel tool compound called
DTHIB, which has been validated to selectively inhibit HSF1 activity, we found inhibition of HSF1 with DTHIB
attenuated HCMV lytic replication and stimulated death of latently infected monocytes. These studies provide
the beginnings of a proof-of-concept study that HSF1 antagonists may have the capacity to provide the double
“hit” necessary to suppress HCMV replication and eliminate latently infected myeloid cells in a single drug. Thus,
our central hypothesis is that inhibition of HSF1 with the tool compound DTHIB will limit both infection
and spread within an infected host by concomitantly attenuating HCMV lytic replication in permissive
cell types and eliminating latently infected monocytes. The first aim will continue to evaluate the antiviral
potential of DTHIB as an inhibitor of HCMV lytic replication by examining the drug efficacy on different HCMV
permissive cell types, viral strains, and multiplicities of infection (MOIs). We will also conduct transcriptome (RNA
sequencing) analyses and functional studies using DTHIB to identify genes dependent on HCMV-induced HSF1
activity responsible for promoting lytic replication and the impact of DTHIB on the expression of this HCMV-
induced, HSF1-dependent gene profile. The second aim will continue to assess the ability of DTHIB to stimulate
the death of latently infected monocytes by testing the selective drug toxicity on monocytes infected with different
viral strains and at different MOIs. In conjunction, we will perform translatome (polysomal profiling) analyses and
functional studies using DTHIB to identify HSF1-dependent genes responsible for promoting the survival of
latently infected monocytes. The third aim will assess the in vivo antiviral activity of DTHIB on lytic replication,
viral spread, and pathogenesis using a novel murine transplant model with human skin organ, which can
simultaneously monitor HCMV replication in human tissue as well as monitor monocyte-mediated HCMV spread
to distal sites.

Grant Number: 5R01AI170834-04
NIH Institute/Center: NIH
Principal Investigator: Gary Chan