Targeting Nuclear HSF1 as a Novel Anti-HCMV Strategy

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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.