A role of hypoxia-inducible factor 1 alpha in Murine Gammaherpesvirus 68 (MHV68) lytic replication and reactivation from latency

Abstract

Lytic replication of Kaposi's Sarcoma Associated Herpes Virus (KSHV) exacerbates Kaposi's sarcoma (KS) progression, an angiogenic spindle‐cell sarcoma associated with AIDS. Current antiviral therapy targeting lytic replication can prevent KS in seropositive patients. KSHV lytic infection is not manifested in vitro, and currently there are no animal models that display pathogenic phenotypes. In this study, we employed a biological and genetically mouse pathogen similar to KSHV, the murine gammaherpes virus (gHV) 68 (MHV68), that readily infects laboratory mice providing a valuable small animal model. Moreover, MHV68 in vitro infection exhibits a default lytic infection. Several studies have shown that during infection KSHV employs several viral proteins to de‐regulate the host transcription factor hypoxia inducible factor 1 alpha (HIF1α) and KSHV‐induced activation of HIF1α is necessary for viral persistence and KS progression. However, little is known about the role of HIF1 α in gHV replication and pathogenesis. To further investigate the role of this host factor, we induced transcriptional inactivation of HIF1α in MHV68 virus‐specific cells in vivo. Conditional knock out of HIF1α was achieved by infecting transgenic mice with Cre‐recombinase (Cre) LoxP specific site within the functional domain of HIF1α gene using a recombinant MHV68 that expressing a CMV driven Cre expression. Our data demonstrated for the first time that HIF1α inactivation during gammaherpes virus infection in vivo affects viral gene transcription resulting in impaired virus expansion and early clearance of acute infection in a mouse model. In addition, our results from in vitro MHV68 lytic infection of mouse fibroblasts lacking HIF1α showed that lytic virus production and transcription is decreased. During latency establishment in vivo, the frequency of MHV68 latent splenocytes undergoing latent to lytic replication was largely decreased as well. Our data suggest that HIF1α is required for sustained acute infection since it's deletion in virus‐infected cells resulted in early clearance of productive infection and impairment in reactivation. Moreover, HIF1α is required for mRNA upregulation of glycolytic enzymes during MHV68 lytic infection suggesting a role for HIF1a as a modulator of cell energetics and viral gene expression. We conclude that gammaherpes viruses required the function of the cellular host factor HIF1α in order to effectively replicate and establish latency within its host. Support or Funding Information National Cancer Institute 3R01CA136387‐08S1 This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

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