Gene regulatory role of vIRF1 in KSHV infection

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Abstract Infection of humans by the oncogenic Kaposi's sarcoma-associated herpesvirus (KSHV) starts in the oral cavity by replicating in oral epithelial cells. Regulation of lytic KSHV infection of the oral epithelium is still poorly understood, which hampers the development of effective antiviral therapies to block KSHV transmission. One of the unique features of KSHV is that it encodes four different viral interferon regulatory factors (vIRFs), which are homologous with cellular interferon regulatory factors (IRFs). One of them is vIRF1, which is expressed the earliest and at the highest level during KSHV infection and is used by KSHV to control many different aspects of the pathogenesis such as blocking antiviral response or stimulating oncogenesis and the growth of infected cells. While the function of vIRF1 in the inhibition of different immune response signaling pathways have been studied in detail, the transcriptional function of vIRF1 in the regulation of both KSHV and host cellular genes that are important in viral pathogenesis is still poorly understood. vIRF1 is 449 amino acid long protein. It has a putative DNA-binding domain (DBD), which also contains a nuclear localization signal (NLS), and it has a C-terminal IRF interaction domain (IAD). My preliminary experiments revealed that the DNA-binding domain (DBD) of vIRF1 is required for vIRF1-mediated host and viral gene induction, indicating vIRF1 induces both viral and host genes by binding to their promoters. Our research group has also identified the viral and host proteins interacting with vIRF1 by protein complex purification. This revealed the interaction of vIRF1 with histone acetyltransferases (HATs) that often serve as co-factors for various DNA-binding transcription factors in gene induction. I hypothesize that vIRF1 can bind to specific host and viral promoters and uses HATs to induce their corresponding genes to enhance the lytic KSHV infection in oral epithelial cells. I propose two specific aims to test my hypothesis. Aim 1 focuses on identifying the host genes that are directly targeted by vIRF1 in the absence of the other vIRFs in KSHV-infected oral epithelial cells. Aim 2 is to determine the vIRF1 response element in vIRF1 target KSHV promoters that is required for vIRF1-mediated promoter activation. The completion of this project will provide in-depth training in virology, epigenetics and genomics approaches as these methods will be used to elucidate this critical host pathogen interactions. The Comprehensive Training Program in Oral Biology at the University of Florida College of Dentistry will provide me an outstanding environment to prepare me for a career as a dentist scientist by providing personalized mentorship and excellent clinical and research training.