Herpes Simplex Virus-1 (HSV-1), a highly transmissible infection, is common and endemic throughout the world. Similar to other human herpesviruses (HHV), HSV-1 maintains lifelong latency inside host that requires immune evasion through various sophisticated mechanisms. Although HSV-1 is equipped with large repertoire (>80) of protein coding genes, the commonly accepted manifestations of viral gene expression during latency are the accumulation of a noncoding transcript and a set of microRNAs (miR). HSV-1 encoded viral miRNAs (v-miRs) are demonstrated to control expression of both viral and host transcripts and regulate viral tropism, lytic switching, immune subversion, etc. While multiple studies have examined HSV-1 profiles in various cell lines, key biological functions of these v-miRs remain unknown. Therefore, we propose to evaluate: (1) systematic expression dynamics of v-miRs during disease progression and reactivation, (2) comprehensive role in the pathogenesis by perturbing immune cells functions and (3) therapeutic targeting of v-miR by synthetic oligonucleotides to mitigate HSV-1-mediated ocular herpes. Using our established mouse model of ocular herpes, we will compare HSV-1 miRNA profiles in primary and reactivated mice corneal tissues and blood. Identifying positive and negative regulatory v-miRs can yield novel insights into host-virus interaction. The information gained will be used in designing therapeutic v-miR Inhibitors to silence candidate v-miRs functions. Effect of synthetic oligonucleotides (v-miR Inhibitors) targeting candidate v-miRs will be assessed on ocular disease progression in a mice model. V-miR inhibitors (alone or in combination) will be topically delivered and virus release, viral transcript/genome, and disease severity score will be measured. Next, we will evaluate how v-miRs can render host immune system dysfunctional, an integral feature required for HSV-1 persistence. Using v-miR inhibitors, we will assess whether immune infiltration and functions can be restored in vivo. Immune cell subsets will be comprehensively profiled in virus-infected animals treated with v-miR inhibitor using flow cytometry and single cell RNA sequencing. In addition, transcript expression profiles of genes related to antigen processing/presentation pathway, critical for potent antiviral response, will be quantified. This will identify the in vivo mechanisms through which v-miRs can facilitate immune evasion in ocular tissues. Next, we will dissect underlying mechanisms of v-miR-mediated dysregulation of antigen processing/presentation by macrophages and dendritic cells and activation of T cells. V-miR expressing myeloid cells will be assessed for uptake and processing of viral antigens and activation of autologous T helper (CD4+) and T cytotoxic (CD8+) cells. In addition, we will assess the impact of v-miRs on the polarization of CD4+ T cells. The data generated will provide significant information to existing knowledge gaps. Overall, the proposed translational study focuses on identifying the therapeutic and mechanistic aspect of v-miRs in ocular disease pathogenesis through modulation of immune cell responses.

Herpes Simplex Virus-1 (HSV-1) causes ocular (eye) herpes that affects ~500,000 people in the United States. HSV-1 encoded microRNAs (miRNA) facilitate virus to evade defense responses. We propose to identify viral miRNA species during disease progression, identify their targets and design strategy for inhibiting HSV-1 miRNAs in the eye.