The SARS-CoV2 pandemic has demonstrated on a global scale that viral infections can be highly contagious, can evolve rapidly, and are challenging to treat. The immune system provides cells with various control mechanisms to detect and prevent the spread of viral infection and further damage to the host. However, viruses have evolved methods to evade immunity, resulting in persevered viral replication and proliferation. Chronic viral infections occur when a virus evades immunity and persists in the body for an extended period, which can lead to increasingly harmful damage to the host, including increased risk of cancer. When immunity proves insufficient, alternative methods to sense virally infected cells can allow for detection and targeted elimination of the virus, which is especially necessary in cases of chronic viral infection. In this thesis, the development and characterization of RNA-editing enzymes based on adenosine deaminase acting on RNA (ADAR) that have been engineered to activate in response to viral protease is discussed. Specifically, methods for targeting ADAR editing to specific mRNA transcripts and strategies in which the editing activity of engineered ADARs has been made conditional upon viral proteolytic activity are explored. The development of fluorescent and quantitative assays to characterize systems are described and the implementation of the system to control downstream transcriptional activity is discussed. This thesis explores establishing the viability of a viral protease sensor able to be self-contained in an RNA circuit, which in the future may provide a treatment method for patients with severe symptoms or chronic viral infection. The ability to sense virally infected cells and create a functional output in specific response to viral protease presence as a potential future treatment of chronic viral infection is explored through viral protease activation of engineered ADAR enzymes to enable editing of specific mRNA transcripts. / 2025-05-24T00:00:00Z