Targeting virus-induced vulnerabilities using synthetic lethality as a new class of host-based antivirals

ABSTRACT

RNA viruses are the major class of human pathogens responsible for many global health crises, including the COVID-19 pandemic. However, the current repertoire of U.S. Food and Drug Administration (FDA)-approved antivirals is limited to only nine out of the known 214 human-infecting RNAviruses, and almost all these antivirals target viral proteins. Traditional antiviral development generally proceeds in a virus-centric fashion, and successful therapies tend to be only marginally effective as monotherapies, due to dose-limiting toxicity and the rapid emergence of drug resistance. Host-based antivirals have potential to alleviate these shortcomings, but do not typically discriminate between infected and uninfected cells, thus eliciting unintended effects. In infected cells where host proteins are repurposed by a virus, normal host protein functions are compromised;a situation analogous to a loss-of-function mutation, and cells harboring the hypomorph have unique vulnerabilities. As well-established in model systems and in cancer therapeutics, these uniquely vulnerable cells can be selectively killed by a drug that inhibits a functionally redundant protein. This is the foundation of synthetic lethality (SL). To test if viral induced vulnerabilities can be exploited for viral therapeutics, we selectively targeted synthetic lethal partners of GBF1, a Golgi membrane protein and a critical host factor for many RNA viruses including poliovirus, Coxsackievirus, Dengue, Hepatitis C and E virus, and Ebola virus. GBF1 becomes a hypomorph upon interaction with the poliovirus protein 3A. A genome-wide chemogenomic CRISPR screen identified synthetic lethal partners of GBF1 and revealed ARF1 as the top hit. Disruption of ARF1, selectively killed cells that synthesize poliovirus 3A alone or in the context of a poliovirus replicon. Combining 3A expression with sub-lethal amounts of GCA - a specific inhibitor of GBF1 further exacerbated the GBF1-ARF1 SL effect. Together our data demonstrate proof of concept for host-based SL targeting of viral infection. We are currently testing all druggable synthetic lethal partners of GBF1 from our chemogenomic CRISPR-screen, in the context of dengue virus infection for their abilities to selectively kill infected cells and inhibit viral replication and infection. Importantly, these SL gene partners of viral-induced hypomorphs only become essential in infected cells and in principle, targeting them will have minimal effects on uninfected cells. Our strategy to target SL interactions of the viral-induced hypomorph has the potential to change the current paradigm for host-based therapeutics that can lead to broad-spectrum antivirals and can be applied to other intracellular pathogens. This work is supported by National Institutes of Health grants R01 GM112108 and P41 GM109824, R21 AI151344 and foundation grant FDN-167277 from the Canadian Institutes of Health Research.Copyright © 2023 The American Society for Biochemistry and Molecular Biology, Inc.