Rifampicin for COVID-19

RNA viruses, such as SARS-CoV-2 and influenza, pose a persistent threat to global public health. Their high mutation rates undermine the effectiveness of conventional direct-acting antivirals (DAAs) and facilitate drug resistance. As obligate intracellular parasites, RNA viruses rely extensively on host cellular machinery and metabolic pathways throughout their life cycle. This dependency has prompted a strategic shift in antiviral research—from targeting the mutable virus to targeting relatively conserved host dependency factors (HDFs). In this review, we systematically analyze how RNA viruses exploit HDFs at each stage of infection: utilizing host receptors for entry; remodeling endomembrane systems to establish replication organelles; hijacking transcriptional, translational, and metabolic systems for genome replication and protein synthesis; and co-opting trafficking and budding machinery for assembly and egress. By comparing strategies across diverse RNA viruses, we highlight the broad-spectrum potential of HDF-targeting approaches, which offer a higher genetic barrier to resistance, providing a rational framework for developing host-targeting antiviral therapies.

Abstract Background Viruses such as Ebola, Marburg, influenza, mpox, MERS-CoV, SARS-CoV, and SARS-CoV-2 pose a significant risk for future pandemics. Developing novel antiviral medicines can be time-consuming and resource intensive. Repurposing existing medicines with antiviral activity offers a faster, cost-effective strategy to expand treatment options during public health emergencies. This scan aimed to identify and synthesise recent evidence on repurposed antiviral medicines under investigation for these viruses. Method A horizon scanning approach was employed, starting with a targeted search in Embase, followed by a systematic search of ClinicalTrials.gov to capture the developmental stages of the technologies. Eligible technologies included UK- or EU-licensed medicines repurposed as antiviral therapies for the viruses of interest. Vaccines, unlicensed medicines, and already approved treatments for the targeted viruses were excluded. Results A total of 196 repurposed technologies targeting the viruses were identified from published literature, and the expanded search on the clinical trials registry yielded 58 technologies in active clinical development. Interventional clinical trial activity was limited to influenza and COVID-19, with 29 technologies for COVID-19 and two for influenza advancing to phase III evaluation. For other viruses, proposed antiviral candidates were identified in the literature but had not progressed into clinical development. Commonly investigated pharmacological classes included direct-acting antivirals, tyrosine kinase inhibitors, immunomodulators, and anti-inflammatory agents. Conclusion Repurposing antiviral medicines represents a pragmatic strategy for rapid therapeutic deployment against emerging viral threats. Collaboration among researchers, policymakers, research funders, and regulatory bodies will be essential to improve pandemic preparedness and support repurposing efforts in emergency situations.