{ "abstract": "Human cytomegalovirus (HCMV) is a major pathogen affecting immunocompromised individuals. Current antiviral drugs target the mid-to-late stages of viral replication but are limited by toxicity and drug resistance. The IE1 protein serves as a key early regulator of HCMV replication; however, it has long been considered undruggable due to the lack of conventional drug-binding sites. In this study, by integrating molecular docking-based virtual screening with in-vitro surface plasmon resonance (SPR) validation, we discovered for the first time that the HIV protease inhibitor ritonavir may bind to the IE1 protein. Further experiments demonstrated that ritonavir significantly reduces IE1 protein levels in a time- and dose-dependent manner without affecting its mRNA expression. Mechanistic investigations revealed that ritonavir promotes selective degradation of IE1 through activation of the ubiquitin-proteasome pathway. Functional assays confirmed that ritonavir effectively inhibits HCMV replication, markedly reducing viral DNA loads and the production of infectious viral particles. Notably, ritonavir exhibited synergistic antiviral effects when combined with the first-line drug ganciclovir (GCV). In summary, this study successfully repurposes the approved drug ritonavir as a regulator of IE1 protein expression, demonstrating not only its anti-HCMV activity and synergistic effects with GCV but also providing a new therapeutic strategy for HCMV infection. Author summary: Human cytomegalovirus (HCMV) represents a major threat to immunocompromised patients. However, currently available antivirals, which primarily target the mid-to-late stages of viral replication, are limited by toxicity, drug resistance, and insufficient efficacy against latent infection. Early viral regulators therefore constitute promising therapeutic targets. Here, using molecular docking-guided drug repurposing, followed by in vitro SPR binding assays we identified the HIV protease inhibitor ritonavir as a binder of the immediate-early protein IE1, a critical early regulator of HCMV replication that has long been considered undruggable owing to the absence of canonical drug-binding pockets. Ritonavir promoted ubiquitin–proteasome-dependent degradation of IE1, thereby exerting antiviral activity. Notably, ritonavir exhibited synergistic antiviral effects when combined with GCV. These findings provide a mechanistic rationale for combining drug-repurposing strategies with proteasome-dependent degradation approaches in future anti-HCMV investigations.", "abstract_shown": true, "affiliations": [ "Wenzhou Collaborative Innovation Center of Gastrointestinal Cancer in Basic Research and Precision Medicine, Wenzhou Key Laboratory of Cancer-related Pathogens and Immunity, Department of Microbiology and Immunology, School of Basic Medical Sciences, Wenzhou Medical University, Wenzhou, China.", "College of Information Engineering, Northwest A&F University, Xianyang, Shaanxi, China.", "The Second Affiliated Hospital, Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China.", "Zhejiang Key Laboratory of Intelligent Cancer Biomarker Discovery and Translation, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China." ], "article_type": "Research Article", "arxiv": null, "author_total": 10, "authors": [ { "affs": [ 0 ], "name": "Wanfeng Liu" }, { "affs": [ 0 ], "name": "Yu Shi" }, { "affs": [ 1 ], "name": "Xudong Guo" }, { "affs": [ 0 ], "name": "Chenyu Lou" }, { "affs": [ 0 ], "name": "Zhangyi Xie" }, { "affs": [ 0 ], "name": "Yitian Shen" }, { "affs": [ 2 ], "name": "Liang Zhang" }, { "affs": [ 0 ], "name": "Sunzhong Mao" }, { "affs": [ 0, 3 ], "name": "Xiangyang Xue" }, { "affs": [ 0, 3 ], "name": "Shiyu Feng", "orcid": "0009-0009-9622-9726" } ], "bibtex": "https://research.draconitic.com/paper/fv4ycqq8en56m.bib", "cited_by": 0, "doi": "10.1371/journal.pcbi.1014867", "fulltext_url": "https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1014867", "id": "fv4ycqq8en56m", "issns": [ "1553-7358", "1553-734X" ], "landing_url": "https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1014867", "language": "eng", "licence": "CC-BY", "licence_label": "CC BY", "licence_source": "article", "licence_url": "https://creativecommons.org/licenses/by/4.0/", "metadata_licence": null, "native_subjects": [ [ "openalex", "2713|Cytomegalovirus and herpesvirus research" ], [ "plos", "/Biology and life sciences/Biochemistry/Proteins/Post-translational modification/Ubiquitination" ], [ "plos", "/Biology and life sciences/Immunology/Vaccination and immunization/Antiviral therapy" ], [ "plos", "/Biology and life sciences/Microbiology/Medical microbiology/Microbial pathogens/Viral pathogens/Herpesviruses/Human cytomegalovirus" ], [ "plos", "/Biology and life sciences/Microbiology/Virology/Viral replication" ], [ "plos", "/Biology and life sciences/Molecular biology/Molecular biology techniques/Molecular biology assays and analysis techniques/Gene expression and vector techniques/Protein expression" ], [ "plos", "/Biology and life sciences/Organisms/Viruses/DNA viruses/Herpesviruses/Human cytomegalovirus" ], [ "plos", "/Biology and life sciences/Organisms/Viruses/Viral pathogens/Herpesviruses/Human cytomegalovirus" ], [ "plos", "/Medicine and health sciences/Immunology/Vaccination and immunization/Antiviral therapy" ], [ "plos", "/Medicine and health sciences/Pathology and laboratory medicine/Pathogens/Microbial pathogens/Viral pathogens/Herpesviruses/Human cytomegalovirus" ], [ "plos", "/Medicine and health sciences/Public and occupational health/Preventive medicine/Vaccination and immunization/Antiviral therapy" ], [ "plos", "/Physical sciences/Chemistry/Computational chemistry/Molecular dynamics" ], [ "plos", "/Physical sciences/Physics/Thermodynamics/Free energy" ], [ "plos", "/Research and analysis methods/Chemical characterization/Binding analysis" ], [ "plos", "/Research and analysis methods/Molecular biology techniques/Molecular biology assays and analysis techniques/Gene expression and vector techniques/Protein expression" ] ], "openalex": "W7220676219", "pdf_url": "https://journals.plos.org/ploscompbiol/article/file?id=10.1371/journal.pcbi.1014867&type=printable", "pmcid": "PMC13705602", "pmid": "42837399", "published": "2026-10-06", "publisher": "Public Library of Science", "ris": "https://research.draconitic.com/paper/fv4ycqq8en56m.ris", "sources": [ { "first_seen": "2026-10-30T12:17:37Z", "native_id": "10.1371/journal.pcbi.1014867", "source": "plos", "url": "https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1014867" }, { "first_seen": "2026-10-30T12:18:10Z", "native_id": "MED:42837399", "source": "europepmc", "url": "https://europepmc.org/article/MED/42837399" } ], "subjects": [ { "field": "biochemistry", "origin": "plos:molecular biology", "subfield": "molecular-biology" }, { "field": "biology", "origin": "plos:immunology", "subfield": "immunology" }, { "field": "biology", "origin": "plos:microbiology", "subfield": "microbiology" } ], "title": "Repurposing ritonavir to induce proteasomal degradation of IE1 for inhibition of human cytomegalovirus replication", "title_text": "Repurposing ritonavir to induce proteasomal degradation of IE1 for inhibition of human cytomegalovirus replication", "type": "peer-reviewed", "updated_at": "2026-10-30T12:18:10Z", "url": "https://research.draconitic.com/paper/fv4ycqq8en56m", "venue": "PLOS Computational Biology", "versions": [] }