Shanghai, March 23, 2026 – Shanghai Ark Biopharmaceutical Co., Ltd. ("ArkBio"), in collaboration with the research group led by Professor Wei Peng from the Innovative Center for Pathogen Research at Guangzhou National Laboratory, has published a mechanistic work of ziresvior in the international journal PLOS Pathogens . Utilizing cryo-electron microscopy (cryo-EM), the study reveals the molecular mechanism how the anti-respiratory syncytial virus (RSV) drug ziresovir interacts with the RSV fusion glycoprotein at the atomic levels, providing the direct structural information for the future development of RSV therapeutics.

Source: PLOS Pathogens

RSV is a major pathogen causing severe respiratory infections in infants, young children, and the elderly, for which there is currently no specific treatment available. Ziresovir is the first anti-RSV drug to achieve positive results in a pivotal phase 3 clinical trial. Its phase 3 clinical results have been published in the New England Journal of Medicine and The Lancet Child & Adolescent Health. The drug  has since been included in the World Health Organization's (WHO) Priority List of Pediatric Drug Optimization (PADO) for treatment of RSV.

This study used cryo-EM and solved the atomic structure of ziresovir in complex with the RSV F protein. It reveals how ziresovir precisely interacts and stabilizes the prefusion conformation (preF) of the F protein, thereby blocking viral fusion with the host cell membrane. The research further confirms that ziresovir exhibits nanomolar potency against a broad range of RSV clinical isolates, including both A and B subtypes. In addition, drug-resistant mutants to ziresovir come at a high fitness cost to the virus, suggesting a low risk of clinical resistance.

This collaborative effort provides a structural foundation for the optimization of RSV therapeutics. ArkBio is committed to leveraging its R&D capabilities and partner with scientific institutes to advance its antiviral drug discovery and development programs for respiratory and lung diseases with a goal to deliver breakthrough therapeutics for unmet medical needs globally.

Reference: Yan M, Zou J, Gao Z, et al. Molecular mechanism of ziresovir targeting the fusion glycoprotein of respiratory syncytial virus. PLoS Pathog. 2026;22(1):e1013864.

About ArkBio

ArkBio is a commercial-stage biotechnology company focused on the discovery and development of innovative therapeutics for respiratory and pediatric diseases. Founded in 2014, the company has established proprietary technology platforms and a differentiated R&D pipeline through internal innovation and strategic collaborations.

Key pipeline assets include: Ziresovir (AK0529), the first direct-acting antiviral for RSV with positive pivotal Phase 3 results; AK3280, a potentially best-in-class anti-fibrotic agent with positive Phase 2 results in idiopathic pulmonary fibrosis and is advancing into Phase 3 registrational trials; AK0901, approved in China for the treatment of ADHD and currently commercialized. The company also has multiple first-in-class or best-in-class innovative candidates in clinical or preclinical development.

ArkBio has established strategic partnerships with multinational pharmaceutical companies including Roche and Genentech, leading academic institutions such as The Scripps Research Institute and the Institute of Microbiology of the Chinese Academy of Sciences, as well as domestic and international biotech companies and CROs.

For more information, please visit: www.arkbiosciences.com

Investor Inquiries: IR@arkbiosciences.com

About Guangzhou Laboratory

Guangzhou Laboratory was formally established in May 2021, with its headquarters located in Guangzhou International BioIsland. It is a new-type scientific research institution focusing on respiratory diseases and their prevention and control. As an important part of China's strategic scientific and technological strength, the laboratory adheres to the principles of being oriented to the world's scientific and technology frontiers, the main economic battlefield, major national needs, and people's lives and health. It focuses on solving key core scientific and technological problems in the field of respiratory diseases and their prevention and control, builds comprehensive innovative research platforms and facility clusters, and creates key scientific and technological forces for the prevention, early warning, and control of respiratory diseases. It strives to become a large-scale comprehensive research base and a source of original innovation that integrates breakthrough, leading, and platform-based approaches with global influence.