The Journal of Infectious Diseases FILOVIRUS SYMPOSIUM SUPPLEMENT DOI: 10.1093/infdis/jiad226 1 Pathogenicity of Lloviu and Bombali viruses in IFNAR -/- mice Paige Fletcher 1 , Friederike Feldmann 2 , Ayato Takada 3 , Nicholas A. Crossland 4,5 , Adam J. Hume 4,6 , César Albariño 7 , Gábor Kemenesi 8 , Heinz Feldmann 1 , Elke Mühlberger 4,6 , and Andrea Marzi 1* 1 Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA 2 Rocky Mountain Veterinary Branch, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA 3 Division of Global Epidemiology, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Japan 4 National Emerging Infectious Diseases Laboratories, Boston University School of Medicine, Boston, MA, USA 5 Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, MA, USA 6 Department of Microbiology, Boston University School of Medicine, Boston, MA, USA 7 Viral Special Pathogens Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA 8 National Laboratory of Virology, Szentágothai Research Center, and Institute of Biology, Faculty of Sciences, University of Pécs, Pécs, Hungary Type I interferon receptor knockout (IFNAR -/- ) mice are not able to generate a complete innate immune response, therefore, these mice are often considered to assess the pathogenicity of emerging viruses. We sought to assess the pathogenicity of emerging wildtype filovirus infections in IFNAR -/- mice since filovirus models using immunocompetent mice require a mouse-adapted viral strain. We infected IFNAR -/- mice with a low or high dose of Lloviu virus (LLOV) or Bombali virus (BOMV) by the intranasal (i.n.) or intraperitoneal (i.p.) route and compared virus loads at early and late timepoints after infection. No signs of disease and no viral RNA were detected after i.n. infection regardless of LLOV dose. In contrast, i.p. infections resulted in increased viral loads in the high-dose LLOV and BOMV groups at the early timepoint. The low-dose LLOV and BOMV groups achieved higher viral loads at the late —————————————————————————————————————————— *Corresponding author: marzia@niaid.nih.gov Published by Oxford University Press on behalf of Infectious Diseases Society of America 2023. This work is written by (a) US Government employee(s) and is in the public domain in the US. ACCEPTED MANUSCRIPT Downloaded from https://academic.oup.com/jid/advance-article/doi/10.1093/infdis/jiad226/7205841 by guest on 25 June 2023