Fig. 1: Vaccine antigens and study timeline.
A Schematic representation of CCHFV proteins encoded from S and M segments. Transmembrane domains indicated in green; signal peptide indicated in white. The second half of the figure shows the CCHFV proteins used in this study as vaccine antigens. Protein sequences were derived from CCHFV Hoti strain (accession numbers: S segment DQ133507.1; M segment EU037902.1). B Timeline showing vaccination, immunosuppression, and challenge schedule. Groups of 6 mice were vaccinated subcutaneously with NP + GP38, NP, GP38, GP85, or GP160. For pre-challenge studies, groups of mice were euthanized 14 days after their vaccination (on D14). Another group received two vaccinations with a two-week interval and was euthanized 14 days after the second vaccination (on D0). For post-challenge studies, animals received two vaccinations two weeks apart. Fourteen days after their second vaccination, animals were immunosuppressed with anti-interferon alpha/beta receptor subunit 1 monoclonal antibody (anti-IFNAR-1 mAb) MAR1-5A3 intraperitoneally before being subcutaneously challenged with 1000 TCID50 of recombinant CCHFV IbAr10200 on D0. One group of mice was euthanized on D4 to evaluate immune responses, disease progression, and virus spread. Another group was monitored for 14 days to evaluate protective efficacy of the vaccines; survivors were euthanized on D14. Graphical illustrations were prepared with BioRender (www.biorender.com).
