Fig. 6: Disease progression and infectious virus titers in organs following HPAI (H5N1) infection.

To determine median lethal dose (LD₅₀), groups of 6-week-old female BALB/c or C57BL/6J mice were anaesthetized and intranasally inoculated with 10^0.1, 10⁰, 10¹, 10² TCID₅₀ of A/bovine/OH/B24OSU-342/2024 (H5N1) in 50 µl of DMEM without supplements. Four mice per inoculation group were monitored for survival (A, B) until day 21 post inoculation or their death, whichever was earlier. To determine viral replication kinetics and tissue tropism, groups of 18 C57BL/6 J or BALB/c mice were anaesthetized and inoculated with DMEM (mock) or 10³ TCID₅₀ of A/bovine/OH/B24OSU-342/2024 intranasally in volume of 50 µl. Six mice per inoculation group were monitored for weight loss (C) survival (D) until day 28 post inoculation or their death, whichever was earlier. Six mice per inoculation group were euthanized at 2- or 4 days post inoculation at which blood and tissues (brain, lung, liver) were collected for virus titration using a TCID₅₀ assay (E–H). Dashed line indicates limit of detection. Statistical comparisons were calculated using log-rank test with Bonferroni correction for multiple comparisons (D) two-way ANOVA with Tukey’s multiple comparison test (E–H) and results are indicated as *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. Comparisons with p values > 0.05 were not displayed. C Data shown as mean plus standard deviation. E–H Violin plots show interquartile range, median and density curve.