Figure 2. Effects of prior H1N1 immunity on bovine H5N1 virus replication in ferrets.

A. Schematic of experimental timeline. Two groups of ferrets were intranasally infected with cow/Tx/24 H5N1; group 1 had been infected with H1N1pdm09 98 days prior (N=5) and group 2 were immunologically naïve (N=5). Three animals from each group were sacrificed at day 3 post-infection. The remaining ferrets from group 1 and 2 were monitored until day 14 post-infection or until the endpoint criteria were reached. Schematic was created in BioRender. B. Tissues from cow/Tx/24 H5N1 infected ferrets with no prior immunity (black, N=3) or H1N1pdm09 prior immunity (red, N=3) were collected at day 3 post-infection. Mean +/− SD of viral titers are shown with each circle representing an individual ferret. Unpaired t-test analysis was used to determine statistically significant differences (lungs p=0.0124; trachea p<0.0080; soft palate p=0.0072; nasal turbinates (NT) p=0.0061; small intestine p=0.0014). Open circles indicate those values that are above the limit of detection. C. Viral titers from nasal secretions of each individual ferret are represented by each circle with a line indicating the mean for each group. Nasal wash samples were collected on the indicated days post-infection (N=5 on days 1–3; N=2 on day 4 until end of the study). The dashed line represents the limit of detection.