Viral titration of the mouse lung, spleen, and brain for the AB14 (H5N1) and BC15 (H7N9) strain isolates. Mice were intranasally infected with 103 PFU, 104 PFU, or 105 PFU of AB14 (H5N1) or BC15 (H7N9). The lung, spleen, and brain tissues were collected and homogenized for virus titration by TCID50 assay. Lung viral titration from (A) AB14 (H5N1) and (B) BC15 (H7N9) infection for all doses. Brain viral titration from (C) AB14 infection (H5N1). Spleen viral titration from (D) AB14 (H5N1) infection. Please note that BC15 (H7N9) was not detected in the spleen and brain of mice infected by all three doses.