Fig 4.

T3D^C S1 gene enhances respiratory infection and systemic dissemination. CBA/J mice were inoculated intranasally with 10⁷ PFU of T3D^F or rsT3D^F/T3D^CS1. Organs were harvested at the indicated times postinoculation, and viral titers in the lungs (A), mediastinal lymph nodes (B), and spleen (C) were determined by plaque assay using L929 cells. Results are expressed as mean viral titers for 6 mice per time point. Error bars indicate SEM. No statistically significant differences were observed between groups within panels A and B.