RT-PCR was performed on frozen tissues of the lung, kidney, liver, spleen and heart. High levels of mRNA were detected in the lungs of 2CLP animals, similar to those found in the plasmid pGL3 used as positive control for luciferase. Minimal levels were present in the liver, kidney spleen and none at all in the heart, confirming minimal systemic spread of the vector after direct intratracheal instillation. Interestingly, in T0 and SO controls, minimal Detection of the VP1 capsid protein in lung tissue Figure 4 Detection of the VP1 capsid protein in lung tissue. 4a: Positive staining for VP1 protein appears as red intracytoplasmatic coloration: moderate for SO rats (above) and high for 2CLP rats (below). DAPI (blue) was used as nuclear counter-stain. 4b: Negative control for VP1 immunostaining. Above: lung tissue from control septic rats given intratracheal PBS, and below: normal lung tissue from a control T0 rats. The minimal staining seen represents the background. DAPI (blue) was used as nuclear counter-stain. Shown at ×40 magnification. Figure 3 Luciferase immunostaining. Was performed on the lung tissue harvested from 2CLP and SO rats given intratracheal SV/luc. Positive immunostaining appears as brown intracytoplasmatic coloration (Black arrows). Shown at ×100 magnification.