Induction of acquired immunity assessed by CTL activity (a) and anti-SeV antibody (b) following pulmonary administration of rSeVs. (a) CTL activities against rSeV in adults (left graph) and neonates (right graph) using splenocytes 2 weeks after vector inoculation. No significant difference could be found irrespective of the types of vectors in both animals. Note the higher levels of CTL activity in neonatal mice than those seen in adult mice. These experiments were repeated three or more times with similar results. (b) Serum levels of anti-SeV antibody 4 weeks after inoculation using commercially available ELISA. No vector-type-related difference in anti-SeV antibody was found in adult mice (left graph); in contrast, a mild but significant decrease in antibody production was observed in neonatal mice inoculated with rSeV/dFdMdNH-luciferase (right graph). The data represent a total of two independent experiments.