Fig. 1. Construction of replication-defective adenoviruses expressing nucleoprotein (NP) of influenza B virus and expression in HEK293 cells. (A) Cytotoxic T lymphocyte epitope sequences of NP restricted to MHC class I H-2D^d. (B) The recombinant adenovirus encoding NP is generated following homologous recombination with the shuttle vector and adenoviral genome. (C) Expression of NP antigens in HEK293 cells (arrow indicated) infected with each recombinant adenovirus is confirmed by Western blotting as described in the Materials and Methods.