The production of a neutralizing antibody is the primary step to combat viral infection. Another important mechanism for virus elimination is the initiation of a cell-mediated immune response involving the induction of effector CD8+ cytotoxic T lymphocytes (CTL). Conserved components within the influenza A viral genome are good targets for inducing CTL responses because they can withstand viral mutations and have the capability to induce cross-reactive immune response among different subtypes and variations [14, 15, 24] .