T-cell epitopes are intensively studied as an alternative to the current vaccine strategy based mainly on the induction of the strain specific virus-neutralizing antibodies. Identification of conserved CTL epitopes shared by many influenza strains could represent the basis of vaccination strategies. This approach would be beneficial in the case of annual influenza epidemic and a potential pandemic, when humoral immunity is poorly or not protective due to the absence of pre-existing antibodies against emerging strains in the population [90, 91] .