Cell-mediated immunity to influenza virus infections: From the perspective to the vaccine development against highly pathogenic avian influenza

Abstract

Inactivated vaccines have been incorporated in the control strategies for highly pathogenic avian influenza (HPAI) in several countries. However, these conventional vaccines confer protective immunity in the hemagglutinin (HA) subtype-specific manner and inevitably promote antigenic drifts in HA of target viruses. Therefore, the efficacy of the conventional vaccines needs to be evaluated occasionally to assure that they still provide immunity against emerging or circulating field virus strains. To cover these pitfalls, novel vaccine strategies which target conserved viral antigens are currently being investigated. We hypothesize that such vaccines can be developed by utilizing cytotoxic CD8+ T cell-mediated immunity. However, we do not fully understand the mechanisms of the generation, maintenance and recall of cell-mediated immunity to influenza virus infections. Here we briefly review the current knowledge of cell-mediated immunity to influenza virus infections based on the studies using mouse models and discuss the future application of this immunological arm to the vaccines against HPAI in poultry.