Role of Memory T Cells in Influenza Viral Infection

The major role of memory T cells is to ensure protection upon re-exposure to pathogens through rapid clonal proliferation and functional activation. This immunity usually persists for periods which can extend for over 60 years. These memory T cells are generated during acute viral infections. In the context of influenza viral infection, the presence of neutralizing antibodies against influenza virus proteins provides the first line of defense that prevents viral colonization and replication. Long-lasting humoral protective immunity is also needed for protection. However, antibodies against one subtype are usually inefficient in providing protection against other subtypes in humans. Major cytotoxic T-cell responses are usually targeted against conserved internal viral proteins. Moreover, the generated CTL responses are cross-reactive between influenza subtypes. In this review, we will discuss the generation and persistence of memory T cells and the role they play during influenza viral infection. An overview of new vaccine approaches aiming at the development of protective T-cell immune memory against influenza infection will also be provided.