Memory T Cell Dynamics in the Lung during Influenza Virus Infection

Influenza A virus is highly contagious, infecting 5-15% of the global population every year. It causes significant morbidity and mortality, particularly among immuno-compromised and at-risk individuals. Influenza virus is constantly evolving, undergoing continuous, rapid, and unpredictable mutation, giving rise to novel viruses that can escape the humoral immunity generated by current influenza virus vaccines. Growing evidence indicates that influenza-specific T cells resident along the respiratory tract are highly effective at providing potent and rapid protection against this inhaled pathogen. As these T cells recognize fragments of the virus that are highly conserved and less prone to mutation, they have the potential to provide cross-strain protection against a wide breadth of influenza viruses, including newly emerging strains. In this review, we will discuss how influenza-specific memory T cells in the lung are established and maintained and how we can harness this knowledge to design broadly protective influenza A virus vaccines.