Innate and adaptive immune responses against Influenza A Virus: Immune evasion and vaccination strategies

Influenza A virus (IAV) is a contagious respiratory infection causing pathogen responsible for high morbidity and mortality rates across the planet. The human immune system contains a wide range of soluble activators, membrane-bound receptors, and regulators to eliminate IAVs. Despite these various immune mechanisms that neutralize IAVs or restrict their replication, IAVs have developed distinct strategies to evade host immunity and establish a successful infection. Given the higher and continuous rate of mutations in IAVs, decades of research have focused on understanding the host's immune mechanisms against IAVs, and the evasion strategies employed by the virus to overcome the host immune system. Future IAV pandemics or epidemics remain inevitable, and a greater understanding of the host-pathogen interaction involved is required to develop universal vaccines and treatments against IAV. Here, we review how the host immune system responds to IAV infection as well as the strategies employed by the IAV to evade host immune surveillance. Furthermore, this review also focuses on the treatments and vaccines that have been developed to counter IAV infection.