Modeling the viral dynamics of influenza A virus infection

Influenza virus causes an acute, mostly self-limited, infection of the upper respiratory tract. Yearly epidemics of influenza infect up to 20% of the population, and in the US cause an average of 36,000 deaths every year. Because influenza is a short-term infection lasting 4 to 7 d in most cases, studying the dynamics of the virus and the immune response in vivo is difficult. Here we review the most recent attempts at mathematical modeling of influenza dynamics within the host to better understand the kinetics of the virus and associated immune responses. These models have been developed based on very successful kinetic studies of chronic infections, such as human immunodeficiency and hepatitis C viruses. We briefly review the approach taken for these infections before discussing the results obtained in the case of influenza. The dynamics of the latter have been studied both in vitro and in vivo. It was shown that the virus turnover is very fast, which helps to explain the accumulation of diversity. Moreover, initial attempts have been made at modeling the immune response to influenza, but these are still incipient and further studies, both experimental and theoretical, are needed to better elucidate the interplay of the virus and the immune response.