Swine-origin influenza-virus-induced acute lung injury: Novel or classical pathogenesis?

Influenza viruses are common respiratory pathogens in humans and can cause serious infection that leads to the development of pneumonia. Due to their host-range diversity, genetic and antigenic diversity, and potential to reassort genetically in vivo, influenza A viruses are continual sources of novel influenza strains that lead to the emergence of periodic epidemics and outbreaks in humans. Thus, newly emerging viral diseases are always major threats to public health. In March 2009, a novel influenza virus suddenly emerged and caused a worldwide pandemic. The novel pandemic influenza virus was genetically and antigenically distinct from previous seasonal human influenza A/H1N1 viruses; it was identified to have originated from pigs, and further genetic analysis revealed it as a subtype of A/H1N1, thus later called a swine-origin influenza virus A/H1N1. Since the novel virus emerged, epidemiological surveys and research on experimental animal models have been conducted, and characteristics of the novel influenza virus have been determined but the exact mechanisms of pulmonary pathogenesis remain to be elucidated. In this editorial, we summarize and discuss the recent pandemic caused by the novel swine-origin influenza virus A/H1N1 with a focus on the mechanism of pathogenesis to obtain an insight into potential therapeutic strategies.