Enhanced viral infectivity and reduced interferon production are associated with high pathogenicity for influenza viruses
Fig 7
A model diagram of immune response to influenza viral infection.
A detailed model (Eqs 1–10)) description is given in Materials and Methods. Plus (+) superscript indicates the promotion of a biological process, and minus (−) superscript means the inhibition of a process. In brief, influenza virus (V) turns susceptible epithelium cells (T) into eclipse-phase infected cells (L) which in turn, become infected cells (I) that actively produce new viruses. The virus also infects resting macrophages (MR) and turns them into pro-inflammatory macrophages (M1). Viruses are cleared through the MR macrophage ingestion and antibody neutralisation. Infected cells (I) and M1 macrophages produce interferons (F) that turns susceptible cells (T) into refractory cells (R). The refractory cells (R) lose protection and turn back to T. Infected cells (I) are killed and become dead cells (D) through interferons- and CD8+ T cells-mediated clearance. M1 macrophages clear dead, which facilitates the conversion of MR to anti-inflammatory M2 macrophages. Both activated M1 and M2 macrophages convert back to MR macrophages at certain rates. For clarity, flows depicting the natural decay of activated macrophages (M1 and M2), virus (V) and interferons (F), and the replenishment of resting macrophages (MR) and target cells (T) are not shown in the diagram. The figure was created with BioRender.com.