Host restriction factors are cellular components that interfere with viral multiplication. They are up-regulated and expressed upon viral infection and in consequence their activity is specific. So far several important restriction factors have been described against diverse viruses. The cellular antiviral mechanisms defined include proteins with the ability to interfere with early steps of viral replication and others that have been shown to block viral morphogenesis. However, other strategies by which the antiviral action is exerted still remain elusive. An additional interesting matter is how viruses also developed ways to by-pass these host-specific obstacles. Thus, unusual cell localization or re-localization represents a frequent virus choice to evade the cellular surveillance. In the present chapter, we summarize methods to identify cell restriction factors, their antiviral activity, and possible subcellular locations where their activity can take place.
Keywords: Antiviral proteins; Dengue; Junín; Lipid droplets; Microscopy; Viral restriction; siRNA.