Figure 9.

A model of the WNV 3′SL acting as an RNA thermometer during host switching. Due to the lower body temperature and low activities of p30/p32 in the mosquito host, the 3′SL exhibits a higher stability, which leads to inefficient cyclization and slow replication kinetics. In this way, persistent non-lethal infections in mosquitos can be established. In vertebrate hosts the higher body temperature and the strong activity of AUF1 renders the 3′SL more flexible. Consequently, cyclization is efficient, replication is fast, and high viral titers are produced, which can lead to pathogenic or lethal infections.