TLR4 and Drosophila C virus infection: Although up-regulation of expression of AMPs by RNA viruses has been reported previously (including Drosophila C virus infection of Drosophila (Zhu, Ding & Zhu, 2013) and dengue virus infection of Aedes aegypti (Luplertlop et al., 2011)), it remains unclear how the Toll and Imd signaling pathways are activated by these viruses as they normally respond to the peptigoglycans of Gram-positive and Gram-negative bacteria respectively (Lemaitre & Hoffmann, 2007).