The viral burden is increased in Isg15 silenced cells. A) RNAi efficiency of specific genes. The mRNA levels of a specific gene were analyzed by Q-RT-PCR and normalized to mouse beta-actin gene. B and C) DENV (B) or WNV (C) burdens in RAW264.7 cells after RNAi silencing. Results are expressed as the mean + the SEM. * p < 0.05 and ** p < 0.01. Representative results from at least 3 independent experiments.