As a first step towards the understanding of the pathogenicity difference between CedPV and HeV, we examined the IFN responses in human HeLa cells upon virus infection. As shown in Fig. 6 , while the induction of IFN-a was similar in cells infected with HeV or CedPV, there was a significant difference of IFN-b production upon infection by HeV or CedPV, with CedPVinfected cell producing a much higher level of IFN-b.