Figure 2: PARP1 is required for synthesis of influenza nucleoprotein. (a) Host factors were targeted by RNA interference in human lung A549 cells, and after 36h knockdown, cells were infected with low-path, avian-derived influenza virus strain A/Viet Nam/1203/04 (H5N1) HALo (MOI = 0.1). Host factors targets: nucleophosmin 1 (NPM), PARP1, DEAD-box RNA helicase 17 (DDX17), and inosine monophosphate dehydrogenase 2 (IMPDH2, here shortened to IDH2), in comparison to scrambled negative control siRNA (nontarget). (b) Mean, normalized relative fluorescence intensity of total NP immunofluorescence in images quantified by (Alexa 555nm) fluorescent microscopy. siRNA targets are shown on horizontal axis.