RNPC3 and viral infectious disease: To pursue the hypothesis that a viral polypeptide acts as an adapter between the viral transcription machinery and the cellular export pathway, we compared the localization of individual viral mRNAs in the context of virus infection and in the context of an RNP reconstitution system, reasoning that the latter approach might reveal a role for a viral component other than the minimal requirements of the three polymerase subunits and NP (3PNP) needed for transcription in a minireplicon assay.