Nuclear export of influenza virus ribonucleoproteins: Identification of anexport intermediate at the nuclear periphery

A critical phase of the influenza virus life cycle is the regulated translo cation of genomic ribonucleoproteins (vRNPs) from the nuclear interior, acr oss the nuclear envelope, and into the cytoplasm. Two viral proteins, M1 an d NS2, have previously been implicated as mediators of vRNP export. We show here that vRNP nuclear export is prevented by leptomycin B (LMB), an inhib itor of the cellular factor CRM1. in LM a-treated cells, vRNPs were found i n a peripheral nuclear location that localized with the nuclear lamina. vRN Ps were not colocalized with either M1 or NS2. In situ extraction of cells late in infection also revealed a peripheral localization of nuclear vRNPs, whereas early in infection vRNPs were dispersed throughout the nuclear int erior. We believe that vRNPs at the nuclear periphery represent a novel int ermediate in the influenza Virus nuclear export pathway. (C) 2001AcademicPr ess.