Influenza Virus Uncoating in Infected Cells and Effect of Rimantadine

Abstract

Uncoating of influenza virus (strain WSN) in Madin-Darby canine kidney [MDCK] cells was studied by following the fate of the virus labeled with radioactive precursors. The accumulation of subviral components of input virus was observed in nuclear-associated cytoplasm (NAC) obtained by treatment of the nuclei with citric acid. Two types of subviral components were found there, ribonucleoproteins (RNP) and larger subviral particles (SVP) containing RNP in association with M protein. SVP, with different relative amounts of M protein, were revealed in NAC, suggesting that M protein was gradually released from RNP. The released RNP entered the nuclei while M protein accumulated within perinuclear membranes. Thus, SVP could be regarded as probable intermediates in virus uncoating. Rimantadine prevented the release of M protein from RNP and their penetration into the nuclei provoking the accumulation of subviral components in NAC.