[Influenza virus proteins. Subcellular distribution and intracellular transport of de novo synthesized viral proteins in infected cells].

Subcellular distribution and intracellular transportation of influenza virus (WSN) proteins were studied in chick embryo cell culture. After cumulative labeling with 14C-amino acids proteins M, NSI, NP, P1, P2, P3 were found in the nuclei. In addition to these proteins, the cytoplasm contained viral hemagglutinin (HA). The content of P1, P3 and particularly P2 proteins as compared with NP was much lower in the nuclei than in the cytoplasm. P1 and P3 proteins recovered from the nuclei had a higher electrophoretic mobility in gel than similar proteins from the cytoplasmic RNP and from the virus. HA, M, and NSI proteins in the cytoplasm were detected mainly in the membrane fraction, and NP, P1, P2, and P3 in viral RNP some of which were associated with the membranes. Analysis of proteins in polyacrylamide gel showed protein P3 in RNPs associated with membranes to have a higher mobility than that in free viral RNPs. Protein P2 also accumulated in significant amounts in the cytoplasm in the soluble form. The intracellular transport of proteins was studied by the pulse-chase technique at two intervals: 3 1/2 and 6 1/2 hours postinfection. NP, M, NSI, P1, P2, and P3 proteins migrated into the nuclei at a different relative rate. The rate of migration into the nuclei of individual proteins (particularly P1, P2, and M) changed in the course of infection. A large portion of molecules of P1 and P3 proteins was present in the nuclei for 1 1/2 - 2 hours after synthesis only. The newly synthesized NP, P1, P2, and P3 proteins integrated into the free cytoplasmic RNP of the virus asynchronously.