Defective RNA replication and late gene expression in temperature-sensitive influenza viruses expressing deleted forms of the NS1 protein.
Influenza A virus mutants expressing C-terminally deleted forms of the NS1 protein (NS1-81 and NS1-110) were generated by plasmid rescue. These viruses were temperature sensitive and showed a small plaque size at the permissive temperature. The accumulation of virion RNA in mutant virus-infected cells was reduced at the restrictive temperature, while the accumulation of cRNA or mRNA was not affected, indicating that the NS1 protein is involved in the control of transcription versus replication processes in the infection. The synthesis and accumulation of late virus proteins were reduced in NS1-81 mutant-infected cells at the permissive temperature and were essentially abolished for both viruses at the restrictive temperature, while synthesis and accumulation of nucleoprotein (NP) were unaffected. Probably as a consequence, the nucleocytoplasmic export of virus NP was strongly inhibited at the restrictive temperature. These results indicate that the NS1 protein is essential for nuclear and cytoplasmic steps during the virus cycle.
Falcón
Ana M
AM
Centro Nacional de Biotecnología, CSIC, 28049 Madrid, Spain.
Marión
Rosa M
RM
Zürcher
Thomas
T
Gómez
Paulino
P
Portela
Agustín
A
Nieto
Amelia
A
Ortín
Juan
J
D021581:Active Transport, Cell Nucleus; D000818:Animals; D019556:COS Cells; D002460:Cell Line; D004285:Dogs; D015870:Gene Expression; D005814:Genes, Viral; D006801:Humans; D009980:Influenza A virus / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D009154:Mutation; D012367:RNA, Viral / Q000096:biosynthesis* / Q000235:genetics; D017384:Sequence Deletion; D013696:Temperature; D014158:Transcription, Genetic; D014763:Viral Matrix Proteins / Q000096:biosynthesis / Q000235:genetics; D017361:Viral Nonstructural Proteins / Q000235:genetics*
C085820:INS1 protein, influenza virus; D012367:RNA, Viral; D014763:Viral Matrix Proteins; D017361:Viral Nonstructural Proteins