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Nuclear Export of Influenza A Virus mRNAs Requires Ongoing RNA Polymerase II Activity
Author(s) -
Amorim MariaJoao,
Read Eliot K.,
Dalton Rosa M.,
Medcalf Liz,
Digard Paul
Publication year - 2007
Publication title -
traffic
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.677
H-Index - 130
eISSN - 1600-0854
pISSN - 1398-9219
DOI - 10.1111/j.1600-0854.2006.00507.x
Subject(s) - biology , polymerase , rna polymerase , transcription (linguistics) , rna dependent rna polymerase , rna , viral replication , rna polymerase ii , nuclear export signal , influenza a virus , five prime cap , messenger rna , microbiology and biotechnology , virus , gene expression , virology , gene , genetics , promoter , linguistics , philosophy
Influenza A virus transcribes its segmented negative sense RNA genome in the nuclei of infected cells in a process long known to require host RNA polymerase II (RNAP‐II). RNA polymerase II synthesizes pre‐mRNAs whose 5′‐cap structures are scavenged by the viral RNA‐dependent RNA polymerase during synthesis of viral mRNAs. Drugs that inhibit RNAP‐II therefore block viral replication, but not necessarily solely by denying the viral polymerase a source of cap‐donor molecules. We show here that 5,6‐dichloro‐1‐β‐D‐ribofuranosyl‐benzimidazole (DRB), a compound that prevents processive transcription by RNAP‐II, inhibits expression of the viral HA , M1 and NS1 genes at the post‐transcriptional level. Abundant quantities of functionally and structurally intact viral mRNAs are made in the presence of DRB but with the exception of NP and NS2 mRNAs, are not efficiently translated. Taking M1 and NP mRNAs as representatives of DRB‐sensitive and insensitive mRNAs, respectively, we found that the block to translation operates at the level of nuclear export. Furthermore, removal of DRB reversed this block unless a variety of chemically and mechanistically distinct RNAP‐II inhibitors were added instead. We conclude that influenza A virus replication requires RNAP‐II activity not just to provide capped mRNA substrates but also to facilitate nuclear export of selected viral mRNAs.