Insertion and deletion analyses identify regions of non-structural protein 5A of Hepatitis C virus that are dispensable for viral genome replication

Department of Veterinary and Biomedical Sciences and Nebraska Center for Virology, University of Nebraska-Lincoln (UNL), E126 Beadle Center, 1901 Vine Street, Lincoln, NE 68588-0666, USA Correspondence Asit K. Pattnaik apattnaik2{at}unl.edu Hepatitis C virus (HCV) non-structural protein 5A (NS5A) plays an essential role in viral genome replication. A series of transposon-mediated insertion mutants and deletion mutants of NS5A was used to examine the colony-forming ability of HCV subgenomic replicons encoding the mutant proteins. The results reveal that two regions of NS5A can tolerate insertions: one spanning residues 240–314, which contain the interferon sensitivity-determining region (ISDR), and the other spanning residues 349–417 at the carboxy terminus. The majority of these sites also tolerated insertion of enhanced green fluorescent protein. Furthermore, replicons encoding NS5A with deletions in ISDR or in the carboxy-terminal regions were replication-competent, indicating that these regions of NS5A are not necessary for replication. Taken together, the results suggest that the central region spanning the ISDR and the carboxy-terminal region of the molecule are dispensable for the functions of NS5A in viral genome replication.