Antisense Oligonucleotides Targeting Influenza A Segment 8 Genomic RNA Inhibit Viral Replication.

Influenza A virus (IAV) affects 5%-10% of the world's population every year. Through genome changes, many IAV strains develop resistance to currently available anti-influenza therapeutics. Therefore, there is an urgent need to find new targets for therapeutics against this important human respiratory pathogen. In this study, 2'-O-methyl and locked nucleic acid antisense oligonucleotides (ASOs) were designed to target internal regions of influenza A/California/04/2009 (H1N1) genomic viral RNA segment 8 (vRNA8) based on a base-pairing model of vRNA8. Ten of 14 tested ASOs showed inhibition of viral replication in Madin-Darby canine kidney cells. The best five ASOs were 11-15 nucleotides long and showed inhibition ranging from 5- to 25-fold. In a cell viability assay they showed no cytotoxicity. The same five ASOs also showed no inhibition of influenza B/Brisbane/60/2008 (Victoria lineage), indicating that they are sequence specific for IAV. Moreover, combinations of ASOs slightly improved anti-influenza activity. These studies establish the accessibility of IAV vRNA for ASOs in regions other than the panhandle formed between the 5' and 3' ends. Thus, these regions can provide targets for the development of novel IAV antiviral approaches.