Reverse transcriptase polymerase chain reaction for amantadine susceptibility testing of influenza viruses

The clinical use of amantadine for influenza A viruses infection is increasing. A novel quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assay was developed to determine the IC50 (dose of 50% inhibitory) of amantadine. The traditional amantadine susceptibility testing by plaque inhibition assay took 3 days to observe plaque formation. In contrast, the proposed assay took 3 hours to detect viral RNA. The RT-PCR products can be directly sequenced for screening and identifying the resistant strains.