The virus begins an infection by attaching itself to a healthy cell. The healthy cell surrounds the flu virus and takes it inside the cell through a process called endocytosis. Once inside the cell, the virus uses a protein called M2 to open a channel to the healthy cell. Protons from the healthy cell flow through the channel into the virus and raise its acidity. That triggers the release of the virus' genetic material into the healthy cell. The virus hijacks the healthy cell's resources and uses them to reproduce and spread.

When amantadine binds to and blocks the M2 proton channel, the process doesn't work and a virus can't infect a cell and spread.

Hong and the research team developed powerful techniques to study the proton channel using solid-state NMR spectroscopy, the technology behind medical magnetic resonance imaging. The techniques provided the researchers with a detailed look at the antiviral drug within the proton channel, showed them the structure of the protein at the drug-binding site and allowed them to make accurate measurements of the distances between the drug and the protein.

The researchers also found that amantadine spins when it binds to the inside of the proton channel. That means it doesn't fill the channel. And Hong said that leaves room for development of other drugs that do a better job blocking the channel, stopping the flu and evading development of drug resistance.

The research project was supported by grants of $687,411 from the National Science Foundation and $616,295 from the National Institutes of Health.

Source: Iowa State University