Researchers from Florida State and BYU recently used a 900 megahertz magnet to image the M2 protein of influenza A. The magnet offers an inside view of the virus similar to the images seen with magnetic resonance imaging (MRI). Because the M2 protein exists in a water-repellent cell membrane, it cannot be imaged using MRI because MRI scans spin hydrogen water molecules. To image M2 researchers used a technique called solid-state nuclear magnetic resonance spectroscopy that spins molecules other than hydrogen and makes it possible to image proteins outside of a watery medium.
By focusing on nitrogen atoms, researchers found that M2 is activated in an acidic environment. Histidine carries protons from the host cell into the virus and tryptophan acts as a gate to let the protons through. Apparently, the passage of protons through M2 eventually allows the virus to reproduce.
Recently, major M2 inhibitors such as Amantadine and Rimantidine have suffered in their effectiveness because of viral mutation (i.e. M2 has changed shape). In 2006, the CDC even recommended against the use of these common drugs. Because this atomic mechanism is novel, researchers hope that it can be used to develop new antivirals against influenza. Its uniqueness makes researchers believe that any drug that utilizes the pathway will be extremely effective for a long time because it appears essential to viral replication.