Influenza: The Hundred-Year Hunt to Cure the 1918 Spanish Flu Pandemic

by Dr Jeremy Brown

Sticking out of its exterior are two important proteins that look like tiny spikes and pitchforks. The spiky protein is called hemagglutinin, or HA for short. After the virus is inhaled into our lungs, it is the HA that latches on to the surface of our cells. Now the virus has one foot in the door. The cell is tricked into absorbing the virus, and once inside the cell the viral membrane dissolves and releases its eight genes. These enter the nucleus of the invaded cell. From there they commandeer the normal machinery and direct the cell to make millions of copies of the viral particle. These baby particles then rise back to the cell membrane, like bubbles in a boiling pot. At the surface, they become tethered and must break free in order to invade other cells. This is where the second, pitchfork-shaped protein on the surface of the flu virus steps in. It is called neuraminidase, or NA. Its function is to break the bond between the surface of the cell and the surface of the virus. The viral progeny is now free to be coughed or sneezed out, to invade another victim. The whole process takes only a few hours, and it leaves behind destroyed respiratory cells. That is when the symptoms of influenza begin.