Illustration of replication of influenza virus. At top right, a virus particle, or virion, docks with the cell surface and enters the cell. The viral RNA is released and travels to the nucleus (where the cell’s DNA is housed). From the nucleus, the viral genes direct the production of new viral components. These aggregate below the cell surface and organise themselves into new virus particles. The newly forming virus particles bud from the cell and are released to infect other cells.