The flu virus causes chaos by knocking down your immune system with its protein NS1. This is the flu’s secret weapon which prevents your cells from raising the alarm until it’s too late. A lot is known about NS1, but until recently some of its functions have been misunderstood. Understanding how it behaves when it infects human cells is vital to designing effective drugs against it. The main aim of this project was to understand whether NS1 is carried from one infected cell to another by the virus. “ColourFlu” viruses are newly developed viruses which allow the viruses effects to be seen down the microscope. This makes it easier to understand how the virus infects the cell, and what it is doing to hide itself from the immune system. This investigation aims to purify one of these viruses and to use it to visualise the localisation of NS1 during early infection. To show that these viruses can be visualised by confocal microscopy, and to determine whether NS1 is carried from one cell to another via the influenza virus particle. The data produced shows these viruses can be purified in an infectious form, and that NS1 can be visualised using 3D imaging techniques. In addition to this, the 3D images produced suggested that NS1, which is traditionally thought of as a non-structural protein, is transduced from one cell to another by the influenza virion.