MODEL RELEASED. Medical analysis of virus samples. These are control samples, as part of work on virus samples that are being studied for the cytopathic effect (CPE). This effect is where cellular structure degenerates due to the multiplication of viruses in the cells. The changes in cellular structure will be examined using a microscope, such as the one in the background. A digital video camera is mounted on top of the microscope. Photographed in an NHS hospital in Cambridge, in the UK.