MODEL RELEASED. Genetic analysis. Medical technician pipetting a reagent into a sample vial as part of a PCR (polymerase chain reaction) extraction. The PCR technique is used in laboratories to amplify small amounts of DNA (deoxyribonucleic acid), and is extensively used in genetics research and analysis. Here, the analysis is testing for the presence of a flu virus, and attempting to identify its genome. This work is being carried out by an employee of the UK's Health Protection Agency. The ability to quickly identify different strains of a flu virus, and develop a vaccine, is an important part of the defence against an influenza epidemic.