Herpesviruses are highly successful pathogens of man and animal. Over 4 billion people worldwide are infected with the best-known herpesvirus in man, herpes simplex virus (HSV). However, there is still no HSV vaccine. A successful HSV vaccine will need to activate several parts of the immune system. The immune system protects the body against infections, including by viruses, and is composed of several players. Concerning virus infections, one of the important players are the natural killer (NK) cells. It is long known that NK cells can kill virus-infected cells and can produce messenger molecules (cytokines) that help shape the antiviral immune response. However, NK cells were not considered very important in vaccine design as it was thought that they were limited to killing and cytokine secretion and that they could not 'remember' a virus (e.g. not recognise the same virus when it infects the body again, the basis of vaccination). Recent evidence challenges these ideas, with clear indications that some NK cells can present fragments of virus to other immune cells (e.g. T cells) to boost the antiviral immune response and that some NK cells do have a 'memory'. Based on our exciting recent evidence that pig NK cells highly resemble human NK cells in some of these respects, we will investigate the potential of these new NK features in herpesvirus vaccine design, using the pig and a porcine herpesvirus (pseudorabies virus, PRV) that closely resembles HSV as a model.