Viral diseases in animals cause animal suffering and financial losses. Therefore, vaccines have been developed to overcome these problems. This is successful for most diseases. However, for some viral diseases, vaccines are insufficiently or totally not effective. Sometimes they even cause an aggravation of the clinical sings. In order to find a solution, it is important to get better insights in the pathogenesis of these viral diseases and to orient the vaccine development. In this way, we are still successful to make a vaccine against these diseases. In the Laboratory of Virology at the Faculty of Veterinary Medicine, UGent, Prof. Nauwynck is very active in unraveling complex pathogeneses and based on the results in developing new vaccines. In shrimp, which do not possess an adaptive immunity, he introduces nanobody-genes in the genome of the host, by which the animals produce continuously antibodies against pathogens and virulence factors. As a result, these animals are protected against these noxes.