Beijerinck's contribution to the virus concept - an introduction.- The Prussian State and microbiological research - Friedrich Loeffler and his approach to the "invisible" virus.- The legacy of Friedrich Loeffler - the Institute on the Isle of Riems.- The post-Loeffler-Frosch era: contribution of German virologists.- Importance and impact of veterinary virology in Germany.- The evolution of viruses, the emergence of viral diseases: a synthesis that Martinus Beijerinck might enjoy.- Life beyond eradication: veterinary viruses in basic science.- Immune modulation by proteins secreted from cells infected by vaccinia virus.- Learning from our foes: a novel vaccine concept for influenza virus.- Pathogenic aspects of measles virus infections.- The glycoproteins of Marburg and Ebola virus and their potential roles in pathogenesis.- Retroviruses: ancient and modern.- Foot-and-mouth disease and beyond: vaccine design, past, present and future.- Viruses and gene silencing in plants.- Viroids and the nature of viroid diseases.