In June 1986 a symposium was held in Giessen on Modern Trends in Virology. It was initiated by the Deutsche Forschungsgemeinschaft, which had supported virus research for the past 18 years in the Sonderforschungsbereich 47 at the University of Giessen. The purpose of the meeting was to serve as a forum for the members of the Sonderforschungsbereich to discuss scientific topics of mutual interest with about 200 virologists that had come from various parts of Europe, the United States, and Japan. It was not by chance that the symposium took place shortly after the 60th birthday of Rudolf Rott, who had founded the Sonderforschungsbereich in 1968 and has been its speaker ever since. Without his vision and his never resting energy Giessen would not have gained the position in the field of virology that it has today. This Festschrift, which contains the contributions presented at the plenary sessions of the symposium, is therefore dedicated to Rudolf Rott. HEINZ BAuER HANS-DIETER KLENK CHRISTOPH SCHOLTISSEK Table of Contents A Genetic Approach to Determining Glycoprotein Topology: The Influenza B Virus NB Glycoprotein has an Extracellular NHz-Terminal Domain Containing two N-linked Carbohydrate Chains R. A. LAMB and M. A. WILLIAMS. 1 Paramyxovirus Metabolisms Associated with the Cytoskeletal Framework Y. NAGAI, T. ToYODA, and M. HAMAGUCHI. 15 Correlation of High Evolutionary Rate of Influenza A Viruses in Man with High Mutation Rate Measured in Tissue Culture: A Hypothesis P. PALESE.