Opening Lecture.- 1 Attentuation in the Control of Gene Expression in Animal Viruses.- Reassortment of Viruses with Divided Genome.- 2 The Use of Reassortant Bunvaviruses to Deduce Their Coding and Pathogenic Potentials.- 3 Genetic Diversity of Buvnaviruses and Mechansisms of Genetic Variation.- 4 Variations In Rift Valley Fever Virus.- Molecular Mechanisms In Acute, Persistent and Latent Infections.- 5 Pathogenic Aspects of Murine Coronavirus Infection In Rats.- 6 Persistent Paramvxovirus Infection In Vitro and In Vivo.- 7 Factors Involved In Measles Virus Persistence.- 8 Mechanism of Adeno-Associated Virus Latent Infection.- 9 Host Range Transition of Lymphotropic Minute Virus of Mice During Persistent Infection In L-Cells.- 10 Transplantation of Mouse Genes into Rat Cells Chronically Infected by Moloney Leukemia Virus (Mo-MuLV).- Promoters in Pathogenesis.- 11 Transforming Genes of Retroviruses and Cancer Cells.- 12 Control Elements for the Expression of DNA Tumor Viruses.- 13 Non-Expressed Tumor Virus Oncogenes Can Be Activated by Tumor Promoters.- 14 Rearrangement and Activation of a Cellular Oncogene.- 15 Pathogenicity of Vesicular Stomatitis Virus Is Potentially Mediated by Wild-Type Leader RNA which Inhibits Initiation of Transcription.- 16 Structural Features of Picornavirus RNA Involved in Pathogenesis: A Very High Affinity Binding Site for A Messenger RNA-Recognizing Protein.- 17 Molecular Approach to Virulence: Isolation and Characterization of Avirulent Mutants of Rabies Virus.- Cleavae of Glycoprotein In Pathogenesis.- 18 Studies on The Structure and Activities of Influenza Virus Haemagglutinin.- 19 On The Role of Viral Envelope Proteins in Pathogenesis.- 20 On The Pathogenicity of Avian Influenza Virus.- 21 Glycoproteins of Venezuelan Equine Encephalitis (VEE) Virus: Molecular Structure and Function in Virus Pathogenicity and Host Immunity.- Viral Enzymes In Pathogenesis.- 22 Isolation and Characterization of the Viral RNA Dependent RNA Polymerases from Cells Infected with Either the Mahoney or Sabin Attenuated (LSc,2ab) Strains of Poliovirus Type 1.- 23 Herpes Simplex Virus Type 1 Thymidine Kinase Controls Virus Pathogenesis and Latency in the Neivous System.- 24 Round Table Discussion.- Author Index.