Initiation of Viral DNA Replication; Vaccinia: Virus, Vector, Vaccine; The pre-S Region of Hepadnavirus Envelope Proteins; Archaebacterial Viruses; The Lentiviruses: Maedi/Visna, Caprine Arthritis-Encephalitis, and Equine Infectious Anemia; Poliovirus Neurovirulence; The Molecular Biology of Influenza Virus Pathogenicity; Measurement of the Affinity of Antiviral Antibodies.