Overview of viral gastroenteritis.- Rotavirus structure interactions between the structural proteins.- Structure and function of rotavirus nonstructural protein NSP3.- Genome rearrangements of rotaviruses.- Structure and function of rotavirus NSP1.- Identification of the minimal replicase and the minimal promoter of (-)-strand synthesis, functional in rotavirus RNA replication in vitro.- Rotavirus protein expression is important for virus assembly and pathogenesis.- A hypothesis about the mechanism of assembly of double-shelled rotavirus particles.- Development of rotavirus molecular epidemiology electrophero-typing.- Molecular epidemiology of human rotaviruses genogrouping by RNA-RNA hybridization.- Classification of rotavirus VP4 and VP7 serotypes.- VP4 and VP7 typing using monoclonal antibodies.- Natural history of human rotavirus infection.- Protective immunity against group A rotavirus infection and illness in infants.- Rotavirus immunity in the mouse.- The gnotobiotic piglet as a model for studies of disease pathogenesis and immunity to human rotaviruses.- Jennerian and modified Jennerian approach to vaccination against rotavirus diarrhea using a quadrivalent rhesus rotavirus (RRV) and human-RRV reassortant vaccine.- Trials of oral bovine and rhesus rotavirus vaccines in Finland a historical account and present status.- WC3 reassortant vaccines in children. Brief review.- Rotavirus subunit vaccines.- DNA vaccines against rotavirus infections.- Prophylaxis of rotavirus gastroenteritis using immunoglobulin.- Historical background and classification of caliciviruses and astroviruses.- Structure of Norwalk virus.- Recombinant Norwalk virus-like particles as an oral vaccine.- Genetic and antigenic diversity of human caliciviruses (HuCVs) using RT-PCR and new EIAs.- The epidemiology of human calicivirus/Sapporo/82/Japan.- Reverse transcription-polymerase chain reaction detection and sequence analysis of small round-structured viruses in Japan.- The molecular biology of astroviruses.- The changing epidemiology of astrovirus-associated gastroenteritis a review.- Structural features unique to enteric adenoviruses.- Closing remarks.