[Genomic organization of Norwalk-like viruses and functions of viral gene products].

Norwalk-like viruses(NLVs) that is one genus of the family Caliciviridae are major causative agents of nonbacterial acute gastroenteritis in human. NLVs have not yet been propagated in cell cultures and model animals, which restricts the fundamental studies. However, cDNA from several NLVs can be expressed in the cell-free system, bacterial cells, insect cells and mammalian cells. Studies on polyprotein processing by virus-encoded protease, enzymatic properties of RNA helicase, protease and RNA polymerase, capsid assembly, interaction between viral proteins or genomes and cellular proteins, the molecular mechanism of translation and transcription, and the crystal structure of the capsid protein and other viral proteins are in progress. Results will be useful for development of drugs for diarrheal therapy.