from other virus families with similar properties. Ef fi cient propagation of astrovirus
strains from both human and animal origin in cultured cells has permitted advances
in the characterization of their life cycle (Fig. 2.1 ). After astrovirus cell entry, the
genomic RNA is uncoated and is then translated into a polyprotein precursor that is
subsequently cleaved into the proteins required for replication of the virus genome
and assembly of progeny viruses. These processes most likely take place in association
with cellular membranes, and completion of the virus life cycle requires the
action of caspases for the virus particles to exit the cell.