Construction of a genome-length cDNA clone for human astrovirus serotype 1 and synthesis of infectious RNA transcripts.

We have constructed a genome-length cDNA clone for human astrovirus serotype 1. When a human colon cancer-derived cell line, CaCo-2, is transfected with RNA transcribed in vitro from this cDNA clone, infectious virus is produced at titers close to those observed after infection with intact astrovirus. A rodent cell line, BHK, which is largely refractory to astrovirus infection, was found to support efficient growth of the virus if transfected with viral RNA. The high transfection efficiency seen in the BHK cells allows studies of the viral replication in the transfected cells and thus should prove useful for the characterization of noninfectious astroviral mutants.