HRV A2 sequences had a higher G+C content (average, 42.4%) than all other HRVs (average 38.7%) or HEV Ds and a shorter coding region (average, 2144 aa) than any other picornavirus investigated. The final residue of the HRV A2 genomes was an isoleucine, distinguishing them from all other picornavirus genomes we investigated, which ended at the preceding phenylalanine; the biological implications of this feature are unknown.