Fig. (1) Schematic comparison of the genome organization of coronaviruses infecting humans. Genomic maps shown are based on the complete genome sequences (NCBI accession numbers are shown in brackets): HCoV-NL63: Human coronavirus HCOV-NL63 (NC_005831); HCoV-229E: Human coronavirus 229E (NC_002645); SARS-CoV: Severe acute respiratory syndrome coronavirus (NC_004718); HKU1-CoV: Human coronavirus HKU1 (NC_006577); HCoV-OC43: Human coronavirus OC43 (NC_005147). ORFs S (1), E (2), M (3) and N (4) are shown and open reading frames encoding for accessory genes are shaded in grey. *ORF4 of HCoV-229E is shown as a single open reading frame [34].