Isolates from civets and from early phase of the 2002/2003 pandemic contained a single long ORF8, while in the human SARS-CoV isolates from the middle and late phase of the pandemic the ORF8 was disrupted into two ORFs, ORF8a and ORF8b, as a result of the acquisition of a 29-nt deletion after interspecies transmission to humans.
