Genetic distance of SARS coronavirus from the recent natural case.

Phylogenetic analysis of SARS coronavirus isolates based on the spike gene and protein sequence using Neighbor-Joining, maximum likelihood and Bayesian inference methods indicated that a recent human SARS-CoV isolate was closer to some human SARS-CoV isolates from earlier epidemic phase than to the SARS-CoV-like viruses isolated from wild animals during previous epidemic phase. A reasonable judgment based on phylogenetic relationship and sequence variations it is likely that the recent human SARS-CoV isolate is closer to an unknown SARS-CoV predecessor.