Monophyletic relationship between severe acute respiratory syndrome coronavirus and group 2 coronaviruses

Although primary genomic analysis has revealed that severe acute respiratory syndrome coronavirus (SARS CoV) is a new type of coronavirus, the different protein trees published in previous reports have provided no conclusive evidence indicating the phylogenetic position of SARS CoV. To clarify the phylogenetic relationship between SARS CoV and other coronaviruses, we compiled a large data set composed of 7 concatenated protein sequences and performed comprehensive analyses, using the maximum-likelihood, Bayesian-inference, and maximum-parsimony methods. All resulting phylogenetic trees displayed an identical topology and supported the hypothesis that the relationship between SARS CoV and group 2 CoVs is monophyletic. Relationships among all major groups were well resolved and were supported by all statistical analyses.