Phylogenetic evidence for the distinction of Saaremaa and Dobrava hantaviruses

Dobrava virus (DOBV) and Saaremaa virus (SAAV) are two closely related hantaviruses carried by different rodent species. The distinction of these two viruses has been a matter of debate. While the phylogenies based on the viral M segment sequences were repeatedly showing monophyly of SAAV strains, some trees based on the S segment sequences were not, thus causing questions on the demarcation between these two viruses. In order to clarify this issue, the current collection of the virus S segment sequences was subjected to extensive phylogenetic analysis using maximum likelihood, maximum parsimony and distant matrix methods. In all inferred phylogenies, the SAAV sequences were monophyletic and separated from DOBV sequences, thus supporting the view that SAAV and DOBV are distinct hantavirus species. Since collection of the S segment sequences used in this study "obeyed" the molecular clock, calculations of the split of DOBV and SAAV were now repeated resulting in an estimation of 3.0-3.7 MYA that is very close to the values obtained earlier.