Analysis of the phylogenetic placement of different spumaretroviral genes reveals complex pattern of foamy virus evolution.

Foamy or spumaviruses are complex retroviruses. Phylogenetic trees have been constructed previously for either the polymerase or integrase domains showed a clustering of the foamy viruses relatively distant from other retroviruses. The most related retrovirus was found to be murine leukemia virus, irrespective of the method used or foamy viral gene analyzed. We analyze bel genes of different foamy viruses and compared the corresponding phylogenetic trees with those obtained from the pol genes that were constructed with refined computer programs. In addition, the nucleocapsid protein sequence of foamy viruses was used for a comparative phylogenetic analysis. Known biological properties of the individual FV protein domains are discussed to ascertain the apparent phylogenetic relatedness.