Testing the extent of sequence similarity among viroids, satellite RNAs, and hepatitis delta virus

A Monte Carlo method was used to test the extent of sequence similarity amo ng viroids, satellite RNAs, and hepatitis delta virus. This analysis reveal ed that there is insufficient sequence similarity among these pathogens to support the hypothesis that they have a common evolutionary origin. Further more, while definite patterns of sequence similarity were observed among so me viroids, there was a clear lack of overall similarity, indicating that a monophyletic origin for even this group cannot be reliably supported from sequence data alone.