New insights into the phylogeny of Entamoeba species provided by analysis of four new small-subunit rRNA genes

C. Graham Clark, Farrokh Kaffashian, Blessing Tawari, Jeffrey J. Windsor, Anke Twigg-Flesner, Mina C G Davies-Morel, Joerg Blessmann, Frank Ebert, Babett Peschel, An Le Van, Colin J. Jackson, Lorna Macfarlane, Egbert Tannich

Research output: Contribution to journalJournal Articlepeer-review

73 Citations (Scopus)


Sequences of small-subunit rRNA genes have been obtained for four new isolates of Entamoeba. Phylogenetic analyses give new insights into the evolution of these organisms. A novel Entamoeba from pigs in Vietnam that produces uninucleate cysts proved to be unrelated to other uninucleated cyst-producing species. Revival of the name Entamoeba suis for this organism is proposed. Instead of being related to Entamoeba polecki, it shares a recent common ancestor with the non-encysting Entamoeba gingivalis in a lineage that is basal to the tetranucleate cyst-producing clade. This suggests that species producing cysts with four nuclei are descended from an ancestor that produced cysts with a single nucleus. An Entamoeba from a horse was isolated in culture. No cysts were observed in the original stool sample but the sequence is placed unequivocally within the clade of tetranucleate cyst-producing species with no other sequences being specifically related. Revival of the name Entamoeba equi for this organism is proposed. The Entamoeba ecuadoriensis sequence was found to be the most closely related to Entamoeba histolytica and Entamoeba dispar, as predicted, despite the organism having been an environmental isolate originally assigned to Entamoeba moshkovskii. Finally, a partial E. polecki gene sequence from a pig proved to be virtually identical to that of Entamoeba struthionis from an ostrich, suggesting that the latter name is a synonym.
Original languageEnglish
Pages (from-to)2235-2239
Number of pages5
JournalInternational Journal of Systematic and Evolutionary Microbiology
Issue number9
Publication statusPublished - Sept 2006
Externally publishedYes


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