Cloning of a 1.8 kb repeated sequence for the identification and comparison of Giardia intestinalis isolates

Restriction enzyme digestion of bulk DNA from Giardia intestinalis reveals the presence of repeated sequences. A prominent 1.8 kb band in the Alu I profile was cloned into the pUC8 plasmid (pGI7) and used for comparing strains. When blots of DNA of 34 isolates from different geographic areas are probed with pGI7, hybridization with identical intensities can be detected. However, some strains give different hybridization patterns with several restriction enzymes. No hybridization of pGI7 can be detected with DNA from Trypanosoma brucei, Naegleria fowleri, Entamoeba histolytica and Trichomonas vaginalis. Therefore probe pGI7 may be useful in comparing different isolates as well as in screening for G. intestinalis infection.