title: Is human giardiasis caused by two different Giardia species?
abstract: We have recently sequenced the genome of the human Giardia intestinalis assemblage B isolate GS.1 comparisons to the earlier sequenced genome of the human assemblage A isolate WB showed that the average amino acid identity in 4,300 orthologous proteins was only 78%. Here we discuss these results in the light of new genome sequencing data from the hoofed-animal assemblage E (isolate P15, isolated from a pig) and further characterization of assemblage A and B isolates from humans. There is a highly conserved set of core genes (4,557 genes, 91% of genome) common to all isolates. The largest genomic differences are found in variable, Giardia-specific gene families and a large number of chromosomal rearrangements were detected, even between different chromosomes. Surprisingly, the assemblage E and A isolates are more similar at the amino-acid level than the two human isolates are to each other. This strengthens our earlier data suggesting that humans are infected by two different species of Giardia.
authors.affiliation: Department of Cell and Molecular Biology, BMC, Uppsala University, Uppsala, Sweden.
authors.forename: Jon
authors.initials: J
authors.lastname: Jerlström-Hultqvist
authors.forename: Johan
authors.initials: J
authors.lastname: Ankarklev
authors.forename: Staffan G
authors.initials: SG
authors.lastname: Svärd
mesh_terms: D000818:Animals; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics*; D015321:Gene Rearrangement; D017125:Genes, Protozoan; D016678:Genome; D005838:Genotype; D005872:Giardia / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D005873:Giardiasis / Q000469:parasitology* / Q000662:veterinary*; D006801:Humans
chemical_list: D016054:DNA, Protozoan