Giardia intestinalis- a model organism for studies of intestinal infections and cellular differenttiation
Giardia intestinalis is a major contributor to the enormous burden of diarrheal diseases with 250 million symptomatic human infections per year and it is now included in WHOs Neglected Disease Initiative. The focus of our research group is to understand the biology and pathogenesis of Giardia but also other diarrhea-inducing protozoa like Cryptosporidium.
We do this by using several different approaches that are complementary. Genome sequencing of different Giardia isolates is one approach. We have participated in the sequencing and annotation of the three first Giardia genomes from parasites in three of the major genetic groups of Giardia (see www.giardiadb.org). By using comparative genomics we have identified several genotype-specific genes that can be used in diagnosis. Genome sequencing is complemented by gene expression analyses using proteomics, microarrays, SAGE and RNA sequencing. Gene expression in Giardia is studied during different conditions like host cell interactions, differentiation and stress-conditions. This has identified several new potential virulence genes but also taught us much about the biology of the parasite. Potential virulence factors are studied further in our in vitro system that mimics host cell interaction in the human small intestine. These in vitro studies are complemented by studies using giardiasis patient material collected in Sweden, Nicaragua and Uganda. We try to study differences and similarities in the genomes of the parasites and we also study differences in the immune responses to the parasite. We also study the biology of other Diplomonads like Spironucleus and Trepomonas. The main focus has been the cytoskeleton, differentiation and the mitosome.