Popular Science Presentation

Giardia intestinalis is an intestinal, protozoan parasite affecting approximately 250 million people yearly worldwide causing symptoms such as diarrhea, nausea, vomiting and epigastric pain. Up to date there is only limited information on how G.intestinalis causes disease. We try define the role of released parasite proteins as key players involved in the host-parasite interaction, and thus in disease development. Our intention is to study several important parameters of intestinal infections and the project consists of seven major parts. We test the general hypothesis that infectious organisms decrease the level of L-arginine available for host cells by releasing arginine metabolizing enzymes in order to interfere with the innate and adaptive immune responses. Proteases and surface proteins up-regulated and released by the parasite during infection will be studied.

The fastest growing food sector in the world is aquaculture, with salmon and carp being the two most important fish species used in fish farming. Infections are well-known problems in fish farming, involving viruses, bacteria and parasites. Spironucleus salmonicida is a parasitic, eukaryotic microbe known to cause severe systemic infections, spironucleosis, in farmed salmonids. Treatment is currently not possible, making studies of diagnostic, drug and vaccine targets important so that spread can be limited. We use an infection biology approach to identify virulence genes in S. salmonicida and to understand the host-pathogen interaction during parasitic infections of salmonids. We have sequenced the genomes of S. salmonicida and other Spironucleus spp. infecting fish. The genomic information is used for studies of gene expression changes in host cells and parasites during early stages of S. salmonicida infection in vitro. This is complemented by investigations of host and parasite responses during Spironucleus infection in live salmonids and zebrafish. The project will generate tools to follow spironucleosis in wild and farmed fish and it will reveal targets for treatment. This will be important for development of aquaculture in Sweden and in the rest of the world.  It will also generate unique insights into key components of the fish immune system and we will create an interdisciplinary platform for further studies of fish infections in Sweden.