Svärd lab

Gastrointestinal (GI) parasites, worms and protozoa, infects right now over 1 billion people and also most of our pets. Parasites can also infect fish. We study some of these intestinal parasites: Giardia intestinalis, Giardia muris, Spironucleus salmonicida and Spironucleus vortens.

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.


Research projects

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.

Group members

Research leader: Staffan Svärd

People

Staffan Svärd, PhD
Professor

Jon Jerlström-Hultqvist, PhD Researcher

Jana Grüttner, PhD student

Sascha Krakovka, PhD student

Laura Rojas, PhD student

Lorenzo Assentato, PhD student

Group alumni

Feifei Xu, former postdoc

Ásgeir Ástvaldsson, former PhD student

Dimitra Peirasmaki, former PhD student

Showgy Ma'ayeh, former postdoc

Jingyi Liu, former PhD student

Mattias Andersson, former postdoc

Johan Ankarklev, former PhD student

Marcela Ferella, former postdoc

Louise Nilsson, former PhD student

Emma Ringqvist, former PhD student (2004-2009)

Britta Stadelmann, former postdoc

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