The virulence of the Toxoplasma parasite identified
A research group led by Antonio Barragan of the Swedish Institute for Infectious Disease Control (SMI) and Karolinska Institutet (KI) has identified, with the help of colleagues from Washington University, the gene in the Toxoplasma parasite that accounts for its ability to cause disease. What the scientists have located is the kinase (an enzyme) that seems to be the main virulence factor. The results are presented in the prestigious scientific journal Science.
Between 14 and 25 per cent of the population of Sweden, and between 25 and 50 per cent of the global population, are bearers of a chronic, dormant infection from the Toxoplasma parasite. This makes the parasite possibly the most common in the world. It exists in our natural environment and is transferred into people through food, dirty water or contact with cats.
A healthy person who becomes infected with the parasite can develop influenza-like symptoms; it can then become dormant, making these people life-long carriers. However, for a person with weakened immune defence, such as someone with HIV/AIDS, an organ recipient or a cancer patient, the infection can prove life-threatening. An infection during pregnancy can also have serious consequences for the foetus.
The scientists have found that parasites that exist in the environment or in chronically infected individuals carry either a “benign” (non-virulent) or a malignant (virulent) variant of the identified gene. The studies carried out in the SMIs laboratories show that when the virulent variant of the gene is transferred to a benign parasite it leads to a 100% lethal infection in mice; in other words, the formerly benign parasite becomes highly virulent.
The group believes that their findings will be of decisive importance for vaccine development and the diagnosis and treatment of serious Toxoplasma infection.
The article is published back to back” with a scientific article from Stanford University, where a group of scientists have arrived independently at exactly the same results, something that is very rare in the world of research.
Publication:
A Secreted Serine-Threonine; Kinase Determines Virulence in the
Eukaryotic Pathogen Toxoplasma gondii
S. Taylor, A. Barragan, C. Su, B. Fux, S. J. Fentress, K. Tang, W. L. Beatty,
H. El Hajj, M. Jerome, M. S. Behnke, M. White, J. C. Wootton, L. D. Sibley
Science, 15 December 2006, Vol. 314.
Kontaktinformation
For further information, please contact:
Antonio Barragan, research scientist at the SMI and KI, section manager at the SMI
Tel: +46 (0)8-457 25 24 or +46 (0)70-379 25 24 (mobile)
E-post: antonio.barragan@smi.ki.se
Press contact:
Aase Sten, press officer at the SMI
Tel: +46 (0)8-457 23 32 or +46 (0)70-338 23 32 (mobile)
Email: aase.sten@smi.ki.se
Katarina Sternudd, KI Press Officer
Tel: +46 (0)8-524 838 95 or +46 (0)70-224 38 95 (mobile)
Email: katarina.sternudd@ki.se
The Swedish Institute for Infectious Disease Control (SMI) is a government expert authority and research institute with overall responsibility for Swedish infectious disease control and prevention. Its mission is to monitor the epidemiology of infectious diseases and develop better protection against them. For more information, visit: www.smittskyddsinstitutet.se
Karolinska Institutet is one of the leading medical universities in Europe. Through research, education and information, Karolinska Institutet contributes to improving human health. Each year, the Nobel Assembly at Karolinska Institutet awards the Nobel Prize in Physiology or Medicine. For more information, visit ki.se
