Brain is the predilection site of Toxoplasma gondii in experimentally inoculated pigs as revealed by magnetic capture and real-time PCR Jana Juránková a, * , 1 , Walter Basso b,1 , Helena Neumayerová a , Vojtech Balá  z c , Eva Jánová d , Xaver Sidler e , Peter Deplazes b ,B  retislav Koudela f a Department of Pathology and Parasitology, University of Veterinary and Pharmaceutical Sciences, Palackého 1-3, 612 42 Brno, Czech Republic b Institute of Parasitology, University of Zurich, Winterthurerstrasse 266a, CH-8057 Zurich, Switzerland c Department of Biology and Wildlife Diseases, University of Veterinary and Pharmaceutical Sciences, Palackého 1-3, 612 42 Brno, Czech Republic d Department of Animal Genetics, University of Veterinary and Pharmaceutical Sciences, Palackého 1-3, 612 42 Brno, Czech Republic e Department for Farm Animals, Division of Swine Medicine, Vetsuisse-Faculty, University of Zurich, Winterthurerstrasse 260, CH-8057 Zurich, Switzerland f Central European Institute of Technology, University of Veterinary and Pharmaceutical Sciences, Palackého 1-3, 612 42 Brno, Czech Republic article info Article history: Received 21 February 2013 Received in revised form 25 June 2013 Accepted 15 August 2013 Available online 31 August 2013 Keywords: Toxoplasma gondii Pigs Magnetic capture Real-time PCR abstract Pigs represent an important source of food in many countries, and undercooked pork containing tissue cysts is one of the most common sources of Toxoplasma gondii infection for humans. A magnetic capture method for the isolation of T. gondii DNA and quantitative real-time PCR targeting the 529 bp TOXO repeat element were used to estimate the parasite burden in different tissues of pigs experimentally infected with T. gondii oocysts, and to determine the predilection sites of T. gondii in this host species. The highest concentration of T. gondii DNA was found in brain tissues, equivalent to [median] 553.7 (range 3857.7e121.9) parasites per gram, followed by lungs, heart and dorsal muscles with median values corresponding to 0.3 (range 61.3e0.02); 2.6 (range 7.34e0.37) and 0.6 (range 2.81e0.31) parasites per gram of tissue, respectively. Skeletal muscles from fore and hindlimb, liver and kidney presented very low infection burdens equivalent to [median] 0.2 parasites per gram of tissues, and no parasite DNA could be detected in the spleen. This study contributes to understanding the value of different pig tissues as a source of T. gondii infection for humans and shows that the brain, while not being of major importance as human food source, may represent a first-line selection tissue when performing non- serological surveys (e.g. bioassays, histopathological, immunohistochemical or molecular studies) to detect T. gondii infections in pigs. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Toxoplasma gondii is a widespread, obligate intracellular cocci- dian parasite affecting humans and many warm-blooded animal species. Main transmission routes of T. gondii include ingestion of sporulated oocysts shed by cats to the environment, ingestion of raw or undercooked tissues from infected animals containing tissue cysts, and transplacental infection (Tenter et al., 2000). Consump- tion of raw or undercooked meat has been regarded as a major route of transmission to humans (Cook et al., 2000). Despite the fact that most of infections in adult immunocompetent humans are asymptomatic, severe complications are described in immuno- compromised patients, as well as after congenital infections (Weiss and Dubey, 2009). The ingestion of tissue cysts in infected pork is considered one important source of human T. gondii infection (Dubey, 1986). Serological surveys have reported a worldwide dis- tribution of T. gondii in pigs, with dramatically varying prevalences among the cohorts of pigs surveyed, which is also influenced by management systems (e.g. market pigs versus sows, indoor pigs from biosecure housing systems versus free-range or organic pigs) (Dubey, 2010). Numerous studies have shown a substantial decrease of the T. gondii prevalence in meat-producing animals over the past 20 years owing to intensive farm management (Edelhofer, 1994; van Knapen et al., 1995; Kijlstra et al., 2004; van der Giessen et al., 2007). Due to an increased concern about the pigs’ welfare and due to consumer requests, more organic farms are being set up according to EU regulations (EU regulation, 2092/91). Nevertheless, the prevalence of T. gondii is higher in animal-friendly surroundings with outdoor access than on regular intensive farms (Dubey et al., 2002; Kijlstra et al., 2004; van der Giessen et al., 2007; Hill et al., 2010; Dubey et al., 2012), but the levels of infection in * Corresponding author. Tel.: þ420 541562269; fax: þ420 541562266. E-mail address: yanniska@seznam.cz (J. Juránková). 1 Both authors contributed equally to this study. Contents lists available at ScienceDirect Food Microbiology journal homepage: www.elsevier.com/locate/fm 0740-0020/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.fm.2013.08.011 Food Microbiology 38 (2014) 167e170