Cryptosporidium tyzzeri and Cryptosporidium muris originated from wild West-European house mice (Mus musculus domesticus) and East-European house mice (Mus musculus musculus) are non-infectious for pigs Martin Kvác ˇ a,b,⇑ , Michaela Kestr ˇánová b , Dana Kve ˇton ˇ ová a , Michaela Kotková c , Ynés Ortega d , John McEvoy e , Bohumil Sak a a Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, v.v.i., C ˇ eské Bude ˇjovice, Czech Republic b Faculty of Agriculture, University of South Bohemia in C ˇ eské Bude ˇjovice, Czech Republic c Faculty of Science, University of South Bohemia in C ˇ eské Bude ˇjovice, Czech Republic d Center for Food Safety, Department of Food Science & Technology, University of Georgia, Griffin, USA e Veterinary and Microbiological Sciences Department, North Dakota State University, Fargo, USA article info Article history: Received 19 December 2011 Received in revised form 13 March 2012 Accepted 15 March 2012 Available online 23 March 2012 Keywords: Pigs Cryptosporidium tyzzeri Cryptosporidium muris Experimental infection PCR Histology abstract Three and 8 week old pigs were inoculated with Cryptosporidium muris HZ206 (Mus musculus musculus isolate), Cryptosporidium tyzerri CR2090 (M. m. musculus isolate) or C. tyzzeri CR4293 (isolate from a hybrid between Mus musculus domesticus and M. m. musculus) at a dose of 1  10 7 oocysts per animal. Inoculated pigs showed no detectable infection and no clinical symptoms of cryptosporidiosis during 30 days post infection (DPI), and no macroscopic changes were detected in the digestive tract following necropsy. Developmental stages were not detected in gastrointestinal tract tissue by histology or PCR throughout the duration of the experiment. The infectivity of isolates was verified on SCID mice, in which oocysts shedding started from 4 to 8 DPI. Based on our findings, it can be concluded that pigs are not sus- ceptible to C. muris or C. tyzzeri infection. Ó 2012 Elsevier Inc. All rights reserved. 1. Introduction Apicomplexan parasites of the genus Cryptosporidium infect the gastrointestinal tract of most vertebrates, including humans. The host specificity of Cryptosporidium species and genotypes can vary from narrow (e.g. Cryptosporidium hominis, which almost exclu- sively infects humans) to broad (e.g. Cryptosporidium ubiquitum). Identifying susceptible hosts contributes to our understanding of the biology, evolution, and epidemiology of Cryptosporidium. Hosts infected with Cryptosporidium shed environmentally sta- ble oocysts in their feces. Unlike cysts of Giardia intestinalis, Cryp- tosporidium oocysts are produced continuously and can be shed for the entire patent period. The concentration of oocysts in feces is often below the detection limit of standard parasitologic meth- ods (Jeníková et al., 2011), and more sensitive, PCR based methods have therefore become routine. As a consequence of the wide- spread use of sensitive molecular tools to detect Cryptosporidium in feces, the host range of species and genotypes is rapidly expand- ing. However, low levels of Cryptosporidium can be present in feces as a result of mechanical transport through a host that is refractory to infection (Crawshaw and Mehren, 1987; Xiao et al., 2004; Ng et al., 2006). Therefore, reliance on fecal detection without verifica- tion that the host is infected could lead to erroneous conclusions about host specificity. Among the Cryptosporidium species and genotypes reported to in- fect pigs, Cryptosporidium suis and Cryptosporidium pig genotype II are considered pig-adapted and have been detected in pigs of all ages worldwide (e.g. Ryan et al., 2003; Vítovec et al., 2006; Hamnes et al., 2007; Langkjær et al., 2007; Suárez-Luengas et al., 2007; Kvác ˇ et al., 2009a). Cryptosporidium parvum was experimentally infectious for pre-weaned piglets but is only occasionally detected in pigs in a few areas. C. hominis and Cryptosporidium meleagridis are infective in a gnotobiotic pig model; however, these species are not naturally infective for pigs (Vítovec and Koudela 1992; Akiyoshi et al., 2003a,b). Two rodent adapted cryptosporidia, Cryptosporidium muris and Cryptosporidium tyzzeri (formerly Cryptosporidium mouse genotype I), have been detected in pigs. C. muris has been reported to occur sporadically in adult pigs at slaughter (Kvác ˇ et al., 2009a), in pig slurry (Xiao et al., 2006), and in waste lagoons from pig rearing facil- ities (Jenkins et al., 2010). C. tyzzeri has been reported in adult pigs 0014-4894/$ - see front matter Ó 2012 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.exppara.2012.03.016 ⇑ Corresponding author. Address: Biology Centre of the Academy of Sciences of the Czech Republic, v.v.i., Branišovská 31, 370 05 C ˇ eské Bude ˇjovice, Czech Republic. Fax: +420 38 531 0388. E-mail address: kvac@paru.cas.cz (M. Kvác ˇ). Experimental Parasitology 131 (2012) 107–110 Contents lists available at SciVerse ScienceDirect Experimental Parasitology journal homepage: www.elsevier.com/locate/yexpr