Submitted to: International Journal for Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 1, 2004
Publication Date: August 30, 2004
Citation: Dubey, J.P., Sreekumar, C., Rosenthal, B.M., Vianna, M.C., Nylund, M.M., Nikander, S., Oksanen, A. 2004. Redescription of Besnoitia tarandi (Protozoa: Apicomplexa) from the reindeer (Rangifer tarandus). International Journal for Parasitology. 34:1273-1287.
Interpretive Summary: Besnoitia species are single-celled parasites that cause morbidity and mortality in animals. Scientists at the Beltsville Agricultural Research Center and a University in Finland describe the structure and life cycle of Besnoitia tarandi from reindeer. The results will be of interest to biologists, parasitologists and veterinarians.
Besnoitia tarandi tissue cysts were found in naturally-infected reindeer (Rangifer tarandus) from Finland. Infectivity of its tissue cysts, bradyzoites, and tachyzoites to animals and cell culture was studied. The bradyzoites and tissue cysts were not infectious to out-bred mice, rabbits or gerbils. When fed tissue cysts, neither cats nor dogs excreted oocysts. However, the parasite was lethal to interferon-gamma gene knock out (KO) mice irrespective of the route of inoculation. The parasite was grown successfully in African Green Monkey cells from tissues of two reindeer for the first time. Non-dividing, uninucleate tachyzoites from smears from cell cultures were 5.6 x 1.4 µm (4.5-7.4 x 1.0-1.9, n=50) in size. Longitudinally-cut bradyzoites in tissue sections measured 7.4 x 1.3 µm (6.5-7.8 x 1.0-1.6, n= 30). Ultrastructurally, tachyzoites and bradyzoites were similar to those in other Besnoitia species, and in particular to parasites described from cattle (Besnoitia besnoiti) and equids (Besnoitia bennetti) in that their bradyzoites lacked enigmatic bodies. Based on comparative analysis of three portions of nuclear ribosomal DNA (the small and large subunits and the first internal transcribed spacer) B. tarandi was found to be more closely related to the other congeners described from ungulates. The parasite was formally redescribed and specimens deposited in the US National Parasite Collection.