Sarcocystis cruzi (Hasselmann, 1923) Wenyon, 1926: redescription, molecular characterization, and deposition of life cycle stages specimens in the Smithsonian Museum

Authors: Dubey, Jitender; GUPTA, ADITYA - Orise Fellow; DE ARAUJO, LARISSA - Orise Fellow; Kwok, Oliver; Khan, Asis; Rosenthal, Benjamin

Submitted to: Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2023
Publication Date: 10/18/2023
Citation: Dubey, J.P., Gupta, A., De Araujo, L., Kwok, O.C., Khan, A., Rosenthal, B.M. 2023. Sarcocystis cruzi (Hasselmann, 1923) Wenyon, 1926: redescription, molecular characterization, and deposition of life cycle stages specimens in the Smithsonian Museum. Parasitology. 150(13):1192-1206. https://doi.org/10.1017/S003118202300094X.
DOI: https://doi.org/10.1017/S003118202300094X

Interpretive Summary: Members of the genus Sarcocystis are single-celled organisms, comprising of more than 200 species. Some species of the genus are zoonotic and some species cause serious illness in livestock and humans. Sarcocystis species have 2-host cycle. Carnivores are the definitive hosts (reservoirs) and become infected by eating tissues of intermediate herbivorous hosts. An environmentally resistant stage of the parasite (oocyst/sporocyst) is excreted in feces of carnivores. Herbivorous hosts become infected by consumption of feed or water contaminated with carnivore feces. Cattle are routinely infected with Sarcocystis. Of the seven or more species of Sarcocystis in cattle, two species S. hominis and S. heydorni are transmissible to humans via consumption of undercooked beef and one species, S. cruzi is the most pathogenic and causes economic losses to cattle producers. Proper identification of Sarcocystis species is important for control and diagnosis. Here, we reevaluated studies on the life cycle of S. cruzi, identified additional morphological details of the developmental stages, redescribe the parasite, provide the first molecular characterization from experimentally infected cattle, and deposit life cycle stages in the Smithsonian Museum for future reference. This paper will be of interest to biologists, veterinarians, and parasitologists.

Technical Abstract: Currently, 7 named Sarcocystis species infect cattle: Sarcocystis hirsuta, S. cruzi, S. hominis, S. bovifelis, S. heydorni, S. bovini and S. rommeli; other, unnamed species also infect cattle. Of these parasites of cattle, a complete life cycle description is known only for S. cruzi, the most pathogenic species in cattle. The life cycle of S. cruzi was completed experimentally in 1982, before related parasite species were structurally characterized, and before the advent of molecular diagnostics; to our knowledge, no archived frozen tissues from the cattle employed in the original descriptions remain for DNA characterization. Here, we isolated DNA from a paraffin-embedded kidney of a calf experimentally infected with S. cruzi in 1980; we then sequenced portions of 18S rRNA, 28S rRNA, COX1 and Acetyl CoA genes and verified that each shares 99–100% similarity to other available isolates attributed to S. cruzi from naturally infected cattle. We also reevaluated histological sections of tissues of calves experimentally infected with S. cruzi in the original description, exploiting improvements in photographic technology to render clearer morphological detail. Finally, we reviewed all available studies of the life cycle of S. cruzi, noting that S. cruzi was transmitted between bison (Bison bison) and cattle (Bos taurus) and that the strain of parasite derived from bison appeared more pathogenic than the cattle strain. Based on these newfound molecular, morphological and physiological data, we thereby redescribed S. cruzi and deposited reference material in the Smithsonian Museum for posterity.