Sarcocystis cymruensis: Discovery in Western hemisphere in the Brown rat (Rattus norvegicus) from Grenada, West Indies: Redescription, molecular characterization, transmission to IFN-gamma gene knockout mice via sporocysts

Authors: MURATA, FERNANDO - Non ARS Employee; CERQUEIRA-CEZAR, CAMILA - Non ARS Employee; THOMPSON, PETER - Non ARS Employee; TEWARI, KESHAV - St George'S University; Mowery, Joseph; VERMA, SHIV - Non ARS Employee; Rosenthal, Benjamin; SHARMA, RAVINDRA - St George'S University; Dubey, Jitender

Submitted to: Parasitology Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2018
Publication Date: 2/19/2018
Citation: Murata, F., Cerqueira-Cezar, C., Thompson, P., Tewari, K., Mowery, J.D., Verma, S., Rosenthal, B.M., Sharma, R., Dubey, J.P. 2018. Sarcocystis cymruensis: Discovery in Western hemisphere in the Brown rat (Rattus norvegicus) from Grenada, West Indies: Redescription, molecular characterization, transmission to IFN-gamma gene knockout mice via sporocysts. Parasitology Research. 117:1195–1204. https://doi.org/10.1007/s00436-018-5799-5
DOI: https://doi.org/10.1007/s00436-018-5799-5

Interpretive Summary: Toxoplasma and Sarcocystis are related single celled parasites of livestock and humans. While Toxoplasma has long been recognized to cause neurologic disease in many warmblooded hosts, certain species of Sarcocystis are zoonotic and cause clinical disease in humans and animals. Rodents are often used to study biology of Sarcocystis. Sarcocystis cymruensis is one of these species whose life cycle can be completed in the laboratory between rats and domestic cat.In the present study authors report S. cymruensis infection in naturally infected rats from the Americas. Its life cycle was completed in the laboratory by feeding naturally infected rat tissues to laboratory raised cats. Additionally, immunodeficient interferon gene knockout mice could be infected with this parasite for the first time. The results will be of interest to biologists, zoo veterinarians, and parasitologists.

Technical Abstract: Rodents are intermediate hosts for many species of Sarcocystis. Little is known of Sarcocystis cymruensis that uses the Brown rat (Rattus norvegicus) as intermediate hosts and the domestic cat (Felis catus) as experimental definitive host. Here, we identified and described Sarcocystis cymruensis in naturally infected R. norvegicus from Grenada, West Indies. Rats (n=167) were trapped in various locations in 2 parishes (St. George and St. David). Microscopic, thin (< 1µm) walled, slender sarcocysts were found in 11 of 156 (7.0%) rats’ skeletal muscles by squash examination. A laboratory-raised cat fed naturally infected rat tissues excreted sporocysts that were infectious for the interferon gamma gene knock out (KO) mice, but not to Swiss Webster outbred albino mice. All inoculated mice remained asymptomatic, and microscopic S. cymruensis-like sarcocysts were found in the muscles of KO mice euthanized on day 70 and 106 post-inoculation (p.i.). Sarcocysts from infected KO mice were infective for cats at day 106 but not at 70 days p.i. By transmission electron microscopy, the sarcocyst wall was “type 1a.” Morphological details of the cyst wall, metrocytes and bradyzoites, and molecular characteristic are described for the first time. Molecular characterization of sarcocysts 18S rDNA rDNA and 28S rDNA rDNA, ITS-1 and cox1 loci showed the highest similarity with Sarcocystis muris that uses domestic cat as definitive host and house mouse (Mus musculus) as intermediate host. In conclusion, the present study described the natural infection of S. cymruensis in Brown rat for the first time in a Caribbean country, confirmed its experimental transmission between domestic cat and KO mice but not outbred house mouse, and provided its molecular characteristics.