Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/10/2000
Publication Date: N/A
Citation: Interpretive Summary: Sarcocystis speeri is a newly described single-celled parasite from the North American opossum, Didelphis virginiana. Its natural intermediate host is unknown. Immunodeficient mice can act as intermediate host. Scientists at the Beltsville Agricultural Research Center and the Cornell University have found S. speeri in the South American opossum, Didelphis albiventris and transmitted it to the North American opossum via the mouse tissues. These results will be of interest to biologists, parasitologists and pathologists.
Technical Abstract: Sarcocystis speeri Dubey and Lindsay, 1999 from the South American opossum Didelphis albiventris, was successfully transmitted to the North American opossum D. virginiana. Sporocysts from a naturally infected D. albiventris from Argentina were fed to 2 gamma interferon knockout (KO) mice. The mice were killed 64 and 71 days after sporocyst feeding (DAF). Muscles containing sarcocysts from the KO mouse killed 71 DAF were fed to a captiv D. virginiana; this opossum shed sporocysts 11 days after ingesting sarcocysts. Sporocysts from D. virginiana were fed to 9 KO mice and 4 budgerigars (Melopsittacus undulatus). Schizonts, sarcocysts or both of S. speeri were found in tissues of all 7 KO mice killed 29-85 DAF; 2 mice died 39 and 48 and DAF were not necropsied. Sarcocystis stages were not found in tissues of the 4 budgerigars fed S. speeri sporocysts and killed 35 DAF. These results indicate that S. speeri is distinct from S. falcatula and S. neurona, and that S. speeri is present in both D. albiventris and D. virginiana.