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We are interested in the disease ecology of Sarcocystis species that infect birds of prey as definitive and intermediate hosts. The present study was done to test our hypothesis that a laboratory model can be developed for sarcocystis infection in mammals using gamma interferon gene knockout (KO) mice as a source of Sarcocystis strixi bradyzoites and mammalian cell cultures as a source of sporulated S. strixi oocysts. Sporocysts of S. strixi from a naturally infected barred owl (Strix varia) were fed to KO mice to produce sarcocysts, and the enclosed bradyzoites were obtained by acid-pepsin digestion of abdominal and thigh muscles. Bradyzoites, metrocytes, and an unusual spherical stage were seen in digest before the inoculation of host cells. The spherical stages stained dark with Giemsa stain, but no nucleus was observed, and they were seen free and associated with the concave portion of some bradyzoites. Examination of infected cell cultures demonstrated that macrogamonts and microgamonts were present at 24 hr post-inoculation. Since sporulated oocysts were not observed, we had to reject our current hypothesis. ; National Science Foundation Historically Black Colleges and Universities Undergraduate Program [1505407]; Virginia-Maryland College of Veterinary Medicine; DOEUnited States Department of Energy (DOE) [DE-SC0014664] ; Published version ; This work was supported in part by grant number 1505407 from the National Science Foundation Historically Black Colleges and Universities Undergraduate Program to A.R.V.D. and an Internal Research Competition (IRC) grant from the Virginia-Maryland College of Veterinary Medicine to D.S.L. This research was supported in part by an appointment to the Agricultural Research Service (ARS) Research Participation Program administered by the Oak Ridge Institute for Science and Education (ORISE) through an interagency agreement between the U.S. Department of Energy (DOE) and the U.S. Department of Agriculture (USDA). ORISE is managed by Oak Ridge Associated Universities (ORAU) under DOE contract number DE-SC0014664. All opinions expressed in this paper are the authors' and do not necessarily reflect the policies and views of USDA, ARS, DOE, or ORAU/ORISE. The USDA is an equal opportunity provider and employer. ; Public domain authored by a U.S. government employee

Here, we report a new species, Sarcocystis pantherophisi n. sp., with the Eastern rat snake (Pantherophis alleghaniensis) as natural definitive host and the interferon gamma gene knockout (KO) mouse as the experimental intermediate host. Sporocysts (n = 15) from intestinal contents of the snake were 10.838.9 lm. Sporocysts were orally infective to KO mice but not to laboratory-raised albino outbred house mice (Mus musculus). The interferon gamma KO mice developed schizont-associated neurological signs, and schizonts were cultivated in vitro from the brain. Mature sarcocysts were found in skeletal muscles of KO mice examined 41 days postinoculation (PI). Sarcocysts were slender, up to 70 lm wide and up to 3.5 mm long. By light microscopy, sarcocysts appeared thin-walled (, 1 lm) without projections. By transmission electron microscopy, the sarcocyst wall was a variant of "type 1'' (type 1i, new designation). The parasitophorous vacuolar membrane (pvm) had approximately 100-nm-wide3100-nm-long bleb-like evaginations interspersed with 100-nm-wide 3 650-nm-long elongated protrusions at irregular distances, and invaginations into the ground substance layer (gs) for a very short distance (6 nm). The gs was smooth, up to 500 nm thick, without tubules, and contained a few vesicles. Longitudinally cut bradyzoites at 54 days PI were bananashaped, 7.832.2 lm (n = 5). Molecular characterization using 18S rRNA, 28S rRNA, ITS-1, and cox1 genes indicated a close relationship with other Sarcocystis parasites that have snake-rodent life cycles. The parasite in the present study was molecularly and biologically similar to a previously reported isolate (designated earlier as Sarcocystis sp. ex Pantherophis alleghaniensis) from P. alleghaniensis, and it was structurally different from other Sarcocystis species so far described. ; Public domain authored by a U.S. government employee

Here, we report a new species of Sarcocystis with red-tailed hawk (RTH, Buteo jamaicensis) as the natural definitive host and IFN-gamma gene knockout (KO) mice as an experimental intermediate host in which sarcocysts form in muscle. Two RTHs submitted to the Carolina Raptor Center, Huntersville, North Carolina, were euthanized because they could not be rehabilitated and released. Fully sporulated 12.5 x 9.9-mu m sized sporocysts were found in intestinal scrapings of both hawks. Sporocysts were orally fed to laboratory-reared outbred Swiss Webster mice (SW, Mus musculus) and also to KO mice. The sporocysts were infective for KO mice but not for SW mice. All SW mice remained asymptomatic, and neither schizonts nor sarcocysts were found in any SW mice euthanized on days 54, 77, 103 (n = 2) or 137 post-inoculation (PI). The KO mice developed neurological signs and were necropsied between 52 to 68 days PI. Schizonts/merozoites were found in all KO mice euthanized on days 52, 55 (n = 3), 59, 61 (n = 2), 66, and 68 PI and they were confined to the brain. The predominant lesion was meningoencephalitis characterized by perivascular cuffs, granulomas, and necrosis of the neural tissue. The schizonts/merozoites were located in neural tissue and were apparently extravascular. Brain homogenates from infected KO mice were infective to KO mice by subcutaneous inoculation and when seeded on to CV-1 cells. Microscopic sarcocysts were found in skeletal muscles of 5 of 8 KO mice euthanized between 55-61 days PI. Only a few sarcocysts were detected. Sarcocysts were microscopic, up to 3.5 mm long. When viewed with light microscopy, the sarcocyst wall appeared thin (< 1 mu m thick) and smooth. By transmission electron microscopy, the sarcocyst wall classified as "type 1j'' (new designation). Molecular characterization using 18S rRNA, 28S rRNA, ITS-1, and cox1 genes revealed a close relationship with Sarcocystis microti and Sarcocystis glareoli; both species infect birds as definitive hosts. The parasite in the present study was biologically and molecularly different from species so far described in RTHs and we therefore propose a new species name, Sarcocystis jamaicensis n. sp. ; National Science Foundation Historically Black Colleges and Universities Undergraduate Program [1505407]; Internal Research Competition (IRC) grant from the Virginia-Maryland College of Veterinary Medicine ; This work was supported in part by grant no. 1505407 from the National Science Foundation Historically Black Colleges and Universities Undergraduate Program to A.R.V.D. and an Internal Research Competition (IRC) grant from the Virginia-Maryland College of Veterinary Medicine to D.S.L. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture (USDA); USDA is an equal opportunity provider and employer. ; Public domain authored by a U.S. government employee

Here we report a new species of Sarcocystis with a barred owl (Strix varia) as the natural definitive host and interferon gamma gene knockout (KO) mice as an experimental intermediate host. A barred owl submitted to the Carolina Raptor Center, Huntersville, North Carolina, was euthanized because of paralysis. Fully sporulated 12.539.9 lm sporocysts were found in intestinal scrapings from the owl. Sporocysts from the barred owl were orally fed to 4 laboratory-reared outbred Swiss Webster (SW) (Mus musculus) and 8 KO mice. All mice remained asymptomatic. Microscopic sarcocysts were found in all 5 KO mice euthanized on day 32, 59, 120, 154, and 206 post- inoculation (PI), not in KO mice euthanized on day 4, 8, and 14 PI. Sarcocysts were not found in any SW mice euthanized on day 72, 120, 206, and 210 PI. Sarcocysts were microscopic, up to 70 lm wide. By light microscopy, the sarcocyst wall, 2 lm thick had undulating, flat to conical, protrusions of varying dimensions. Numerous sarcocysts were seen in the histological sections of tongue and skeletal muscles from the abdomen, limbs, and eye but not in the heart. By transmission electron microscopy, the sarcocyst wall was "type 1j.'' The ground substance layer (gs) was homogenous, up to 2 lm thick, with very fine granules, and a few vesicles concentrated toward the villar projections. No microtubules were seen in the gs. Longitudinally cut bradyzoites at 206 days PI were 7.8 3 2.2 lm. Based on molecular characterization using 18S rRNA, 28S rRNA, and cox1 genes and morphology of sarcocysts, the parasite in the present study was biologically and structurally different from species so far described, and we therefore propose a new species name, Sarcocystis strixi n. sp. ; National Science Foundation Historically Black Colleges and Universities Undergraduate Program [1505407]; IRC grant from the Virginia-Maryland College of Veterinary Medicine ; This work was supported by grant 1505407 from the National Science Foundation Historically Black Colleges and Universities Undergraduate Program to A.R. von D. and an IRC grant from the Virginia-Maryland College of Veterinary Medicine to D.S.L. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA; USDA is an equal opportunity provider and employer. ; Public domain authored by a U.S. government employee