Sarcocystis jamaicensis, n. sp. from red-tailed hawks (Buteo jamaicensis) definitive host and IFN-Gamma gene knockout mice as experimental intermediate host

Authors: VERMA, SHIV - Non ARS Employee; ROSYPAL VON DOHLEN, ALEXA - Johnson C Smith University; Mowery, Joseph; SCOTT, DAVID - Carolina Raptor Center; Rosenthal, Benjamin; Dubey, Jitender; LINDSAY, DAVID - Virginia-Maryland Regional College Of Veterinary Medicine (VMRCVM)

Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/23/2017
Publication Date: 6/23/2017
Citation: Verma, S., Rosypal Von Dohlen, A., Mowery, J.D., Scott, D., Rosenthal, B.M., Dubey, J.P., Lindsay, D. 2017. Sarcocystis jamaicensis, n. sp. from red-tailed hawks (Buteo jamaicensis) definitive host and IFN-Gamma gene knockout mice as experimental intermediate host. Journal of Parasitology. 103:555-564. https://doi.org.10.1645/17-10
DOI: https://doi.org/10.1645/17-10

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 warm blooded hosts, several species of Sarcocystis (S.) also cause a variety of disorders in livestock, pets, and wild animals and some of them are zoonotic, that is, able to infect humans. Recently, a new species, S. calchasi was identified as killing raptors and other avian species. Identification of Sarcocystis species is difficult. In the present study, authors describe a new species of Sarcocystis from the intestine of the red-tailed hawk that was found to be infectious to immunosuppressed mice. The results will be of interest to biologists, zoo veterinarians, and parasitologists, and help diagnosis of sarcocystosis.

Technical Abstract: Sarcocystis species have 2-host life cycles with the sexual cycle in the definitive hosts and an asexual cycle in the intermediate hosts. The common buzzard (Buteo buteo) is the definitive host for 2 species of Sarcocystis; Sarcocystis (Frenkelia) microti (forms macroscopic, lobulated sarcocysts) and Sarcocystis (Frenkelia) glareoli (forms microscopic, non-lobulated sarcocysts). Both species are distinctive with sarcocysts in brain but not in muscle. The Red-tailed hawk (Buteo jamaicensis) is known definitive hosts for Sarcocystis microti but not for Sarcocystis species that form sarcocysts in the muscle of intermediate hosts. Here, we report a new species of Sarcocystis with the red-tailed hawk (RTH) being the natural definitive host and IFN- 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 of paralysis. Fully sporulated 12.5 x 9.9 'm sized sporocysts were found in intestinal scrapings of both hawks. Sporocysts were orally fed to laboratoriesreared outbred Swiss Webster mice (SW) (Mus musculus) and also to KO mice. The sporocysts were infective for KO mice, but not to SW mice. All SW mice remained asymptomatic, and neither schizonts nor sarcocysts were found in any SW mice euthanized on day 54, 77, 103 (n=2) or 137 PI. The KO mice developed neurological signs, and were necropsied between 52 to 68 days post inoculation (PI) Schizonts/merozoites were found in all KO mice euthanized on day 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 neuropil. The schizonts/merozoites were located in neuropil, 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'm thick) and smooth. . By transmission electron microscopy, the sarcocyst wall classified as “type 1j” that consists of undulating parasitophorous vacuolar membrane (pvm), lined by thin electron dense layer. Villar protrusions (vp) on the sarcocyst wall were stump-shaped, close together, distributed at uneven distances, varied in sizes, lacked microtubules and electron dense granules. The pvm had minute invaginations towards the sarcocyst interior. The ground substance layer beneath the pvm was smooth, up to 1 'm thick Molecular characterization using 18S rRNA, 28S rRNA, ITS-1, and cox1 genes revealed a close relationship with S. microti, S. glareoli, S. cornixi, S. turdusi, S. calchasi, S. wobeseri, Sarcocystis sp. ex Phalacrocorax carbo, S. corvusi, and S. columbae; all these infect birds. The parasite in the present study was biologically and molecularly different from species so far described in RTH and we therefore propose a new species name Sarcocystis jamaicensis n. sp.