Sarcocystis pantherophisi n. sp., from Eastern Rat Snakes (Pantherophis alleghaniensis) as Definitive Hosts and Interferon Gamma Gene Knockout Mice as Experimental Intermediate Hosts

Abstract

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 10.8 × 8.9 μm. 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 μm wide and up to 3.5 mm long. By light microscopy, sarcocysts appeared thin-walled (<1 μm) 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-wide × 100-nm-long bleb-like evaginations interspersed with 100-nm-wide × 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 banana-shaped, 7.8 × 2.2 μm (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.

Description of Sarcocystis scandentiborneensis sp. nov. from treeshrews (Tupaia minor, T. tana) in northern Borneo with annotations on the utility of COI and 18S rDNA sequences for species delineation

“…There is also no match with another nine, relatively thick-walled snakehost Sarcocystis spp. as accounted for in Dubey et al (2016) and discussed by Verma et al (2017) : S . acanthocolubri , S .…”

“…clethrionomyelaphis , and representatives of the S2 lineage of snakehost Sarcocystis ( Wassermann et al, 2017 ) such as S . pantherophisi ( Verma et al, 2017 ) and S . eothenomysi ( Hu et al, 2014 ), cystozoites of the Sarcocystis sp.…”

Morphological and molecular phylogenetic characterization of Sarcocystis kani sp. nov. and other novel, closely related Sarcocystis spp. infecting small mammals and colubrid snakes in Asia

“…To account for members of the second Sarcocystis -lineage S2 from snakes ( Wassermann et al, 2017 ), we selected S . pantherophisi (KU891600, isolated from an Eastern rat snake in North America by Verma et al, 2017 ), two Sarcocystis sequences from viperid definitive hosts in Africa ( S . atheridis , AF120114; Sarcocystis ex- Pseudocerastes , AF513491), and the Indo-Australian S .…”

Biodiversity of the Coccidia (Apicomplexa: Conoidasida) in vertebrates: what we know, what we do not know, and what needs to be done

“…Duszynski and Upton (2010) listed and discussed 156 named species of coccidia in snakes that included 52 species of Caryospora Léger, 1904, two of Cryptosporidium Tyzzer, 1907, four of Cyclospora Schneider, 1881, 66 of Eimeria, seven of Isospora, 22 of Sarcocystis, two of Tyzzeria Allen, 1936, and one species of Wenyonella Hoare, 1933. Since their treatise, at least (or only) three additional species of Sarcocystis (Hu et al 2012, Roberts et al 2015, Verma et al 2017, four species of Caryospora (Daszak et al 2011a, McAllister et al 2012a, Viana et al 2013, de Santana Miglionico and Viana 2017, two species of Eimeria (Alyousif et al 2003, Daszak et al 2011b, one species of Choleoeimeria (Abdel-Baki et al 2014a), two species of Isospora (McAllister et al 2015(McAllister et al , 2016, and one species of Hepatozoon (Tomé et al 2013) have brought the total of named of species coccidia in snakes to 169.…”