Molecular characterization of three Sarcocystis spp. from wild sika deer (Cervus nippon yesoensis) in Hokkaido, Japan

Diaphragm samples from 65 hunted sika deer (Cervus nippon yesoensis) from Hokkaido, Japan were examined for the presence of sarcocysts based on histological sections. Morphologically, the detected sarcocysts grouped into three types: (Type 1) 108.0-305.0 μm in width, thick-walled (4.3-7.0 μm) with tombstone-like protrusions; (Type 2) 25.0-69.5 μm in width, thick-walled (3.8-8.0 μm) with finger-like protrusions; and (Type 3) 22.5-55.0 μm in width, thin-walled (under 1 μm) with no visible protrusions under light microscopy. All samples contained at least one sarcocyst type, and multiparasitism was apparent in 58 samples. Morphologically, Type 1 sarcocysts were found in 19 (29.2%) samples, Type 2 in 62 (95.4%) samples, and Type 3 in 60 (92.3%) samples. The sarcocysts were collected using laser microdissection, the DNA extracted from them was PCR-amplified, and their 18S ribosomal RNA and cytochrome c oxidase subunit 1 genes were sequenced. Phylogenetic analysis showed that, for both genes, each morphological sarcocyst type (Types 1, 2, and 3) aligned most closely with S. silva/S. truncata, S. tarandi/S. elongata, and S. pilosa, respectively. Based on the sequence identities between taxa and the molecular information for sarcocysts in C. nippon centralis, the sarcocyst types were presumed to be S. truncata-like (Type 1), S. tarandi-like (Type 2), and S. pilosa (Type 3). The phylogenetic analyses based on the present comprehensive molecular characterization of three Sarcocystis spp. from C. nippon yesoensis in Hokkaido suggest that canids (e.g., wild foxes) may be the definitive hosts for S. pilosa, and felids (or unknown species) the definitive hosts for the other two species.