Ultrastructural and molecular identification of Sarcocystis tenella (Protozoa, Apicomplexa) in naturally infected Korean native goats

Sheep is the intermediate host of the protozoan parasite Sarcocystis tenella, while the dog is its definitive host. This study was conducted to determine the prevalence of natural infection with S. tenella in slaughtered Korean native goat, Capra hircus coreanae, in the Republic of Korea. H-E stained heart tissues were investigated for the presence of sarcocysts. Of the 103 goats, three (2.91%) were diagnosed as positive for S. tenella by light, electron microscopic and molecular examination. The histopathological study showed a low frequency of microscopic Sarcocystis infection in slaughtered goats. In transmission electron microscopy, the sarcocysts were confirmed as S. tenella. Further DNA sequencing and phylogenic analysis support our identification of S. tenella with a 18S rRNA sequence identity of 100% between the experimental sequence and S. tenella. To our knowledge, this is the first record of S. tenella in Korean native goats from Korea. We thus report that the domestic goat is another intermediate host for S. tenella.

Phylogenetic relationships between Toxoplasma and Sarcocystis deduced from a comparison of 18S rDNA sequences

SUMMARYThe current taxonomy of parasites in the genus Sarcocystis is largely based on morphological characteristics as well as on host specificity and life-cycle structure. Recently, phylogenetic analyses of partial ribosomal RNA (rRNA) sequences provided support for paraphyly of Sarcocystis. We have tested the validity of this hypothesis by sequencing the complete 18S rRNA genes of Sarcocystis arieticanis, Sarcocystis gigantea and Sarcocystis tenella and comparing them with gene sequences derived from other taxa of the phylum Apicomplexa. The results obtained from this study do not reject the hypothesis of monophyly of Sarcocystis species, although the bootstrap data were inconclusive for some species.