Hiroshi Ushirogawa    Department   Kawasaki Medical School  Kawasaki Medical School, Department of Microbiology,    Position   Instructor
Language	English
Title	Establishment of a newly isolated triploid clone of Spirometra (Cestoda: Diphyllobothriidae) as a powerful tool for studying the molecular and cellular bases of sparganosis
Conference	14th International Congress of Parasitology
Conference Type	International society and overseas society
Presentation Type	Speech
Lecture Type	General
Publisher and common publisher	◎Tetsuya Okino, Hiroshi Ushirogawa, Kumiko Matoba, Shin-ichiro Nishimatsu, Mineki Saito
Date	2018/08/23
Venue (city and name of the country)	Daegu, Korea
Summary	Spirometra larvae (plerocercoid) cause sparganosis, a food borne zoonosis that is most commonly observed in humans in Asian countries. Methods to maintain the life cycle of pathogenic organisms have become powerful tools for studying the molecular and cellular basis of infectious diseases. However, till date, there have been no reports establishing the complete life cycle in the laboratory because S. erinaceieuropaei has a complex life cycle with different stages and host species requirements. In this study, we established the complete life cycle of S. erinaceieuropaei using a newly established triploid (3n=27) clone. Both the diploid (2n=18) and triploid forms exist in populations of S. erinaceieuropaei (Uchida & Kawakami, 2005), and the parthenogenetic triploid is desirable because of its genetic uniformity. Using cyclops as the first intermediate host, mouse as the experimental second intermediate host, and dog as the final host, we succeeded in maintaining S. erinaceieuropaei in the laboratory for its complete life cycle. A karyotype study showed that the isolated clone possessed a triploid genome. The strain was named Kawasaki triploid (Kt) (Okino et al. 2017). A partial sequence (443 bp) of the mitochondrial cox1 gene of strain Kt showed more than 98% similarity with the sequences of S. erinaceieuropaei isolates from Australia, China, and South Korea, indicating that Kt is a member of a distinctive clade from East Asia and Oceania. However, consistent with recent observations that S. erinaceieuropaei in Asia forms a cryptic species complex that includes S. decipiens (Eom et al. 2015, Jeon et al. 2015, 2016), further phylogenetic and morphological analysis suggested that the strain Kt belongs to S. decipiens, not S. erinaceieuropaei. In conclusion, although taxonomic reconsideration is needed to elucidate their specific status, our system will be particularly useful for studying S. erinaceieuropaei infection and human sparganosis.