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Diseases of Aquatic Organisms

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DAO 78:155-160 (2007)  -  DOI:

In vitro culture technique for Cryptocaryon irritans, a parasitic ciliate of marine teleosts

Tomoyoshi Yoshinaga1,*, Kousuke Akiyama1, Sayoko Nishida1, Motoyuki Nakane2, Kazuo Ogawa1, Hitomi Hirose2

1Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
2College of Bioresource Science, Nihon University, Kameino 1866, Fujisawa, Kanagawa 252-8510, Japan

ABSTRACT: A medium for the in vitro culture of Cryptocaryon irritans, which is an obligatorily parasitic ciliate of marine teleosts and causes ‘white spot disease’, was developed. The medium consisted of a layer of cultured fish cells (FHM), with an agarose gel layer covering the cell layer. The agarose gel contained 0.22% agarose, 10% fetal calf serum, 100 I.U. ml–1 Penicillin G potassium and 100 µg ml–1 streptomycin sulphate. Theronts of C. irritans transformed to trophonts and grew to 180 µm in mean length in the medium, although they gradually decreased in number. When trophonts fully developed in medium were transferred into seawater 4 d after inoculation, approximately 70% of them transformed to encysted tomonts and released theronts. When fish were challenged with theronts obtained from in vitro-raised parasites, approximately 40% of the theronts were recovered from fish, indicating comparative infectivity of in vitro-raised theronts to those of in vivo-raised theronts. This is the first report that C. irritans fully developed in vitro and its entire life cycle was completed without a host fish.

KEY WORDS: Cryptocaryon irritans · Ciliophora · In vitro culture · White spot disease · Marine fish

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Cite this article as: Yoshinaga T, Akiyama K, Nishida S, Nakane M, Ogawa K, Hirose H (2007) In vitro culture technique for Cryptocaryon irritans, a parasitic ciliate of marine teleosts. Dis Aquat Org 78:155-160.

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