DAO 36:209-212 (1999)  -  doi:10.3354/dao036209

Molecular evidence that the proliferative kidney disease organism unknown (PKX) is a myxosporean*

Denis Saulnier1,**, Hervé Philippe2, Pierre de Kinkelin1

1Unité de Virologie et Immunologie Moléculaires, Pathologie infectieuse et Immunité des Poissons, INRA, F-78362 Jouy-en-Josas cedex, France
2Laboratoire de Biologie Cellulaire, Bâtiment 444, Université Paris-Sud, F-91415 Orsay cedex, France
*Nucleotide sequence data reported in this paper are available in the GenBankTM databases under the accession number U70623
**Present address: Laboratoire d'Aquaculture Tropicale, Centre Océanologique du Pacifique, IFREMER, BP 7004, 98719 Taravao, Tahiti, French Polynesia. E-mail:

ABSTRACT: The proliferative kidney organism unknown (PKX), a serious salmonid fish pathogen, is considered to be a myxosporean on the basis of ultrastructural studies, but its real taxonomic position has never been confirmed. In order to ascertain its position, genomic DNA was extracted from PKX and small subunit (SSU) ribosomal DNA was amplified by PCR, cloned and sequenced. A phylogenetical analysis on SSU rDNA from 76 or 128 eucaryotic species was carried out. Whatever the tree reconstruction methods used, PKX was found to be a sister group of the Myxozoa phylum, providing the first molecular evidence for its membership in this phylum.


KEY WORDS: Myxozoan · Myxosporeans · PKX · Small subunit rDNA sequence · Molecular phylogeny


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