Kudoa septempunctata (Myxozoa: Multivalvulida) infects the muscles of olive flounder (Paralichthys olivaceus, Paralichthyidae) in the form of spores. To investigate the effect of K. septempunctata spores in mammals, adult BALB/c mice were fed with spores of K. septempunctata genotype ST3 (1.35 × 105 to 1.35 × 108 spores/mouse). After ingestion of spores, the mice remained clinically normal during the 24-h observation period. No spores were found in any tissue examined by histopathological screening. Quantitative PCR screening of the K. septempunctata 18S rDNA gene revealed that the K. septempunctata spores were detected only in the stool samples from the spore-fed groups. Collectively, these findings suggest that K. septempunctata spores are excreted in faeces and do not affect the gastrointestinal tract of adult mice.

-This study investigated the effects of Kudoa septempunctata genotype ST3 spores on ddY suckling mice. Purified Kudoa septempunctata spores were administered into the stomachs of the mice at 5 · 10 6 or 5 · 10 7 spores/ mouse, with inactivated Kudoa (5 · 10 6 spores/mouse) or vehicle as controls. No abnormal clinical symptoms were observed and there were no variations in fluid accumulation ratio and cytokine gene expression in all groups. In addition, intact Kudoa spores and the 18S rDNA gene were only detected (by microscopy and quantitative PCR, respectively) in the groups administered such spores. This study thus confirms that spores from the ST3 strain of Kudoa septempunctata were excreted in the faeces without infecting the gastrointestinal tract in ddY suckling mice.Key words: Kudoa septempunctata, ST3 genotype, Food-borne disease, Myxozoa, Paralichthys olivaceus, suckling mice.Résumé -Effets de Kudoa septempunctata, génotype ST3 isolé de Corée, sur des souriceaux ddY à la mamelle. Cette étude a examiné les effets des spores de Kudoa septempunctata, de génotype ST3, sur des souriceaux à la mamelle de race ddY. Les spores purifiées de Kudoa septempunctata ont été administrées dans les estomacs des souris à 5 · 10 6 ou 5 · 10 7 spores/souris, avec comme témoins des Kudoa inactivés (5 · 10 6 spores/souris) ou un véhicule. Dans tous les groupes, aucun symptôme clinique anormal n'a été observé et il n'y avait pas de variation dans les taux d'accumulation de fluide ni dans l'expression des gènes de cytokines. De plus, des spores de Kudoa intactes et le gène d'ADNr 18S de Kudoa ont été détectés uniquement (par microscopie et PCR quantitative, respectivement) dans les groupes auxquels ont été administrées ces spores. Cette étude confirme donc que les spores de la souche ST3 de Kudoa septempunctata ont été excrétées dans les fèces sans infecter le tractus gastrointestinal chez les souriceaux ddY à la mamelle.

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Kudoa septempunctata (Myxosporea, Multivalvulida) is a parasite of the trunk muscle of cultured olive flounder (Paralichthys olivaceus). We investigated whether K. septempunctata genotype ST3 spores induce cell damage and the secretion of inflammatory mediators in Caco-2 cells, which exhibit characteristics similar to human intestinal epithelial cells. Purified K. septempunctata spores were heated at 95 °C for 5 min. Lactate dehydrogenase (LDH) release was measured to determine the efficacy of denaturation. Naïve and heated spores, lipopolysaccharide (positive control) and vehicle (negative control) were added to Caco-2 cells. Cells were subjected to the cytotoxic LDH assay and western blot analysis to examine the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2. Supernatants were collected to measure nitric oxide (NO) and prostaglandin E2 (PGE2). Most spores were denaturated by heating, and the spore morphology was found to be wrinkled with shell valves and polar capsules. In addition, cytotoxicity and inflammatory mediators, such as NO, PGE2, iNOS, and COX-2, remained unchanged in Caco-2 cells following exposure to naïve and heated spores compared with the positive controls. Collectively, the findings of this study imply that spores of K. septempunctata genotype ST3 do not cause inflammation in Caco-2 cells.

The localization of carbohydrate terminals in Kudoa septempunctata ST3-infected muscle of olive flounder (Paralichthys olivaceus) was investigated using lectin histochemistry to determine the types of carbohydrate sugar residues expressed in Kudoa spores. Twenty-one lectins were examined, i.e., N-acetylglucosamine (s-WGA, WGA, DSL-II, DSL, LEL, STL), mannose (Con A, LCA, PSA), galactose/N-acetylgalactosamine (RCA12, BSL-I, VVA, DBA, SBA, SJA, Jacalin, PNA, ECL), complex type N-glycans (PHA-E and PHA-L), and fucose (UEA-I). Spores encased by a plasmodial membrane were labeled for the majority of these lectins, with the exception of LCA, PSA, PNA, and PHA-L. Four lectins (RCA 120, BSL-I, DBA, and SJA) belonging to the galactose/N-acetylgalactosamine group, only labeled spores, but not the plasmodial membrane. This is the first confirmation that various sugar residues are present in spores and plasmodial membranes of K. septempunctata ST3.