Enteromyxum leei is an intestinal myxozoan species affecting a wide range of fish and causing important economic loses in gilthead sea bream farms. The parasite was partially purified from intestinal extracts of infected fish, mainly containing spores and some disporous sporoblasts. Band profiles of E. leei were obtained by SDS-PAGE and Western blotting with a polyclonal antibody (Pab) against the parasite. The carbohydrate composition of the parasite¿s antigens was analyzed in periodic acid/Schiff stained of gels, in periodate and proteinase K treated immunoblots and in Lectin blots. Additionally, the cross-reaction of the parasite with a Pab raised against the polar filament of the myxozoan Myxobolus pendula [1] was studied. Both Pabs detected proteic epitopes on antigenic proteins and glycoproteins of E. leei in a broad molecular weight range. Particularly, two glycoproteic bands (15 and 140 kDa), immunoreactive to both Pabs and with glucose and mannose moieties, could correspond to common antigens shared between E. leei and M. pendula. The 140 kDa band presented also galactose, N-acetyl-galactosamine and N-acetyl-glucosamine, pointing to its possible origin on chitin-built spore valves and to its possible involvement in host-parasite interactions. Several proteases with apparent molecular weights ranging between 45 and 245 kDa were found in zymographies of E. leei extracts, which may have a potential role in the parasite¿s dispersion and pathogenesis, but still deserve further investigation. To conclude, the heterologue anti-M.pendula Pab has been proved to cross-react with some cnidarian nematocysts in support of the phylogenetic affinity between this phylum and Myxozoa [1]. Interestingly, the 15 kDa glycoproteic antigen matches for its molecular weight with minicollagen, a cnidarian-specific protein of nematocysts with a myxozoan homologue, but still needs to be confirmed. [1] Ringuette MJ, Koehler A, Desser SS (2011) Shared antigenicity between the polar filaments of myxosporeans and other Cnidaria. Journal of Parasitology 97:163-166. Acknowledgments: This work was funded by MICINN through project AGL2009-13282-C02-01, and by the ¿Generalitat Valenciana¿ (projects PROMETEO 2010/006 and ISIC 2012/003). I. E. received a Ph D FPI fellowship.

Ponencia presentada en la 16th Conference on Diseases of Fish and Shellfish celebrada en Tampere (Finlandia) del 2 al 6 de septiembre de 2013

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