Recent advances in our knowledge of the Myxozoa

Michael L. Kent, Karl B. Andree, Jerri L. Bartholomew, Mansour El-Matbouli, Sherwin S. Desser, Robert H. Devlin, Stephen W. Feist, Ronald Hedrick, Rudolf W. Hoffmann, Jaswinder Khattra, Sascha L. Hallett, Robert J.G. Lester, Matthew Longshaw, Oswaldo Palenzeula, Mark E. Siddall, Chongxie Xiao

Research output: Contribution to journalReview article

449 Scopus citations

Abstract

In the last few years two factors have helped to significantly advance our understanding of the Myxozoa. First, the phenomenal increase in fin fish aquaculture in the 1990s has lead to the increased importance of these parasites; in turn this has lead to intensified research efforts, which have increased knowledge of the development, diagnosis, and pathogenesis of myxozoans. The hallmark discovery in the 1980s that the life cycle of Myxobolus cerebralis requires development of an actinosporean stage in the oligochaete, Tubifex tubifex, led to the elucidation of the life cycles of several other myxozoans. Also, the life cycle and taxonomy of the enigmatic PKX myxozoan has been resolved: it is the alternate stage of the unusual myxozoan, Tetracapsula bryosalmonae, from bryozoans. The 18S rDNA gene of many species has been sequenced, and here we add 22 new sequences to the data set. Phylogenetic analyses using all these sequences indicate that: 1) the Myxozoa are closely related to Cnidaria (also supported by morphological data); 2) marine taxa at the genus level branch separately from genera that usually infect freshwater fishes; 3) taxa cluster more by development and tissue location than by spore morphology; 4) the tetracapsulids branched off early in myxozoan evolution, perhaps reflected by their having bryozoan, rather than annelid hosts; 5) the morphology of actinosporeans offers little information for determining their myxosporean counterparts (assuming that they exist); and 6) the marine actinosporeans from Australia appear to form a clade within the platysporinid myxosporeans. Ribosomal DNA sequences have also enabled development of diagnostic tests for myxozoans. PCR and in situ hybridisation tests based on rDNA sequences have been developed for Myxobolus cerebralis, Ceratomyxa shasta, Kudoa spp., and Tetracapsula bryosalmonae (PKX). Lectin-based and antibody tests have also been developed for certain myxozoans, such as PKX and C. shasta. We also review important diseases caused by myxozoans, which are emerging or re-emerging. Epizootics of whirling disease in wild rainbow trout (Oncorhynchus mykiss) have recently been reported throughout the Rocky Mountain states of the USA. With a dramatic increase in aquaculture of fishes using marine netpens, several marine myxozoans have been recognized or elevated in status as pathological agents. Kudoa thyrsites infections have caused severe post-harvest myoliquefaction in pen-reared Atlantic salmon (Salmo salar), and Ceratomyxa spp., Sphaerospora spp., and Myxidium leei cause disease in pen-reared sea bass (Dicentrarchus labrax) and sea bream species (family Sparidae) in Mediterranean countries.

Original languageEnglish (US)
Pages (from-to)395-413
Number of pages19
JournalJournal of Eukaryotic Microbiology
Volume48
Issue number4
DOIs
StatePublished - Jan 1 2001

Keywords

  • Actinosporea
  • Ceratomyxa
  • Disease
  • Fin fish
  • Kudoa
  • Myxidium
  • Myxosporean
  • Myxozoa
  • Nomenclature
  • Phylogeny
  • Sphaerospora
  • Tetracapsula
  • Whirling disease

ASJC Scopus subject areas

  • Microbiology

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  • Cite this

    Kent, M. L., Andree, K. B., Bartholomew, J. L., El-Matbouli, M., Desser, S. S., Devlin, R. H., Feist, S. W., Hedrick, R., Hoffmann, R. W., Khattra, J., Hallett, S. L., Lester, R. J. G., Longshaw, M., Palenzeula, O., Siddall, M. E., & Xiao, C. (2001). Recent advances in our knowledge of the Myxozoa. Journal of Eukaryotic Microbiology, 48(4), 395-413. https://doi.org/10.1111/j.1550-7408.2001.tb00173.x