Infection by the Parasite Myxobolus bejeranoi (Cnidaria: Myxozoa) Suppresses the Immune System of Hybrid Tilapia

Keren Maor-Landaw, Margarita Smirnov, Vera Brekhman, Maya Ofek-Lalzar, Tal Yahav, Tamar Lotan

Research output: Contribution to journalArticlepeer-review


Myxozoa (Cnidaria) is a large group of microscopic obligate endoparasites that can cause emerging diseases, affecting wild fish populations and fisheries. Recently, the myxozoan Myxobolus bejeranoi was found to infect the gills of hybrid tilapia (Nile tilapia (Oreochromis niloticus) × Jordan/blue tilapia (O. aureus)), causing high morbidity and mortality. Here, we used comparative transcriptomics to elucidate the molecular processes occurring in the fish host following infection by M. bejeranoi. Fish were exposed to pond water containing actinospores for 24 h and the effects of minor, intermediate, and severe infections on the sporulation site, the gills, and on the hematopoietic organs, head kidney and spleen, were compared. Enrichment analysis for GO and KEGG pathways indicated immune system activation in gills at severe infection, whereas in the head kidney a broad immune suppression included deactivation of cytokines and GATA3 transcription factor responsible for T helper cell differentiation. In the spleen, the cytotoxic effector proteins perforin and granzyme B were downregulated and insulin, which may function as an immunomodulatory hormone inducing systemic immune suppression, was upregulated. These findings suggest that M. bejeranoi is a highly efficient parasite that disables the defense mechanisms of its fish host hybrid tilapia.

Original languageEnglish
Article number1893
Issue number10
StatePublished - 23 Sep 2022

Bibliographical note

Publisher Copyright:
© 2022 by the authors.


  • Myxobolus
  • Myxozoa
  • gills
  • head kidney
  • immune response
  • immune suppression
  • infection
  • parasite
  • tilapia
  • transcriptome

ASJC Scopus subject areas

  • Microbiology
  • Microbiology (medical)
  • Virology


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