Evidence for the role of extrusomes in evading attack by the host immune system in a scuticociliate parasite

• Published in: Fish & Shellfish Immunology
• Main Authors: Folgueira López, Iria, Lamas Fernández, Jesús, Felipe González, Ana Paula de, Sueiro Benavides, Rosa Ana, Leiro Vidal, José Manuel
• Other Authors: Universidade de Santiago de Compostela. Departamento de Bioloxía Funcional, Universidade de Santiago de Compostela. Departamento de Microbioloxía e Parasitoloxía, Universidade de Santiago de Compostela. Instituto de Acuicultura, Universidade de Santiago de Compostela. Instituto de Investigación e Análises Alimentarias
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier
• Subjects: Philasterides dicentrarchi; Turbot; Exocytosis; Extrusomes; Trichocyst matrix proteins; Mucin-like glycoproteins; Lamas; Leiro
• Online Access: http://hdl.handle.net/10347/19714; https://doi.org/10.1016/j.fsi.2019.07.008

This is the accepted manuscript of the following article: Folgueira I, Lamas J, De Felipe AP, Sueiro RA, Leiro JM. (2019). Evidence for the role of extrusomes in evading attack by the host immune system in a scuticociliate parasite. Fish Shellfish Immunol. 2019 Jul 5;92:802-812. doi:10.1016/j.fsi.2019.07.008 Like other ciliates, Philasterides dicentrarchi, the scuticociliate parasite of turbot, produces a feeding-only or growing stage called a trophont during its life cycle. Exposure of the trophonts to heat-inactivated serum extracted from the turbot host and containing specific antibodies that induce agglutination/immobilization leads to the production of a mucoid capsule from which the trophonts later emerge. We investigated how these capsules are generated, observing that the mechanism was associated with the process of exocytosis involved in the release of a matrix material from the extrusomes. The extruded material contains mucin-like glycoproteins that were deposited on the surface of the cell and whose expression increased with time of exposure to the heat-inactivated immune serum, at both protein expression and gene expression levels. Stimulation of the trophonts with the immune serum also caused an increase in discharge of the intracellular storage compartments of calcium necessary for the exocytosis processes in the extrusomes. The results obtained suggest that P. dicentrarchi uses the extrusion mechanism to generate a physical barrier protecting the ciliate from attack by soluble factors of the host immune system. Data on the proteins involved and the potential development of molecules that interfere with this exocytic process could contribute to improving the prevention and control of scuticociliatosis in turbot This study was financially supported by grants from the Ministerio de Economía y Competitividad and Fondo Europeo de Desarrollo Regional -FEDER- (European Union) (AGL2017-83577-R) and from the Xunta de Galicia (ED431C2017/31) and also by the PARAFISHCONTROL project, which received ...