RNA-seq analysis of early enteromyxosis in turbot (Scophthalmus maximus): new insights into parasite invasion and immune evasion strategies.
Enteromyxum scophthalmi, an intestinal myxozoan parasite, is the causative agent of a threatening disease for turbot (Scophthalmus maximus, L.) aquaculture. The colonisation of the digestive tract by this parasite leads to a cachectic syndrome associated with high morbidity and mortality rates. This myxosporidiosis has a long pre-patent period and the first detectable clinical and histopathological changes are subtle. The pathogenic mechanisms acting in the early stages of infection are still far from being fully understood. Further information on the host-parasite interaction is needed to assist in finding efficient preventive and therapeutic measures. Here, a RNA-seq-based transcriptome analysis of head kidney, spleen and pyloric caeca from experimentally-infected and control turbot was performed. Only infected fish with early signs of infection, determined by histopathology and immunohistochemical detection of E. scophthalmi, were selected. The RNA-seq analysis revealed, as expected, less intense transcriptomic changes than those previously found during later stages of the disease. Several genes involved in IFN-related pathways were up-regulated in the three organs, suggesting that the IFN-mediated immune response plays a main role in this phase of the disease. Interestingly, an opposite expression pattern had been found in a previous study on severely infected turbot. In addition, possible strategies for immune system evasion were suggested by the down-regulation of different genes encoding complement components and acute phase proteins. At the site of infection (pyloric caeca), modulation of genes related to different structural proteins was detected and the expression profile indicated the inhibition of cell proliferation and differentiation. These transcriptomic changes provide indications regarding the mechanisms of parasite attachment to and invasion of the host. The current results contribute to a better knowledge of the events that characterise the early stages of turbot enteromyxosis and provide valuable information to identify molecular markers for early detection and control of this important parasitosis.
Departamento de Ciencias Clínicas Veterinarias, Facultad de Veterinaria, Universidade de Santiago de Compostela, 27002 Lugo, Spain.
Paolo
P
Ronza
Departamento de Genética, Facultad de Biología (CIBUS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
Diego
D
Robledo
Departamento de Anatomía y Producción Animal, Facultad de Veterinaria, Universidade de Santiago de Compostela, 27002 Lugo, Spain.
Roberto
R
Bermúdez
Departamento de Ciencias Clínicas Veterinarias, Facultad de Veterinaria, Universidade de Santiago de Compostela, 27002 Lugo, Spain.
Ana Paula
AP
Losada
Departamento de Genética, Facultad de Veterinaria, Universidade de Santiago de Compostela, 27002 Lugo, Spain.
Belén G
BG
Pardo
Instituto de Acuicultura Torre de la Sal (IATS-CSIC), 12595 Ribera de Cabanes, Castellón, Spain.
Ariadna
A
Sitjà-Bobadilla
Departamento de Ciencias Clínicas Veterinarias, Facultad de Veterinaria, Universidade de Santiago de Compostela, 27002 Lugo, Spain. Electronic address: misabel.quiroga@usc.es.
María Isabel
MI
Quiroga
Departamento de Genética, Facultad de Veterinaria, Universidade de Santiago de Compostela, 27002 Lugo, Spain.
Paulino
P
Martínez
D000209:Acute-Phase Proteins / Q000235:genetics; D000818:Animals; D002432:Cecum / Q000469:parasitology; D003165:Complement System Proteins / Q000235:genetics; D003599:Cytoskeleton / Q000737:chemistry / Q000235:genetics / Q000469:parasitology; D015536:Down-Regulation; D005109:Extracellular Matrix / Q000737:chemistry / Q000235:genetics / Q000469:parasitology; D005393:Fish Diseases / Q000276:immunology / Q000469:parasitology* / Q000473:pathology; D005412:Flatfishes / Q000469:parasitology*; D015870:Gene Expression; D020869:Gene Expression Profiling; D057131:Immune Evasion / Q000502:physiology*; D007150:Immunohistochemistry; D007372:Interferons / Q000235:genetics / Q000276:immunology; D007411:Intestinal Diseases, Parasitic / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*; D007422:Intestines / Q000469:parasitology / Q000473:pathology; D007668:Kidney / Q000469:parasitology; D055764:Myxozoa / Q000235:genetics* / Q000276:immunology / Q000502:physiology; D010273:Parasitic Diseases, Animal / Q000276:immunology / Q000469:parasitology* / Q000473:pathology; D017423:Sequence Analysis, RNA; D013154:Spleen / Q000469:parasitology; D015854:Up-Regulation
D000209:Acute-Phase Proteins; D003165:Complement System Proteins; D007372:Interferons
Enteromyxum scophthalmi; Myxozoa; Pathogenesis; RNA-seq; Transcriptome; Turbot