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Type of publication: Journal Article
Type of document: Full Paper

Year: 2017

Authors: Majeed, M; Kumar, G; Schlosser, S; El-Matbouli, M; Saleh, M

Title: In vitro investigations on extracellular proteins secreted by Aphanomyces invadans, the causative agent of epizootic ulcerative syndrome.

Source: Acta Vet Scand. 2017; 59(1):78



Authors Vetmeduni Vienna:

El-Matbouli Mansour
Kumar Gokhlesh
Majeed Muhammad Bilal Bin
Saleh Mona
Schlosser Sarah

Vetmed Research Units
University Clinic for Poultry and Fish Medicine, Clinical Unit of Fish Medicine
VetCore


Project(s): Isolation and identification of the emerging etiological agent of carp edema virus/Koi sleepy disease

The role of SOCS Proteins in salmonid whirling disease


Abstract:
Proteases produced by many microorganisms, including oomycetes, are crucial for their growth and development. They may also play a critical role in disease manifestation. Epizootic ulcerative syndrome is one of the most destructive fish diseases known. It is caused by the oomycete Aphanomyces invadans and leads to mass mortalities of cultured and wild fish in many countries. The areas of concern are Australia, China, Japan, South and Southeast Asian countries and the USA. Extracellular proteases produced by this oomycete are believed to trigger EUS pathogenesis in fish. To address this activity, we collected the extracellular products (ECP) of A. invadans and identified the secreted proteins using SDS-PAGE and mass spectrometery. A. invadans was cultivated in liquid Glucose-Peptone-Yeats media. The culture media was ultra-filtered through 10 kDa filters and analysed using SDS-PAGE. Three prominent protein bands from the SDS gel were excised and identified by mass spectrometery. Furthermore, we assessed their proteolytic effect on casein and immunoglobulin M (IgM) of rainbow trout (Oncorhynchus mykiss) and giant gourami (Osphronemus goramy). Antiprotease activity of the fish serum was also investigated.BLASTp analysis revealed that the prominent secreted proteins were proteases, mainly of the serine and cysteine types. Proteins containing fascin-like domain and bromodomain were also identified. We could demonstrate that the secreted proteases showed proteolytic activity against the casein and the IgM of both fish species. The anti-protease activity experiment showed that the percent inhibition of the common carp serum was 94.2% while that of rainbow trout and giant gourami serum was 7.7 and 12.9%, respectively.The identified proteases, especially serine proteases, could be the potential virulence factors in A. invadans and, hence, are candidates for further functional and host-pathogen interaction studies. The role of identified structural proteins in A. invadans also needs to be investigated further.

Keywords Pubmed: Animals
Aphanomycesphysiology
Caseinsmetabolism
Cells, Cultured
Fish Diseasesenzymologyparasitology
Fishes
Immunoglobulin Mmetabolism
Infectionsenzymologyparasitologyveterinary
Peptide Hydrolasesmetabolism
Protease Inhibitorsbloodmetabolism
Virulence Factorsmetabolism

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