Mycobiology.  2017 Dec;45(4):297-311. 10.5941/MYCO.2017.45.4.297.

Saprolegnia parasitica Isolated from Rainbow Trout in Korea: Characterization, Anti-Saprolegnia Activity and Host Pathogen Interaction in Zebrafish Disease Model

• Shin S
• Kulatunga
• Dananjaya
• Nikapitiya C
• Lee J
• De Zoysa M

• KMID: 2401059
• DOI: http://doi.org/10.5941/MYCO.2017.45.4.297

Abstract

Saprolegniasis is one of the most devastating oomycete diseases in freshwater fish which is caused by species in the genus Saprolegnia including Saprolegnia parasitica. In this study, we isolated the strain of S. parasitica from diseased rainbow trout in Korea. Morphological and molecular based identification confirmed that isolated oomycete belongs to the member of S. parasitica, supported by its typical features including cotton-like mycelium, zoospores and phylogenetic analysis with internal transcribed spacer region. Pathogenicity of isolated S. parasitica was developed in embryo, juvenile, and adult zebrafish as a disease model. Host-pathogen interaction in adult zebrafish was investigated at transcriptional level. Upon infection with S. parasitica, pathogen/antigen recognition and signaling (TLR2, TLR4b, TLR5b, NOD1, and major histocompatibility complex class I), pro/anti-inflammatory cytokines (interleukin [IL]-1β, tumor necrosis factor α, IL-6, IL-8, interferon γ, IL-12, and IL-10), matrix metalloproteinase (MMP9 and MMP13), cell surface molecules (CD8⁺ and CD4⁺) and antioxidant enzymes (superoxide dismutase, catalase) related genes were differentially modulated at 3- and 12-hr post infection. As an anti-Saprolegnia agent, plant based lawsone was applied to investigate on the susceptibility of S. parasitica showing the minimum inhibitory concentration and percentage inhibition of radial growth as 200 μg/mL and 31.8%, respectively. Moreover, natural lawsone changed the membrane permeability of S. parasitica mycelium and caused irreversible damage and disintegration to the cellular membranes of S. parasitica. Transcriptional responses of the genes of S. parasitica mycelium exposed to lawsone were altered, indicating that lawsone could be a potential anti-S. parasitica agent for controlling S. parasitica infection.

Keyword

Host-pathogen interactions; Lawsone; Saprolegnia parasitica; Saprolegniasis; Zebrafish

MeSH Terms

Adult
Cytokines
Embryonic Structures
Fresh Water
Host-Pathogen Interactions
Humans
Interferons
Interleukin-12
Interleukin-6
Interleukin-8
Korea*
Major Histocompatibility Complex
Membranes
Microbial Sensitivity Tests
Mycelium
Oncorhynchus mykiss*
Oomycetes
Permeability
Plants
Saprolegnia*
Tumor Necrosis Factor-alpha
Virulence
Zebrafish*
Cytokines
Interferons
Interleukin-12
Interleukin-6
Interleukin-8
Tumor Necrosis Factor-alpha