Molecular insights into the mechanisms of susceptibility of Labeo rohita against oomycete Aphanomyces invadans

Abstract

Aphanomyces invadans, the causative agent of epizootic ulcerative syndrome, is one of the most destructive pathogens of freshwater fishes. To date, the disease has been reported from over 160 fish species in 20 countries and notably, this is the first non-salmonid disease that has resulted in major impacts globally. In particular, Indian major carps (IMCs) are highly susceptible to this disease. To increase our knowledge particularly with regards to host immune response against A. invadans infection in a susceptible host, the gene expression profile in head kidney of A. invadans-infected and control rohu, Labeo rohita was investigated using RNA sequencing. Time course analysis of RNA-Seq data revealed 5608 differentially expressed genes, involved among others in Antigen processing and presentation, Leukocyte transendothelial migration, IL-17 signaling, Chemokine signaling, C-type lectin receptor signaling and Toll-like receptor signaling pathways. In the affected pathways, a number of immune genes were found to be downregulated, suggesting an immune evasion strategy of A. invadans in establishing the infection. The information generated in this study offers first systematic mechanistic understanding of the host–pathogen interaction that might underpin the development of new management strategies for this economically devastating fish-pathogenic oomycete A. invadans.

A global review of problematic and pathogenic parasites of farmed tilapia

“…Subsequent contact of the zoospore with the host triggers encystment, which in turn initiates germination and results in infection. During infection, oomycetes secrete effector proteins that modulate its host's immune responses or inhibit the host's cell functions to the advantage of the pathogen 210–215 . Species of the genera Saprolegnia and Achlya infect the gills, skin, fins and eggs of fish (Figure 4a,c,d).…”

“…During infection, oomycetes secrete effector proteins that modulate its host's immune responses or inhibit the host's cell functions to the advantage of the pathogen. [210][211][212][213][214][215] Species of the genera Saprolegnia and Achlya infect the gills, skin, fins and eggs of fish (Figure 4a,c,d). 187,206,216,217 The infection progresses to the development of large wounds on the body surface leading to impaired osmoregulation and haemodilution; extensive lesions in the gills cause respiratory failure; both can lead to mortality.…”

Contaminants from dredged sediments alter the transcriptome of Manila clam and induce shifts in microbiota composition

“…High-quality reads and a reference transcriptome from the digestive gland [ 38 ] were employed to perform the mapping and the count table was obtained through Kallisto/v0.46.1 [ 103 ] with default settings and finally the “abundance_estimates_to_matrix.pl” script from the Trinity suite [ 104 ]. Raw reads count were then imported into R/v3.6.0 (R Core Team 2014) and filtered: contigs with less than 5 reads in at least 20% of total libraries (out of 130 for the first) were removed to limit the background noise [ 105 , 106 ]. Filtered reads were then normalized using the RUVs function (with parameter “ k = 7”) from the RUVSeq/v1.18 library [ 107 , 108 ] and then normalized counts were used to perform pairwise comparisons with edgeR/v3.26.0 [ 109 ].…”

Immunomodulatory Potency of Eclipta alba (Bhringaraj) Leaf Extract in Heteropneustes fossilis against Oomycete Pathogen, Aphanomyces invadans

“…Aphanomyces invadans , an aquatic oomycete most frequently recognized as a causative agent of the epizootic ulcerative syndrome (EUS) is a seasonal epidemic pathogen of great importance in wild and farmed fish in both freshwater and estuarine environments [ 1 , 2 , 3 , 4 ]. EUS is an OIE-listed disease, causing complex infectious etiology, which leads to necrosis ulcerative lesions and granulomatous response in fishes.…”