Regulation of virulence genes in Aphanomyces invadans

Epizootic ulcerative syndrome (EUS) is an OIE-listed notifiable disease that leads to considerable morbidities and mortalities in aquaculture. It is caused by the pathogenic oomycete Aphanomyces invadans, which has a wide range distribution and poses a serious threat to aquaculture production worldwide. Nevertheless, information about its virulence factors and genetics, which is key for developing novel approaches for disease management, is limited. Recent work suggests that fascin and bromodomain proteins, which are among several proteins and proteases secreted by A. invadans, are virulence determinants and possible virulence factors. The role of fascin and bromodomain proteins in oomycetes is largely unknown. Bromodomain is a well characterized reader that mediates protein- protein interaction via acetyl-lysine recognition, thereby regulating chromatin modulation and gene expression. A novel nuclear function for fascin in regulating transcription has been described. Investigating the role of fascin and bromodomain proteins in controlling the expression of virulence genes the development and pathogenicity in A. invadans. We will use the CRISPR/Cas9 system, functioning as molecular scissors, to knock out A. invadans fascin and bromodomains genes and examine the effects on the mRNA and protein levels. In addition, we shall investigate whether the manipulation affects the expression of other genes associated with the development or virulence of this oomycete, such as nucleases, trypsin, cystein and serine proteases. Samples will be collected from manipulated and wild-type A. invadans and analyzed at the mRNA and protein levels. This project will represent a pioneering exploration of the role of fascin and bromodomains in the regulation of virulence gene expression in fish pathogenic oomycetes, which is a novel area of investigation important for drug target discovery. The promising approach for functional genomics studies in A. invadans can provide novel avenues to explore epigenetic mechanisms in oomycetes, to expand our knowledge of factors that regulate virulence gene expression and help to investigate novel approaches to prevent fish pathogenic oomycetes.