Host transcriptomic response to oyster oedema disease (OOD) in Pinctada maxima

Pinctada maxima is the most commercially important oyster species in Australia. However production is currently suffering from oyster oedema disease (OOD), the symptoms of which include oedema of interstitial tissues resulting in swelling of tissues such as the kidney and mantle. Here, the goal was to analyse the host transcriptomic response to disease, to better classify and understand OOD, and to test whether anti-viral responses were evident in OOD-affected oysters. RNA-seq next generation nucleotide sequencing analysed the host transcriptome of OOD-affected and OOD-unaffected P. maxima and a comparison of transcriptional responses identified a number of up- and down-regulated genes. These genes were further classified into functional biological pathways regulated during the disease state, providing an insight into the causative agent of OOD. Differentially expressed genes were able to be segregated into two main categories – general stress response related genes and immune response/wound healing related genes. Although the response was not characteristic to a viral infection, therefore ruling out a viral stressor, the response profile was not able to further implicate what remaining stressor could be the cause of OOD.