mammalian macrophage activation and cancer cells e.g., Irg-1 gene activation and the. Warburg effect (Figure 3F). These novel findings have huge evolutionary ...
OsHV-1 hijacks host metabolism in oyster larvae Tim Young1,2, Aditya Kesarcodi-Watson3, Andrea C. Alfaro1, Fabrice Merien4, Hannah Mae3, Thao Nguyen1, Viet Dung Le1, & Silas G. Villas-Bôas2 1Aquaculture
Biotechnology Group, Institute for Applied Ecology New Zealand, Auckland University of Technology 2Centre for Genomics, Proteomics and Metabolomics, University of Auckland 3Cawthron Institute, Nelson, New Zealand 4AUT-Roche Diagnostics Laboratory, Auckland University of Technology
Aquaculture Biotechnology Group
OsHV-1 & infections
Introduction The Pacific oyster, Crassostrea gigas, is highly susceptible to infection by Ostreid herpesvirus microvariant (OsHV-1 µVar). A number of recent virus outbreaks are thought to be responsible for increased incidences of mass mortalities around the globe, resulting in significant losses for the oyster aquaculture sector. Early life-stages are particularly vulnerable to the virus, but little information exists regarding metabolic or pathophysiological responses of larval hosts. Characterisation of the host-virus interaction provides knowledge for the development of antiviral therapeutics and could also assist the aquaculture sector by identifying phenotypic traits which are useful for selective breeding programs. We have thus conducted the first metabolomics-based investigation to characterise the host-virus interaction.
B
Capsid Tegument Viral DNA
A
Lipid membrane Glycoprotein complex
C
Methods
GC-MS
Figure 1. Mechanism of OsHV-1 infection and proliferation in an oyster larva (A); Virion structure (B); aTransmission Electron Microscopy image of infected cells (C).
Biochemical pathway analysis D
A
F Warburg effect aerobic glucose fermentation
Multivariate pattern recognition & correlation analysis A
C
E
B
C
Figure 3. Quantitative enrichment & topology analysis (A); examples of altered pathways where B = TCA cycle, C = alanine, aspartate & glutamate metabolism, D = glutathione biosynthesis, E = transulphuration); Summary of asome major distruptions in energy metabolism e.g., signatures of Irg-1 expression & the Warburg effect.
Summary B
D
• We detected 105 metabolites, 36 of which were differentially regulated in virusinfected oyster larvae (Figure 2A). • Multivariate analysis of the global metabolite data could clearly separate healthy larvae from unhealthy infected larvae (Figure 2B), and identified unique health biomarkers. • Correlation analysis discovered unknown metabolite relationships and revealed major changes in the underlying structure of the metabolic networks (Figure 2C & D). • Secondary bioinformatics techniques were used to interrogate biochemical information stored in online databases (Kyoto Encyclopaedia of Genes and Genomes) which identified >15 pathways with signs of being impacted (Figure 3A-E).
Figure 2. Metabolite profile differences between non-infected and infected oyster larvae. Heatmap & cluster analysis of top 30 metabolite changes (p < 0.05) (A); PLS-DA plot of oyster samples based on all detected qmetabolites (n = 105); Correlation network analyses of non-infected (C) and infected (D) larvae where R2 > 0.9
Acknowledgements We are thankful to Francesca Casu and Erica Zarate from the University of Auckland for their technical assistance, and Henry Kaspar from Cawthron Institute for facilitating larval production. We are indebted to the entire ‘crew’ at the Cawthron Aquaculture Park for their support and guidance, and thank the rest of the AUT Aquaculture Biotechnology Group for many fruitful discussions. We also acknowledge support from an AUT Vice Chancellor Doctoral Scholarship to T. Young under the supervision of A.C. Alfaro. This work was funded by the New Zealand Ministry of Business, Innovation and Employment (CAWX0802 and CAWX1315).
• We detected very strong evidences for immunoresponsive mechanisms associated with mammalian macrophage activation and cancer cells e.g., Irg-1 gene activation and the Warburg effect (Figure 3F). These novel findings have huge evolutionary implications. • OsHV-1 hijacks host metabolism to provide biomaterial for virion assembly and proliferation, and alters energetic pathways to keep host cells alive during infection.
Future research We are now extending this work to investigate molecular and metabolic traits in families of oysters which have been selectively bred to display various levels of resistance to OsHV-1 µVar. Experimental trials have been conducted and analyses are underway!
