An Invertebrate Warburg Effect: A Shrimp Virus Achieves Successful Replication by Altering the Host Metabolome via the PI3K-Akt-mTOR Pathway

Abstract

In this study, we used a systems biology approach to investigate changes in the proteome and metabolome of shrimp hemocytes infected by the invertebrate virus WSSV (white spot syndrome virus) at the viral genome replication stage (12 hpi) and the late stage (24 hpi). At 12 hpi, but not at 24 hpi, there was significant up-regulation of the markers of several metabolic pathways associated with the vertebrate Warburg effect (or aerobic glycolysis), including glycolysis, the pentose phosphate pathway, nucleotide biosynthesis, glutaminolysis and amino acid biosynthesis. We show that the PI3K-Akt-mTOR pathway was of central importance in triggering this WSSV-induced Warburg effect. Although dsRNA silencing of the mTORC1 activator Rheb had only a relatively minor impact on WSSV replication, in vivo chemical inhibition of Akt, mTORC1 and mTORC2 suppressed the WSSV-induced Warburg effect and reduced both WSSV gene expression and viral genome replication. When the Warburg effect was suppressed by pretreatment with the mTOR inhibitor Torin 1, even the subsequent up-regulation of the TCA cycle was insufficient to satisfy the virus's requirements for energy and macromolecular precursors. The WSSV-induced Warburg effect therefore appears to be essential for successful viral replication.

One type of VEGFR is involved in WSSV infection to the Pacific whiteleg shrimp Litopenaeus vannamei

“…The ERK gene was also reported beneficial to WSSV infection (Shi et al, 2012). In crustaceans, WSSV replication was suppressed when the PI3K-Akt-mTOR pathway was inhibited by inhibitors (Su et al, 2014). In the present study, we found that the expression levels of LvFAK and LvPI3K were both down-regulated after silencing of LvVEGFR.…”

To complete its replication cycle, a shrimp virus changes the population of long chain fatty acids during infection via the PI3K-Akt-mTOR-HIF1α pathway

“…In a previous study (Su et al, 2014), we used LC-MS/MS to analyze the proteome of WSSV-infected hemocytes. These results were subsequently compiled into a database, and this was used here to analyze the proteins involved in TAG/FA metabolism.…”

“…WSSV, which is a large enveloped (approximately 300 kbp) dsDNA invertebrate virus with an in vivo replication cycle of 22e24 h, was found to trigger the Warburg effect at the WSSV genome replication stage (12 hpi [hours post infection]) via the activation of the PI3K-Akt-mTOR pathway (Su et al, 2014). This pathway also mediates the Warburg effect in cancer cells (Deberardinis et al, 2008;Vander Heiden et al, 2009;Robey and Hay, 2009;Bhatt et al, 2012) and in vertebrate cells infected by oncogenic viruses (Street et al, 2004;Mannov a and Beretta, 2005;Guo et al, 2007;Peng et al, 2010;Martin et al, 2012;Bhatt and Damania, 2013), and it also involved in lipogenesis.…”

“…In the first part of this study, we used a previously constructed database to identify and measure the expression levels of proteins involved in TAG (triacylglycerols)/ FA (fatty acid) metabolism in shrimp hemocytes at 12 and 24 hpi. This database was compiled from results obtained by liquid chromatography tandem mass spectrometry (LC-MS/MS) as described in our study (Su et al, 2014). We also used gas chromatographyemass spectrometry (GC/MS) to monitor global lipodomic changes in long chain fatty acids (LCFAs) induced by WSSV in shrimp stomachs at the same time points.…”

Role of Litopenaeus vannamei Yin Yang 1 in the Regulation of the White Spot Syndrome Virus Immediate Early Gene ie1

“…Since WSSV infection is extremely lethal to shrimp, infection with large amounts of the virus would have made our study difficult due to rapid shrimp death. A previous study examining the Warburg effect in shrimp used low levels of virus to investigate the host metabolic shift after virus infection (55), and in this study, we used similar conditions to investigate the effect of dsYY1 RNA on the expression of ie1 at 24 to 48 h postinfection (Fig. 7E).…”