Replication of Marek's Disease Virus Is Dependent on Synthesis of De Novo Fatty Acid and Prostaglandin E2.

Nitish Boodhoo,Benedikt B Kaufer,Shahriar Behboudi,Nitin Kamble,Richard M Longnecker

doi:10.1128/jvi.00352-19

Nitish Boodhoo, Benedikt B Kaufer + Show 3 more

Open Access

https://doi.org/10.1128/jvi.00352-19

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Abstract

Marek's disease virus (MDV) causes deadly lymphoma and induces an imbalance of the lipid metabolism in infected chickens. Here, we discovered that MDV activates the fatty acid synthesis (FAS) pathway in primary chicken embryo fibroblasts (CEFs). In addition, MDV-infected cells contained high levels of fatty acids and showed increased numbers of lipid droplets (LDs). Chemical inhibitors of the FAS pathway (TOFA and C75) reduced MDV titers by approximately 30-fold. Addition of the downstream metabolites, including malonyl-coenzyme A and palmitic acid, completely restored the inhibitory effects of the FAS inhibitors. Furthermore, we could demonstrate that MDV infection activates the COX-2/prostaglandin E2 (PGE2) pathway, as evident by increased levels of arachidonic acid, COX-2 expression, and PGE2 synthesis. Inhibition of the COX-2/PGE2 pathway by chemical inhibitors or knockdown of COX2 using short hairpin RNA reduced MDV titers, suggesting that COX-2 promotes virus replication. Exogenous PGE2 completely restored the inhibition of the COX-2/PGE2 pathway in MDV replication. Unexpectedly, exogenous PGE2 also partially rescued the inhibitory effects of FAS inhibitors on MDV replication, suggesting that there is a link between these two pathways in MDV infection. Taken together, our data demonstrate that the FAS and COX-2/PGE2 pathways play an important role in the replication of this deadly pathogen.IMPORTANCE Disturbances of the lipid metabolism in chickens infected with MDV contribute to the pathogenesis of disease. However, the role of lipid metabolism in MDV replication remained unknown. Here, we demonstrate that MDV infection activates FAS and induces LD formation. Moreover, our results demonstrate that MDV replication is highly dependent on the FAS pathway and the downstream metabolites. Finally, our results reveal that MDV also activates the COX-2/PGE2 pathway, which supports MDV replication by activating PGE2/EP2 and PGE2/EP4 signaling pathways.

Highlights

Marek’s disease virus (MDV) causes deadly lymphoma and induces an imbalance of the lipid metabolism in infected chickens
The results demonstrate that acetyl-coenzyme A (CoA) carboxylase (ACC) and fatty acid synthase (FASN) genes were highly upregulated at 72 hpi (Fig. 2B)
The results demonstrate that the expression of ACC subunit 1 (62 kDa) (Fig. 2C) and FASN proteins (Fig. 2D) is increased in MDV-infected cells

Summary

Introduction

Marek’s disease virus (MDV) causes deadly lymphoma and induces an imbalance of the lipid metabolism in infected chickens. We could demonstrate that MDV infection activates the COX-2/prostaglandin E2 (PGE2) pathway, as evident by increased levels of arachidonic acid, COX-2 expression, and PGE2 synthesis. Our data demonstrate that the FAS and COX-2/ PGE2 pathways play an important role in the replication of this deadly pathogen. MDV has been shown to disturb the lipid metabolism of the infected chickens, as it causes atherosclerotic plaque formation [4]. Excess lipid biosynthesis triggers cellular deposition of lipid droplets in MDV-infected cells [4, 5] Despite these intriguing observations, the role of lipid metabolism in MDV-infected cells remained unknown. A direct association between induction of COX-2 activity and enhancement of human cytomegalovirus (HCMV) replication has been reported [10, 11]

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