Replication of Marek's Disease Virus Is Dependent on Synthesis of De Novo Fatty Acid and Prostaglandin E(2)

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 E(2) (PGE(2)) pathway, as evident by increased levels of arachidonic acid, COX-2 expression, and PGE(2) synthesis. Inhibition of the COX-2/PGE(2) pathway by chemical inhibitors or knockdown of COX2 using short hairpin RNA reduced MDV titers, suggesting that COX-2 promotes virus replication. Exogenous PGE(2) completely restored the inhibition of the COX-2/PGE(2) pathway in MDV replication. Unexpectedly, exogenous PGE(2) 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/PGE(2) 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/PGE(2) pathway, which supports MDV replication by activating PGE(2)/EP2 and PGE(2)/EP4 signaling pathways.