Glutaminolysis and Glycolysis Are Essential for Optimal Replication of Marek’s Disease Virus

Abstract

Viruses may hijack glycolysis, glutaminolysis, or fatty acid β-oxidation of host cells to provide the energy and macromolecules required for efficient viral replication. Marek’s disease virus (MDV) causes a deadly lymphoproliferative disease in chickens and modulates metabolism of host cells. Metabolic analysis of MDV-infected chicken embryonic fibroblasts (CEFs) identified elevated levels of metabolites involved in glutamine catabolism, such as glutamic acid, alanine, glycine, pyrimidine, and creatine. In addition, our results demonstrate that glutamine uptake is elevated by MDV-infected cells in vitro. Although glutamine, but not glucose, deprivation significantly reduced cell viability in MDV-infected cells, both glutamine and glucose were required for virus replication and spread. In the presence of minimum glutamine requirements based on optimal cell viability, virus replication was partially rescued by the addition of the tricarboxylic acid (TCA) cycle intermediate, α-ketoglutarate, suggesting that exogenous glutamine is an essential carbon source for the TCA cycle to generate energy and macromolecules required for virus replication. Surprisingly, the inhibition of carnitine palmitoyltransferase 1a (CPT1a), which is elevated in MDV-infected cells, by chemical (etomoxir) or physiological (malonyl-CoA) inhibitors, did not reduce MDV replication, indicating that MDV replication does not require fatty acid β-oxidation. Taken together, our results demonstrate that MDV infection activates anaplerotic substrate from glucose to glutamine to provide energy and macromolecules required for MDV replication, and optimal MDV replication occurs when the cells do not depend on mitochondrial β-oxidation. IMPORTANCE Viruses can manipulate host cellular metabolism to provide energy and essential biosynthetic requirements for efficient replication. Marek’s disease virus (MDV), an avian alphaherpesvirus, causes a deadly lymphoma in chickens and hijacks host cell metabolism. This study provides evidence for the importance of glycolysis and glutaminolysis, but not fatty acid β-oxidation, as an essential energy source for the replication and spread of MDV. Moreover, it suggests that in MDV infection, as in many tumor cells, glutamine is used for generation of energetic and biosynthetic requirements of the MDV infection, while glucose is used biosynthetically.

Targeting Host Defense System and Rescuing Compromised Mitochondria to Increase Tolerance against Pathogens by Melatonin May Impact Outcome of Deadly Virus Infection Pertinent to COVID-19

“…Any mitochondrial dysfunction will jeopardize melatonin production. In many cases, viruses direct the host cell metabolism to anaerobic glycolysis for their rapid replication while the cellular energy demand will be adapted to glutamine metabolism (glutaminolysis) [ 159 , 160 ]. A mechanism for this is that viruses infection triggers mitochondrial ROS production, which stabilizes hypoxia-inducible factor-1α (HIF-1α) and consequently promotes anaerobic glycolysis in COVID-19 infection [ 161 ], as known for other viruses.…”

Occurrence of Marek’s disease in Poland on the basis of diagnostic examination in 2015–2018

“…For many years, an increase in the pathogenicity of MDV strains has been observed despite immunoprophylaxis being used in day-old chicks. Such an increase was observed as early as 1997 in the vaccinated flocks of birds ( 3 , 4 ).…”

“…Only weight loss and an increase in the number of deaths among birds are observed. In the internal organs of infected birds, mainly enlargement of the liver and spleen is noted with the presence of necrotic foci in these organs ( 2 , 3 ). Virological methods (isolation in cell cultures or chicken embryos) and methods based on molecular biology principally using amplification reactions (PCR) together with their variants, e.g.…”

De Novo Cholesterol Biosynthesis and Its Trafficking in LAMP-1-Positive Vesicles Are Involved in Replication and Spread of Marek’s Disease Virus

“…All viral plaques were measured using the ImageJ software area tool (NIH, USA). The freehand tool was used to measure the defined plaque area (square micrometers) based on anti-gB staining as described previously ( 5 , 6 ). Data were corrected and exported as plaque size areas (square millimeters).…”

“…MDV can infect many cell types; however, latency is mainly established in CD4 + T cells, which are transformed into lymphoma cells ( 1 – 4 ). We have recently shown that MDV infection modulates cell metabolism and specifically enhances fatty acid synthesis and the formation of lipid droplets ( 5 , 6 ). It has been suggested that the alteration of lipid metabolism by MDV causes atherosclerosis in infected chickens ( 7 , 8 ).…”