De novo Fatty Acid Biosynthesis Contributes Significantly to Establishment of a Bioenergetically Favorable Environment for Vaccinia Virus Infection

Abstract

The poxvirus life cycle, although physically autonomous from the host nucleus, is nevertheless dependent upon cellular functions. A requirement for de novo fatty acid biosynthesis was implied by our previous demonstration that cerulenin, a fatty acid synthase inhibitor, impaired vaccinia virus production. Here we show that additional inhibitors of this pathway, TOFA and C75, reduce viral yield significantly, with partial rescue provided by exogenous palmitate, the pathway's end-product. Palmitate's major role during infection is not for phospholipid synthesis or protein palmitoylation. Instead, the mitochondrial import and β-oxidation of palmitate are essential, as shown by the impact of etomoxir and trimetazidine, which target these two processes respectively. Moreover, the impact of these inhibitors is exacerbated in the absence of exogenous glucose, which is otherwise dispensable for infection. In contrast to glucose, glutamine is essential for productive viral infection, providing intermediates that sustain the TCA cycle (anaplerosis). Cumulatively, these data suggest that productive infection requires the mitochondrial β-oxidation of palmitate which drives the TCA cycle and energy production. Additionally, infection causes a significant rise in the cellular oxygen consumption rate (ATP synthesis) that is ablated by etomoxir. The biochemical progression of the vaccinia life cycle is not impaired in the presence of TOFA, C75, or etomoxir, although the levels of viral DNA and proteins synthesized are somewhat diminished. However, by reversibly arresting infections at the onset of morphogenesis, and then monitoring virus production after release of the block, we determined that virion assembly is highly sensitive to TOFA and C75. Electron microscopic analysis of cells released into C75 revealed fragmented aggregates of viroplasm which failed to be enclosed by developing virion membranes. Taken together, these data indicate that vaccinia infection, and in particular virion assembly, relies on the synthesis and mitochondrial import of fatty acids, where their β-oxidation drives robust ATP production.

Host sphingomyelin increases West Nile virus infection in vivo

“…Considering that SM could play a structural role in WNV particles ( 8 ), the expected reduction on SM content due to SMS inhibition could result in a reduced availability of SM for viral envelopment, thus causing a decrease in the infectious viral particles produced. Similar effects have been observed in other viral models using other drugs that also block lipid synthesis (48)(49)(50). The amount of cellassociated viral RNA was also measured in cells treated with the inhibitors ( Fig.…”

Modification of the Host Cell Lipid Metabolism Induced by Hypolipidemic Drugs Targeting the Acetyl Coenzyme A Carboxylase Impairs West Nile Virus Replication

“…In such scenarios, the pharmacological manipulation of cellular lipids can reduce virus infection by different mechanisms. These mechanisms include (i) the impairment of membrane rearrangements associated with viral replication, (ii) the generation of an unfavorable metabolic environment for virus replication, or (iii) the alteration of the viral envelope composition and the impairment of viral particle assembly (8,17,18,31).…”

“…Blockage of infectious virus production has been described for other viruses treated with drugs affecting lipid metabolism (31,40). In this regard, it should be considered that replication and assembly of viral particles are coupled processes in flaviviruses (5).…”

“…TOFA is an inhibitor of ACC that has been used to evaluate the involvement of this enzyme in infections by a variety of viruses (18,(31)(32)(33)(34). To determine its effect on the cellular lipid content, Vero cells were treated with TOFA for 24 h and the lipid content was analyzed by mass spectrometry and compared to that of control cells treated in parallel with the same amount of drug solvent (Fig.…”

Dengue Virus Induces and Requires Glycolysis for Optimal Replication

“…For example, similar to tumor cells, HCMV-infected cells use glutamine to feed the TCA cycle so that glucose carbon can be utilized for fatty acid synthesis (FAS) (2, 15). Alternatively, VACV implements a unique carbon utilization program wherein glutamine is essential for maximal viral replication by maintaining the TCA cycle but glucose is completely dispensable for virus production (10,16). These studies demonstrate that although viruses have metabolic requirements in common, they also induce distinct alterations in host cellular metabolism to complete their life cycles.…”