Proteomic and lipidomic profiling was performed over a time course of acute hepatitis C virus (HCV) infection in cultured Huh-7.5 cells to gain new insights into the intracellular processes influenced by this virus. Our proteomic data suggest that HCV induces early perturbations in glycolysis, the pentose phosphate pathway, and the citric acid cycle, which favor host biosynthetic activities supporting viral replication and propagation. This is followed by a compensatory shift in metabolism aimed at maintaining energy homeostasis and cell viability during elevated viral replication and increasing cellular stress. Complementary lipidomic analyses identified numerous temporal perturbations in select lipid species (e.g. phospholipids and sphingomyelins) predicted to play important roles in viral replication and downstream assembly and secretion events. The elevation of lipotoxic ceramide species suggests a potential link between HCV-associated biochemical alterations and the direct cytopathic effect observed in this in vitro system. Using innovative computational modeling approaches, we further identified mitochondrial fatty acid oxidation enzymes, which are comparably regulated during in vitro infection and in patients with histological evidence of fibrosis, as possible targets through which HCV regulates temporal alterations in cellular metabolic homeostasis.
As parasites, viruses rely on the cells they infect to provide the energy and building blocks required for their survival and propagation. However, relatively little is known about the extent to which viruses modulate host cell metabolism and the consequences of these disruptions. Here we integrate proteomic and lipidomic profiling with computational modeling approaches to probe the impact of HCV infection on the global metabolism of cultured hepatoma cells, and to understand the potential contribution of such perturbations to viral pathogenesis. Our findings suggest that increases in host catabolic and biosynthetic activities occur early during infection, providing the host macromolecules necessary for viral growth. As infection progresses and cellular stress increases, however, a compensatory metabolic shift occurs in an attempt to maintain energy homeostasis and cell viability. This shift is accompanied by changes in lipid abundance, which has predicted consequences for the viral life cycle and pathogenesis. Computational modeling was then used to identify novel host proteins functioning as key regulators of this HCV-associated metabolic reprogramming. In summary, these studies provide new insights into the marked disruption of cellular metabolic homeostasis that occurs during HCV infection and that may contribute to liver disease progression.