Which cellular pathways could increase in response to a viral infection?

In response to a viral infection, the pentose phosphate pathway (PPP) is particularly significant due to its role in providing ribose-5-phosphate and NADPH, both of which are crucial for the biosynthesis of nucleotides and nucleic acids. Viruses, especially those that replicate within the host cell, require a vast amount of nucleic acids to produce new viral particles.

The PPP serves as an important metabolic route that can generate the necessary precursors needed for the synthesis of RNA and DNA, which are essential for virus replication. Moreover, the PPP helps produce NADPH, which is vital for the synthesis of fatty acids and for maintaining the reducing environment of the cell, important for defending against oxidative stress caused by the immune response during viral infection.

While other pathways like aerobic respiration, glycolysis, and the citric acid cycle play critical roles in energy metabolism, they do not specifically support the rapid biosynthesis of nucleotides and the antioxidant defense mechanisms in the same way that the PPP does during a viral infection. Thus, the increase in the PPP is a key adaptive response of cells to ensure they can effectively manage the demands imposed by viral replication processes.