Impact of diverse nutrient environment on viral replication and metabolite flow in human cytomegalovirus infection

Project Abstract Human cytomegalovirus (HCMV) is a prevalent herpesvirus that establishes lifelong infection. HCMV infection causes severe disease in immunocompromised individuals and is a leading cause of congenital disabilities. Like all viruses, HCMV relies on host metabolism for the building blocks of viral replication, such as

nucleotides for viral genome synthesis, amino acids for viral proteins, and lipids for the virus membrane. HCMV is highly species-specific, which limits molecular investigation of virus replication to cell culture models of infection. Prior research on HCMV metabolic remodeling of host metabolism utilized high nutrient culture media

with a focus on obtaining optimal virus production. However, high nutrient media that supports optimal virus replication does not recapitulate the nutrient environment in the human body. This project will address this drawback by identifying how low nutrient environments alter nutrient utilization to support HCMV replication. I

hypothesize that HCMV can replicate to sub-optimal levels in diverse nutrient environments via metabolic flexibility. I am initiating these studies by focusing on glucose utilization and alternative nutrient flow in glucose-free cultures during HCMV infection. Preliminary data demonstrate that viral genome synthesis, viral protein levels,

and virus production are decreased during glucose deprivation. Rescuing viral genome levels does not restore virus production, suggesting that glucose supports multiple steps of virus replication. While lipids are normally made from glucose during HCMV replication, I found that lipids are synthesized during HCMV infection despite

the loss of glucose, suggesting that alternative nutrient flow is occurring. In aim 1, I will determine how glucose loss impacts HCMV replication stages. These studies will define the stages of virus replication that require glucose and will determine which nutrients can compensate for glucose to support virus replication. In aim 2, I

will identify how glucose loss alters nutrient flow to support lipid synthesis during HCMV replication. This work will determine if glutamine is compensating for glucose for lipid synthesis and investigate how glucose levels impact nutrient flow. These studies build upon prior research that identified the complexities of HCMV metabolic

control. The resulting discoveries will increase our understanding of metabolic remodeling and alternative nutrient use during HCMV replication while providing insight for developing a more physiological-relevant model of HCMV interaction with host metabolism.