Nick Denniston, Queens University

N.G. Denniston (Queens University), M. Bossert (Queens University), K. Dunham-Snary (Queens University) and B. W. Banfield (Queens University)

Expressing & Multiplying

The conserved viral protein, pUL16, is implicated in several processes in HSV infected cells, including virion morphogenesis and cell-to-cell spread of infection. Previous research has also demonstrated that pUL16 localizes to mitochondria during HSV-1 infection. We hypothesized that the interaction between pUL16 and mitochondrial components regulates mitochondrial physiology to promote viral replication. We characterized the influence of pUL16 on host cell energy metabolism by quantifying parameters of mitochondrial respiration, glycolysis, ATP metabolism, and mitochondrial morphology in mock, HSV-2 WT and HSV-2 pUL16 null mutant (∆16), infected human keratinocytes (HaCaT). Mitochondrial stress tests indicated that WT infected cells exhibited a greater capacity to respond to increasing metabolic energy demands under stress via oxidative phosphorylation relative to mock and ∆16 infected cells. By contrast, we found an overall increase in glycolytic rate in ∆16 infected cells relative to WT infected cells. No significant differences in ATP metabolism between WT and ∆16 infected cells were observed, suggesting that enhanced glycolytic rate in ∆16 infected cells compensate for inefficiencies in oxidative phosphorylation. Importantly, uninfected HaCaT cells stably expressing pUL16 exhibited enhanced oxidative phosphorylation and glycolytic rate in comparison to parental HaCaT cells suggesting that pUL16 expression is sufficient to support enhanced metabolic activity. Interestingly, mitochondria in WT infected cells exhibited elongated morphology contributing to a more tubular mitochondrial network associated with promotion of mitochondrial function, while mitochondria in ∆16 infected cells exhibited punctate and bifurcated morphology resulting in a more fragmented mitochondrial network predicted to negatively impact mitochondrial function.