Sphingolipids are present in membranes of all eukaryotic cells. Bioactive sphingolipids also function as signaling molecules that regulate cellular processes such as proliferation, migration, and apoptosis. Human cytomegalovirus (HCMV) exploits a variety of cellular signaling pathways to promote its own replication. However, whether HCMV modulates lipid signaling pathways is an essentially unexplored area of research in virus-host cell interactions. In this study, we examined the accumulation of the bioactive sphingolipids and the enzymes responsible for the biosynthesis and degradation of these lipids. HCMV infection results in increased accumulation and activity of sphingosine kinase (SphK), the enzyme that generates sphingosine 1-phosphate (S1P) and dihydrosphingosine 1-phosphate (dhS1P). We also utilized a mass spectrometry approach to generate a sphingolipidomic profile of HCMV-infected cells. We show that HCMV infection results in increased levels of dhS1P and ceramide at 24 h, suggesting an enhancement of de novo sphingolipid synthesis. Subsequently dihydrosphingosine and dhS1P decrease at 48 h consistent with attenuation of de novo sphingolipid synthesis. Finally, we present evidence that de novo sphingolipid synthesis and sphingosine kinase activity directly impact virus gene expression and virus growth. Together, these findings demonstrate that host cell sphingolipids are dynamically regulated upon infection with a herpes virus in a manner that impacts virus replication. Human cytomegalovirus (HCMV)3 is a ␤-herpes virus that is endemic in the human population, and in healthy adults infection with this virus is relatively benign. The dramatic exceptions in which HCMV can cause serious diseases are in congenitally and perinatally infected infants, and in immunocompromised individuals or immunosuppressed transplant recipients (1). In recent years, some studies have suggested a potential link between HCMV and several chronic diseases including atherosclerosis, coronary restenosis, and possibly cancer (1-5). The key aspects of host cell-virus interactions responsible for HCMV persistence and pathogenesis are poorly understood. In addition to advancing fundamental aspects of virus and host cell biology, more detailed knowledge of this virus-host cell interface may also reveal rational points of intervention that could be exploited for the treatment of HCMVassociated diseases.Many cell processes succumb to regulation by viral gene products, including cell communication systems. For example, HCMV can attenuate or block autocrine and paracrine signaling pathways that culminate in the activation of antiviral cellular defenses (6 -12). Many cell signaling pathways are also activated by virus infection. Binding of the HCMV glycoprotein B (gB) to the epidermal growth factor receptor and the ␣v␤3 integrin coreceptor during virus binding and entry (13, 14) results in activation of phosphoinositide 3-kinase and phospholipase C␥ pathways promoting capsid transport to the nucleus (14 -16).Very early interactions of the ...

The human cytomegalovirus tegument protein pp71 is the product of the UL82 gene. Roles for pp71 in stimulating gene transcription, increasing infectivity of viral DNA, and the degradation of retinoblastoma family proteins have been described. Here we report a novel function for pp71 in limiting accumulation of cell surface major histocompatibility complex (MHC) class I complexes. MHC molecules were analyzed in glioblastoma cells exposed to a replication-defective adenovirus expressing UL82 (Adpp71) or after transient transfection of the UL82 gene. Accumulation of cell surface MHC class I levels diminished in a specific and dose-dependent manner after exposure to Adpp71 but not after exposure to an adenovirus expressing ␤-galactosidase (Ad␤gal). UL82 expression did not interfere with accumulation of either MHC class I heavy-chain transcript or protein, nor did UL82 expression correlate with markers of apoptosis. Rather, UL82 expression correlated with an increased proportion of MHC class I molecules exhibiting sensitivity to endoglycosidase H treatment. Finally, we show that, in cells infected with recombinant virus strain missing all of the unique short region MHC class I evasion genes, disruption of UL82 expression by short, interfering RNAs led to increased accumulation of cell surface MHC class I complexes. These findings support a novel role for HCMV pp71 in disruption of the MHC class I antigen presentation pathway.

In 2004, Deere & Company's Commercial & Consumer Equipment Division (C&CE) engaged in a new logistics initiative to further enhance its outbound distribution network. The goal was to offer faster and more reliable replenishment to 2,500 North American independent dealers while keeping logistics costs in check by deploying different tactics during the peak (February–July) and offpeak (August–January) selling and shipping seasons. Deere and SmartOps worked together under a shared reward contract based on actual cost reductions accomplished (that are additive over the benefits that may have accrued for other reasons). Through careful analysis, validation, and verification of the data available, the team was able to develop detailed models of the current and alternative distribution systems. By formulating the key replenishment and transportation decisions and constraints as a mixed-integer mathematical program, the team was able to use powerful off-the-shelf solution software to find improvements. The ability to fix variables to perform what-if analysis also helped in the acceptance of the recommendations. Over a period of three years, Deere significantly improved service to 82% of their dealers (without any reduction in service to the other 18%) while reducing logistics costs by over $10 million. The novelty of this work stems from the dynamic seasonal optimization of Deere C&CE distribution network and replenishment decisions as a way of meeting service and cost reduction mandates, the creative use of tactical network optimization operations research models and what-if analysis to meet the implementation goals under time constraints and in the scrutiny given to the results.