Effect of fatty acids on growth of Japanese encephalitis virus cultivated in BHK-21 cells and phospholipid metabolism of the infected cells

Untargeted Lipidomics of Vesicular Stomatitis Virus-Infected Cells and Viral Particles

The viral lifecycle is critically dependent upon host lipids. Enveloped viral entry requires fusion between viral and cellular membranes. Once an infection has occurred, viruses may rely on host lipids for replication and egress. Upon exit, enveloped viruses derive their lipid bilayer from host membranes during the budding process. Furthermore, host lipid metabolism and signaling are often hijacked to facilitate viral replication. We employed an untargeted HILIC-IM-MS lipidomics approach and identified host lipid species that were significantly altered during vesicular stomatitis virus (VSV) infection. Many glycerophospholipid and sphingolipid species were modified, and ontological enrichment analysis suggested that the alterations to the lipid profile change host membrane properties. Lysophosphatidylcholine (LPC), which can contribute to membrane curvature and serve as a signaling molecule, was depleted during infection, while several ceramide sphingolipids were augmented during infection. Ceramide and sphingomyelin lipids were also enriched in viral particles, indicating that sphingolipid metabolism is important during VSV infection.

Viral hijacking of cellular metabolism

This review discusses the current state of the viral metabolism field and gaps in knowledge that will be important for future studies to investigate. We discuss metabolic rewiring caused by viruses, the influence of oncogenic viruses on host cell metabolism, and the use of viruses as guides to identify critical metabolic nodes for cancer anabolism. We also discuss the need for more mechanistic studies identifying viral proteins responsible for metabolic hijacking and for in vivo studies of viral-induced metabolic rewiring. Improved technologies for detailed metabolic measurements and genetic manipulation will lead to important discoveries over the next decade.

Metabolomics of Rhabdomyosarcoma Cell During Echovirus 30 Infection

Background

Echovirus 30 (E30) causes acute aseptic meningitis. Viral replication requires energy and macromolecular precursors derived from the metabolic network of the host cell. The effect of viral infection within a host cell metabolic activity remains unclear.

Methods

To gain an insight into cell-virus interaction during E30 infection we used a human rhabdomyosarcoma cell line. In a new approach to metabolomics, ^1H NMR was used to measure the level of various cellular metabolites at different times of infection and morphological examination of the cells. Statistical analysis was done by using Confidence interval (CI) 95% and One-way ANOVA test.

Results

The¹H NMR metabolite spectrum signals were observed between mock infected and virus infected cells. Both mock infected and virus infected cells utilized glucose through metabolic pathways and released metabolic end products. Upon infection, the concentration of Alanine, Lactate, Acetate, Glutamate, Tyrosine, Histidine, Phenylalanine, Creatine, Choline and Formate, increased. Interestingly, all of these augmented metabolites were decreased during later stage of infection. The cells showed wide-ranging lipid signals at the end of infection, which correlates with the morphological changes as apoptosis (programmed cell death) of cells was observed. A significant association was found between time interval (12 h, 24 h, and 48 h) and metabolites likewise Alanin, Lactate, Acetate, Glutamate, Tyrosine, Histidine, Phenylalanine, Creatine, Choline and Formate respectively released by cell during infection, which is highly significant (p < 0.01).

Conclusion

Progressive breakdown and utilization of all cellular components were observed as the infection increased. This study is useful for monitoring the cellular metabolic changes during viral infection.

Membrane requirements for uridylylation of the poliovirus VPg protein and viral RNA synthesis in vitro

Efficient translation of poliovirus (PV) RNA in uninfected HeLa cell extracts generates all of the viral proteins required to carry out viral RNA replication and encapsidation and to produce infectious virus in vitro. In infected cells, viral RNA replication occurs in ribonucleoprotein complexes associated with clusters of vesicles that are formed from preexisting intracellular organelles, which serve as a scaffold for the viral RNA replication complex. In this study, we have examined the role of membranes in viral RNA replication in vitro. Electron microscopic and biochemical examination of extracts actively engaged in viral RNA replication failed to reveal a significant increase in vesicular membrane structures or the protective aggregation of vesicles observed in PV-infected cells. Viral, nonstructural replication proteins, however, bind to heterogeneous membrane fragments in the extract. Treatment of the extracts with nonionic detergents, a membrane-altering inhibitor of fatty acid synthesis (cerulenin), or an inhibitor of intracellular membrane trafficking (brefeldin A) prevents the formation of active replication complexes in vitro, under conditions in which polyprotein synthesis and processing occur normally. Under all three of these conditions, synthesis of uridylylated VPg to form the primer for initiation of viral RNA synthesis, as well as subsequent viral RNA replication, was inhibited. Thus, although organized membranous structures morphologically similar to the vesicles observed in infected cells do not appear to form in vitro, intact membranes are required for viral RNA synthesis, including the first step of forming the uridylylated VPg primer for RNA chain elongation.

Examination of various cell culture techniques for co-incubation of virulent Treponema pallidum (Nichols I strain) under anaerobic conditions

Treponema pallidum (Nichols virulent) was incubated with and without cells in cell culture medium reduced to -275 mV Ecal, pH 7.3, under deoxygenated conditions. Five to ten percent of the treponemes attached to cells and remained motile for at least 120 h in cell-treponeme systems of co-incubation. Virulent treponemes could be detected after 120 to 144 h in the supernatant fluids of cell-treponeme co-incubation cultures and in cell-free tubes containing medium harvested from aerobically cultivated mammalian cells. Medium supplemented with ox serum ultrafiltrate, pyruvate, and sodium thioglycolate and gas mixtures containing H2 and CO2 enhanced treponemal survival. Increases in treponemal numbers were observed using dark-field microscopy but were not substantiated using the rabbit lesion test. Continuous passage of the treponeme was not achieved in vitro.

Adaptation of BHK-21 cells to growth in shaker culture and subsequent challenge by Japanese encephalitis virus

Baby hamster kidney (BHK-21) cells were adapted to grow in shaker culture using Waymouth medium 752/1 containing 20 mM N-2-hydroxyethyl-piperazine-N'-2'-ethanesulfonic acid buffer and supplemented with 2.5% (vol/vol) calf serum, 0.002% (wt/vol) sodium oleate, and 0.2% fatty acid-free bovine serum albumin (WO2.5). Infectivity of Japanese encephalitis virus grown in the cells adapted to WO2.5 approached 2 x 10(8) plaque-forming units per ml. The culture volume of infected cells was reduced fivefold 12 h after infection. This step resulted in a 10-fold increase in infectivity over that obtained from infected cultures not subjected to volume reduction.