Influence of the infection with lipid-containing viruses on the metabolism and pools of phospholipid precursors in animal cells.

The influence of infection with three different lipid-containing RNA viruses, Newcastle disease virus, fowl plague virus, and Semliki Forest virus on the phosphatidylcholine precursors of chick embryo cells and of baby hamster kidney (BHK) cells has been measured. In chick embryo cells infection with Newcastle disease virus does not influence the energy charge, or the distribution and absolute pool sizes of the precursors or the choline phosphotransferase activity. In chick embryo cells infected with fowl plague virus the CDP-choline pool increases because of an inhibition of the choline phosphotransferase activity. The phosphorylcholine and CTP pools are smaller in infected cells when compared with mock-infected ones, although the energy charge is not influenced by infection. In chick embryo cells as well as in BHK cells the energy charge is diminished by infection with Semliki Forest virus. Therefore the CTP and phosphorylcholine pools are decreased. The CDP-choline pool in chick embryo cells becomes extremely small after infection with Semliki Forest virus because of a significant stimulation of the choline phosphotransferase. In BHK cells infected with Semliki Forest virus the opposite effect is observed. There are also severe effects on the uptake of the labeled precursors by infection. One and the same virus (Semliki Forest virus) has two completely different effects on the phosphatidylcholine precursors when infecting two different cell types. If one and the same cell type (chick embryo cells) is infected with three different lipid-containing RNA viruses also completely different effects on the phosphatidylcholine precursors were observed. Thus, each virus develops its own strategy to influence the lipid metabolism of the host cell, depending also on the choice of the host. This explains the many disturbing contradictory results described in the literature about the influence of lipid-containing viruses on the lipid metabolism of the host.