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I L van Genderen

Publications and source records attributed to I L van Genderen.

5 recordsLinked to original sources
PubMed1994

The phospholipid composition of extracellular herpes simplex virions differs from that of host cell nuclei.

Enveloped viruses of eukaryotes obtain their membrane by budding through a cellular membrane. Therefore, most frequently the lipid composition of the virion envelope reflects that of the membrane where budding took place. In the case of herpes simplex viruses, nucleocapsids assemble in the nucleus and bud through the inner nuclear membrane. The pathway from the perinuclear space to the extracellular medium is as yet poorly understood. Here we demonstrate that the phospholipid composition of extracellular herpes simplex virions differs from that of nuclei isolated from the infected cells. The viral membrane contains threefold higher concentrations of sphingomyelin and phosphatidylserine. These lipids are typically enriched in the Golgi apparatus and plasma membrane. The data are in agreement with a model in which herpes simplex virus, after budding through the inner nuclear membrane, loses its envelope by fusing with the outer nuclear membrane and obtains a new membrane by budding into a compartment late in the exocytotic pathway, very likely the Golgi apparatus or membranes derived from it. Alternatively, because the perinuclear space is continuous with the ER lumen, the virus after its first budding may be transported through the exocytotic pathway without ever leaving the lumen of the subsequent compartments. In that case, either the virions, while budding through the nuclear membrane select for sphingomyelin and phosphatidylserine, or the original lipids of the viral envelope are exchanged for lipids of an exocytotic membrane, most likely by a transient membrane continuity between the virion and the vesicle by which it is surrounded. Light particles, virus-like particles that lack capsid and DNA but contain tegument and envelope proteins, displayed the same lipid composition as complete herpes simplex virions, suggesting that they also acquired their envelope from a Golgi membrane.

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PubMed1991

Subcellular localization of Forssman glycolipid in epithelial MDCK cells by immuno-electronmicroscopy after freeze-substitution.

Forssman antigen, a neutral glycosphingolipid carrying five monosaccharides, was localized in epithelial MDCK cells by the immunogold technique. Labeling with a well defined mAb and protein A-gold after freeze-substitution and low temperature embedding in Lowicryl HM20 of aldehyde-fixed and cryoprotected cells, resulted in high levels of specific labeling and excellent retention of cellular ultrastructure compared to ultra-thin cryosections. No Forssman glycolipid was lost from the cells during freeze-substitution as measured by radio-immunostaining of lipid extracts. Redistribution of the glycolipid between membranes did not occur. Forssman glycolipid, abundantly expressed on the surface of MDCK II cells, did not move to neighboring cell surfaces in cocultures with Forssman negative MDCK I cells, even though they were connected by tight junctions. The labeling density on the apical plasma membrane was 1.4-1.6 times higher than basolateral. Roughly two-thirds of the gold particles were found intracellularly. The Golgi complex was labeled for Forssman as were endosomes, identified by endocytosed albumin-gold, and lysosomes, defined by double labeling for cathepsin D. In most cases, the nuclear envelope was Forssman positive, but the labeling density was 10-fold less than on the plasma membrane. Mitochondria and peroxisomes, the latter identified by catalase, remained free of label, consistent with the notion that they do not receive transport vesicles carrying glycosphingolipids. The present method of lipid immunolabeling holds great potential for the localization of other antigenic lipids.

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