Phospholipid and cholesterol composition of rubella virus and its host cell BHK 21 grown in suspension cultures

Abstract

Analysis of total lipid, phospholipid and cholesterol distribution has been conducted in parallel on BHK 21/13S cells grown in suspension cultures, on purified Rubella virus and on cells infected by the virus. Extracellular virus was purified by use of a previously described procedure (3,4). A higher content of lipid and phospholipid was found in infected cells (versus control cells) which were characterized by the presence of an unidentified nonphosphorylated lipid fraction that was detected neither in the control cells nor in the purified virus. The level and the nature of phospholipids and cholesterol of BHK 21/13S cells (infected or not) were compared to those of various clones of BHK 21cells. The same phospholipids were detected in the virus and in the cells but phosphatidyl choline level was much higher than in the control cells and lower than in the infected cells, while phosphatidyl ethanolamine content was lower than in the cells (infected or not). The presence of cardiolipin (4.4 per cent), the amount of sphingomyelin (6.9 per cent) and the molar ratio of cholesterol to phospholipids (0.26) in varions seem to favor a rubella virus maturation site in the cells.

Rubella Virus Capsid Associates with Host Cell Protein p32 and Localizes to Mitochondria

“…The localization of capsid to the mitochondria and association with a mitochondrial protein is intriguing in light of previous studies which document a link between RV replication complexes and mitochondrial function and localization (2,3,24,25). In RV-infected cells, clustering of mitochondria occurs and electron-dense plaques form between the membranes of apposing mitochondria and between mitochondria that associate with the endoplasmic reticulum.…”

Interactions between Rubella Virus Capsid and Host Protein p32 Are Important for Virus Replication

“…Mitochondria have long been thought to have an important role in the replication of RV (1,2,33). Moreover, we recently demonstrated that expression of the RV structural proteins induces relocalization of mitochondria to the perinuclear region (6).…”

“…Rather, it is thought that aggregation of mitochondria to sites in close proximity to virus replication or assembly factories serves to provide a source of cellular energy to assist virus replication (17,33,40,47). A second but not mutually exclusive possibility is that the capsidinduced association of mitochondria with virus replication sites facilitates the incorporation of cardiolipin into virions (2).…”

“…The association of capsid with mitochondria is intriguing, given that a significant role for this organelle in RV replication was first reported more than 25 years ago (2). Specifically, cardiolipin, a phospholipid associated exclusively with mitochondria, was found to be a component of the RV envelope.…”

Intracellular transport of rubella virus structural proteins expressed from cloned cDNA

“…In addition, although some authors have observed RV budding at the plasma membrane, particularly in BHK cells (Chatterji et al, 1969;Higashi, 1973;Murphy et al, 1968;Oshiro et al, 1969), most others (even using the same cell line) have failed to see budding at the plasma membrane of the host cell, finding it rather at internal membranes, possibly of Golgi origin (Bardeletti et al, 1979;Bonissol & Sisman, 1968;Hamvas et al, 1969;Higashi, 1973;Kouri et al, 1974;McCombs et al, 1968 ;Tuchinda et al, 1966;von Bonsdorff & Vaheri, 1969). The lipid composition of the virus (Bardeletti & Gautheron, 1976) lies midway between that of the endoplasmic reticulum (ER) and that of the plasma membrane (van Meer, 1989), particularly with regard to the cholesterol/phospholipid molar ratio, again suggesting that the virus buds from an intracellular compartment.…”