Human Cytomegalovirus Carries a Cell-Derived Phospholipase A2 Required for Infectivity

Abstract

Human cytomegalovirus (HCMV) is known to carry host cell-derived proteins and mRNAs whose role in cell infection is not understood. We have identified a phospholipase A2 (PLA2) activity borne by HCMV by using an assay based on the hydrolysis of fluorescent phosphatidylcholine. This activity was found in all virus strains analyzed and in purified strains. It was calcium dependent and was sensitive to inhibitors of cytosolic PLA2 (cPLA2) but not to inhibitors of soluble PLA2 or calcium-independent PLA2. No other phospholipase activity was detected in the virus. Purified virus was found to contain human cellular cPLA2␣, as detected by monoclonal antibody. No homology with PLA2 was found in the genome of HCMV, indicating that HCMV does not code for a PLA2. Decreased de novo expression of immediate-early proteins 1 and 2 (IE1 and IE2), tegument phosphoprotein pp65, and virus production was observed when HCMV was treated with inhibitors of cPLA2. Cell entry of HCMV was not altered by those inhibitors, suggesting the action of cPLA2 was postentry. Together, our results indicate a selective sorting of a cell-derived cPLA2 during HCMV maturation, which is further required for infectivity.

Overexpression of Cytosolic Group IVA Phospholipase A2 Protects Cells from Ca2+-dependent Death

“…In a recent report, Allal et al (45) have found that cPLA 2 ␣ is one of the several host-derived proteins carried by human cytomegalovirus. Although the function of these host cell-derived proteins is mostly unknown, cPLA 2 ␣ has been suggested to be required for proper infectivity (46,47).…”

Activation of Peroxisome Proliferator-Activated Receptor Gamma by Human Cytomegalovirus for De Novo Replication Impairs Migration and Invasiveness of Cytotrophoblasts from Early Placentas

“…It has been known for a long time that c-PLA2 activity can be induced by HCMV infection (1), but more interestingly, a connection between infection and PPAR␥ activation was supported by a study demonstrating that HCMV particles carry a cell-derived PLA2 that is boarded during the assembly process, which plays a major role in infectivity of MRC5 fibroblasts (2). PLA2 activity is responsible for the production of arachidonic acid, a substrate for both Cox-2 and lipoxygenase activities, and we assume that it is a reason why c-PLA2-specific inhibitors dramatically impair virus production (2).…”

Exosomes account for vesicle-mediated transcellular transport of activatable phospholipases and prostaglandins

“…When calcium was not required, Ca 2+ /Mg 2+ free-PBS was used. Concentrations of inhibitors and their specifi city have already been documented ( 24,25 ). When GTP dependency was checked, the nonhydrolysable analog of GTP (GTP ␥ S) was added 10 min before monitoring phospholipase activity.…”

“…2C ). The concentration of inhibitors was 50 µM; i.e., above that used to inhibit the various PLA 2 in cells ( 24,25 ). The sum of the inhibitions triggered by pyrrolidine-1 and BEL in exosomes.…”