Sendai virus induced leakage of liposomes containing gangliosides

Abstract

Sendai virus induced liposome leakage has been studied by using liposomes containing a self-quenching fluorescent dye, calcein. The liposomes used in this study were prepared by a freeze and thaw method and were composed of phosphatidylcholine, phosphatidylserine, and phosphatidylethanolamine (1:2.60:1.48 molar ratio) as well as various amounts of gangliosides and cholesterol. The leakage rate was calculated from the fluorescence increment as the entrapped calcein leaked out of the liposomal compartment and was diluted into the media. It was shown that the target liposome leakage was virus dose dependent. Trypsin-treated Sendai virus in which the F protein had been quantitatively removed did not induce liposome leakage, indicating that the leakage was a direct result of F-protein interaction with the target bilayer membrane. The activation energy of this process was approximately 12 kcal/mol below 17 degrees C and approximately 25 kcal/mol above 17 degrees C. Gangliosides GM1, GD1a, and GT1b could serve as viral receptor under appropriate conditions. Liposome leakage showed a bell-shaped curve dependence on the concentration of ganglioside in the liposomes. No leakage was observed if the ganglioside content was too low or too high. Inclusion of cholesterol in the liposome bilayer suppressed the leakage rate of liposomes containing GD1a. It is speculated that the liposome leakage is a consequence of fusion between Sendai virus and liposomes.

Lysozyme-induced fusion of liposomes with erythrocyte ghosts at acidic pH.

“…This value is in excellent agreement with kinetic data reported for the fusion of Sendai virus envelope with erythrocyte membranes (Ea = 26 kcal/mol) (21) and of ganglioside-containing liposomes with Sendai virus (Ea = 26 kcal/mol) (22). pHdependence profiles for rates and equilibrium percentages of fusion follow closely the pH-dependent activity curve of lysozyme.…”

Design, Synthesis and Characterisation of Guanosine‐Based Amphiphiles

“…[27] Even at a concentration of 5 %, G5 is unable to promote the leakage of calcein ( Figure S10 in the Supporting Information), suggesting that the pore formed is relatively small and not large enough to allow the transit of this large anionic dye.…”

The plasma-membrane Ca2+-ATPase of Leishmania donovani is an extrusion pump for Ca2+

“…Further, the vesicles did not show any obvious discontinuity and appeared to be sealed (Figure 1, bottom). Sealing of vesicles was confirmed with the help of the fluorescent dye calcein by exploiting its selfquenching property at high concentrations [30] and also by Rb + trapping [25]. Total scanning of the field revealed the presence of some broken membranes and a few vesicles of original polarity (results not shown).…”