Sendai virus membrane fusion: time course and effect of temperature, pH, calcium, and receptor concentration

Abstract

The conditions that optimize Sendai virus membrane fusion with liposomes have been studied. No fusion occurs in the absence of ganglioside receptors. Maximum fusion occurs when the molar ratio of ganglioside GD1a to phospholipid is 0.02 or greater. The amount of fusion at 37 degrees C increases with time up to at least 6.5 h. The rate of fusion increases from the lowest temperature tested, 10 degrees C, to 40 degrees C. Above 43 degrees C the amount of fusion decreases because of thermal inactivation of the viral proteins. There is a broad pH maximum between pH 7.5 and pH 9.0. At both ends of the pH range the amount of fusion increases and exceeds that found in the physiologic pH range. Neither ethylenediaminetetraacetic acid nor Ca2+ changes the amount of membrane fusion. The optimal conditions for membrane fusion of Sendai virus membranes with liposomes are the same as the optimal conditions for fusion with host cells and with red blood cells. Since the liposomes contain no proteins, the optimal conditions for Sendai virus membrane fusion must be determined by the viral proteins and be mostly independent of the nature or presence of the host proteins.

Electric pulse-induced fusion of mouse lymphoma cells: Roles of divalent cations and membrane lipid domains

“…5B). A similar temperature dependency with a transition temperature was also found in Sendal virus-induced fusion of liposomes (Haywood & Boyer, 1982) and in histamine exocytosis by mast cells (Lagunoff & Wan, 1974). However, a transition temperature found in the present study (11~ is lower than that observed in liposome fusion (18~ or mast cell exocytosis (16~ There is a possibility that the local temperature between platinum electrodes was somewhat higher than the temperature measured in the bulk solution because of heat production (Joule heating) by the electric fields.…”

Time and Temperature Dependence of Influenza Virus Membrane Fusion at Neutral pH

“…Since the lipids used in these liposomes are fluid at all temperatures used, the effect of temperature is probably related to the viral proteins as has been described for Sendal virus membrane fusion with liposomes at neutral pH (Haywood & Boyer, 1982). The temperature dependence of the segmental and rotational motion of the Sendal virus membrane proteins is similar to the temperature requirement of virus-induced haemolysis, which suggests that the temperature requirement lor membrane lusion relates to viral protein mobility (Lee et al, 1983).…”

“…The fraction of Sendai virions that fuse their membranes with liposomes (Haywood & Boyer, 1982, 1984) is comparable to the fraction of influenza virions that fuse their membranes with liposomes at neutral pH. Fusion of Sendai virus with liposomes requires an active F1 protein (Homma & Ohuchi, 1973;Scheid & Choppin, 1974) and occurs at the leading edge of a developing vesicle where the bilayer is stressed and where the curvature facilitates close approach of the bilayers (Haywood & Boyer, 1981 ;Haywood, 1983).…”

Partial Fusion Activity of Influenza Virus toward Liposomes and Erythrocyte Ghosts Is Distinct from Viral Inactivation

“…Furthermore, at neutral pH, Sendai virus and HIV-1 are not inactivated but they exhibit partial fusion activity toward liposomes. Following a previously described procedure (22), results with Sendai virus fusing with liposomes 2 (3), indicated that bound, unfused virions can be released by sucrose gradient centrifugation. The separated unfused virions subsequently fused when incubated with a "fresh" batch of liposomes.…”