Fusion of reconstituted influenza virus envelopes with liposomes mediated by streptavidin/biotin interactions

Schoen, Pieter; Leserman, Lee; Wilschut, Jan

doi:10.1016/0014-5793(96)00682-5

Cited by 23 publications

(17 citation statements)

References 21 publications

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“…However, as both DTT-based inhibition of fusion and the formation of gp64 HC were observed in infected Sf9 cells (expressing all viral envelope proteins including the hypothetical “binding” protein), we believe that main conclusions of our study pertain to biologically relevant gp64-mediated fusion. Similar to baculovirus, influenza HA fusion also appears to be independent of the specific binding mechanism ( Schoen et al, 1996 ).…”

Section: Discussionmentioning

confidence: 99%

Membrane Fusion Mediated by Baculovirus gp64 Involves Assembly of Stable gp64 Trimers into Multiprotein Aggregates

Markovic

Pulyaeva

Sokoloff

et al. 1998

The Journal of Cell Biology

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The baculovirus fusogenic activity depends on the low pH conformation of virally-encoded trimeric glycoprotein, gp64. We used two experimental approaches to investigate whether monomers, trimers, and/or higher order oligomers are functionally involved in gp64 fusion machine. First, dithiothreitol (DTT)- based reduction of intersubunit disulfides was found to reversibly inhibit fusion, as assayed by fluorescent probe redistribution between gp64-expressing and target cells (i.e., erythrocytes or Sf9 cells). This inhibition correlates with disappearance of gp64 trimers and appearance of dimers and monomers in SDS-PAGE. Thus, stable (i.e., with intact intersubunit disulfides) gp64 trimers, rather than independent monomers, drive fusion. Second, we established that merger of membranes is preceded by formation of large (greater than 2 MDa), short-lived gp64 complexes. These complexes were stabilized by cell–surface cross-linking and characterized by glycerol density gradient ultracentrifugation. The basic structural unit of the complexes is stable gp64 trimer. Although DTT-destabilized trimers were still capable of assuming the low pH conformation, they failed to form multimeric complexes. The fact that formation of these complexes correlated with fusion in timing, and was dependent on (a) low pH application, (b) stable gp64 trimers, and (c) cell–cell contacts, suggests that such multimeric complexes represent a fusion machine.

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Section: Discussionmentioning

confidence: 99%

Membrane Fusion Mediated by Baculovirus gp64 Involves Assembly of Stable gp64 Trimers into Multiprotein Aggregates

Markovic

Pulyaeva

Sokoloff

et al. 1998

The Journal of Cell Biology

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“…It has been demonstrated that specific interaction of HA1 with sialic acid is not a prerequisite for fusion. HA-expressing membranes (HA membranes) readily fuse with bound membranes lacking receptors (Schoen et al, 1996;White et al, 1982), although the kinetics of fusion can differ from that in the presence of receptors (Alford et al, 1994;de Lima et al, 1995;Niles and Cohen, 1993;Stegmann et al, 1995). Furthermore, the HA1-sialic acid connection is not required for fusion completion at low pH-independent stages of fusion subsequent to low pH triggering (Chernomordik et al, 1997Schoch et al, 1992).…”

Section: Introductionmentioning

confidence: 99%

Delay of Influenza Hemagglutinin Refolding into a Fusion-Competent Conformation by Receptor Binding: A Hypothesis

Leikina

Markovic

Chernomordik

et al. 2000

Biophysical Journal

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Two subunits of influenza hemagglutinin (HA), HA1 and HA2, represent one of the best-characterized membrane fusion machines. While a low pH conformation of HA2 mediates the actual fusion, HA1 establishes a specific connection between the viral and cell membranes via binding to the sialic acid-containing receptors. Here we propose that HA1 may also be involved in modulating the kinetics of HA refolding. We hypothesized that binding of the HA1 subunit to its receptor restricts the major refolding of the low pH-activated HA to a fusion-competent conformation and, in the absence of fusion, to an HA-inactivated state. Dissociation of the HA1-receptor connection was considered to be a slow kinetic step. To verify this hypothesis, we first analyzed a simple kinetic scheme accounting for the stages of dissociation of the HA1/receptor bonds, inactivation and fusion, and formulated experimentally testable predictions. Second, we verified these predictions by measuring the extent of fusion between HA-expressing cells and red blood cells. Three experimental approaches based on 1) the temporal inhibition of fusion by lysophosphatidylcholine, 2) rapid dissociation of the HA1-receptor connections by neuraminidase treatment, and 3) substitution of membrane-anchored receptors by a water-soluble sialyllactose all provided support for the proposed role of the release of HA1-receptor connections. Possible biological implications of this stage in HA refolding and membrane fusion are being discussed.

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“…Previous studies have shown that influenza virus HA‐mediated fusion is independent of binding to sialic acid [15]. The binding step can be replaced by any other molecular interaction such as biotin/streptavidin interactions, which indicates that fusion is independent of any specific behavioral property of the underlying (cell surface) protein or lipid to which the sialic acid is linked.…”

Section: Discussionmentioning

confidence: 99%

“…Membrane fusion experiments were carried out essentially as described before [15]. In short, virosomes at a final concentration of 2.5 μM phospholipid and donor membranes (either erythrocyte ghosts or OVCAR‐3 membrane vesicles at a final concentration of 50 μM or 200μM phospholipid, respectively) were added to a thermostatted and stirred cuvette that contained HBS.…”

Section: Methodsmentioning

confidence: 99%

Targeting influenza virosomes to ovarian carcinoma cells

et al. 2001

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Reconstituted influenza virus envelopes (virosomes)containing the viral hemagglutinin (HA) have attracted attention as delivery vesicles for cytosolic drug delivery as they possess membrane fusion activity. Here, we show that influenza virosomes can be targeted towards ovarian carcinoma cells (OVCAR-3) with preservation of fusion activity. This was achieved by incorporating poly(ethylene glycol) (PEG)-derivatized lipids into the virosome membrane. This PEG layer serves as shield to prevent interaction of HA with ubiquitous sialic acid residues and as spatial anchor for antibody attachment. Coupling of FabP P fragments of mAb 323/A3 (anti-epithelial glycoprotein-2) to the distal ends of PEG lipids resulted in specific binding of virosomes to OVCAR-3 cells. These antibody-redirected virosomes fused with membranes of OVCAR-3 cells in a pHdependent fashion. ß 2001 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.

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Fusion of reconstituted influenza virus envelopes with liposomes mediated by streptavidin/biotin interactions

Cited by 23 publications

References 21 publications

Membrane Fusion Mediated by Baculovirus gp64 Involves Assembly of Stable gp64 Trimers into Multiprotein Aggregates

Membrane Fusion Mediated by Baculovirus gp64 Involves Assembly of Stable gp64 Trimers into Multiprotein Aggregates

Delay of Influenza Hemagglutinin Refolding into a Fusion-Competent Conformation by Receptor Binding: A Hypothesis

Targeting influenza virosomes to ovarian carcinoma cells

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