Document Detail


Cellular cytoplasmic delivery of a polypeptide toxin by reconstituted influenza virus envelopes (virosomes).
MedLine Citation:
PMID:  8049214     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In this paper it is demonstrated that reconstituted influenza virus envelopes (virosomes) fuse efficiently with membranes of the endosomal cell compartment of cultured cells, after internalization through receptor-mediated endocytosis. As a consequence, molecules, encapsulated in the virosomal interior, are transferred to the cell cytoplasm. This process was monitored on the basis of delivery of subunit A of diphtheria toxin (DTA), initially encapsulated in the virosomal lumen. Virosome-mediated cytoplasmic delivery of DTA resulted in a virtually complete inhibition of cellular protein synthesis. DTA delivery was blocked by factors inhibiting the pH-dependent fusion activity of viral hemagglutinin, i.e., 20 mM NH4Cl, preincubation of the virosomes at low pH, and anti-hemagglutinin antibodies. Quantitation of the extent of virosome-mediated delivery of biologically active DTA demonstrated that a lower bound of approximately 10% of the virosomes entering the cells deposited their aqueous contents into the cytosol. This is in good agreement with the final extent of virosome fusion of 40%, as determined by a fluorescence lipid mixing assay based on the dilution of pyrene-labeled phosphatidylcholine from the virosomal into the endosomal membrane. At an added concentration of 1 microM virosomal lipid per 50,000 cells, depending on the condition of the experiment, a minimum of 4000 virosomes per cell were found to be internalized. Virosomes could also be induced to fuse with the cell plasma membrane by a transient lowering of the extracellular pH, as detected by appearance of virosome-encapsulated DTA in the cytoplasm.(ABSTRACT TRUNCATED AT 250 WORDS)
Authors:
R Bron; A Ortiz; J Wilschut
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biochemistry     Volume:  33     ISSN:  0006-2960     ISO Abbreviation:  Biochemistry     Publication Date:  1994 Aug 
Date Detail:
Created Date:  1994-09-08     Completed Date:  1994-09-08     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  9110-7     Citation Subset:  IM    
Affiliation:
Department of Physiological Chemistry, University of Groningen, The Netherlands.
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MeSH Terms
Descriptor/Qualifier:
Animals
Cell Line
Cell Membrane / metabolism
Chick Embryo
Cricetinae
Cytoplasm / metabolism
Diphtheria Toxin / metabolism*,  toxicity
Drug Carriers
Influenza A virus / physiology*
Kidney
Kinetics
Phosphatidylcholines
Protein Synthesis Inhibitors / metabolism,  toxicity
Viral Envelope Proteins / biosynthesis,  metabolism*
Chemical
Reg. No./Substance:
0/Diphtheria Toxin; 0/Drug Carriers; 0/Phosphatidylcholines; 0/Protein Synthesis Inhibitors; 0/Viral Envelope Proteins

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