Membrane fusion mutants of Semliki Forest virus

Margaret Kielian, S. Keranen, L. Kaariainen, A. Helenius

Research output: Contribution to journalArticle

68 Citations (Scopus)

Abstract

Previous reports have indicated that the entry of Semliki Forest virus (SFV) into cells depends on a membrane fusion reaction catalyzed by the viral spike glycoproteins and triggered by the low pH prevailing in the endosomal compartment. In this study the in vitro pH-dependent fusion of SFV with nuclease-filled liposomes has been used to select for a new class of virus mutants that have a pH-conditional fusion defect. The mutants obtained had a threshold for fusion of pH 5.5 as compared with the wild-type threshold of 6.2, when assayed by polykaryon formation, fusion with liposomes, or fusion at the plasma membrane. They were fully capable of infecting cells under standard infection conditions but were more sensitive to lysosomotropic agents that increase the pH in acidic vacuoles of the endocytic pathway. The mutants were, moreover, able to penetrate and infect baby hamster kidney-21 cell at 20°C, indicating that the endosomes have a pH below 5.5. The results confirm the involvement of pH-triggered fusion in SFV entry, emphasize the central role played by acidic endosomal vacuoles in this reaction, shed further light on the mechanism of SFV inhibition by lysosomotropic weak bases, and demonstrate the usefulness of mutant viruses as biological pH probes of the endocytic pathway.

Original languageEnglish (US)
Pages (from-to)139-145
Number of pages7
JournalJournal of Cell Biology
Volume98
Issue number1
StatePublished - 1984
Externally publishedYes

Fingerprint

Semliki forest virus
Membrane Fusion
Vacuoles
Liposomes
Viruses
Virus Internalization
Endosomes
Cricetinae
Glycoproteins
Cell Membrane
Kidney

ASJC Scopus subject areas

  • Cell Biology

Cite this

Kielian, M., Keranen, S., Kaariainen, L., & Helenius, A. (1984). Membrane fusion mutants of Semliki Forest virus. Journal of Cell Biology, 98(1), 139-145.

Membrane fusion mutants of Semliki Forest virus. / Kielian, Margaret; Keranen, S.; Kaariainen, L.; Helenius, A.

In: Journal of Cell Biology, Vol. 98, No. 1, 1984, p. 139-145.

Research output: Contribution to journalArticle

Kielian, M, Keranen, S, Kaariainen, L & Helenius, A 1984, 'Membrane fusion mutants of Semliki Forest virus', Journal of Cell Biology, vol. 98, no. 1, pp. 139-145.
Kielian M, Keranen S, Kaariainen L, Helenius A. Membrane fusion mutants of Semliki Forest virus. Journal of Cell Biology. 1984;98(1):139-145.
Kielian, Margaret ; Keranen, S. ; Kaariainen, L. ; Helenius, A. / Membrane fusion mutants of Semliki Forest virus. In: Journal of Cell Biology. 1984 ; Vol. 98, No. 1. pp. 139-145.
@article{0abd92c605aa4658af8bde838b85f5ff,
title = "Membrane fusion mutants of Semliki Forest virus",
abstract = "Previous reports have indicated that the entry of Semliki Forest virus (SFV) into cells depends on a membrane fusion reaction catalyzed by the viral spike glycoproteins and triggered by the low pH prevailing in the endosomal compartment. In this study the in vitro pH-dependent fusion of SFV with nuclease-filled liposomes has been used to select for a new class of virus mutants that have a pH-conditional fusion defect. The mutants obtained had a threshold for fusion of pH 5.5 as compared with the wild-type threshold of 6.2, when assayed by polykaryon formation, fusion with liposomes, or fusion at the plasma membrane. They were fully capable of infecting cells under standard infection conditions but were more sensitive to lysosomotropic agents that increase the pH in acidic vacuoles of the endocytic pathway. The mutants were, moreover, able to penetrate and infect baby hamster kidney-21 cell at 20°C, indicating that the endosomes have a pH below 5.5. The results confirm the involvement of pH-triggered fusion in SFV entry, emphasize the central role played by acidic endosomal vacuoles in this reaction, shed further light on the mechanism of SFV inhibition by lysosomotropic weak bases, and demonstrate the usefulness of mutant viruses as biological pH probes of the endocytic pathway.",
author = "Margaret Kielian and S. Keranen and L. Kaariainen and A. Helenius",
year = "1984",
language = "English (US)",
volume = "98",
pages = "139--145",
journal = "Journal of Cell Biology",
issn = "0021-9525",
publisher = "Rockefeller University Press",
number = "1",

}

TY - JOUR

T1 - Membrane fusion mutants of Semliki Forest virus

AU - Kielian, Margaret

AU - Keranen, S.

AU - Kaariainen, L.

AU - Helenius, A.

PY - 1984

Y1 - 1984

N2 - Previous reports have indicated that the entry of Semliki Forest virus (SFV) into cells depends on a membrane fusion reaction catalyzed by the viral spike glycoproteins and triggered by the low pH prevailing in the endosomal compartment. In this study the in vitro pH-dependent fusion of SFV with nuclease-filled liposomes has been used to select for a new class of virus mutants that have a pH-conditional fusion defect. The mutants obtained had a threshold for fusion of pH 5.5 as compared with the wild-type threshold of 6.2, when assayed by polykaryon formation, fusion with liposomes, or fusion at the plasma membrane. They were fully capable of infecting cells under standard infection conditions but were more sensitive to lysosomotropic agents that increase the pH in acidic vacuoles of the endocytic pathway. The mutants were, moreover, able to penetrate and infect baby hamster kidney-21 cell at 20°C, indicating that the endosomes have a pH below 5.5. The results confirm the involvement of pH-triggered fusion in SFV entry, emphasize the central role played by acidic endosomal vacuoles in this reaction, shed further light on the mechanism of SFV inhibition by lysosomotropic weak bases, and demonstrate the usefulness of mutant viruses as biological pH probes of the endocytic pathway.

AB - Previous reports have indicated that the entry of Semliki Forest virus (SFV) into cells depends on a membrane fusion reaction catalyzed by the viral spike glycoproteins and triggered by the low pH prevailing in the endosomal compartment. In this study the in vitro pH-dependent fusion of SFV with nuclease-filled liposomes has been used to select for a new class of virus mutants that have a pH-conditional fusion defect. The mutants obtained had a threshold for fusion of pH 5.5 as compared with the wild-type threshold of 6.2, when assayed by polykaryon formation, fusion with liposomes, or fusion at the plasma membrane. They were fully capable of infecting cells under standard infection conditions but were more sensitive to lysosomotropic agents that increase the pH in acidic vacuoles of the endocytic pathway. The mutants were, moreover, able to penetrate and infect baby hamster kidney-21 cell at 20°C, indicating that the endosomes have a pH below 5.5. The results confirm the involvement of pH-triggered fusion in SFV entry, emphasize the central role played by acidic endosomal vacuoles in this reaction, shed further light on the mechanism of SFV inhibition by lysosomotropic weak bases, and demonstrate the usefulness of mutant viruses as biological pH probes of the endocytic pathway.

UR - http://www.scopus.com/inward/record.url?scp=0021351778&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0021351778&partnerID=8YFLogxK

M3 - Article

VL - 98

SP - 139

EP - 145

JO - Journal of Cell Biology

JF - Journal of Cell Biology

SN - 0021-9525

IS - 1

ER -