Effects of Membrane Potential and Sphingolipid Structures on Fusion of Semliki Forest Virus

Samsonov, A. A.; Chatterjee, Prodyot K.; Razinkov, Vladimir I.; Eng, Christina H.; Kielian, Margaret; Cohen, Fredric S.

doi:10.1128/jvi.76.24.12691-12702.2002

Cited by 35 publications

(32 citation statements)

References 63 publications

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“…Residual fusion activity at 37 uC in the absence of sphingomyelin has been described for SFV Waarts et al, 2002), but not for SINV (Smit et al, 1999). It has been found that sphingolipids support cholesterol-mediated virus binding and stimulate the conformational changes required for membrane fusion (Ahn et al, 2002;Moesby et al, 1995;Nieva et al, 1994;Samsonov et al, 2002). In line with these findings, we observed that the fusion rate of CHIKV is not dependent on sphingomyelin concentrations, and therefore not dependent on the physical properties of the membrane that would vary with changing sphingomyelin concentrations.…”

supporting

confidence: 90%

Chikungunya virus fusion properties elucidated by single-particle and bulk approaches

Duijl-Richter

Blijleven

Oijen

et al. 2015

Journal of General Virology

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Chikungunya virus (CHIKV) is a rapidly spreading, enveloped alphavirus causing fever, rash and debilitating polyarthritis. No specific treatment or vaccines are available to treat or prevent infection. For the rational design of vaccines and antiviral drugs, it is imperative to understand the molecular mechanisms involved in CHIKV infection. A critical step in the life cycle of CHIKV is fusion of the viral membrane with a host cell membrane. Here, we elucidate this process using ensemble-averaging liposome-virus fusion studies, in which the fusion behaviour of a large virus population is measured, and a newly developed microscopy-based single-particle assay, in which the fusion kinetics of an individual particle can be visualised. The combination of these approaches allowed us to obtain detailed insight into the kinetics, lipid dependency and pH dependency of hemifusion. We found that CHIKV fusion is strictly dependent on low pH, with a threshold of pH 6.2 and optimal fusion efficiency below pH 5.6. At this pH, CHIKV fuses rapidly with target membranes, with typically half of the fusion occurring within 2 s after acidification. Cholesterol and sphingomyelin in the target membrane were found to strongly enhance the fusion process. By analysing our single-particle data using kinetic models, we were able to deduce that the number of rate-limiting steps occurring before hemifusion equals about three. To explain these data, we propose a mechanistic model in which multiple E1 fusion trimers are involved in initiating the fusion process.

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supporting

confidence: 90%

Chikungunya virus fusion properties elucidated by single-particle and bulk approaches

Duijl-Richter

Blijleven

Oijen

et al. 2015

Journal of General Virology

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“…In the course of studies investigating the dependence of fusion upon lipids, however, we noticed that during the fusion of cells expressing SFV E1 to voltage-clamped planar bilayer membranes, the bilayer quickly ruptured after lowering pH at transpositive potentials, a polarity that corresponds to positive potentials inside target cells. In contrast, for trans-negative potentials, as would exist across the endosomal membrane, fusion proceeded efficiently (41). This difference suggested that the interactions of the fusion protein with the Tg planar bilayer were dependent on the polarity of voltage across the bilayer.…”

mentioning

confidence: 62%

“…Cells (Tva950) stably expressing avian sarcoma leukosis virus (ASLV) Env (33) or the receptor (Tva) of ASLV Env (33) were also maintained as previously described. To express the SFV fusion protein, HEK293T cells were transfected with the pCB3-wt vector by use of a standard calcium phosphate transfection method (41). This vector encodes the SFV structural proteins E1, p62 (precursor of E2), 6K, and capsid; transfection produces transient cell surface expression of the E1 fusion protein and the mature E2 protein.…”

Section: Methodsmentioning

confidence: 99%

Fusion Induced by a Class II Viral Fusion Protein, Semliki Forest Virus E1, Is Dependent on the Voltage of the Target Cell

Markosyan

Kielian

Cohen

2007

J Virol

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“…7C). (Several low-pH viral fusion proteins, such as those from influenza virus [27] and Semliki Forest virus [38], can induce fusion at 18°C.) As soon as dye transfer was detected, the laser was shut off, lowering temperature to 4°C.…”

Section: Vol 78 2004 Low Ph Is Required For Aslv Env Fusion 3757mentioning

confidence: 99%

Low pH Is Required for Avian Sarcoma and Leukosis Virus Env-Induced Hemifusion and Fusion Pore Formation but Not for Pore Growth

Melikyan

Barnard

Markosyan

et al. 2004

J Virol

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Binding of avian sarcoma and leukosis virus (ASLV) to its cognate receptor on the cell surface causes conformational changes in its envelope protein (Env). It is currently debated whether low pH is required for ASLV infection. To elucidate the role of low pH, we studied the association between ASLV subgroup B (ASLV-B) and liposomes and fusion between effector cells expressing Env from ASLV-A and ASLV-B and target cells expressing cognate receptors. Neither EnvA nor EnvB promoted cell-cell fusion at neutral pH, but lowering the pH resulted in quick and extensive fusion. As expected for a low-pH-triggered reaction, fusion was a steep function of pH. Steps that required low pH were identified. Binding a soluble form of the receptor caused ASLV-B to hydrophobically associate with liposome membranes at neutral pH, indicating that low pH is not required for insertion of Env's fusion peptides into membranes. But both cell-cell hemifusion and fusion pore formation were pH dependent. It is proposed that fusion peptide insertion stabilizes the conformation of ASLV Env into a form that can be acted upon by low pH. At this point, but not before, low pH can induce fusion and is in fact required for fusion to occur. However, low pH is no longer necessary after formation of the initial fusion pore: pore enlargement does not require low pH.After an enveloped virus binds to receptors on plasma membranes, one of two triggers directly causes the membrane fusion that allows the virus to deposit its genome into the cell. In the first case, association of the fusion protein with receptors at the plasma membrane is the trigger for the conformational changes required for fusion at neutral pH. In the second case, the virus is internalized and trafficked to an endosome, where the low-pH environment triggers these changes in the viral glycoprotein. For most viruses that fuse within endosomes at low pH, receptor binding does no more than anchor the virus to the cell membrane and all of the fusogenic conformational changes are induced solely by low pH. Thus, it had been thought that the trigger for viral fusion was either receptor binding or low pH but never both. This view was recently challenged by evidence that strongly indicated that avian sarcoma and leukosis virus (ASLV) entry is not triggered through only one of these known patterns but instead utilizes both in combination (35).ASLV entry into a host cell is strictly receptor dependent. ASLVs are classified into ten subgroups (A through J) according to their receptor specificities (22). Expressing the TVA and TVB receptors on cells deficient in the receptor renders those cells susceptible to infection by ASLV subgroup A (ASLV-A) or ASLV-B, respectively (2,4,8). Moreover, binding soluble forms of the ectodomains of the receptors (soluble TVA [sTVA] or sTVB) to their respective viral counterparts allow infection of receptor-deficient cells (6,12,25,(40)(41)(42)(43).There is strong evidence to indicate that both receptor interaction and low pH are required for ASLV entry. When reverse ...

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Effects of Membrane Potential and Sphingolipid Structures on Fusion of Semliki Forest Virus

Cited by 35 publications

References 63 publications

Chikungunya virus fusion properties elucidated by single-particle and bulk approaches

Chikungunya virus fusion properties elucidated by single-particle and bulk approaches

Fusion Induced by a Class II Viral Fusion Protein, Semliki Forest Virus E1, Is Dependent on the Voltage of the Target Cell

Low pH Is Required for Avian Sarcoma and Leukosis Virus Env-Induced Hemifusion and Fusion Pore Formation but Not for Pore Growth

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