Membrane Uncoating of Intact Enveloped Viruses

Haywood, Anne M.

doi:10.1128/jvi.00229-10

Cited by 24 publications

(13 citation statements)

References 54 publications

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“…This method is supported by experiments that have shown that SV is capable of infection at low temperatures that do not allow endocytosis or membrane fusion to occur (51). Direct observation by electron microscopy also provides evidence that virus penetration occurs at the cell surface via formation of a pore (15,41).…”

supporting

confidence: 55%

“…An alternate method of entry is that SV attaches to the cell surface receptor and directly injects its RNA by forming a pore in the cell membrane (15,41). The nucleocapsid core is responsible for maintaining the rigid structure of the virus (9), so after release of the genome the virus is no longer stable and can be released from the cell surface (41), leaving the pore in the membrane temporarily intact (28,31).…”

mentioning

confidence: 99%

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Role of the Vacuolar-ATPase in Sindbis Virus Infection

Hunt

Hernandez

Brown

2011

J Virol

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Bafilomycin A 1 is a specific inhibitor of the vacuolar-ATPase (V-ATPase), which is responsible for pH homeostasis of the cell and for the acidification of endosomes. Bafilomycin A 1 has been commonly used as a method of inhibition of infection by viruses known or suspected to follow the path of receptor-mediated endocytosis and low-pH-mediated membrane fusion. The exact method of entry for Sindbis virus, the prototype alphavirus, remains undetermined. Sindbis virus (SV) is the prototype virus of the genus Alphavirus in the family Togaviridae. It consists of two nested protein shells with Tϭ4 icosahedral symmetry. The inner shell consists of 240 copies of the capsid protein (C) and encloses the singlestranded positive-sense RNA genome of the virus. The outer protein shell is a lattice of 240 copies of each of the two structural proteins E1 and E2 (1, 40). Evidence suggests E1 forms the base of the structural lattice, and E2 is responsible for receptor recognition and binding (33). Between the two protein shells exists a host-derived lipid bilayer (1,40).When SV infects a cell, the positive-sense RNA must first be translated and transcribed into a negative-sense RNA template. Translation of the positive-sense RNA results in the four nonstructural proteins (47). The uncleaved P123 and nsP4 form the minus-strand RNA replicase, which translates the positive-sense RNA genome into a negative-sense RNA template. P123 is cleaved into three separate proteins (nsP1, nsP2, and nsP3) that form the plus-strand RNA replicase with nsP4.

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supporting

confidence: 55%

mentioning

confidence: 99%

Role of the Vacuolar-ATPase in Sindbis Virus Infection

Hunt

Hernandez

Brown

2011

J Virol

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“…However, this process is very similar in many aspects to the entry mechanism proposed for nonenveloped viruses such as poliovirus (39) and also suggested to occur with Sendai virus (18). Previous studies have observed a rapid and highly efficient RNA release for poliovirus, which also occurs in an endocytosis-independent manner but is dependent on temperature, actin cytoskeleton, and tyrosine kinases (40).…”

Section: Discussionmentioning

confidence: 88%

“…It is significant that in the process of infection by arboviruses the viral membranes remain outside the cell. If the virus membrane disengages from the host cell membrane instead of merging with it, then not only would the cell not have viral proteins on its surface but also the release of the virus membrane pieces with embedded proteins could serve as immunologic decoys (18).…”

Section: Discussionmentioning

confidence: 99%

“…Direct observation of viruscell interaction by electron microscopy can be challenging when the infectivity ratio and physical integrity of these particles are not taken into consideration. If the infectivity ratio of these preparations is poor, the observation of particles in endosomes, for example, may reflect the uptake of noninfectious virus and lead to an inaccurate interpretation of the infection process (18). Thus, the sensitivity of enveloped viruses to laboratory purification and storage procedures needs to be considered when designing any penetration study with membrane-containing viruses.…”

mentioning

confidence: 99%

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Alphavirus Genome Delivery Occurs Directly at the Plasma Membrane in a Time- and Temperature-Dependent Process

Vancini

Wang

Ferreira

et al. 2013

J Virol

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It is widely held that arboviruses such as the alphavirus Sindbis virus gain entry into cells by a process of receptor-mediated endocytosis followed by membrane fusion in the acid environment of the endosome. We have used an approach of direct observation of Sindbis virus entry into cells by electron microscopy and immunolabeling of virus proteins with antibodies conjugated to gold beads. We found that upon attaching to the cell surface, intact RNA-containing viruses became empty shells that could be identified only by antibody labeling. We found that the rate at which full particles were converted to empty particles increased with time and temperature. We found that this entry event takes place at temperatures that inhibit both endosome formation and membrane fusion. We conclude that entry of alphaviruses is by direct penetration of cell plasma membranes through a pore structure formed by virus and, possibly, host proteins.

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