HIV-cell membrane fusion intermediates are restricted by Serincs as revealed by cryo-electron and TIRF microscopy

Ward, Amanda E.; Kiessling, Volker; Pornillos, Owen; White, Judith M.; Ganser‐Pornillos, Barbie K.; Tamm, Lukas K.

doi:10.1074/jbc.ra120.014466

Cited by 45 publications

(85 citation statements)

References 56 publications

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“…SERINC5 is thought to inhibit HIV-1 infection by targeting the step of fusion between the viral lipid envelope and the host cell plasma membrane ( 4 , 8 , 36 ). Therefore, we tested whether EnvCT truncation allowed HIV-1 to evade SERINC5 inhibition of virion fusion using the Blam-Vpr fusion assay ( 37 ).…”

Section: Resultsmentioning

confidence: 99%

HIV envelope tail truncation confers resistance to SERINC5 restriction

Haider

Snetkov

Jolly

2021

Proc. Natl. Acad. Sci. U.S.A.

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SERINC5 is a potent lentiviral restriction factor that gets incorporated into nascent virions and inhibits viral fusion and infectivity. The envelope glycoprotein (Env) is a key determinant for SERINC restriction, but many aspects of this relationship remain incompletely understood, and the mechanism of SERINC5 restriction remains unresolved. Here, we have used mutants of HIV-1 and HIV-2 to show that truncation of the Env cytoplasmic tail (ΔCT) confers complete resistance of both viruses to SERINC5 and SERINC3 restriction. Critically, fusion of HIV-1 ΔCT virus was not inhibited by SERINC5 incorporation into virions, providing a mechanism to explain how EnvCT truncation allows escape from restriction. Neutralization and inhibitor assays showed ΔCT viruses have an altered Env conformation and fusion kinetics, suggesting that EnvCT truncation dysregulates the processivity of entry, in turn allowing Env to escape targeting by SERINC5. Furthermore, HIV-1 and HIV-2 ΔCT viruses were also resistant to IFITMs, another entry-targeting family of restriction factors. Notably, while the EnvCT is essential for Env incorporation into HIV-1 virions and spreading infection in T cells, HIV-2 does not require the EnvCT. Here, we reveal a mechanism by which human lentiviruses can evade two potent Env-targeting restriction factors but show key differences in the capacity of HIV-1 and HIV-2 to exploit this. Taken together, this study provides insights into the interplay between HIV and entry-targeting restriction factors, revealing viral plasticity toward mechanisms of escape and a key role for the long lentiviral EnvCT in regulating these processes.

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Section: Resultsmentioning

confidence: 99%

HIV envelope tail truncation confers resistance to SERINC5 restriction

Haider

Snetkov

Jolly

2021

Proc. Natl. Acad. Sci. U.S.A.

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“…In all cases, such assays rely heavily on the use of virus particles labeled with multiple fluorophores. Often, a lipophilic membrane dye is included within the viral lipid membrane at self-quenching concentrations [ 45 , 58 , 59 ], allowing for the observation of lipid mixing and of the hemifusion and fusion process (Fig. 2D ) [ 45 , 58 , 59 ].…”

Section: Methodological Considerationsmentioning

confidence: 99%

“…Often, a lipophilic membrane dye is included within the viral lipid membrane at self-quenching concentrations [ 45 , 58 , 59 ], allowing for the observation of lipid mixing and of the hemifusion and fusion process (Fig. 2D ) [ 45 , 58 , 59 ]. In addition to this, a soluble fluorescent marker can be included in the lumen of the viral particle [ 45 , 58 , 60 ], or the viral capsid can be labeled directly [ 60 – 63 ].…”

Section: Methodological Considerationsmentioning

confidence: 99%

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Physicochemical tools for studying virus interactions with targeted cell membranes in a molecular and spatiotemporally resolved context

et al. 2021

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The objective of this critical review is to provide an overview of how emerging bioanalytical techniques are expanding our understanding of the complex physicochemical nature of virus interactions with host cell surfaces. Herein, selected model viruses representing both non-enveloped (simian virus 40 and human norovirus) and enveloped (influenza A virus, human herpes simplex virus, and human immunodeficiency virus type 1) viruses are highlighted. The technologies covered utilize a wide range of cell membrane mimics, from supported lipid bilayers (SLBs) containing a single purified host membrane component to SLBs derived from the plasma membrane of a target cell, which can be compared with live-cell experiments to better understand the role of individual interaction pairs in virus attachment and entry. These platforms are used to quantify binding strengths, residence times, diffusion characteristics, and binding kinetics down to the single virus particle and single receptor, and even to provide assessments of multivalent interactions. The technologies covered herein are surface plasmon resonance (SPR), quartz crystal microbalance with dissipation (QCM-D), dynamic force spectroscopy (DFS), total internal reflection fluorescence (TIRF) microscopy combined with equilibrium fluctuation analysis (EFA) and single particle tracking (SPT), and finally confocal microscopy using multi-labeling techniques to visualize entry of individual virus particles in live cells. Considering the growing scientific and societal needs for untangling, and interfering with, the complex mechanisms of virus binding and entry, we hope that this review will stimulate the community to implement these emerging tools and strategies in conjunction with more traditional methods. The gained knowledge will not only contribute to a better understanding of the virus biology, but may also facilitate the design of effective inhibitors to block virus entry.

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“…The mechanism by which virion-associated SERINC5 inhibits HIV-1 entry is unknown. The block is manifest after virion attachment to target cells, apparently at the stage of fusion pore expansion; virion contents mix with target cell cytoplasm but virion core transfer to the cytoplasm is inhibited [ 18 , 20 , 26 ]. Virions that are otherwise isogenic exhibit a range of dependency on Nef and of sensitivity to SERINC5 when pseudotyped with HIV-1 Env glycoproteins from different HIV-1 isolates [ 27 , 28 ].…”

Section: Introductionmentioning

confidence: 99%

Influence of Different Glycoproteins and of the Virion Core on SERINC5 Antiviral Activity

Diehl

Guney

Vanzo

et al. 2021

Viruses

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Host plasma membrane protein SERINC5 is incorporated into budding retrovirus particles where it blocks subsequent entry into susceptible target cells. Three structurally unrelated proteins encoded by diverse retroviruses, human immunodeficiency virus type 1 (HIV-1) Nef, equine infectious anemia virus (EIAV) S2, and ecotropic murine leukemia virus (MLV) GlycoGag, disrupt SERINC5 antiviral activity by redirecting SERINC5 from the site of virion assembly on the plasma membrane to an internal RAB7+ endosomal compartment. Pseudotyping retroviruses with particular glycoproteins, e.g., vesicular stomatitis virus glycoprotein (VSV G), renders the infectivity of particles resistant to inhibition by virion-associated SERINC5. To better understand viral determinants for SERINC5-sensitivity, the effect of SERINC5 was assessed using HIV-1, MLV, and Mason-Pfizer monkey virus (M-PMV) virion cores, pseudotyped with glycoproteins from Arenavirus, Coronavirus, Filovirus, Rhabdovirus, Paramyxovirus, and Orthomyxovirus genera. SERINC5 restricted virions pseudotyped with glycoproteins from several retroviruses, an orthomyxovirus, a rhabdovirus, a paramyxovirus, and an arenavirus. Infectivity of particles pseudotyped with HIV-1, amphotropic-MLV (A-MLV), or influenza A virus (IAV) glycoproteins, was decreased by SERINC5, whether the core was provided by HIV-1, MLV, or M-PMV. In contrast, particles pseudotyped with glycoproteins from M-PMV, parainfluenza virus 5 (PIV5), or rabies virus (RABV) were sensitive to SERINC5, but only with particular retroviral cores. Resistance to SERINC5 did not correlate with reduced SERINC5 incorporation into particles, route of viral entry, or absolute infectivity of the pseudotyped virions. These findings indicate that some non-retroviruses may be sensitive to SERINC5 and that, in addition to the viral glycoprotein, the retroviral core influences sensitivity to SERINC5.

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HIV-cell membrane fusion intermediates are restricted by Serincs as revealed by cryo-electron and TIRF microscopy

Cited by 45 publications

References 56 publications

HIV envelope tail truncation confers resistance to SERINC5 restriction

HIV envelope tail truncation confers resistance to SERINC5 restriction

Physicochemical tools for studying virus interactions with targeted cell membranes in a molecular and spatiotemporally resolved context

Influence of Different Glycoproteins and of the Virion Core on SERINC5 Antiviral Activity

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