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. 2000 Mar;74(6):2885-7.
doi: 10.1128/jvi.74.6.2885-2887.2000.

The intact retroviral Env glycoprotein of human foamy virus is a trimer

T Wilk  1 , F de Haas, A Wagner, T Rutten, S Fuller, R M Flügel, M Löchelt
Affiliations

The intact retroviral Env glycoprotein of human foamy virus is a trimer

T Wilk et al. J Virol. 2000 Mar.

Abstract

Electron microscopy of negatively stained human foamy virus particles provides direct evidence for the trimeric nature of intact Env surface glycoproteins. Three-dimensional image reconstruction reveals that the Env trimer is a tapering spike 14 nm in length. The spikes were often arranged in hexagonal rings which shared adjacent Env trimers.

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Figures

FIG. 1
FIG. 1
Surface features of HFV particles detected by negative-staining EM. HFV isolated from the supernatant of infected Hel299 cells 4 days postinfection was purified by sucrose gradient centrifugation, and rapid, negative staining with uranyl acetate revealed surface features. Particles with a diameter of ∼100 nm often showed a network of trimeric viral spike proteins on the particle surface and were predominantly arranged into rings of six subunits. When grouped in hexameric rings, a stain-filled hole with a diameter of about 8 nm was formed (b, asterisks). Adjacent rings always shared two completely integrated spikes. Images at higher magnification revealed three separate densities (arrowheads) in the triangular spike (b). Bars represent 50 nm (a) and 25 nm (b).
FIG. 2
FIG. 2
Three-dimensional reconstruction of HFV spike glycoproteins. The reconstruction was performed with 626 images of negatively stained HFV Env trimers in hexagonal clusters by using a model-based, iterative approach. The top row of the figure shows the averaged particle images (A, B, C, and D) corresponding to the projections (E, F, G, and H) of the reconstruction shown in the middle row. The bottom row shows surface representations of the reconstruction (I, J, K, and L) contoured at a volume which corresponds to that expected for four Env trimers. The four views displayed are at the following orientations of θ, ϕ: 0°, 0° (A, E, and I), 90°, 0° (B, F, and J), 45°, 30° (C, G, and K), and 30°, 180° (D, H, and L), where the z axis (θ, ϕ = 0°, 0°) lies along the threefold axis. The bar represents 10 nm.
FIG. 3
FIG. 3
Improvement of the image reconstruction with iterated cycles of refinement. The 626 particle images were divided into two sets and used to generate independent reconstructions. Comparison of these two reconstructions by FSC defined the resolution of the reproducible detail between the reconstructions. The resolution improved from 3.6 nm in the first cycle through 3.4 nm in the fourth cycle, as seen by the shift in the position at which the FSC curve first drops to a value of 0.5 (11).
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References

    1. Fass D, Kim P S. Dissection of a retrovirus envelope protein reveals structural similarity to influenza hemagglutinin. Curr Biol. 1995;5:1377–1383. - PubMed
    1. Fischer N, Heinkelein M, Lindemann D, Enssle J, Baum C, Werder E, Zentgraf H, Müller J G, Rethwilm A. Foamy virus particle formation. J Virol. 1999;72:1610–1615. - PMC - PubMed
    1. Gelderblom H, Frank H. Spumavirinae. In: Nermut M V, Steven A C, editors. Animal virus structure. Amsterdam, The Netherlands: Elsevier Science Publishers; 1987. pp. 305–311.
    1. Grief C, Hockley D J, Fromholc C E, Kitchin P A. The morphology of simian immunodeficiency virus as shown by negative staining electron microscopy. J Gen Virol. 1999;70:2215–2219. - PubMed
    1. Hunter E. Viral entry and receptors. In: Coffin J M, Hughes S, Varmus H E, editors. Retroviruses. Cold Spring Harbor, N.Y: Cold Spring Harbor Laboratory Press; 1997. pp. 71–120. - PubMed

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