Organization of Immature Human Immunodeficiency Virus Type 1

Abstract

Immature retrovirus particles contain radially arranged Gag polyproteins in which the N termini lie at the membrane and the C termini extend toward the particle's center. We related image features to the polyprotein domain structure by combining mutagenesis with cryoelectron microscopy and image analysis. The matrix (MA) domain appears as a thin layer tightly associated with the inner face of the viral membrane, separated from the capsid (CA) layer by a low-density region corresponding to its C terminus. Deletion of the entire p6 domain has no effect on the width or spacing of the density layers, suggesting that p6 is not ordered in immature human immunodeficiency virus type 1 (HIV-1). In vitro assembly of a recombinant Gag polyprotein containing only capsid (CA) and nucleocapsid (NC) domains results in the formation of nonenveloped spherical particles which display two layers with density matching that of the CA-NC portion of immature HIV-1 Gag particles. Authentic, immature HIV-1 displays additional surface features and an increased density between the lipid bilayers which reflect the presence of gp41. The other internal features match those of virus-like particles.

HIV-1 Maturation Inhibitor Bevirimat Stabilizes the Immature Gag Lattice

“…5A, B, and C are also about 10 nm thick and also appear as doublets, which we attribute to the two CA domains, NTD (outer peak) and CTD (inner peak) (49). The inward shift of the CA layer in BVM-treated particles is apparent in Fig.…”

“…The MA domain contacts the viral membrane, and the rest of the Gag molecule extends radially inwards (49). Cryo-EM and cryo-electron tomography (cryo-ET) have revealed that the Gag shell has ordered patches of a honeycomblike lattice (11,52).…”

The size of sinusoidal fenestrae is a critical determinant of hepatocyte transduction after adenoviral gene transfer

“…[36][37][38] The size of fenestrae may also be a determinant of hepatocyte transduction after transfer with retroviral or lentiviral vectors, which have a diameter between 126 and 133 nm. [39][40][41] A role of the size of fenestrae in the biodistribution of adenoviral vectors in the adrenal gland has been previously suggested by Wang et al 42 Systemic administration of adenoviral vectors in mice induced transgene expression in the adrenal gland that was comparable but somewhat lower than in the liver and predominant in the zona fasciculata, the part of the adrenal cortex with the largest diameter of fenestrae. However, a major difference between sinusoidal fenestrae and fenestrae in other organs is the presence of diaphragms in the latter.…”

Do lipid rafts mediate virus assembly and pseudotyping?

“…The morphology of this particle is quite distinct from that of FFV. The FLV core is round rather than angular and displays a radial arrangement of rod-like features (small arrows) characteristic of Gag in other retroviruses (Fuller et al, 1997;Wilk et al, , 2001b. The membrane lacks prominent surface spikes and appears broader (large arrow) due to the presence of a submembrane protein layer.…”

“…Cryo-electron micrographs ( Fig. 1) of a preparation of feline foamy virus (FFV) grown in Crandel feline kidney (CrFK) cells show that it contains two morphologically distinct viruses: FFV (Fischer et al, 1998;Wilk et al, 2000Wilk et al, , 2001bWinkler et al, 1997;Yu et al, 1996;Zemba et al, 1998) and feline leukaemia virus (FLV) (Bolognesi, 1974;Essex et al, 1973;Gallo & Wong-Staal, 1982). These are seen as individual particles in Fig.…”