Virion conformational changes

Esser, M.T., et al. 1999. Cyanovirin-N binds to gpl20 to interfere with CD4-dependent human immunodeficiency virus type 1 virion binding, fusion, and infectivity but does not affect the CD4 binding site on gpl20 or soluble CD4- induced conformational changes in gpl20. J Virol 73 4360. 

During cellular entry via the endosomes, the cr3 protein is removed from virions by acid-dependent proteolysis [160, 161]. This is the first necessary step for penetration of reovirus into the cytoplasm [162-164]. This is hypothesized to facilitate a conformational change in crl to a more extended form [156]. Monoclonal antibodies to each of the reovirus outer capsid proteins have been isolated and characterized [158, 165]. crl-specific mAbs are serotype specific [158, 165] and some of these mAbs are effective at neutralizing infectivity in vitro [158, 165, 166]. 

Two cryo-EM reconstructions have been published of poliovirus complexed with soluble forms of PVR (Belnap et al, 2000b He et al, 2000). Both density maps are similar and show the bound soluble PVR density extending outward from the virion surface by 115 A with three segmented domains (Fig. 5 see Color Insert). Poliovirus, like rhinovirus, has a narrow surface depression called the canyon that encircles each of the twelve 5-fold vertices. The cryo-EM reconstructions of the complex reveal that PVR penetrates into the canyon and makes contract with both the north wall of the canyon, which is toward the 5-fold axis, and the south wall, which is toward the 2- and 3-fold axes. Control cryo-EM reconstructions were also done of uncomplexed poliovirus. These studies suggest that there are no major conformational changes in the virion on binding soluble PVR however, incubations of the virus with PVR were done at 4°G. It is presumed that the cryo-EM reconstructions of the poliovirus-PVR complexes represent the initial recognition event between the virus and its receptor. 

The first enh y inhibitor to be licensed in the United States was enfuvirtide. A synthetic peptide, this compound has the ability to inhibit fusion of virions to the host cells by preventing the conformational change of gp4l. The peptide... 

Hoover-Litty, H., Greve, J.M., 1993. Formation of rhinovirus-soluble ICAM-1 complexes and conformational changes in the virion. J. Virol. 67, 390-397. 

Influenza neuraminidase cleaves terminal sialic acid residues and destroys the receptors recognized by viral hemagglutinin, which are present on the cell surface, in progeny virions, and in respiratory secretions. This enzymatic action is essential for release of virus from infected cells. Interaction of oseltamivir carboxylate with the neuraminidase causes a conformational change within the enzyme s active site and inhibits its activity. Inhibition of neuraminidase activity leads to viral aggregation at the cell surface and reduced virus spread within the respiratory tract. 

Viral Infection. The infection cycle is initiated when the glycoprotein spikes on the virion bind to receptors on the cell surface. The virus is localized initially to coated pits, where it is engulfed in a coated vesicle and transported to the endosomal compartment within the interior of the cell. A decrease in the pH in the interior of the vesicle induces a conformational change in the glycoprotein spikes, and rearrangement of the El glycoprotein mediates fusion of the virion envelope with the endosomal membrane.76 This fusion results in the release of the nucleocapsid into the cytoplasm, where disassembly of the nucleocapsid releases the viral RNA genome to the synthetic apparatus of the cell. 

Dryden, K. A., Wang, G., Yeager, M., Nibert, M. L., Coombs, K. M., Furlong, D. B., Fields, B. N., and Baker, T. S. (1993). Early steps in reovirus infection are associated with dramatic changes in supramolecular structure and protein conformation Analysis of virions and subviral particles by cryoelectron microscopy and image reconstruction./. Cell Biol. 122, 1023-1041. 

Both forms, however, contained intact RNA and the full complement of capsid polypeptides (50) Further evidence that a substantial conformational alteration of entero- and rhinovirus capsids accompanies the D to C antigenicity change has been obtained by examining the accessibilities of individual capsid proteins in intact virions, A-particles and naturally-occurring empty capsids to lacto-peroxidase-catalyzed iodination or alkylation with acetic anhydride (5I> 52). The results of these experiments are summarized in Table lY. Since under the experimental conditions employed the radioactive reagents formed covalent bonds with tyrosine residues... 

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