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Fusion of the lentogenic strain “Clone 30” of Newcastle disease virus (NDV) with the cell line COS-7 has been studied. Fusion was monitored using the octadecylrhodamine B chloride dequenching assay [Hoekstra, D., de Boer, T., Klappe, K. and Wilschut, J. (1984). Biochemistry 23, 5675–5681]. In the present work, fusion of NDV with COS-7 cells was found to occur in a time- and temperature-dependent fashion...
Semliki Forest Virus (SFV) is an enveloped alphavirus that infects cells by a low-pH-dependent membrane fusion reaction. SFV fusion is catalyzed by the spike protein E1 subunit, which contains a putative fusion peptide between residues 79 and 97. Prior mutagenesis studies demonstrated that an E1 G91D mutation blocks both virus-membrane fusion and the formation of a highly stable E1 trimer believed...
Human herpesvirus entry mediator C (HveC) is an alphaherpesvirus receptor which binds to virion glycoprotein D (gD). We identified porcine HveC and studied its interaction with pseudorabies virus (PrV) and herpes simplex virus type 1 (HSV-1) gD. Porcine and human HveC have 96% amino acid identity and HveC from African green monkey, mouse, hamster, and cow are similarly conserved. Porcine HveC mediates...
Human cytomegalovirus (HCMV) causes a broad spectrum of clinical manifestations in immunocompromised patients, including infection of the gastrointestinal tract. To investigate the role of epithelial cells in the gastrointestinal HCMV disease, we used the intestinal epithelial cell line Caco-2, which is permissive for HCMV replication. In differentiated Caco-2 cells, we showed previously that HCMV...
Glycoprotein C (gC) of pseudorabies virus, a swine herpesvirus, initiates virus attachment by binding to heparan sulfate (HS) linked to proteoglycans (HSPGs) on the cell surface. This interaction facilitates a required step in virus entry, the binding to a non-HS coreceptor, likely by another viral glycoprotein, gD. We demonstrate that gC has an even more direct role in virus entry than simply promoting...
This study attempts to isolate and characterize West Nile virus-binding molecules on the plasma membrane of Vero and murine neuroblastoma cells that is responsible for virus entry. Pretreatment of Vero cells with proteases, glycosidases (endoglycosidase H, α-mannosidase), and sodium periodate strongly inhibited West Nile virus infection, whereas treatments with phospholipases and heparinases had no...
The enveloped alphavirus Semliki Forest virus (SFV) infects cells via a low pH-triggered membrane fusion reaction mediated by the E1 protein. E1's fusion activity is regulated by its heterodimeric interaction with a companion membrane protein E2. Mature E2 protein is generated by furin processing of the precursor p62. Processing destabilizes the heterodimer, allowing dissociation at acidic pH, E1...
Cholesterol-labeled oligonucleotides were found several years ago to inhibit HIV-1 in tissue culture at nanomolar concentrations. We present evidence that this is mainly due to an electrostatic interaction between polyanionic oligonucleotide concentrated at the cell surface and a positively charged region in the V3 loop of the HIV-1 envelope protein. When added to tissue culture, cholesterol-labeled...
In HSV types 1 and 2, gH forms a noncovalent heterodimer with gL. Previous studies demonstrated that the first 323 amino acids of gH1 and the first 161 amino acids of gL1 are sufficient for gH/gL binding. For gL1, substitution of any of its four cysteine (C) residues (all located within the gH/gL binding region) destroyed gH binding and function. Although gH1 contains 8 cysteines in its ectodomain,...
Vesicular stomatitis virus (VSV) is well established to enter cells by pH-dependent endocytosis, but mechanistic aspects of its internalization have remained unclear. Here, we examined the functional role of clathrin in VSV entry by expression of a dominant-negative mutant of Eps15 (GFP-Eps15Δ95/295), a protein essential for clathrin-mediated endocytosis. Whereas expression of GFP alone had no effect...
This study isolated and characterized the West Nile virus (WNV) putative receptor molecule(s) from Aedes albopictus mosquito (C6/36) cells. The binding of WNV to C6/36 cells was saturated with 5000 particles per cell. The entry of WNV into C6/36 cells was strongly inhibited when pretreated with proteinase K and to a lesser extent with sodium periodate. However, pretreatment of C6/36 cells with phospholipases,...
Endogenous retroviral genetic material serves as a reservoir for the generation of retroviral pathogens by recombination between activated endogenous or exogenous infectious agents. Some porcine tissues actively express infectious porcine endogenous retroviruses (PERVs). Of the three classes of PERV characterized to date, two, PERV-A and B, are capable of infecting human cells in vitro, whereas PERV-C...
Virus envelope proteins determine receptor utilization and host range. The choice of receptor not only permits specific targeting of cells that express it, but also directs the virus into specific endosomal trafficking pathways. Disrupting trafficking can result in loss of virus infectivity due to redirection of virions to non-productive pathways. Identification of the pathway or pathways used by...
The initial interaction between mosquito-borne flavivirus West Nile and mosquito cells is poorly characterized. This study analyzed the endocytic and the associated signaling pathway that mediate the infectious entry of West Nile virus (WNV) into mosquito cell line (C6/36). Pretreatment of C6/36 cells with pharmacological drugs that blocks clathrin-mediated endocytosis significantly inhibited virus...
The human glucose transporter protein 1 (GLUT-1) functions as a receptor for human T cell leukemia virus (HTLV). GLUT-1 is a twelve-transmembrane cell surface receptor with six extracellular (ECL) and seven intracellular domains. To analyze HTLV-1 cytotropism, we utilized polyclonal antibodies to a synthetic peptide corresponding to the large extracellular domain of GLUT-1. The antibodies caused significant...
The arenavirus family contains several important human pathogens including Lassa fever virus (LASV), lymphocytic choriomeningitis virus (LCMV) and the New World clade B viruses Junin (JUNV) and Machupo (MACV). Previously, α-dystroglycan (α-DG) was identified as a receptor recognized by LASV and certain strains of LCMV. However, other studies have suggested that α-DG is probably not used by the clade...
Although cell–cell fusion assays are useful surrogate methods for studying virus fusion, differences between cell–cell and virus–cell fusion exist. To examine paramyxovirus fusion in real time, we labeled viruses with fluorescent lipid probes and monitored virus–cell fusion by fluorimetry. Two parainfluenza virus 5 (PIV5) isolates (W3A and SER) and PIV5 containing mutations within the fusion protein...
Human immunodeficiency virus (HIV) delivers its genome to a host cell through fusion of the viral envelope with a cellular membrane. While the viral and cellular proteins involved in entry have been analyzed in detail, the dynamics of virus–cell fusion are largely unknown. Single virus tracing (SVT) provides the unique opportunity to visualize viral particles in real time allowing direct observation...
Herpes simplex virus type 1 (HSV-1) entry into permissive cells involves attachment to cell-surface glycosaminoglycans (GAGs) and fusion of the virus envelope with the cell membrane triggered by the binding of glycoprotein D (gD) to cognate receptors. In this study, we characterized the observation that soluble forms of the gD ectodomain (sgD) can mediate entry of gD-deficient HSV-1. We examined the...
This study demonstrated that the λ- and ι-carrageenans, sulfated polysaccharides containing linear chains of galactopyranosyl residues, are potent inhibitors of dengue virus type 2 (DENV-2) and 3 (DENV-3) multiplication in Vero and HepG2 cells, with values of effective concentration 50% from 0.14 to 4.1 μg/ml. This activity was assayed by plaque reduction, virus yield inhibition and antigen expression...
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