Nipah virus (NiV) and Hendra virus (HeV) have been identified as the causes of outbreaks of fatal meningitis, encephalitis, and respiratory disease in Australia, Malaysia, Bangladesh, and India from 1994 until 2004. In order to accommodate the unique genomic characteristics of NiV and HeV, a new genus within the family Paramyxoviridae was created, named Henipavirus. NiV encodes two surface glycoproteins: the attachment glycoprotein (G) binds to the cellular receptor for the virus, while the fusion glycoprotein (F) mediates membrane fusion between the virus and cell membranes. Expression of F and G in the same cell results in cell-cell fusion in transfected cell monolayers, while expression of F and G on their own in cell monolayers does not result in fusion. Co-culture of singly-transfected F and G cells also does not result in fusion. Expression of NiV G in transgenic CRFK cells results in resistance to NiV- and HeV-induced cytopathic effect. Additionally, neither NiV nor HeV nucleic acid could be detected in CRFK-NiV G that had been exposed to NiV or HeV. NiV G expression also prevents NiV F+NiV G-mediated cell-cell fusion, but does not affect cell surface expression of either virus receptor, ephrin-B2 and ephrin-B3. Chimeric glycoproteins derived from NiV G and CDV H were constructed and characterized. None of the chimeric glycoproteins were able to fuse when coexpressed with either NiV F or CDV F. Only one of the chimeric glycoproteins (H145/G458) was detected on the cell surface by immunofluorescence assay (IFA). None of the chimeric glycoproteins altered cell surface expression levels of ephrin-B2 and ephrin-B3. Finally, recombinant NiV genomes (rNiV and rNiV eGFPG) were constructed, as well as chimeric CDV genomes with NiV ORF substitutions (rCDV eGFPH NiVFG and rCDV eGFPH NiVMFG). The only chimeric virus that was generated, rCDV eGFPH NiVFG, was assessed for its release from infected cells. rCDV eGFPH NiVFG was poorly released from infected cells without a freeze-thaw cycle, but was also found to induce the cellsurface down-regulation of the viral receptors ephrin-B2 and ephrin-B3.

Nipah virus (NiV) and Hendra virus (HeV) have been identified as the causes of outbreaks of fatal meningitis, encephalitis, and respiratory disease in Australia, Malaysia, Bangladesh, and India from 1994 until 2004. In order to accommodate the unique genomic characteristics of NiV and HeV, a new genus within the family Paramyxoviridae was created, named Henipavirus. NiV encodes two surface glycoproteins: the attachment glycoprotein (G) binds to the cellular receptor for the virus, while the fusion glycoprotein (F) mediates membrane fusion between the virus and cell membranes. Expression of F and G in the same cell results in cell-cell fusion in transfected cell monolayers, while expression of F and G on their own in cell monolayers does not result in fusion. Co-culture of singly-transfected F and G cells also does not result in fusion. Expression of NiV G in transgenic CRFK cells results in resistance to NiV- and HeV-induced cytopathic effect. Additionally, neither NiV nor HeV nucleic acid could be detected in CRFK-NiV G that had been exposed to NiV or HeV. NiV G expression also prevents NiV F+NiV G-mediated cell-cell fusion, but does not affect cell surface expression of either virus receptor, ephrin-B2 and ephrin-B3. Chimeric glycoproteins derived from NiV G and CDV H were constructed and characterized. None of the chimeric glycoproteins were able to fuse when coexpressed with either NiV F or CDV F. Only one of the chimeric glycoproteins (H145/G458) was detected on the cell surface by immunofluorescence assay (IFA). None of the chimeric glycoproteins altered cell surface expression levels of ephrin-B2 and ephrin-B3. Finally, recombinant NiV genomes (rNiV and rNiV eGFPG) were constructed, as well as chimeric CDV genomes with NiV ORF substitutions (rCDV eGFPH NiVFG and rCDV eGFPH NiVMFG). The only chimeric virus that was generated, rCDV eGFPH NiVFG, was assessed for its release from infected cells. rCDV eGFPH NiVFG was poorly released from infected cells without a freeze-thaw cycle, but was also found to induce the cellsurface down-regulation of the viral receptors ephrin-B2 and ephrin-B3.

Hepatitis C Virus (HCV) infects more than 170 million people worldwide but no vaccine is available yet. HCV entry may represent a promising target for therapies and is mediated by two envelope glycoproteins, E1 and E2, assembled as heterodimer onto the virus surface. However, how E1 and E2 dialog, structurally rearrange and act together during these steps remain poorly defined. In this work, we aimed to clarify the interrelation of E1E2 during virus entry, thus opening ways to potential new therapeutic strategies. We first investigated whether a strong genetic divergence between E1E2 heterodimers may highlight distinct functions. We observed that B-cell derived E1E2 were specialized for B-cell infection, suggesting that new functions can emerge from the E1E2 conformational plasticity. In a second approach, we identified a conserved dialog between E1 and the domain III of E2 that was critical for virus binding and fusion. Moreover, a computational model predicted a strong co-evolution between E1 and E2 as well as potential structural rearrangements, suggesting that HCV E2 is likely a fusion protein able to fold over via its domain III through the mediation of E1. Altogether, these different works highlight that E1 and E2 are involved in complex dialogs that regulate the heterodimer folding and functions, suggesting that E1E2 heterodimer is more likely a single functional protein entity than an association of two proteins with specific functions.

[Truncated abstract] Human complement receptor 2 (CR2/CD21) is a cell surface glycoprotein detected on specific cells involved in immunity, which binds complement C3 cleavage fragments, cellular ligands IFN-? and CD23 as well as the EBV coat protein, gp350/220. During the early stages of B-cell development CR2/CD21 is silenced. Expression is initiated on immature B-cells escaping negative selection. During peripheral maturation CR2/CD21 is up-regulated with B-cell sub-populations showing distinctive surface levels (comparatively low, intermediate or high). CR2/CD21 is silenced upon terminal plasmacytic differentiation. Appropriate timing and expression level of CR2/CD21 is important for the development of a healthy B-cell repertoire. Previous studies have identified sequences within the proximal promoter and first intron of CR2/CD21 that cooperate within native chromatin to control cell-specific silencing. Further, analysis of cultured human cells has revealed chromatin structural variation causing DNase I hypersensitivity at these regulatory sites in a CR2/CD21-expressing mature B-cell line (Raji) which are absent in a non-lymphoid cell type (K562). The primary focus of the present study involved characterising chromatin structural variation over previously recognized DNase I hypersensitive regions at the CR2/CD21 locus in human cells to understand how chromatin structure might regulate developmental expression of CR2/CD21. ... These studies provide evidence that notch signaling influences CR2/CD21 expression in human cell lines. First, in vivo binding of CBF1 to CR2/CD21 sequences in the proximal promoter and CRS implies that CR2/CD21 is a direct target of notch activation. Second, the effect of exogenous notch signalling molecules on CR2/CD21 proximal promoter activity was modulated by factors binding tandem E-boxes near the transcriptional start site suggesting that the notch pathway may also influence CR2/CD21 expression via control of HLH molecules. Third, initiation of CR2/CD21 expression was observed in a nonexpressing pre-B cell line (Reh) by co-culture with stromal cells expressing a notch ligand (OP9-DL) but not control stroma (OP9-GFP). Together, these findings support a role for notch regulation of B-cell maturation and invite speculation that initiation of CR2/CD21 expression following negative selection of immature B-cells involves crosstalk between HLH transcriptional regulators and the notch pathway. Furthermore, the Reh/OP9-DL co-culture system may provide a model to directly study the relationship between cell signalling molecules, transcription factor regulation, chromatin structural variation and differentiation of B-cells.

Diss. (sammanfattning) Umeå : Umeå universitet, 2006. / Härtill 5 uppsatser.

Diss. (sammanfattning) Linköping : Linköpings universitet, 2006. / Härtill 5 uppsatser.

Thesis (Ph. D.)--School of Pharmacy. University of Missouri--Kansas City, 2007. / "A dissertation in pharmaceutical science and pharmacology." Advisor: Ashim K. Mitra. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed July 16, 2008. Includes bibliographical references (leaves 231-248). Online version of the print edition.

Thesis (Ph.D.)--University of Florida, 2005. / Typescript. Title from title page of source document. Document formatted into pages; contains 162 pages. Includes Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 88-101).

Sialic acid is a highly abundant and a common component of vertebrate glycans, where it can be found in the terminal positions of the cell surface glycoconjugates. The amount of sialylated glycoconjugates as well as their complexity vary between both different species and different tissue types within one individual. Considering the vertebrates, these well studied structures are know to be important for cell-cell interactions, cell adhesion and immunity. In contrary, sialic acid in arthropod glycans has been identified only in a limited number of species. In obligatory blood feeding parasites such as ticks, distinguishing between sialylated glycoproteins of tick and host origin is challenging due to huge volumes of ingested blood containing heavily sialylated structures of host origin. In the tick Ixodes ricinus, the presence of minor amount of tick´s sialylated structures has been shown previously in the ovaries and salivary glands, however, their role remains completely unknown. In this thesis, we study the importance and role of both the tick-originating and the host sialylated glycoproteins for I. ricinus, the tick commonly found in Czech Republic. We show that the tick-originating sialylated glycoproteins are present in I. ricinus eggs, and that their amount changes over time after laying the eggs. Furthermore, these molecules were localized in cryosections of 14 days old eggs and in the larvae using confocal microscopy. In addition, we shed some further light on the role of sialic acid for ticks in the tick blood meal. According to our results, the glycan part of glycoproteins is the key in recognition of these molecules by tick cells.