scholarly journals Antibodies Generated in Cats by a Lipopeptide Reproducing the Membrane-Proximal External Region of the Feline Immunodeficiency Virus Transmembrane Enhance Virus Infectivity

2007 ◽  
Vol 14 (8) ◽  
pp. 944-951 ◽  
Author(s):  
Simone Giannecchini ◽  
Anna Maria D'Ursi ◽  
Cinzia Esposito ◽  
Mario Scrima ◽  
Elisa Zabogli ◽  
...  
Keyword(s):  
Feline Immunodeficiency Virus ◽  
Virus Infectivity ◽  
Membrane Interface ◽  
External Region ◽  
Ordered Structures ◽  
Membrane Proximal External Region ◽  
Transmembrane Glycoprotein ◽  
Immunodeficiency Virus ◽  
Viable Approach

ABSTRACT The immunogenicity of a lipoylated peptide (lipo-P59) reproducing the membrane-proximal external region (MPER) of the transmembrane glycoprotein of feline immunodeficiency virus (FIV) was investigated with cats. In the attempt to mimic the context in which MPER is located within intact virions, lipo-P59 was administered in association with membrane-like micelles. Analyses showed that in this milieu, lipo-P59 had a remarkable propensity to be positioned at the membrane interface, displayed a large number of ordered structures folded in turn helices, and was as active as lipo-P59 alone at inhibiting FIV infectivity in vitro. The antibodies developed differed from the ones previously obtained by immunizing cats with the nonlipoylated version of the peptide (G. Freer, S. Giannecchini, A. Tissot, M. F. Bachmann, P. Rovero, P. F. Serres, and M. Bendinelli, Virology 322:360-369, 2004) in epitope specificity and in the fact that they bound FIV virions. However, they too lacked virus-neutralizing activity and actually enhanced FIV infectivity for lymphoid cell cultures. It is concluded that the use of MPER-reproducing oligopeptides is not a viable approach for vaccinating against FIV.

scholarly journals C-Terminal gp40 Peptide Analogs Inhibit Feline Immunodeficiency Virus: Cell Fusion and Virus Spread

2002 ◽  
Vol 76 (18) ◽  
pp. 9079-9086 ◽  
Author(s):  
R. J. Medinas ◽  
D. M. Lambert ◽  
W. A. Tompkins
Keyword(s):  
Cell Fusion ◽  
Feline Immunodeficiency Virus ◽  
Synthetic Peptides ◽  
Acute Infection ◽  
Surface Glycoprotein ◽  
Heptad Repeat ◽  
Transmembrane Glycoprotein ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The envelope glycoprotein of human immunodeficiency virus type 1 (HIV-1), gp160, is synthesized as a protein precursor that when proteolytically cleaved yields two subunits, gp120 and gp41. gp120 is the surface glycoprotein on HIV-1 responsible for binding to CD4, and gp41 is the transmembrane glycoprotein involved in the membrane fusion process. gp41 is divided into the N-terminal fusion peptide, the heptad repeat 1 (HR1) and HR2 regions, and the C-terminal transmembrane region, which are collectively responsible for virus fusion and entry into the cell. Synthetic peptides derived from the HR2 and HR1 regions of HIV-1LAI have been shown to prevent virus-cell fusion and infection in vitro. In phase II clinical trials in HIV patients, data revealed that T20 has antiviral efficacy and is well tolerated. Similar results were obtained in vitro with HIV-2 and simian immunodeficiency virus, supporting the conservation of the gp41 ectodomain among lentiviruses. Feline immunodeficiency virus (FIV) infection in the cat has been used as a model to develop potential antivirals for HIV. To determine if synthetic gp40 analogs capable of inhibiting FIV infection could be identified, 15 overlapping 35-amino-acid peptides derived from the C-terminal HR2 domain of FIV gp40 were synthesized. These peptides were tested for efficacy against FIV in a syncytium-forming assay with FIV-infected CrFK cells and HeLa cells expressing the FIV receptor CXCR4. Several peptides exhibited activity at the nanogram level. Antiviral activity was confirmed by suppression of reverse transcriptase in a FIV feline CD4+-T-cell (FCD4-E) acute-infection assay. These data demonstrate that synthetic peptides derived from the HR2 domain of the FIV gp41 protein are effective inhibitors of FIV infection.

scholarly journals Feline Immunodeficiency Virus-Infected Cat Sera Associated with the Development of Broad Neutralization Resistance In Vivo Drive Similar Reversions In Vitro

2001 ◽  
Vol 75 (18) ◽  
pp. 8868-8873 ◽  
Author(s):  
Simone Giannecchini ◽  
Donatella Matteucci ◽  
Aldo Ferrari ◽  
Mauro Pistello ◽  
Mauro Bendinelli
Keyword(s):  
Tissue Culture ◽  
Feline Immunodeficiency Virus ◽  
Surface Glycoprotein ◽  
Virus Variant ◽  
Humoral Immune ◽  
Immunodeficiency Virus ◽  
Escape Mutants ◽  
Intervening Factors

ABSTRACT We previously reported that, upon reinoculation into cats, a neutralization-sensitive, tissue culture-adapted strain of feline immunodeficiency virus constantly reverted to the broad neutralization resistance typical of primary virus isolates and identified residue 481 in the V4 region of the surface glycoprotein as a key determinant of the reversion. Here, we found that well-characterized immune sera, obtained from cats in which such reversion had occurred, selected in tissue culture in favor of virus variants that also had a neutralization-resistant phenotype and had amino acid 481 changed, thus indicating that the host's humoral immune response is capable of driving the reversion in the absence of other intervening factors. In contrast, a second group of immune sera, elicited by a virus variant that had already reverted to neutralization resistance in independent cats, induced the emergence of escape mutants lacking broad neutralization resistance and neutralized fewer virus variants. It is proposed that the viral variants used to produce the two sets of sera may have generated different antibody repertoires.

In vitro toxicity and metabolism of 2′,3′-dideoxycytidine, an inhibitor of human immunodeficiency virus infectivity

1991 ◽  
Vol 79 (1) ◽  
pp. 53-64 ◽  
Author(s):  
Giorgio Brandi ◽  
Luigia Rossi ◽  
Giuditta F. Schiavano ◽  
Leonardo Salvaggio ◽  
Amedeo Albano ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
In Vitro Toxicity ◽  
Virus Infectivity ◽  
Immunodeficiency Virus

scholarly journals In Vitro Activation of Feline Immunodeficiency Virus in Ramified Microglial Cells from Asymptomatically Infected Cats

2001 ◽  
Vol 75 (17) ◽  
pp. 8090-8095 ◽  
Author(s):  
Andreas Hein ◽  
Jean-Pierre Martin ◽  
Rüdiger Dörries
Keyword(s):  
Central Nervous System ◽  
Tissue Culture ◽  
Nervous System ◽  
Feline Immunodeficiency Virus ◽  
Mononuclear Cells ◽  
Central Nervous System Infection ◽  
Microglial Cells ◽  
Cell Contact ◽  
Immunodeficiency Virus

ABSTRACT Intravenous infection of cats with feline immunodeficiency virus was used as a model system to study activation of virus replication in brain-resident microglial cells in vitro. Virus release by ramified microglial cells isolated from subclinically infected animals was detectable in cell-free tissue culture supernatant only by reverse transcription and nested PCR of gag-specific RNA sequences and not by virion-associated reverse transcriptase activity. In contrast, cocultivation of in vivo-infected microglial cells with mitogen-activated peripheral blood mononuclear cells (PBMC) regularly allows detection of high virus yields in cell-free tissue culture fluid. Besides uptake and multiplication of microglia-derived virus in PBMC, release of virus from microglia is stimulated by cell contact with PBMC. The data suggest that T lymphocytes patrolling the central nervous system could reactivate the semilatent state of lentiviruses in microglial cells in the course of clinically silent central nervous system infection.

scholarly journals NMR Structure of the FIV gp36 C-terminal Heptad Repeat and Membrane-Proximal External Region

2020 ◽  
Vol 21 (6) ◽  
pp. 2037
Author(s):  
Manuela Grimaldi ◽  
Michela Buonocore ◽  
Mario Scrima ◽  
Ilaria Stillitano ◽  
Gerardino D’Errico ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Host Cell ◽  
Lipid Membrane ◽  
Nmr Structure ◽  
Heptad Repeat ◽  
Virus Envelope ◽  
External Region ◽  
Host Cell Membrane ◽  
Membrane Proximal External Region ◽  
Immunodeficiency Virus

Feline immunodeficiency virus (FIV), a lentivirus causing an immunodeficiency syndrome in cats, represents a relevant model of pre-screening therapies for human immunodeficiency virus (HIV). The envelope glycoproteins gp36 in FIV and gp41 in HIV mediate the fusion of the virus with the host cell membrane. They have a common structural framework in the C-terminal region that includes a Trp-rich membrane-proximal external region (MPER) and a C-terminal heptad repeat (CHR). MPER is essential for the correct positioning of gp36 on the lipid membrane, whereas CHR is essential for the stabilization of the low-energy six-helical bundle (6HB) that is necessary for the fusion of the virus envelope with the cell membrane. Conformational data for gp36 are missing, and several aspects of the MPER structure of different lentiviruses are still debated. In the present work, we report the structural investigation of a gp36 construct that includes the MPER and part of the CHR domain (737-786gp36 CHR–MPER). Using 2D and 3D homo and heteronuclear NMR spectra on 15N and 13C double-labelled samples, we solved the NMR structure in micelles composed of dodecyl phosphocholine (DPC) and sodium dodecyl sulfate (SDS) 90/10 M: M. The structure of 737-786gp36 CHR–MPER is characterized by a helix–turn–helix motif, with a regular α-helix and a moderately flexible 310 helix, characterizing the CHR and the MPER domains, respectively. The two helices are linked by a flexible loop regulating their orientation at a ~43° angle. We investigated the positioning of 737-786gp36 CHR–MPER on the lipid membrane using spin label-enhanced NMR and ESR spectroscopies. On a different scale, using confocal microscopy imaging, we studied the effect of 737-786gp36 CHR–MPER on 1,2-dioleoyl-sn-glycero-3-phosphocholine/1,2-dioleoyl-sn-glycero-3-phospho-(1’-rac-glycerol) (DOPC/DOPG) multilamellar vesicles (MLVs). This effect results in membrane budding and tubulation that is reminiscent of a membrane-plasticizing role that is typical of MPER domains during the event in which the virus envelope merges with the host cell membrane.

scholarly journals Altered Gag Polyprotein Cleavage Specificity of Feline Immunodeficiency Virus/Human Immunodeficiency Virus Mutant Proteases as Demonstrated in a Cell-Based Expression System

2006 ◽  
Vol 80 (16) ◽  
pp. 7832-7843 ◽  
Author(s):  
Ying-Chuan Lin ◽  
Ashraf Brik ◽  
Aymeric de Parseval ◽  
Karen Tam ◽  
Bruce E. Torbett ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Feline Immunodeficiency Virus ◽  
Ex Vivo ◽  
Expression System ◽  
Immunodeficiency Virus ◽  
A Cell ◽  
Virus Mutant ◽  
Substrate Inhibitor ◽  
Hiv 1

ABSTRACT We have used feline immunodeficiency virus (FIV) protease (PR) as a mutational system to study the molecular basis of substrate-inhibitor specificity for lentivirus PRs, with a focus on human immunodeficiency virus type 1 (HIV-1) PR. Our previous mutagenesis studies demonstrated that discrete substitutions in the active site of FIV PR with structurally equivalent residues of HIV-1 PR dramatically altered the specificity of the mutant PRs in in vitro analyses. Here, we have expanded these studies to analyze the specificity changes in each mutant FIV PR expressed in the context of the natural Gag-Pol polyprotein ex vivo. Expression mutants were prepared in which 4 to 12 HIV-1-equivalent substitutions were made in FIV PR, and cleavage of each Gag-Pol polyprotein was then assessed in pseudovirions from transduced cells. The findings demonstrated that, as with in vitro analyses, inhibitor specificities of the mutants showed increased HIV-1 PR character when analyzed against the natural substrate. In addition, all of the mutant PRs still processed the FIV polyprotein but the apparent order of processing was altered relative to that observed with wild-type FIV PR. Given the importance of the order in which Gag-Pol is processed, these findings likely explain the failure to produce infectious FIVs bearing these mutations.

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