The role of neutral glycolipids and phospholipids in myxovirus-induced membrane fusion

Live attenuated and inactivated viral vaccine formulation and nasal delivery: potential and challenges

Vaccines are cost-effective for the prevention of infectious diseases and have significantly reduced mortality and morbidity. Novel approaches are needed to develop safe and effective vaccines against disease. Major challenges in vaccine development include stability in a suitable dosage form and effective modes of delivery. Many live attenuated vaccines are capable of eliciting both humoral and cell mediated immune responses if physicochemically stable in an appropriate delivery vehicle. Knowing primary stresses that impart instability provides a general rationale for formulation development and mode of delivery. Since most pathogens enter the body through the mucosal route, live-attenuated vaccines have the advantage of mimicking natural immunization via non-invasive delivery. This presentation will examine aspects of formulation design, types of robust dosage forms to consider, effective routes of delivery (invasive and noninvasive), and distinctions between live attenuated or inactivated vaccines.

Specific interaction of HIV-1 and HIV-2 surface envelope glycoproteins with monolayers of galactosylceramide and ganglioside GM3

Cellular glycosphingolipids mediate the fusion between some viruses and the plasma membrane of target cells. In the present study, we have analyzed the interaction of human immunodeficiency virus (HIV)-1 and HIV-2 surface envelope glycoproteins from distinct viral isolates with monolayers of various glycosphingolipids at the air-water interface. The penetration of the viral glycoproteins into glycosphingolipid monolayers was detected as an increase in the surface pressure. We found that HIV-1 recombinant gp120 (IIIB isolate) could penetrate into a monomolecular film of alpha-hydroxylated galactosylceramide (GalCer-HFA), while ceramides, GluCer, and nonhydroxylated GalCer were totally inactive. The glycoproteins isolated from HIV-1 isolates LAI and NDK and from HIV-2(ROD) could also interact with a GalCer-HFA monolayer, whereas gp120 from HIV-1(SEN) and HIV-1(89.6) did not react. These data correlated with the ability of the corresponding viruses to gain entry into the CD4(-)/GalCer+ cell line HT-29, demonstrating the determinant role of GalCer-HFA in this CD4-independent pathway of HIV-1 and HIV-2 infection. In contrast, all HIV-1 and HIV-2 glycoproteins tested were found to interact with a monolayer of GM3, a ganglioside abundantly expressed in the plasma membrane of CD4(+) lymphocytes and macrophages. A V3 loop-derived synthetic peptide inhibitor of HIV-1 and HIV-2 infection in both CD4(-) and CD4(+) cells could penetrate into various glycosphingolipid monolayers, including GalCer-HFA and GM3. Taken together, these data suggest that the adsorption of human immunodeficiency viruses to the surface of target cells involves an interaction between the V3 domain of the surface envelope glycoprotein and specific glycosphingolipids, i.e. GalCer-HFA for CD4(-) cells and GM3 for CD4(+) cells.

Identification of annexin 33 kDa in cultured cells as a binding protein of influenza viruses

The binding of three influenza A and one influenza B virus strains to proteins of three continuously cultured cell lines was studied using protein overlay and immunostaining methods. The results obtained indicated the presence of both sialic acid-dependent and -independent binding of the virus strains; virus binding to proteins in the molecular mass range from about 40 to 103 kDa was dependent on sialic acid, whereas binding to the 33 kDa protein was independent of sialic acid. The 33 kDa binding protein was identified as annexin, a widely distributed non-glycosylated calcium-dependent phospholipid-binding protein.

A comparative assessment of TLC overlay technique and microwell adsorption assay in the examination of influenza A and Sendai virus specificities towards oligosaccharides and sialic acid linkages of gangliosides

Influenza A and Sendai viruses bind to neolacto-series gangliosides isolated from human granulocytes. Differences in receptor specificity of influenza viruses A/PR/8/34 (H1N1), A/X-31 (H3N2), and parainfluenza Sendai virus (HNF1, Z-strain) were determined by two direct solid phase binding assays: the overlay technique, which combines high-resolution in the separation of gangliosides on thin-layer chromatograms with direct binding; and the microwell adsorption assay as a convenient binding assay which is performed in microtitre wells to estimate the avidity of binding to an isolated ganglioside. Both methods were applied for comparative binding studies. Viruses were found to exhibit specificity for oligosaccharides and sialic acids as well as for chain length of the neutral carbohydrate backbone, whereas differing fatty acids (C24:1 and C16:0) in the ceramide portion had no impact on virus adsorption. Terminal sialyloligosaccharides Neu5Ac alpha 2-3Gal beta 1-4Glc-R of GM3, and Neu5Ac alpha 2-3Gal beta 1-4GlcNAc-R as well as Neu5Ac alpha 2-6Gal beta 1-4GlcNAc-R of neolacto-series gangliosides with nLcOse4Cer and nLcOse6Cer backbone, exhibited significant specific receptor activity towards the different viruses. To compare the data revealed from both test systems, values of virus binding were ascertained by a non-parametric statistical approach based on rank correlation. The rank correlation coefficient rs was calculated according to Spearman from each virus binding towards GM3, IV3Neu5Ac-nLcOse4Cer, IV6Neu5Ac-nLcOse4Cer and VI3Neu5Ac-nLcOse6SCer. The rank correlation coefficients 0.74, 0.95 and 0.92, which were determined for A/PR/8/34 (H1N1), A/X-31 (H3N2) and Sendai virus (HNF1, Z-strain), respectively, indicated that both assays generate highly correlated experimental data.(ABSTRACT TRUNCATED AT 250 WORDS)

Cellular incorporation and localization of fluorescent derivatives of gangliosides, cerebroside and sphingomyelin

Fluorescent dansyl derivatives of 3 natural sphingolipids (gangliosides, cerebroside and sphingomyelin) were shown to be readily taken up by culture cells (HeLa-, MDCK- and primary rat brain cells). A part of the incorporated fluorescent sphingolipids remained associated with the cells after incubation in a culture medium containing serum, showing a cellular integration of these lipids. Microscopical studies indicated a localization of incorporated lipids in distinct subcellular regions; whereas dansyl cerebroside densely stained structures suggestive of the cytoskeleton and the actin filament, dansyl sphingomyelin and dansyl gangliosides were primarily associated with the plasma membrane. The findings are consistent with the current views on the arrangement of sphingolipids in animal cells.

Conformation and stability of Sendai virus fusion protein

The conformation and stability of Sendai virus fusion (F) protein were studied by circular dichroism spectroscopy, and the protein predictive models of Chou and Fasman and Robson and Suzuki were used to elucidate the secondary structure of Sendai virus F protein. The F protein conformation is predicted to contain 33% alpha-helix, 53% beta-sheet and 15% beta-turn by the Chou and Fasman model, and 30% alpha-helix, 55% beta-sheet, 9% beta-turn and 7% random coil by the Robson and Suzuki model. C.d. studies of F protein purified in the presence of the non-ionic detergent, n-octylglucoside, indicated the presence of 49% alpha-helix and 31% beta-sheet at pH 7.0, 54% alpha-helix and 28% beta-sheet at pH 9.0 and 50% alpha-helix and 23% beta-sheet at pH 5.4. A small change in conformation of the protein occurred when the pH was titrated from 7.0 to 5.4 and from 7.0 to 9.0 and a more pronounced conformational change occurred when the pH was changed from 9.0 to 5.4. The F protein in 0.2% n-octylglucoside was resistant to denaturation by 4 M guanidine hydrochloride, the reducing agent 20 mM mercaptoethanol, and to increases in temperature from 5 to 80 degrees C. Monoclonal anti-F protein antibody showed an increased binding to whole virus when the pH was changed from 7.0 to 9.0. The antibody binding was decreased when the pH was shifted from 9.0 to 5.4 Maximum haemolytic activity was observed with virus that was preincubated at pH 8.0.(ABSTRACT TRUNCATED AT 250 WORDS)