Reduction of hepatitis C virus NS5A phosphorylation through its interaction with amphiphysin II.

Hepatitis C virus non-structural protein 5A (NS5A) is a pleiotropic protein with key roles in viral RNA replication, modulation of cellular-signaling pathways and interferon (IFN) responses. To search for possible host factors involved in mediating these functions of NS5A, we adopted an affinity purification approach coupled with mass spectrometry to examine protein-protein interactions, and found that human amphiphysin II (also referred to as Bin1) specifically interacts with NS5A in mammalian cells. Pull-down assays showed that the Src homology 3 (SH3) domain of amphiphysin II is required for NS5A interaction and that c-Src also interacts with NS5A in cells.

Effect of partial and complete variable loop deletions of the human immunodeficiency virus type 1 envelope glycoprotein on the breadth of gp160-specific immune responses.

Induction of cross-reactive cellular and humoral responses to the HIV-1 envelope (env) glycoprotein was examined after DNA immunization of BALB/c mice with gp140(89.6)-derived constructs exhibiting partial or complete deletions of the V1, V2, and V3 domains. It was demonstrated that specific modification of the V3 loop (mV3) in combination with the V2-modified (mV2) or V1/V2-deleted (DeltaV1/V2) region elicited increased levels of cross-reactive CD8(+) T cell responses.

Liposomes with differential lipid components exert differential adjuvanticity in antigen-liposome conjugates via differential recognition by macrophages.

We previously reported that liposomes having differential lipid components displayed differential adjuvant effects when antigen was coupled with liposomes via glutaraldehyde. In the present study, antigen-liposome conjugates prepared using liposomes having differential lipid components were added to the macrophage culture, and phagocytosis and the antigen digest of liposome-coupled antigen by macrophages were then investigated. Antigen presentation by macrophages to an antigen-specific T-cell clone was further investigated using the same conjugates.

Interferon regulatory factor-2 regulates cell growth through its acetylation.

We have previously shown that interferon regulatory factor-2 (IRF-2) is acetylated by p300 and PCAF in vivo and in vitro. In this study we identified, by mass spectrometry, two lysine residues in the DNA binding domain (DBD), Lys-75 and Lys-78, to be the major acetylation sites in IRF-2. Although acetylation of IRF-2 did not alter DNA binding activity in vitro, mutation of Lys-75 diminished the IRF-2-dependent activation of histone H4 promoter activity.

Selective inhibition of systemic anti-OVA IgE production in response to oral pre-treatment with OVA-liposome conjugates.

Background: We have previously reported that intraperitoneal injection with OVA-liposome conjugates induces OVA-specific and IgE-selective unresponsiveness in mice.

Methods: In the present study, the effects of oral pre-treatment with OVA-liposome conjugates or with plain OVA solution on anti-OVA IgG antibody production were investigated in mice after subsequent immunization with alum-adsorbed OVA. Control mice received only the immunization.

IRF-8/ICSBP and IRF-1 cooperatively stimulate mouse IL-12 promoter activity in macrophages.

IRF-8/ICSBP and IRF-1 are IRF family members whose expression is induced in response to IFN-gamma in macrophages. IL-12 is a cytokine produced in macrophages that plays a critical role in host defense. IFN-gamma and bacterial lipopolysaccharide (LPS) induce IL-12p40 transcription, which is necessary for the production of IL-12.

T cell-independent regulation of IgE antibody production induced by surface-linked liposomal antigen.

Control of IgE Ab production is important for the prevention of IgE-related diseases. However, in contrast to the existing information on the induction of IgE production, little is known about the regulation of the production of this isotype, with the exception of the well-documented mechanism involving T cell subsets and their cytokine products. In this study, we demonstrate an alternative approach to interfere with the production of IgE, independent of the activity of T cells, which was discovered during the course of an investigation intended to clarify the mechanism of IgE-selective unresponsiveness induced by surface-coupled liposomal Ags.

Cholesterol inclusion in liposomes affects induction of antigen-specific IgG and IgE antibody production in mice by a surface-linked liposomal antigen.

In the previous study, we investigated the induction of ovalbumin (OVA)-specific antibody production in mice by OVA-liposome conjugates made using four different lipid components, including unsaturated carrier lipid and three different saturated carrier lipids. All of the OVA-liposome conjugates tested induced IgE-selective unresponsiveness. The highest titer of anti-OVA IgG was observed in mice immunized with OVA-liposomes made using liposomes with the highest membrane fluidity, suggesting that the membrane fluidity of liposomes affects their adjuvant effect.

Protection of monkeys against Shiga toxin induced by Shiga toxin-liposome conjugates.

Background: We previously reported that the purified Shiga toxins (Stx) Stx1 and Stx2, when coupled with liposomes, induced substantial production of anti-Stx1 and anti-Stx2 IgG antibody, respectively, in mice. The levels of anti-Stx antibody in the sera of mice immune to Stx-liposome correlated well with the protection against subsequent challenge with Stx. Furthermore, mice immunized with a mixture of Stx1-liposome and Stx2-liposome were successfully protected against oral infection with cytotoxin-producing Escherichia coli O157:H7.