Countermeasures against Zika virus (ZIKV) epidemics are urgently needed. In this study we generated a ZIKV virus-like particle (VLP) based vaccine candidate and assessed the immunogenicity of these particles in mice. The ZIKV-VLPs were morphologically similar to ZIKV by electron microscopy and were recognized by anti-Flavivirus neutralising antibodies.
View Article and Find Full Text PDFThe development of virus-like particle (VLP) based vaccines for human papillomavirus, hepatitis B and hepatitis E viruses represented a breakthrough in vaccine development. However, for dengue and COVID-19, technical complications, such as an incomplete understanding of the requirements for protective immunity, but also limitations in processes to manufacture VLP vaccines for enveloped viruses to large scale, have hampered VLP vaccine development. Selecting the right adjuvant is also an important consideration to ensure that a VLP vaccine induces protective antibody and T cell responses.
View Article and Find Full Text PDFPrevention of T cell activation is one of the goals of successful organ and tissue transplantation. Blockade of T cell co-stimulation, particularly of the CD28:B7 interaction, has been shown to prolong graft survival. Inducible Co-Stimulator (ICOS) is the third member of the B7 family and here we review the literature on ICOS, its receptor (B7RP-1), and blockade of this pathway in transplant models.
View Article and Find Full Text PDFCell cultures have been successfully used to study hepatitis C virus (HCV) for many years. However, most work has been done using traditional, 2-dimensional (2D) cell cultures (cells grown as a monolayer in growth flasks or dishes). Studies have shown that when cells are grown suspended in an extra-cellular-matrix-like material, they develop into spherical, 'organoid' arrangements of cells (3D growth) that display distinct differences in morphological and functional characteristics compared to 2D cell cultures.
View Article and Find Full Text PDFBackground: Hepatitis B virus (HBV) is the leading cause of liver cancer, but the mechanisms by which HBV causes liver cancer are poorly understood and chemotherapeutic strategies to cure liver cancer are not available. A better understanding of how HBV requisitions cellular components in the liver will identify novel therapeutic targets for HBV associated hepatocellular carcinoma (HCC).
Main Body: The development of HCC involves deregulation in several cellular signalling pathways including Wnt/FZD/β-catenin, PI3K/Akt/mTOR, IRS1/IGF, and Ras/Raf/MAPK.
We have previously reported that ICOS-Ig expressed locally by a PIEC xenograft induces a perigraft cellular accumulation of CD4 CD25 Foxp3 T cells and specific xenograft prolongation. In the present study we isolated and purified CD4 CD25 T cells from ICOS-Ig secreting PIEC grafts to examine their phenotype and mechanism of xenograft survival using knockout and mutant mice. CD4 CD25 T cells isolated from xenografts secreting ICOS-Ig were analysed by flow cytometry and gene expression by real-time PCR.
View Article and Find Full Text PDFFront Immunol
September 2020
Hepatitis C virus (HCV) persistently infects approximately 71 million people globally. To prevent infection a vaccine which elicits neutralizing antibodies against the virus envelope proteins (E1/E2) which are required for entry into host cells is desirable. DNA vaccines are cost-effective to manufacture globally and despite recent landmark studies highlighting the therapeutic efficacy of DNA vaccines in humans against cervical cancer, DNA vaccines encoding E1/E2 developed thus far are poorly immunogenic.
View Article and Find Full Text PDFJ Colloid Interface Sci
June 2019
Hepatitis C virus-like particles (VLPs) are being developed as a quadrivalent vaccine candidate, eliciting both humoral and cellular immune responses in animal trials. Biophysical, biomechanical and biochemical properties are important for virus and VLP interactions with host cells and recognition by the immune system. Atomic force microscopy (AFM) is a powerful tool for visualizing surface topographies of cells, bionanoparticles and biomolecules, and for determining biophysical and biomechanical attributes such as size and elasticity.
View Article and Find Full Text PDFThe development of an effective preventative hepatitis C virus (HCV) vaccine will reside, in part, in its ability to elicit neutralizing antibodies (NAbs). We previously reported a genotype 1a HCV virus like particle (VLP) vaccine that produced HCV specific NAb and T cell responses that were substantially enhanced by Toll-like receptor 2 (TLR2) agonists. We have now produced a quadrivalent genotype 1a/1b/2a/3a HCV VLP vaccine and tested the ability of two TLR2 agonists, RPamCys and EPamCys, to stimulate the production of NAb.
View Article and Find Full Text PDFNaturally occurring and elicited anti-carbohydrate antibodies play a major role in immune responses to xenografts. The original obstacles associated with the Gal antigen have been largely resolved by the generation of knockout pigs. In contrast, much less is known about the nature and role of non-Gal carbohydrate antigens and the antibodies recognizing these.
View Article and Find Full Text PDFAim: Immunophenotype peripheral blood T cells from renal transplant recipients (RTR) using cellular markers of regulatory T cells (Tregs) and flow cytometry, including Foxp3, and correlate these findings with clinical parameters.
Methods: Expression of phenotypic markers of Tregs was assessed by flow cytometric analysis of peripheral blood lymphocytes (PBL) from (i) RTR (n = 95); (ii) patients with end-stage renal failure (ESRF) awaiting transplantation (n = 17); and (iii) normal healthy controls (n = 18).
Results: The percentage of CD4(+) CD25(+) Foxp3(+) cells within the CD4(+) cell population did not significantly alter at different time points post-transplant.
Background: Blockade of the inducible costimulator (ICOS) pathway has been shown to prolong allograft survival; however, its utility in xenotransplantation is unknown. We hypothesize that local expression of ICOS-Ig by the xenograft will suppress the T-cell response resulting in significant prolonged graft survival.
Methods: Pig iliac artery endothelial cells (PIEC) secreting ICOS-Ig were generated and examined for the following: (1) inhibition of allogeneic and xenogeneic proliferation of primed T cells in vitro and (2) prolongation of xenograft survival in vivo.
Naturally occurring anti-carbohydrate antibodies play a major role in both the innate and adaptive immune responses. To elicit an anti-carbohydrate immune response, glycoproteins can be processed to glycopeptides and presented by the classical antigen-presenting molecules, major histocompatibility complex (MHC) Class I and II. In contrast, much less is known about the mechanism(s) for anti-carbohydrate responses to glycolipids, although it is generally considered that the CD1 family of cell surface proteins presents glycolipids to T cells or natural killer T (NKT) cells.
View Article and Find Full Text PDFDendritic cells (DCs) and CTLA4Ig are important in regulating T-cell responses and therefore represent potential therapeutic tools in transplantation. In this study, CTLA4Ig was expressed in a C57BL/6 murine DC line (JAWS II) by lentiviral transduction and these cells were used to examine T-cell immunomodulatory effects in vitro and in vivo. A lower stimulation index to C57BL/6 was observed with splenocytes from BALB/c mice primed with JAWS II-CTLA4Ig compared with control JAWS II-green fluorescent protein (JAWS II-GFP).
View Article and Find Full Text PDFTransplantation of organs across species (xenotransplantation) is being considered to overcome the shortage of human donor organs. However, unmodified pig organs undergo an antibody-mediated hyperacute rejection that is brought about by the presence of natural antibodies to Galalpha(1,3)Gal, which is the major carbohydrate xenoantigen. Genetic modification of pig organs to remove most of the Galalpha(1,3)Gal epitopes has been achieved, but the human immune system may still recognize residual lipid-linked Galalpha(1,3)Gal carbohydrates, new (cryptic) carbohydrates or additional non-Galalpha(1,3)Gal carbohydrate xenoantigens.
View Article and Find Full Text PDFCarbohydrate structures influence many aspects of cell biology. Manipulating the glycosyltransferase enzymes, that sequentially add carbohydrate moieties to proteins and lipids as they pass through the Golgi and secretory pathway, can alter these carbohydrate epitopes. We previously demonstrated that the eight amino acid cytoplasmic tail of alpha1,2fucosyltransferase (FT) contained a sequence for Golgi localisation.
View Article and Find Full Text PDFBackground: Xenotransplantation could ameliorate the severe shortage of donor organs. The initial results of transplantation from genetically-modified pig donors to primate recipients suggest that hyperacute rejection can be overcome, but thrombotic microangiopathy and the human anti-pig cellular immune response remain as significant impediments to successful clinical xenotransplantation. NKG2D is an activating immunoreceptor found on human natural killer (HuNK) cells, CD8(+) and gammadelta T cells.
View Article and Find Full Text PDFThe glycosphingolipid isoglobotrihexosylceramide, or isogloboside 3 (iGb3), is believed to be critical for natural killer T (NKT) cell development and self-recognition in mice and humans. Furthermore, iGb3 may represent an important obstacle in xenotransplantation, in which this lipid represents the only other form of the major xenoepitope Galalpha(1,3)Gal. The role of iGb3 in NKT cell development is controversial, particularly with one study that suggested that NKT cell development is normal in mice that were rendered deficient for the enzyme iGb3 synthase (iGb3S).
View Article and Find Full Text PDFBackground: To overcome cell-mediated xenorejection by transgenic expression of immunomodulatory molecules by a graft, it is likely that expression of multiple molecules will be required. Previous studies support the use of the immunomodulatory agents indoleamine 2,3-dioxygenase (IDO), CD40Ig, interleukin 10 (IL10), and CTLA4Ig for suppression of rejection responses. We examined the effects of local expression of these molecules by a porcine cell line (PIEC) on indirect murine xenorejection responses in vitro and in vivo.
View Article and Find Full Text PDFTryptophan catabolism initiated by the enzyme indoleamine 2,3-dioxygenase (IDO) has been postulated to be a natural regulatory mechanism for T cells. In this study, we generated a pig endothelial cell line expressing full-length human IDO (P-HuIDO) to serve as a simple model of a cellular xenogeneic graft. Splenocytes from mice primed to P-HuIDO cells were found to be as responsive to secondary stimulation as splenocytes from mice primed to parental cells.
View Article and Find Full Text PDFXenotransplantation
September 2006
Background: Many immunologically important interactions are mediated by leukocyte recognition of carbohydrates via cell surface receptors. Uncharacterized receptors on human natural killer (NK) cells interact with ligands containing the terminal Galalpha(1,3)Gal xenoepitope. The aim of this work was to isolate and characterize carbohydrate binding proteins from NK cells that bind alphaGal or other potential xenoepitopes, such as N-acetyllactosamine (NAcLac), created by the deletion of alpha1,3galactosyltransferase (GT) in animals.
View Article and Find Full Text PDFBackground: Co-stimulatory blockade is known to inhibit lymphocyte responses and to prolong allograft and xenograft survival. The present study examines the effect of transgenic expression of cytotoxic T lymphocyte-associated molecule-4 immunoglobulin (CTLA4Ig) by a porcine endothelial cell line (PIEC) transduced by a lentiviral vector, on primed xenogeneic T-cell proliferative and cytokine responses.
Methods: Splenocytes from mice primed with PIEC were used as responder cells in a secondary proliferative assay.
The metalloprotease-dependent extracellular domain cleavage of the adhesion molecule CD44 is frequently observed in human tumors and is thought to promote metastasis. This cleavage is followed by gamma-secretase-dependent release of CD44 intracellular domain (CD44-ICD), which exhibits nuclear signaling activity. Using a reversible Ret-dependent oncogenic conversion model and a restricted proteomic approach, we identified a positive correlation between the neoplastic transformation of Rat-1 cells and the expression of standard CD44.
View Article and Find Full Text PDFThe production of homozygous pigs with a disruption in the GGTA1 gene, which encodes alpha1,3galactosyltransferase (alpha1,3GT), represented a critical step toward the clinical reality of xenotransplantation. Unexpectedly, the predicted complete elimination of the immunogenic Galalpha(1,3)Gal carbohydrate epitope was not observed as Galalpha(1,3)Gal staining was still present in tissues from GGTA1(-/-) animals. This shows that, contrary to previous dogma, alpha1,3GT is not the only enzyme able to synthesize Galalpha(1,3)Gal.
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