Chih-Hsiang Leng

National Health Research Institutes, Miao-li-chieh, Taiwan, Taiwan

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Publications (33)128.7 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: Cross-presentation is a key function of dendritic cells (DCs), which present exogenous Ags on MHC class I molecules to prime CTL responses. The effects of TLR triggering on the cross-presentation of exogenous Ags by DCs remain unclear. In this study, we used synthetic dipalmitoylated peptides and TLR2 agonist-conjugated peptides as models to elucidate the mechanisms of TLR2-mediated cross-presentation. We observed that the internalization of dipalmitoylated peptides by bone marrow-derived DCs was facilitated by TLR2 via clathrin-mediated endocytosis. The administration of these dipalmitoylated peptide-pulsed bone marrow-derived DCs eliminated established tumors through TLR2 signaling. We further demonstrated that the induction of Ag-specific CTL responses and tumor regression by dipalmitoylated peptides was TAP independent. In addition, presentation of dipalmitoylated peptides by MHC class I molecules was blocked in the presence of an endosomal acidification inhibitor (chloroquine) or a lysosomal degradation inhibitor (Z-FL-COCHO). The endocytosed dipalmitoylated peptide also passed rapidly from early endosome Ag-1-positive endosomes to RAS-related GTP-binding protein 7 (Rab7)-associated late endosomes compared with their nonlipidated counterparts. Furthermore, we found that dipalmitoylated peptide-upregulated Rab7 expression correlated with Ag presentation via the TLR2/MyD88 pathway. Both JNK and ERK signaling pathways are required for upregulation of Rab7. In summary, our data suggest that TLR2-mediated cross-presentation occurs through the upregulation of Rab7 and a TAP-independent pathway that prime CTL responses.
    The Journal of Immunology 03/2014; · 5.52 Impact Factor
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    ABSTRACT: Although cytotoxic T lymphocytes (CTLs) play a major role in eradicating cancer cells during immunotherapy, the cancer-associated immunosuppressive microenvironment often limits the success of such therapies. Therefore, the simultaneous induction of cancer-specific CTLs and reversal of the immunosuppressive tumor microenvironment may be more effectively achieved through a single therapeutic vaccine. A recombinant lipoprotein with intrinsic Toll-like receptor 2 (TLR2) agonist activity containing a mutant form of E7 (E7m) and a bacterial lipid moiety (rlipo-E7m) has been demonstrated to induce robust CTL responses against small tumors. This treatment in combination with other TLR agonists is able to eliminate large tumors. Mouse bone marrow-derived dendritic cells (DCs) were employed to determine the synergistic production of pro-inflammatory cytokines upon combination of rlipo-E7m and other TLR agonists. Antigen-specific CTL responses were investigated using immunospots or in vivo cytolytic assays after immunization in mice. Mice bearing various tumor sizes were used to evaluate the anti-tumor effects of the formulation. Specific subpopulations of immunosuppressive cells in the tumor infiltrate were quantitatively determined by flow cytometry. We demonstrate that a TLR9 agonist (unmethylated CpG oligodeoxynucleotide, CpG ODN) enhances CTL responses and eradicates large tumors when combined with rlipo-E7m. Moreover, combined treatment with rlipo-E7m and CpG ODN effectively increases tumor infiltration by CTLs and reduces the numbers of myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs) and regulatory T cells (Tregs) in the tumor microenvironment. These findings suggest that the dramatic anti-tumor effects of the recombinant lipoprotein together with CpG ODN may reflect the amplification of CTL responses and the repression of the immunosuppressive environment. This promising approach could be applied for the development of additional therapeutic cancer vaccines.
    Molecular Cancer 03/2014; 13(1):60. · 5.13 Impact Factor
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    ABSTRACT: The combination of recombinant protein antigens with an immunostimulator has the potential to greatly increase the immunogenicity of recombinant protein antigens. In the present study, we selected the dengue-4 envelope protein domain III as a dengue vaccine candidate and expressed the protein in lipidated form using an Escherichia coli-based system. The recombinant lipidated dengue-4 envelope protein domain III folded into the proper conformation and competed with the dengue-4 virus for cellular binding sites. Mice immunized with lipidated dengue-4 envelope protein domain III without exogenous adjuvant had higher frequencies of dengue-4 envelope protein domain III-specific B cells secreting antibodies than mice immunized with the nonlipidated form. Importantly, lipidated dengue-4 envelope protein domain III-immunized mice demonstrated a durable neutralizing antibody response and had reduced viremia levels after challenge. The study demonstrates that lipidated dengue-4 envelope protein domain III is immunogenic and may be a potential dengue vaccine candidate. Furthermore, the lipidation strategy can be applied to other serotypes of dengue virus.
    Vaccine 01/2014; · 3.77 Impact Factor
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    ABSTRACT: Vaccine adjuvant is conferred on the substance that helps to enhance antigen-specific immune response. Here we investigated the disintegration characteristics and immunotherapy potency of an emulsified delivery system comprising bioresorbable polymer poly(ethylene glycol)-polylactide (PEG-PLA), phosphate buffer saline (PBS), and metabolizable oil squalane. PEG-PLA-stabilized oil-in-water emulsions show good stability at 4 °C and at room temperature. At 37 °C, squalane/PEG-PLA/PBS emulsion with oil/aqueous weight ratio of 7/3 (denominated PELA73) was stable for 6 weeks without phase separation. As PEG-PLA being degraded, 30% of free oil at the surface layer and 10% of water at the bottom disassociated from the PELA73 emulsion were found after 3 months. A MALDI-TOF MS study directly on the DIOS plate enables us to identify low molecular weight components released during degradation. Our results confirm the loss of PLA moiety of the emulsifier PEG-PLA directly affected the stability of PEG-PLA-stabilized emulsion, leading to emulsion disintegration and squalane/water phase separation. As adjuvant for cancer immunotherapeutic use, an HPV16 E7 peptide antigen formulated with PELA73 plus immunostimulatory CpG molecules could strongly enhance antigen-specific T-cell responses as well as anti-tumor ability with respected to non-formulated or Alum-formulated peptide. Accordingly, these advances may be a potential immunoregulatory strategy in manipulating the immune responses induced by tumor-associated antigens.
    Biomaterials 11/2013; · 7.60 Impact Factor
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    ABSTRACT: PELC is a novel emulsion-type adjuvant that contains the bioresorbable polymer poly (ethylene glycol)-block-poly (lactide-co-ε-caprolactone) (PEG-b-PLACL), Span®85 and squalene. To investigate whether PELC is able to enhance CTL responses of antigens for treating tumor, peptide or protein antigen derived from HPV16 E7 were formulated with PELC nanoparticles and CpG oligodeoxynucleotide. We identified that PELC formulation could delay release of antigens in vittro and in vivo. We assessed the immunogenicity of an H-2D(b)-restricted CTL epitope RAHYNIVTF (RAH) formulated with PELC or PELC/CpG and investigated the ability of these formulations to promote tumor regression. Following a single-dose subcutaneous injection in mice, we found that the RAH peptide formulated with PELC/CpG (RAH/PELC/CpG) resulted in increased numbers of IFN-γ-secreting cells and RAH-specific CD8(+) T cells and an enhanced cytotoxic T cell response compared with RAH formulated with PELC or CpG alone. The tumor-bearing mice received a single-dose injection of RAH/PELC/CpG, which induced complete tumor regression. These results demonstrated that peptide antigen formulated with PELC/CpG nanoparticles is feasible for cancer immunotherapy.
    Journal of Controlled Release 10/2013; · 7.63 Impact Factor
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    ABSTRACT: Many attempts have focused on the use of either immunomodulators or antigen delivery systems to obtain an efficacious vaccine. Here, we report a novel approach that combined an immunomodulator and delivery system to enhance antigen association and induce robust immunity. We expressed a recombinant lipidated dengue-1 envelope protein domain III (LD1ED III) and its non-lipidated form, D1ED III, in an Escherichia coli system. The LD1ED III contains a bacterial lipid moiety, which is a potent immunomodulator. We demonstrated that LD1ED III possesses an inherent immunostimulation ability that can activate RAW 264.7 macrophage cells by up-regulating their expression of CD40, CD80, CD83, CD86 and MHC II, whereas D1ED III could not induce the up-regulation of these molecules. Moreover, combining LD1ED III with a multiphase emulsion system (called PELC) increased the antigen association more than either combining D1ED III with PELC or the antigen alone. Enhanced antigen association has been shown to correlate with stronger T cell responses, greater antibody avidity and improved neutralizing capacity. Our results demonstrate that combining recombinant lipoproteins with PELC improved both the intensity and the quality of the immune response. This approach is a promising strategy for the development of subunit vaccines that induce robust immunity.
    Microbes and Infection 06/2013; · 2.92 Impact Factor
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    ABSTRACT: We have previously demonstrated that vaccination with a subunit dengue vaccine containing a consensus envelope domain III with aluminum phosphate elicits neutralizing antibodies against all four serotypes of dengue virus in mice. In this study, we evaluated the immunogenicity of the subunit dengue vaccine in non-human primates. After vaccination, monkeys that received the subunit vaccine with aluminum phosphate developed a significantly strong and long-lasting antibody response. A specific T cell response with cytokine production was also induced, and this correlated with the antibody response. Additionally, neutralizing antibodies against serotype 2 were detected in two of three monkeys. The increase in serotype-2-specific antibody titers and avidity observed in these two monkeys suggested that a serotype-2-biased antibody response occurs. These data provide evidence that a protective neutralizing antibody response was successfully elicited in non-human primates by the dengue subunit vaccine with aluminum phosphate adjuvant.
    Archives of Virology 03/2013; · 2.03 Impact Factor
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    ABSTRACT: Dengue virus is a mosquito-transmitted virus that can cause self-limiting dengue fever, severe life-threatening dengue hemorrhagic fever and dengue shock syndrome. The existence of four serotypes of dengue virus has complicated the development of an effective and safe dengue vaccine. Recently, a clinical phase 2b trial of Sanofi Pasteur's CYD tetravalent dengue vaccine revealed that the vaccine did not confer full protection against dengue-2 virus. New approaches to dengue vaccine development are urgently needed. Our approach represents a promising method of dengue vaccine development and may even complement the deficiencies of the CYD tetravalent dengue vaccine. Two important components of a vaccine, the immunogen and immunopotentiator, were combined into a single construct to generate a new generation of vaccines. We selected dengue-2 envelope protein domain III (D2ED III) as the immunogen and expressed this protein in lipidated form in Escherichia coli, yielding an immunogen with intrinsic immunopotentiation activity. The formulation containing lipidated D2ED III (LD2ED III) in the absence of exogenous adjuvant elicited higher D2ED III-specific antibody responses than those obtained from its nonlipidated counterpart, D2ED III, and dengue-2 virus. In addition, the avidity and neutralizing capacity of the antibodies induced by LD2ED III were higher than those elicited by D2ED III and dengue-2 virus. Importantly, we showed that after lipidation, the subunit candidate LD2ED III exhibited increased immunogenicity while reducing the potential risk of antibody-dependent enhancement of infection in mice. Our study suggests that the lipidated subunit vaccine approach could be applied to other serotypes of dengue virus and other pathogens.
    PLoS Neglected Tropical Diseases 01/2013; 7(9):e2432. · 4.57 Impact Factor
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    ABSTRACT: The major weaknesses of subunit vaccines are their low immunogenicity and poor efficacy. Adjuvants can help to overcome some of these inherent defects with subunit vaccines. Here, we evaluated the efficacy of the newly developed water-in-oil-in-water multiphase emulsion system, termed PELC, in potentiating the protective capacity of dengue-1 envelope protein domain III. Unlike aluminum phosphate, dengue-1 envelope protein domain III formulated with PELC plus CpG oligodeoxynucleotides induced neutralizing antibodies against dengue-1 virus and increased the splenocyte secretion of IFN-γ after in vitro re-stimulation. The induced antibodies contained both the IgG1 and IgG2a subclasses. A rapid anamnestic neutralizing antibody response against a live dengue virus challenge was elicited at week 26 after the first immunization. These results demonstrate that PELC plus CpG oligodeoxynucleotides broaden the dengue-1 envelope protein domain III-specific immune responses. PELC plus CpG oligodeoxynucleotides is a promising adjuvant for recombinant protein based vaccination against dengue virus.
    PLoS Neglected Tropical Diseases 05/2012; 6(5):e1645. · 4.57 Impact Factor
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    ABSTRACT: The E7 oncoprotein of human papillomavirus (HPV) is an ideal target for developing immunotherapeutic strategies against HPV-associated tumors. However, because protein-based immunogens alone are poor elicitors of the cytotoxic T-lymphocyte (CTL) responses, they have been difficult to exploit for therapeutic purposes. In this study, we report that a recombinant lipoprotein consisting of inactive E7 (E7m) biologically linked to a bacterial lipid moiety (rlipo-E7m) induces the maturation of mouse bone marrow-derived dendritic cells through toll-like receptor 2 (TLR2), skews the immune responses toward the Th1 responses and induces E7-specific CTL responses. We further studied the ability of rlipo-E7m to provide protection against a TC-1 tumor cell challenge in an animal model. Mice prophylactically immunized with two 10-µg doses of rlipo-E7m were found to be free of TC-1 tumor growth. Experiments in a therapeutic immunization model showed that the tumor volume in mice receiving a single dose of rlipo-E7m was less than 0.01 cm(3) on day 40, whereas the tumor volume in mice treated with rE7m was 2.28±1.21 cm(3). The tumor volume of the entire control group was over 3 cm(3). In addition, we demonstrated that the CD8+ T cells play a major role in anti-tumor immunity when administration of rlipo-E7m. These results demonstrate that rlipo-E7m could be a promising candidate for treating HPV-associated tumors.
    PLoS ONE 01/2012; 7(7):e40970. · 3.73 Impact Factor
  • Chi-Ling Tseng, Chih-Hsiang Leng
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    ABSTRACT: Bacterial lipoproteins are crucial antigens for protective immunity against bacterial pathogens. Expression of exogenous lipoproteins in Escherichia coli at high levels is thought to be an extremely difficult endeavor because it frequently results in incomplete or absent lipid modification. Previously, we identified a fusion sequence (D1) from a Neisseria meningitidis lipoprotein that induced a non-lipidated protein, E3 (the domain III of the dengue virus envelope protein), to become lipidated. However, without optimizing the growth conditions, some of the D1-fusion proteins were not lipidated. Here, we report the influence of medium components on the expression of recombinant lipoproteins in E. coli. For high-level expression of mature lipoproteins in the C43 (DE3) strain, M9 medium was better than M63 and the rich medium. Furthermore, we analyzed the influence of other media factors (including nitrogen and carbon sources, phosphate, ferrous ions, calcium, magnesium, and pH) on the levels of lipoprotein expression. The results showed that excess nitrogen sources and phosphate in M9 medium could increase the amount of immature lipoproteins, and glucose was a better carbon source than glycerol for expressing mature lipoproteins. We also found that lipoproteins tended to be completely processed in the alkaline environment, even in the nutrient-rich medium. Additional constructs expressing different immunogens or lipid signal peptides as targets were also utilized, demonstrating that these targets could be expressed as completely mature lipoproteins in the M9 medium but not in the rich medium. Our results provide the useful information for expressing mature exogenous lipoproteins in E. coli.
    Applied Microbiology and Biotechnology 08/2011; 93(4):1539-52. · 3.69 Impact Factor
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    ABSTRACT: The structural analysis of post-translational modifications (PTMs) of lipoproteins is difficult due to the hydrophobic properties of their fatty acid moieties. At the present time, the relative positions of fatty acid components on the N-acyl-S-diacylglycerylcysteine core structure has not been specifically identified in any natural or bacterial expressed recombinant lipoproteins. In this study, we describe a rapid solid-phase extraction using acetonitrile and isopropanol method that can be performed manually to isolate large amounts of relatively pure lipopeptides generated by the limited tryptic-digestion of recombinant lipoproteins. Using these lipopeptides and LC/MS mass spectra analysis, two groups of N-terminal lipidated (diacyl or triacyl) molecules that differ by one fatty acid unit were successfully identified. This LC/MS method also provided the separation of lipopeptides differing by 14 Da for the on-line MS identification. Multiple-stage fragmentation analyses of the di- and triacyl lipopeptides using both the positive and negative ion modes enabled to identify the putative structure of the N-acyl-S-diacylglycerylcysteine containing an amide bond to palmitic acid at the N-terminal cysteine, a palmitic acid at sn1 position, and an unsaturated fatty acid of either hexadecenoic acid, cyclopropaneoctanoic acid, oleic acid and nonadecenoic acid at sn2 position of diacylglycerol residue through ester bonding. For diacyl lipoprotein, the saturated palmitoyl fatty acid group is absent at sn1 position of glycerol-derived lipid residue of lipopeptide.
    Proteomics 07/2011; 11(13):2620-7. · 4.43 Impact Factor
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    ABSTRACT: Cross-presentation by DCs is the major mechanism by which exogenous antigens activate CTLs. However, the mechanisms of entry and presentation of vaccine peptides by DCs remain unclear. In this study, we determined that the mechanisms of antigen presentation differed between nonlipidated and monopalmitoylated peptide antigens. We found that a nonlipidated long peptide could be taken up by DCs and that the peptide could be colocalized with early endosomes. The uptake of nonlipidated peptides by DCs was inhibited at low temperatures or by the depolymerization of actin filaments or microtubules. In contrast, lipidated peptides were internalized by DCs at low temperatures, and internalization was not inhibited when actin filaments or microtubules were depolymerized. Moreover, lipidated peptide, but not nonlipidated peptide, was internalized by nonphagocytic Jurkat cells. The endosomal/lysosomal and proteasomal degradation pathways were necessary for nonlipidated presentation leading to the activation of CD8(+) T cells, but the proteasomal degradation pathway alone was sufficient to process lipidated peptides for MHC class I presentation. We further found that lipidated peptides could enhance peptide-specific T cell responses in vitro and in vivo and induced stronger antitumor responses than nonlipidated peptides. Taken together, our results demonstrate that DCs present lipidated peptides through an endocytosis-independent pathway to promote strong anti-tumor effects in vivo.
    Journal of leukocyte biology 04/2011; 90(2):323-32. · 4.99 Impact Factor
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    ABSTRACT: To protect against dengue viral infection, a novel lipidated dengue subunit vaccine was rationally designed to contain the consensus amino acid sequences derived from four serotypes of dengue viruses. We found that the lipidated consensus dengue virus envelope protein domain III (LcED III) is capable of activating antigen-presenting cells and enhancing cellular and humoral immune responses. A single-dose of LcED III immunization in mice without extra adjuvant formulation is sufficient to elicit neutralizing antibodies against all four serotypes of dengue viruses. In addition, strong memory responses were elicited in mice immunized with a single-dose of LcED III. Quick, anamnestic neutralizing antibody responses to a live dengue virus challenge were elicited at week 28 post-immunization. These results demonstrate the promising possibility of a future successful tetravalent vaccine against dengue viral infections that utilizes one-dose vaccination with LcED III.
    PLoS ONE 01/2011; 6(8):e23319. · 3.73 Impact Factor
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    ABSTRACT: Polysaccharide-based vaccines against Neisseria meningitidis (Nm) serogroups A, C, Y and W135 have been available since 1970, but similar vaccine candidates developed for Nm group B (NmB) have not been successful due to both poor immunogenicity and their potential immunological cross-reactivity with human neurological tissue. In previous reports, a protective antigen and vaccine candidate, Ag473, was identified using proteomics and NmB-specific bactericidal monoclonal antibody. To initiate human phase one clinical trials, antigen production and characterization, pre-clinical toxicology and animal studies are required. In the present study, we report the biochemical characterization of Escherichia coli-expressed recombinant Ag473 (rAg473). Using MALDI-TOF mass analysis, chromatographically purified rAg473 was found to have two major isoforms that have molecular masses of 11,306 and 11,544amu, respectively. The isoforms were separated using RP-HPLC and pooled into two fractions. Based on the chromatogram, the ratio of lipoproteins in fractions #1 and #2 was found to be 1-2. GC-MS analysis of lipoproteins was performed, and the acylated fatty acids were identified. The results indicated that the first lipoproteins in fraction #1 contained the lipids palmitic acid (C16:0), cyclopropaneoctanoic acid (C17:1) and, predominately, stearic acid (C18:0). A different lipid composition of cyclopropaneoctanoic acid (C17:1), oleic acid (C18:1) and, predominately, palmitic acid (C16:0) was found in the second lipoprotein fraction. Both lipoprotein isoforms were tested and found to have Toll-like receptor (TLR) agonist activity in stimulating cytokine secretion from THP-1 cells. Circular dichroism (CD) analysis showed the secondary structure of rAg473 to be dominated by α-helices (48%), and the overall protein structure was stable up to 60°C and could refold after having been exposed to a temperature cycle from 20 to 90°C. In addition, the solubility of rAg473 (5mg/mL) was not affected after several freeze-thaw cycles. These biophysical and immunological properties make rAg473 a good vaccine candidate against NmB.
    Vaccine 10/2010; 28(51):8175-82. · 3.77 Impact Factor
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    ABSTRACT: The lipid moiety of a novel recombinant lipoprotein, which contains a dengue virus envelope protein domain 3, rlipo-D1E3, has been shown to activate antigen-presenting cells (APCs) as an intrinsic adjuvant. Because the lipid moiety of rlipo-D1E3 contains an unsaturated fatty acid, it is unclear if the receptor usage by bacterially derived lipoproteins is the same as that of the synthetic lipopeptide palmitoyl-3-Cys-Ser-(Lys)(4) (Pam3). In the present study, we show that the rlipo-D1E3 lipoprotein can induce the activation of spleen cells and bone marrow-derived dendritic cells (BM-DCs) in wild-type and TLR4-deficient mice, but not in TLR2(-/-) mice. After analyzing the co-receptor usage of TLR2 using TLR1(-/-) or TLR6(-/-) mice, the TLR2 signaling triggered by rlipo-D1E3 and Pam3 could use either TLR1 or TLR6 as a co-receptor. Analysis of the MAPK signaling pathway revealed that rlipo-D1E3 could initiate the phosphorylation of p38, ERK1/2 and JNK1/2 earlier than the synthetic lipopeptide. In addition, the expression levels of IL-23, IL-27 and MIP-1 alpha in BM-DCs stimulated by rlipo-D1E3 were higher than the expression levels in BM-DCs stimulated by Pam3. Taken together, these results demonstrate that different TLR2 ligands can promote various immune responses by inducing different levels of biological cytokines and chemokines.
    Molecular Immunology 07/2010; 47(11-12):2015-21. · 2.65 Impact Factor
  • Shih-Chang Lin, Chih-Hsiang Leng, Suh-Chin Wu
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    ABSTRACT: The spike (S) protein of the severe acute respiratory syndrome coronavirus (SARS-CoV) is important for vaccine development. S(TR2) (an 88 kDa truncated SARS-CoV TW1 S protein carrying the S fragments S-74-253, S-294-739, and S-1129-1255) is capable of expressing a major form of glycoprotein as endo H-sensitive (∼115 kDa) in CHO cells. To establish stable expressing cell clones, we transfected CHO/dhFr-cells with the amplifiable vectors ISID (IRES-driven dhfr) and ISIZ (SV40-driven dhfr) to select stepwise MTX, and observed enhanced ∼115 kDa glycoform generation through gene amplification. Following stepwise MTX selection, we compared gene amplification levels between two vectors in engineered CHO cell chromosomes. These results confirm that the IRES-driven dhfr promoter generates greater gene amplification, which in turn enhances S(TR2) expression. Our results indicate that the ∼115 kDa glycoform of S(TR2) protein was capable of increasing after gene amplification. The S(TR2) glycoform did not change between suspension and serum-free cultures, suggesting that the stable and amplified cell clones analyzed in this study have potential for producing homologous S(TR2) on a large scale.
    Biotechnology Progress 01/2010; 26(6):1733-40. · 1.85 Impact Factor
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    ABSTRACT: Antigen sparing and cross-protective immunity are regarded as crucial in pandemic influenza vaccine development. Both targets can be achieved by adjuvantation strategy to elicit a robust and broadened immune response. We assessed the immunogenicity of an inactivated H5N1 whole-virion vaccine (A/Vietnam/1194/2004 NIBRG-14, clade 1) formulated with emulsified nanoparticles and investigated whether it can induce cross-clade protecting immunity. After formulation with PELC, a proprietary water-in-oil-in-water nanoemulsion comprising of bioresorbable polymer/Span(R)85/squalene, inactivated virus was intramuscularly administered to mice in either one-dose or two-dose schedule. We found that the antigen-specific serum antibody responses elicited after two doses of non-adjuvanted vaccine were lower than those observed after a single dose of adjuvanted vaccine, PELC and the conventional alum adjuvant as well. Moreover, 5 microg HA of PELC-formulated inactivated virus were capable of inducing higher antibodies than those obtained from alum-adjuvanted vaccine. In single-dose study, we found that encapsulating inactivated virus into emulsified PELC nanoparticles could induce better antibody responses than those formulated with PELC-adsorbed vaccine. However, the potency was rather reduced when the inactivated virus and CpG (an immunostimulatory oligodeoxynucleotide containing unmethylated cytosine-guanosine motifs) were co-encapsulated within the emulsion. Finally, the mice who received PELC/CpG(adsorption)-vaccine could easily and quickly reach 100% of seroprotection against a homologous virus strain and effective cross-protection against a heterologous virus strain (A/Whooper swan/Mongolia/244/2005, clade 2.2). Encapsulating inactivated H5N1 influenza virus and CpG into emulsified nanoparticles critically influences the humoral responses against pandemic influenza. These results demonstrated that the use of PELC could be as antigen-sparing in preparation for a potential shortage of prophylactic vaccines against local infectious diseases, in particular pandemic influenza. Moreover, the cross-clade neutralizing antibody responses data verify the potential of such adjuvanted H5N1 candidate vaccine as an effective tool in pre-pandemic preparedness.
    PLoS ONE 01/2010; 5(8):e12279. · 3.73 Impact Factor
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    ABSTRACT: Identification of the cytotoxic T lymphocyte (CTL) epitopes of tumor antigens is important for effective immunotherapy. We report that a combination of epitope prediction, enzyme-linked immunosorbent assay (ELISA)-based epitope-HLA complex formation, and DNA immunization methods can improve the efficiency and accuracy of CTL epitope studies. In this study, two HLA-A11-restricted epitopes derived from human papillomavirus (HPV)18 E6 oncoprotein were identified. HLA-A11-transgenic mice immunized with these epitopes could specifically induce interferon-gamma (IFNgamma) production, cytotoxicity and peptide/HLA-A11 tetramer binding in CD8(+) T-cells. To study intracellular processing of CTL epitopes, we constructed a DNA plasmid containing an endoplasmic reticulum (ER) targeting sequence as well as the HPV18 E6 and E7 genes (pEK/HPV18E6E7). CTL responses against peptide-pulsed T2/A11 cells could be detected after immunizing HLA-A11-transgenic mice with pEK/HPV18E6E7. Furthermore, the identified peptides could stimulate T-cells to secrete IFNgamma from HPV18-infected patients. Our results demonstrate that the antigenic E6 peptides derived from HPV18 are potential candidates for the treatment of HPV 18-associated tumors in HLA-A11(+) populations.
    Cancer biology & therapy 12/2009; 8(21):2025-32. · 3.29 Impact Factor
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    ABSTRACT: Two recombinant adenoviruses designated rAd-F0DeltaTM and rAd-F0 carrying the transmembrane truncated and full length of the F gene of the RSV-B1 strain, respectively, were engineered. Comparative immunogenicity studies in BALB/c mice showed that each vector was capable of inducing RSV-B1-specific antibodies that cross-reacted with the RSV-long and RSV-A2 viruses. The anti-RSV-B1 antibodies were neutralizing, and exhibited strong cross-neutralizing activity against the RSV-long and RSV-A2 isolates as well. Analysis of the cellular responses revealed that animals immunized with rAd-F0DeltaTM and rAd-F0 elicited CD4(+) T-cell responses of the Th1 and Th2 phenotypes, as well as F protein-specific CTLs. Production of Th2 cytokines (IL-4, IL-5 and IL-13) by splenocytes of the rAd-F0DeltaTM and rAd-F0 immunized mice was markedly lower than those released by animals administered with heat-inactivated RSV-B1 (HIRSV-B1). Comparison of the overall humoral and cellular responses suggests that rAd-F0DeltaTM is significantly more immunogenic than rAd-F0. The anti-viral immunity generated by both recombinant adenovirus vectors has conferred protection against live RSV-B1 challenge as judged by the lower viral load recovered in the lungs, a faster rate of recovery of body weight loss, and a lower count of eosinophils as compared to eosinophilia in mice immunized with HIRSV-B1. Results from these studies suggest that rAd-F0DeltaTM or rAd-F0 possess immunogenic properties that meet the requirements expected from potential RSV vaccine candidates.
    Vaccine 08/2009; 27(40):5460-71. · 3.77 Impact Factor

Publication Stats

291 Citations
128.70 Total Impact Points


  • 2006–2014
    • National Health Research Institutes
      • National Institute of Infectious Diseases and Vaccinology
      Miao-li-chieh, Taiwan, Taiwan
  • 2009–2011
    • National Institutes of Health
      Maryland, United States
  • 2008
    • National Taiwan University
      T’ai-pei, Taipei, Taiwan
  • 2004–2005
    • Academia Sinica
      • • Institute of Physics
      • • Institute of Biological Chemistry
      Taipei, Taipei, Taiwan