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Chen WH, Chou FP, Wang YK, Huang SC, Cheng CH, Wu TK. Characterization and epitope mapping of Dengue virus type 1 specific monoclonal antibodies. Virol J 2017; 14:189. [PMID: 28969658 PMCID: PMC5625772 DOI: 10.1186/s12985-017-0856-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 09/22/2017] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Dengue virus (DV) infection causes a spectrum of clinical diseases ranging from dengue fever to a life-threatening dengue hemorrhagic fever. Four distinct serotypes (DV1-4), which have similar genome sequences and envelope protein (E protein) antigenic properties, were divided. Among these 4 serotypes, DV1 usually causes predominant infections and fast diagnosis and effective treatments are urgently required to prevent further hospitalization and casualties. METHODS To develop antibodies specifically targeting and neutralizing DV1, we immunized mice with UV-inactivated DV1 viral particles and recombinant DV1 E protein from residue 1 to 395 (E395), and then generated 12 anti-E monoclonal antibodies (mAbs) as the candidates for a series of characterized assays such as ELISA, dot blot, immunofluorescence assay, western blot, and foci forming analyses. RESULTS Among the mAbs, 10 out of 12 showed cross-reactivity to four DV serotypes as well as Japanese encephalitis virus (JEV) in different cross-reactivity patterns. Two particular mAbs, DV1-E1 and DV1-E2, exhibited strong binding specificity and neutralizing activity against DV1 and showed no cross-reactivity to DV2, DV3, DV4 or JEV-infected cells as characterized by ELISA, dot blot, immunofluorescence assay, western blot, and foci forming analyses. Using peptide coated indirect ELISA, we localized the neutralizing determinants of the strongly inhibitory mAbs to a sequence-unique epitope on the later-ridge of domain III of the DV1 E protein, centered near residues T346 and D360 (346TQNGRLITANPIVTD360). Interestingly, the amino acid sequence of the epitope region is highly conserved among different genotypes of DV1 but diverse from DV2, DV3, DV4 serotypes and other flaviviruses. CONCLUSIONS Our results showed two selected mAbs DV1-E1 and DV1-E2 can specifically target and significantly neutralize DV1. With further research these two mAbs might be applied in the development of DV1 specific serologic diagnosis and used as a feasible treatment option for DV1 infection. The identification of DV1 mAbs epitope with key residues can also provide vital information for vaccine design.
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Affiliation(s)
- Wen-Hung Chen
- Department of Biological Science and Technology, National Chiao Tung University, Hsin-Chu, 30068 Taiwan, Republic of China
| | - Feng-Pai Chou
- Department of Biological Science and Technology, National Chiao Tung University, Hsin-Chu, 30068 Taiwan, Republic of China
| | - Yu-Kuo Wang
- Department of Biological Science and Technology, National Chiao Tung University, Hsin-Chu, 30068 Taiwan, Republic of China
| | - Sheng-Cih Huang
- Department of Biological Science and Technology, National Chiao Tung University, Hsin-Chu, 30068 Taiwan, Republic of China
| | - Chuan-Hung Cheng
- Department of Biological Science and Technology, National Chiao Tung University, Hsin-Chu, 30068 Taiwan, Republic of China
| | - Tung-Kung Wu
- Department of Biological Science and Technology, National Chiao Tung University, Hsin-Chu, 30068 Taiwan, Republic of China
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β-Lactoglobulin Influences Human Immunity and Promotes Cell Proliferation. BIOMED RESEARCH INTERNATIONAL 2016; 2016:7123587. [PMID: 27957499 PMCID: PMC5124466 DOI: 10.1155/2016/7123587] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Accepted: 08/01/2016] [Indexed: 12/15/2022]
Abstract
β-Lactoglobulin (LG) is suspected to enhance or modulate human immune responses. Moreover, LG is also hypothesized to increase human cell proliferation. However, these potential functions of LG have not been directly or thoroughly addressed. In this study, we demonstrated that LG is a potent stimulator of cell proliferation using a hybridoma cell (a splenocyte fused with a myeloma cell) model. LG's ability to promote cell proliferation was lost when the protein is denatured. To further investigate the influence of LG's conformation on cell proliferation, we chemically modified LG by either carboxymethylation (CM) or acetylation and observed significantly reduced cell proliferation when the protein structure was altered. Furthermore, we proved that LG enhances cell proliferation via receptor-mediated membrane IgM receptor. These data indicated that nondenatured LG is the major component in milk that modulates cell proliferation. Collectively, our study showed that LG plays a key role in enhancing immune responses by promoting cell proliferation through IgM receptor.
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Chen WH, Hsu IH, Sun YC, Wang YK, Wu TK. Immunocapture couples with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for rapid detection of type 1 dengue virus. J Chromatogr A 2013; 1288:21-7. [DOI: 10.1016/j.chroma.2013.02.030] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 02/07/2013] [Accepted: 02/08/2013] [Indexed: 01/06/2023]
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4
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Monoclonal antibodies against Caprine arthritis-encephalitis virus epitopes in the p28 and p55gag viral proteins. J Virol Methods 2013; 187:352-6. [DOI: 10.1016/j.jviromet.2012.10.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 10/23/2012] [Accepted: 10/30/2012] [Indexed: 11/21/2022]
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5
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Lin S, Sun J, Cao D, Cao J, Jiang W. Distinction of different heat-treated bovine milks by native-PAGE fingerprinting of their whey proteins. Food Chem 2010. [DOI: 10.1016/j.foodchem.2009.12.088] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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6
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Yang MC, Chen NC, Chen CJ, Wu CY, Mao SJT. Evidence for beta-lactoglobulin involvement in vitamin D transport in vivo--role of the gamma-turn (Leu-Pro-Met) of beta-lactoglobulin in vitamin D binding. FEBS J 2009; 276:2251-65. [PMID: 19298386 DOI: 10.1111/j.1742-4658.2009.06953.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Beta-lactoglobulin (LG) is a major bovine milk protein, containing a central calyx and a second exosite beyond the calyx to bind vitamin D; however, the biological function of LG in transporting vitamin D remains elusive. Crystallographic findings from our previous study showed the exosite to be located at the pocket between the alpha-helix and beta-strand I. In the present study, using site-directed mutagenesis, we demonstrate that residues Leu143, Pro144 and Met145 in the gamma-turn loop play a crucial role in the binding. Further evidence is provided by the ability of vitamin D(3) to block the binding of a specific mAb in the gamma-turn loop. Using the mouse (n = 95) as an animal model, we initially demonstrated that LG is a major fraction of milk proteins responsible for uptake of vitamin D. Most interestingly, dosing mice with LG supplemented with vitamin D(3) revealed that native LG containing two binding sites gave a saturated concentration of plasma 25-hydroxyvitamin D at a dose ratio of 2 : 1 (vitamin D(3)/LG), whereas heated LG containing one exosite (lacking a central calyx) gave a ratio of 1 : 1. We have demonstrated for the first time that LG has a functional advantage in the transport of vitamin D, indicating that supplementing milk with vitamin D effectively enhances its uptake.
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Affiliation(s)
- Ming Chi Yang
- Department and College of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan
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Lai YA, Lai IH, Tseng CF, Lee J, Mao SJT. Evidence of tandem repeat and extra thiol-groups resulted in the polymeric formation of bovine haptoglobin: a unique structure of Hp 2-2 phenotype. BMB Rep 2008; 40:1028-38. [PMID: 18047801 DOI: 10.5483/bmbrep.2007.40.6.1028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human plasma Hp is classified as 1-1, 2-1, and 2-2. They are inherited from two alleles Hp 1 and Hp 2, but there is only Hp 1 in almost all the animal species. Hp 2-2 molecule is extremely large and heterogeneous associated with the development of inflammatory-related diseases. In this study, we expressed entire bovine Hp in E. coli as a alphabeta linear form. Interestingly, the antibodies prepared against this form could recognize the subunit of native Hp. In stead of a complicated column method, the antibody was able to isolate bovine Hp via immunoaffinity and gel-filtration columns. The isolated Hp is polymeric containing two major molecular forms (660 and 730 kDa). Their size and hemoglobin binding complex are significantly larger than that of human Hp 2-2. The amino-acid sequence deducted from the nucleotide sequence is similar to human Hp 2 containing a tandem repeat over the alpha chain. Thus, the Hp 2 allele is not unique in human. We also found that there is one additional -SH group (Cys-97) in bovine alpha chain with a total of 8 -SH groups, which may be responsible for the overall polymeric structure that is markedly different from human Hp 2-2. The significance of the finding and its relationship to structural evolution are also discussed.
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Affiliation(s)
- Yi An Lai
- Research Institute of Biochemical Engineering, Department of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan, ROC
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8
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Lai IH, Lin KY, Larsson M, Yang MC, Shiau CH, Liao MH, Mao SJT. A unique tetrameric structure of deer plasma haptoglobin - an evolutionary advantage in the Hp 2-2 phenotype with homogeneous structure. FEBS J 2008; 275:981-93. [DOI: 10.1111/j.1742-4658.2008.06267.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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9
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Yang MC, Guan HH, Liu MY, Lin YH, Yang JM, Chen WL, Chen CJ, Mao SJT. Crystal structure of a secondary vitamin D3 binding site of milk β-lactoglobulin. Proteins 2007; 71:1197-210. [DOI: 10.1002/prot.21811] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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10
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Abstract
Heating is necessary for processing milk in the dairy industry, which evidently produces a conformational change in beta-lactoglobulin (beta-LG). beta-Lactoglobulin, a major protein that accounts for approximately 10 to 15% of total milk proteins, is a globular protein consisting of 162 AA with a relative molecular mass of 18.4 kDa. The purpose of the present study was to determine the antioxidant role of beta-LG in milk and the possible mechanism involved. We showed that beta-LG is a mild antioxidant whose potency is less than that of vitamin E and probucol (the latter being an antioxidant used for clinical therapy). The conversion of the beta-LG monomer to dimer was responsible, in part, for the mode of action in protecting low-density lipoproteins against copper-induced oxidation. Cross-linking the free thiol groups of beta-LG by heating (100 degrees C for 2 min), or chemically modifying the beta-LG by carboxymethylation to block the thiol groups resulted in a substantial loss of antioxidant activity. The data suggest that Cys-121 plays an essential role in the antioxidant nature of beta-LG. By using an anti-LG antibody affinity column to deplete the beta-LG from milk, we observed from the lost antioxidant activity that beta-LG contributes approximately 50% of the total activity. Because beta-LG is extremely sensitive to thermal denaturation, to maintain its antioxidant nature, dairy products consumed daily should not be overheated in order to maintain its antioxidant nature.
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Affiliation(s)
- H C Liu
- Department of Biological Science and Technology, College of Biological Science and Technology, National Chiao Tung University, Taiwan, Republic of China
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Lai IH, Tsai TI, Lin HH, Lai WY, Mao SJT. Cloning and expression of human haptoglobin subunits in Escherichia coli: Delineation of a major antioxidant domain. Protein Expr Purif 2007; 52:356-62. [PMID: 17095249 DOI: 10.1016/j.pep.2006.09.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Revised: 09/25/2006] [Accepted: 09/25/2006] [Indexed: 10/24/2022]
Abstract
Human plasma haptoglobin (Hp) comprises alpha and beta subunits. The alpha subunit is heterogeneous in size, therefore isolation of Hp and its subunits is particularly difficult. Using Escherichia coli, we show that alpha1, alpha2, beta, and alpha2beta chain was abundantly expressed and primarily present in the inclusion bodies consisting of about 30% of the cell-lysate proteins. Each cloned subunit retained its immunoreactivity as confirmed using antibodies specific to alpha or beta chain. By circular dichroism, the structure of each expressed subunit was disordered as compared to the native Hp. The antioxidant activity was found to be associated with both alpha and beta chains when assessed by Cu(2+)-induced oxidation of low density lipoprotein (LDL). Of remarkable interest, the antioxidant activity of beta chain was extremely potent and markedly greater than that of native Hp (3.5x), alpha chain (10x) and probucol (15x). The latter is a clinically proved potent compound used for antioxidant therapy. The "unrestricted" structure of beta subunit may therefore render its availability for free-radical scavenge, which provides a utility for the future design of a "mini-Hp" in antioxidant therapy. It may also provide a new insight in understanding the mechanism involved in the antioxidant nature of Hp.
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Affiliation(s)
- I Hsiang Lai
- Research Institute of Biochemical Engineering, College of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan, ROC
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12
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Cheng TM, Huang PC, Pan JP, Lin KY, Mao SJT. Gel electrophoresis of polyphenol oxidase with instant identification by in situ blotting. J Chromatogr B Analyt Technol Biomed Life Sci 2006; 849:331-6. [PMID: 16973425 DOI: 10.1016/j.jchromb.2006.08.046] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2006] [Revised: 08/19/2006] [Accepted: 08/21/2006] [Indexed: 10/24/2022]
Abstract
Polyphenol oxidase (PPO) or tyrosinase is an important and ubiquitous enzyme responsible for browning in plants and melanization in animals. The molecular size of the plant PPO is varied among the species and its activity can be enhanced by a variety of anionic detergents. In the present study, we developed a simple method for the first-step identification of PPO in fruit and vegetable extracts. First, 3mm chromatographic paper was immersed in 0.5% (w/v) catechol solution as an immobilized PPO substrate. After running the extract with 10% sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), one side of the glass plate was removed. The plate was immediately laid on top of the dried catechol-paper. A dark-brown band corresponding to PPO was visualized within 1 min and was further confirmed by a conventional Western blot using an antibody prepared against mushroom PPO. It also reveals that some vegetation (such as tomato, radish, and oriental melon) with low or no detectable activity in a conventional enzyme assay actually possessed marked levels of PPO activity when assessed by PAGE-blot. We propose that an inhibitor is associated with PPO in some plants; the inhibitor, however, is dissociated during the electrophoresis. Therefore, in addition to identify the molecular form of PPO, the present technique may explore the existence of PPO inhibitor(s) in plants. The detail of the method with respect to its relevance for searching a natural PPO inhibitor is described and discussed.
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Affiliation(s)
- Tsai-Mu Cheng
- College of Biological Science and Technology, National Chiao Tung University, 75 Po-Ai Street, Hsinchu, Taiwan, ROC
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13
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Chen WL, Liu WT, Yang MC, Hwang MT, Tsao JH, Mao SJT. A Novel Conformation-Dependent Monoclonal Antibody Specific to the Native Structure of β-Lactoglobulin and Its Application. J Dairy Sci 2006; 89:912-21. [PMID: 16507685 DOI: 10.3168/jds.s0022-0302(06)72156-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Molten globules are thought to be general intermediates in protein folding and unfolding. beta-lactoglobulin (beta-LG) is one of the major bovine whey proteins, constituting approximately 10 to 15% of total milk proteins. We have recently identified beta-LG as a superior marker for evaluating thermally processed milk. Strand D of beta-LG participates in irreversible thermal unfolding as probed by a monoclonal antibody (mAb) specific to thermally denatured beta-LG. In the present study, we used native beta-LG as an immunogen to test the hypothesis that a specific mAb against the native beta-LG could be established. As result, a mAb (4H11E8) directed against the native structure of beta-LG was made. The antibody did not recognize the heat-denatured form of beta-LG, such as its dimer and aggregates. Immunoassay using this "native" mAb showed that the stability of beta-LG was at temperatures < or =70 degrees C. beta-Lactoglobulin began to deteriorate between 70 and 80 degrees C over time. The denaturation was correlated with the transition temperature of beta-LG. Further chemical modification of Cys (carboxymethylation) or positively charged residues (acetylation) of beta-LG totally abolished its immunoreactivity, confirming the conformation-dependent nature of this mAb. Using competitive ELISA, the 4H11E8 mAb could determine the native beta-LG content in commercially processed milks. Concentrations of native beta-LG varied significantly among the local brands tested. From a technological standpoint, the mAb prepared in this study is relevant to the design and operation of appropriate processes for thermal sanitation of milk and of other dairy products.
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Affiliation(s)
- W L Chen
- Research Institute of Biochemical Engineering, Department of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan, Republic of China
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Chen WL, Hwang MT, Liau CY, Ho JC, Hong KC, Mao SJT. Beta-lactoglobulin is a thermal marker in processed milk as studied by electrophoresis and circular dichroic spectra. J Dairy Sci 2005; 88:1618-30. [PMID: 15829652 DOI: 10.3168/jds.s0022-0302(05)72833-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
As much of the sterilization process involves heat treatment during the preparation of milk on an industrial scale, the unpredictable measures of the process are an essential issue in determining the quality of the milk. The purpose of the present study was to investigate the major protein change(s) of whey proteins in processed milk and extend the knowledge for future reference in the dairy industry. Using a native polyacrylamide gel electrophoresis, we showed almost a 90% loss and denaturation of beta-lactoglobulin (LG), but not alpha-lactalbumin (LA), in some brands of the processed and dry milks. Immunochemical analysis using Western blotting revealed that part of the loss was attributed to the formation of large multiple forms of LG in the processed product. Such denaturation was presumably associated with the heating procedure used in the process. Essentially, LG was the only major fraction converted to aggregates in milk heated at 95 degrees C for 30 min on 2-dimensional PAGE. The detailed thermal denaturation of purified LG and LA at various temperatures (50 to 95 degrees C) and time (5 to 960 s) were investigated using a circular dichroic analysis. The maximal changes of ellipticity at 205 nm (converting beta-structure to disordered structure) were correlated to heating temperature and time. There were no significant conformational changes of LG at temperatures below 70 degrees C for as long as 480 s. Pronounced and rapid changes occurred between 80 to 95 degrees C in a time-dependent manner. Fifty percent of the maximal changes could be reached within 15 s. In conclusion, the unique chemical and immunochemical loss and conformational changes made LG a superior marker for evaluating the thermal processing of milk. The detailed thermal denaturation curves of LG constructed with its time and temperature in this study provide a valuable reference for the dairy industry. We postulate that heat treatment over 80 degrees C in 15 s may induce a significant denaturation of milk LG.
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Affiliation(s)
- W L Chen
- Research Institute of Biochemical Engineering, Department of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan, Republic of China
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Song CY, Chen WL, Yang MC, Huang JP, Mao SJT. Epitope Mapping of a Monoclonal Antibody Specific to Bovine Dry Milk. J Biol Chem 2005; 280:3574-82. [PMID: 15536085 DOI: 10.1074/jbc.m407031200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
beta-Lactoglobulin (beta-LG) is a bovine milk protein sensitive to thermal denaturation. Previously, we demonstrated that such structural change can be detected by a monoclonal antibody (mAb) specific to denatured beta-LG. In the present study, we show a dramatic increase in beta-LG immunoreactivity when heating raw milk between 70 and 80 degrees C. To map out the specific epitope of beta-LG recognized by this mAb, we used a combined strategy including tryptic and CNBr fragments, chemical modifications (acetylation and carboxymethylation), peptide array containing in situ synthesized peptides, and a synthetic soluble peptide for immunoassays. The antigenic determinant we defined was exactly located within the D strand (residues 66-76) of beta-LG. Circular dichroic spectral analysis shows that carboxymethylation on beta-LG not only resulted in a substantial loss of beta-configuration but also exerted a 10 times increase in immunoreactivity as compared with heated beta-LG. The result suggests that a further disordered structure occurred in beta-LG and thus rendered the mAb recognition. Mutations on each charged residue (three Lys and one Glu) revealed that Lys-69 and Glu-74 were extremely essential in maintaining the antigenic structure. We also show an inverse relationship between the immunoreactivity in heated beta-LG and its binding to retinol or palmitic acid. Most interestingly, pH 9-10, which neutralizes the Lys groups of beta-LG, not only reduced its immunoreactivity but also its binding to palmitic acid implicating a role of Lys-69. Taken together, we concluded that strand D of beta-LG participated in the thermal denaturation between 70 and 80 degrees C and the binding to retinol and palmitic acid. The antigenic and biochemical roles of mAb specific to D strand are discussed in detail.
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Affiliation(s)
- Chun Ying Song
- Research Institute of Biochemical Engineering, Department of Biological Science and Technology, National Chiao Tung University, Hsinchu and Genesis Biotech Inc., 131, Lane 235, Bao-Chiao Road, Hsintien, Taipei, Taiwan, Republic of China
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