Development and characterization of neutralizing monoclonal antibodies against the pandemic H1N1 virus (2009)

The 2009 H1N1 influenza pandemic was a major international public health crisis which caused considerable morbidity and mortality worldwide. The goal of this study was to produce anti-H1 monoclonal antibodies (MAbs) for improving diagnostic immunological assays and to develop potential immunotherapeutics. Nine MAbs were produced after immunizing mice with recombinant hemagglutinin (HA) protein from A/California/06/09. Two spleenocyte myeloma fusions yielded 1588 hybridoma cultures. After screening the hybridoma culture supernatants for antibody reactivity to rHA, nine clones were selected for further characterization. Cross-reactivity studies of the anti-rHA antibodies against a panel of influenza viruses (H1-H16) revealed eight out of nine MAbs were specific to the pandemic H1 subtype, except for MAb F256G2sc1 which also cross-reacted with H5 subtype virus. All MAbs were of the IgG1κ isotype, except F256G2sc1 which was IgG2aκ. The anti-rHA MAbs had binding affinities to rHA that ranged from a K(D) (disassociation constant) of 1.34×10(-9)M (F255G7sc1) to the weakest affinity of 4.60×10(-8)M (F255G4sc1). Interestingly, in a plaque reduction neutralization assay, all MAbs except F255G3sc1 demonstrated neutralizing ability. Furthermore, all MAbs except F255G3sc1 and F255G9sc1 exhibited anti-hemagglutinin activity against pandemic H1N1 viruses, but not against classical North American swine influenza viruses of the same subtype. Immunofluorescence assay (IFA) demonstrated that all MAbs except F255G1sc1 and F255G3sc1 were able to detect 2009 pandemic H1N1 (2009) virus- infected MDCK cells. The MAbs were also evaluated for potential use in competitive ELISA (cELISA), and with the exception of F255G3sc1, all MAbs showed competitive activity with serum collected from pigs infected with pandemic H1N1 virus (2009). The developed MAbs have demonstrated utility as immunodiagnostic and research reagents, and their neutralizing capabilities also hold potential for designing antiviral drugs against pandemic influenza.     

Development, characterization, and diagnostic applications of monoclonal antibodies against bovine rotavirus

Hybridomas secreting monoclonal antibodies (MAbs) against the Nebraska calf diarrhea strain of bovine rotavirus (BRV) were characterized. Indirect fluorescent-antibody assay, immunodot assay, and immunoprecipitation were used to select hybridomas that produced anti-BRV MAbs. Seven of the MAbs were shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot assay to be reactive with the BRV outer capsid protein, VP7, which has a molecular mass of 37.5 kDa. None of the seven MAbs were reactive with canine rotavirus, bovine coronavirus, or uninfected Madin-Darby bovine kidney cells. Two clones, 8B4 (immunoglobulin G2a [IgG2a]) and 2B11 (IgG1), were found suitable for use in an antigen capture enzyme-linked immunosorbent assay for detecting BRV in bovine fecal samples. Both were subtype A specific (G6 subtype) but did not react with all isolates of BRV group A.     

人牙冠及根部牙本质内基质金属蛋白酶8，20的测定及分析

背景：基质金属蛋白酶被激活后可降解细胞外基质,其对牙本质胶原的破坏对于牙周病、牙本质龋病、牙髓炎的进展及牙本质黏结的失败有重要影响。 目的：检测冠根部牙本质内基质金属蛋白酶的含量及其分布特点。 方法：牙本质粉经盐酸胍提取,然后经EDTA循环脱矿,再经盐酸胍提取。采用免疫印迹与免疫酶联吸附反应检测提取物中基质金属蛋白酶8,20的含量,对比二者在牙冠部和牙根部内的分布特点。 结果与结论：免疫印迹结果及免疫酶联吸附检测结果均显示,提取物中含有基质金属蛋白酶8,20。未矿化牙本质提取蛋白G1中基质金属蛋白酶8,20含量较低,EDTA反复提取矿化牙本质蛋白E1中含量较高,脱矿后提取蛋白G2中2种基质金属蛋白酶的含量最低。基质金属蛋白酶8,20在牙冠和牙根部表达量基本类似。提示冠根部牙本质中含有基质金属蛋白酶8,20,它们大多存在于矿化牙本质中,其在牙根和牙冠中的含量基本类似。     

A neutralizing recombinant human antibody Fab fragment against Puumala hantavirus

A combinatorial human antibody Fab pComb3H library, generated from splenic lymphocytes of a Puumala hantavirus (PUUV) immune individual, was selected against PUUV using the phage display technique. Panning was carried out with antigens immobilized by MAbs directed to the two PUUV envelope glycoproteins G1 and G2. Thirteen Fabs, with reactivity directed to PUUV and specifically the G2 protein, as assessed by immunofluorescence and ELISA respectively, were isolated in crude preparations. By a focus reduction neutralization test (FRNT), four of the 13 crude Fab preparations exhibited type-specific neutralization of PUUV (strain Sotkamo) with 44-54% reduction in the number of foci. After affinity purification, the four Fab clones exhibited 50% focus reduction of PUUV at concentrations below 2 microg/ml. Sequencing of the heavy and light chain complementarity determining regions (CDR) 1-3 showed that the four selected clones were identical within the antibody binding regions. In inhibition tests with the PUUV G2-specific MAbs, 4G2 and 1C9, a new epitope important for neutralization, designated as G2-a3, was defined. This epitope, overlapping partially the neutralizing epitope recognized by the human MAb 1C9, seems to be unique for the PUUV serotype since none of the Fab clones neutralized any of the other hantaviruses tested.     

Characterization of four new monoclonal antibodies that recognize mouse natural killer activation receptors

With the aim of identifying natural killer (NK) activation receptors, we immunized BALB/c mice with (BALB/cxB6)F1 NK LAK cells and made B-cell hybridomas. These were screened for monoclonal antibody (MAb) reacting with an NK activation receptor by using an antibody-induced redirected lysis (AIRL) assay against FcR-bearing P815 targets. Four hybridomas, clones 1C10, 1F10, 2D10 and 4G4, were selected for further characterization. Protein G-purified MAbs from these clones activated both resting and IL-2 activated B6 or F1 NK cells in the AIRL assay. 1F10 MAb, but not the other three MAbs, could compete for the binding of anti-NK1.1 (PK136) MAb to F1 NK cells. The four MAbs were screened for their ability to bind to or activate NK cells from the mouse strains SJL/J, DBA/2, 129/J, C3H/J, and BALB.K. None showed activity except IC10, which could bind to and activate SJL/J NK cells. When members of the NKR-P1 family from both B6 mice (A, B, and C genes expressed) and SJL mice (only A and B genes expressed) were expressed in Jurkat cells and tested for their antibody reactivity, PK136 MAb was found to recognize B6 NKR-P1C and SJL/J NKR-P1B; IC10 MAb was found to recognize NKR-P1-A, -B and -C from B6, but not NKR-P1A or -B from SJL/J; and 1F10 MAb was found to react only with B6 NKR-P1C.     

Development, Characterization, and Diagnostic Applications of Monoclonal Antibodies against Bovine Rotavirus

Hybridomas secreting monoclonal antibodies (MAbs) against the Nebraska calf diarrhea strain of bovine rotavirus (BRV) were characterized. Indirect fluorescent-antibody assay, immunodot assay, and immunoprecipitation were used to select hybridomas that produced anti-BRV MAbs. Seven of the MAbs were shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot assay to be reactive with the BRV outer capsid protein, VP7, which has a molecular mass of 37.5 kDa. None of the seven MAbs were reactive with canine rotavirus, bovine coronavirus, or uninfected Madin-Darby bovine kidney cells. Two clones, 8B4 (immunoglobulin G2a [IgG2a]) and 2B11 (IgG1), were found suitable for use in an antigen capture enzyme-linked immunosorbent assay for detecting BRV in bovine fecal samples. Both were subtype A specific (G6 subtype) but did not react with all isolates of BRV group A.     

Metalloproteinases and their Tissue Inhibitors in Multiple Sclerosis

Matrix metalloproteinases (MMPs) comprise a family of proteolytic enzymes. MMPs are capable of disrupting the blood-brain barrier (BBB), mediating the destruction of extracellular matrix and myelin components. MMPs are also involved in the processing of a variety of cell surface molecules, including the proinflammatory cytokine TNF-alpha. Each of these mechanisms are thought to be important in the pathogenesis of multiple sclerosis (MS). We investigated mRNA expression of MMP-3, MMP-9 and two tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2) in parallel in blood mononuclear cells (MNC) from patients with MS and controls, using in situ hybridization. Numbers of MMP-9 mRNA-expressing cells in blood were higher in patients with MS compared to other neurological diseases (OND), other inflammatory neurological diseases (OIND) and healthy subjects (P<0.0001 for all comparisons). Patients with MS had also higher levels of MMP-3 and TIMP-1 mRNA expressing blood MNC compared to patients with OND and healthy subjects. A positive correlation was observed for MMP-9 and TIMP-1 mRNA expression in MS. These results demonstrate that MMPs and TIMPs are upregulated in MS and may contribute to the pathogenesis of the disease.     

Calprotectin inhibits matrix metalloproteinases by sequestration of zinc.

BACKGROUND/AIMS: Calprotectin, a 36 kDa protein present in neutrophil cytoplasm, has antimicrobial and apoptosis inducing activities, which are reversed by the addition of zinc. Matrix metalloproteinases (MMPs), a family of zinc dependent enzymes, are important in many normal biological processes including embryonic development, angiogenesis, and wound healing, but also pathological processes such as inflammation, cancer, and tissue destruction. The aim of this study was to investigate whether calprotectin can inhibit MMP activity, and whether such inhibition could be overcome by the addition of zinc. METHODS: MMP activity was measured by the degradation of substrates precoated on to microwells, and visualised by Coomassie blue staining of residual substrate. Seven metalloproteinases (MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, and MMP-13) were tested against two substrates: gelatin and alpha-casein. RESULTS: All MMPs except MMP-1 were active against gelatin, whereas MMP-7 was the only enzyme active against alpha-casein. The addition of calprotectin inhibited the activity of all the MMPs, but different concentrations of the protein, from 0.3 microM to > 11microM, were necessary to produce a 50% inhibition of the MMPs. Inhibition by calprotectin was largely overcome by the addition of zinc. CONCLUSIONS: The findings suggest that calprotectin inhibits MMPs by sequestration of zinc. The data also suggest that MMPs have different affinities for zinc and that calprotectin has a lower zinc affinity than the MMPs.     

Generation and characterization of monoclonal antibodies against dengue virus type 1 for epitope mapping and serological detection by epitope-based peptide antigens

Dengue virus (DEN), the pathogen behind dengue hemorrhagic fever, remains a public health problem in Asia and South America. In this study, monoclonal antibodies (MAbs) against DEN serotype 1 (DEN-1) were generated by fusing NSI/1-Ag4-1 mouse myeloma cells with lymphocytes from BALB/c mice immunized with DEN-1. Twelve MAbs were found to react specifically to the DENs by enzyme-linked immunosorbent assay, immunofluorescence analysis, and immunoblotting analysis. Five MAbs, namely, DA4-7, DA6-7, DA9-5, DA10-2, and DA11-13, were found to react with envelope proteins of DEN-1. Two serotype-specific MAbs of DEN-1, DA6-7 and DA11-13, were further shown to neutralize DEN-1 infection by a plaque reduction neutralization test. The neutralizing epitopes of these MAbs were further identified from a random peptide library displayed on phage. Immunopositive phage clones reacted specifically with these MAbs and did not react with normal mouse serum. Epitope-based peptide antigens were proved able to detect antibodies in serum samples collected from DEN-1-infected patients but not in those taken from DEN-2-infected patients or healthy controls. We believe that these MAbs and neutralizing epitopes will provide information that will lead to the development of DEN-1 serotype-specific diagnostic reagents and vaccines.     

Matrix metalloproteinases-2 and -3 are reduced in cerebrospinal fluid with low beta-amyloid1–42 levels

Matrix metalloproteinases (MMPs), a family of extracellular soluble or membrane bound endopeptidases, are implicated in many physiological and pathophysiological functions—based on their capability to cleave all protein components of the extracellular matrix. Recent studies have implicated several forms of MMPs in chronic neurodegenerative diseases like Alzheimer's disease (AD), vascular dementia (VD), and Parkinson's disease (PD). The aim of the present study was to analyse eight MMPs (MMP-1, -2, -3, -7, -8, -9, -10, -13) in the human cerebrospinal fluid (CSF) and to correlate with the well established biomarkers beta-amyloid_1–42 (Aβ), total-tau and phospho-tau-181. Our data show a significant decrease of MMP-2 and MMP-3 levels in the CSF in samples with significantly reduced Aβ levels. It is concluded that MMP-2 and MMP-3 are directly linked to Aβ in the brain and a dysfunction may influence the processing of Aβ.     

Mouse monoclonal antibodies to hepatitis B virus preS1 produced after immunization with recombinant preS1 peptide

We have efficiently generated mouse monoclonal antibodies (MAbs), which bind specifically to amino acids 21-47 of the preS1 domain of hepatitis B virus (HBV) by immunizing mice with the preS1 peptide (amino acids, aa 1-56) conjugated to keyhole limpet hemocyanin. Hybridomas were screened by an indirect enzyme-linked immunosorbent assay (ELISA) using the purified preS1 peptide as a coated antigen. Eighteen positive hybridomas were selected and subjected to isotyping. Of these, 5 clones secreted immunoglobulin G (IgG) and 13 clones secreted IgM. Four (KR1, KR2, KR3, and KR4) of the 5 IgG MAbs bound to preS1 peptide (aa 21-47). Epitope mapping using bacterially expressed GST fusion proteins revealed that three clones (KR2, KR3, KR4) (IgG1, K) recognize aa 21-35, while KR1 (IgG2a, K) recognizes aa 35-47 of the preS1. These MAbs immunoprecipitated HBV particles, demonstrating that they bind to native HBV particles.     

Interleukin-31 stimulates production of inflammatory mediators from human colonic subepithelial myofibroblasts

Interleukin (IL)-31 is mainly produced by CD4+ T cells, in particular T cells skewed toward a Th2 phenotype. Here we report for the first time that IL-31 stimulates secretion of proinflammatory cytokines, chemokines and matrix metalloproteinases (MMPs) from human colonic subepithelial myofibroblasts (SEMFs). The effects of IL-31 were investigated by cDNA microarrays, enzyme-linked immunosorbent assay, and real-time PCR. IL-31 effectively induced chemokines [IL-8, GRO-alpha (growth-related oncogene-alpha), MCP-3 (monocyte chemoattractant protein-3), CXCL3, CCL13 and CCL15], proinflammatory cytokines (IL-6, IL-16 and IL-32) and matrix metalloproteinases (MMP-1, MMP-3, MMP-25 and MMP-7). IL-31 dose-dependently induced secretion of IL-6, IL-8, GRO-alpha, MCP-3, MMP-1 and MMP-3. The effects of IL-31 were comparable to the effects of IL-17A. IL-31 and IL-17A showed additive effects on IL-6, IL-8, GRO-alpha, MCP-3, MMP-1 and MMP-3 secretion. In conclusion, we demonstrated that IL-31 is a potent inducer of proinflammatory mediators in human colonic SEMFs. IL-31 may function as a proinflammatory cytokine derived from Th2 cells.     

PRL-2基因转染对肝细胞基质金属蛋白酶及其抑制剂表达的影响

目的:研究PRL-2基因增强肿瘤细胞侵袭及转移能力的机制。 方法:采用脂质体转染的方法将PRL-2基因表达质粒转染至正常永生化肝细胞系CL1中，G418筛选阳性克隆。应用明胶酶谱法检测转染肝细胞分泌MMPs 酶谱变化，Western blotting 及RT-PCR检测转染肝细胞MMP-2、MMP-9、TIMP-1和TIMP-2的变化。以PRL-2磷酸酯酶特异性抑制剂处理转染细胞，观察抑制PRL-2活性对上述指标的影响。 结果:经过 8周G418筛选及RT-PCR和Western blotting鉴定,获得稳定表达PRL-2的细胞亚系PRL-2-CL1。转染后的CL1细胞分泌MMP－9 、活性型MMP－9 和MMP－2 ,均显著高于转染前CL1细胞的MMPs 分泌(P<0.01);使用特异性抑制剂后， MMP－9 、活性型MMP－9 和MMP－2活性显著降低(P<0.01)。Western blotting及RT-PCR检测显示PRL-2-CL1细胞MMP2、MMP9蛋白及mRNA含量均较转染前显著升高(P<0.05)，TIMP-2则显著降低(P<0.05)；使用抑制剂后，可以逆转上述变化。 结论:PRL-2在永生化肝细胞中获得稳定、高效表达，PRL-2基因增强肝细胞侵袭及转移能力与其提高细胞MMP2、MMP9表达，降低TIMP-2有关。     

Matrix metalloproteinase-2, -9, -12, and tissue inhibitor of metalloproteinase 2 gene polymorphisms and cutaneous expressions in patients with Behçet's disease

Matrix metalloproteinases (MMPs) induce leukocyte migration into inflammation sites that lead to either promotion or repression of inflammation by activating or inactivating cytokines. An increased level of MMP-9 and a decreased level of MMP-2 have been observed in Beh?et's disease (BD). This study was performed to analyze the relationship between MMP-2, -9, -12 and the tissue inhibitor of metalloproteinase-2 (TIMP-2) promoter polymorphisms in developing BD. The expression of MMP-2 and -9 was also evaluated in the skin of BD. The MMPs and TIMP-2 polymorphisms were confirmed by using polymerase chain reaction-restriction fragment length polymorphism in 251 BD and 312 controls. Cutaneous expression of MMP-2 and -9 in 17 BD patients with erythema nodosum (EN) or EN-like lesion was compared with 14 patients with idiopathic EN by immunohistochemical stains. The frequency of MMP-2-1575*G/*G and MMP-2-735*C/*C genotypes was shown to be lower in BD, whereas MMP-9-1562*C/*C was significantly higher in BD compared with the controls. The frequency of common haplotype MMP-2-1575*G -735*C was significantly lower in BD patients than in controls (P = 0.0046, permutation P = 0.009). No significant differences were observed between BD and controls in the allele and genotype frequencies of MMP-12-82A>G or TIMP-2-418G>C polymorphisms. The tissue expression of MMP-2, shown by immunohistochemistry, was significantly lower in BD compared with the controls. However, the expression of MMP-9 was significantly higher in BD. These results suggest that MMP-2 and -9 could each modulate the development of BD in opposite directions. Major genotypes of the MMP-2-1575*G/*G and MMP-2-735*C/*C and the common MMP-2-1575*G -735*C haplotype may provide some protection against development of BD, while MMP-9-1562*C/*C may promote the disease. The reciprocal expression of MMP-2 and -9 in the skin tissue of BD was also confirmed.     

Soluble EMMPRIN (extra-cellular matrix metalloproteinase inducer) stimulates the migration of HEp-2 human laryngeal carcinoma cells, accompanied by increased MMP-2 production in fibroblasts

The basement membrane functions as a barrier against the invasion of cancer cells. It is therefore important to investigate the mechanism of basement membrane degradation by matrix metalloproteinases (MMPs). Previously, cancer cells were long considered to be the major source of MMPs; however, current evidence indicates that most MMPs in cancer tissue are produced by stromal rather than cancer cells. A glycoprotein highly expressed on the cancer-cell membrane, EMMPRIN (extra-cellular matrix metalloproteinase inducer), exhibits the potential role of the MMP inductor in stromal cells. Depending on the cell type, EMMPRIN can stimulate the production of MMP-1, MMP-2, and MMP-3. We here report that soluble full-length EMMPRIN is liberated from HEp-2 human laryngeal epidermoid carcinoma cells, probably via microvesicle shedding. Soluble EMMPRIN stimulates human fibroblasts to produce MMP-2, after which the augmented migration of HEp-2 cells occurs, as observed in an invasion chamber assay with separately cultured fibroblasts. An anti-EMMPRIN function-blocking antibody reduced MMP-2 activity in the conditioned medium and inhibited the migration of HEp-2; obviously, EMMPRIN activity contributes to cancer-cell migration. We postulate that soluble EMMPRIN probably triggers the promotion of cancer invasion in vivo.     

Filter sterilization of highly infectious samples to prevent false negative analysis of matrix metalloproteinase activity

Matrix metalloproteinases (MMPs) are implicated in the immunopathology of numerous infectious diseases. High risk samples such as those generated after infection with Mycobacterium tuberculosis require filter sterilization for safe analysis of MMP concentrations. Here, we report that commercial filter membranes may cause artefacts by binding MMPs. Anopore 0.2 microM membrane filtration reduced MMP-1 concentrations to undetectable levels by zymography and Western blotting. Polypropylene 0.45 microM filtration removed some MMP-1, while Polysulphone, Durapore and Bio-inert 0.2 microM membranes did not remove MMP-1. Anopore filtration also removed all MMP-7 and -9 activity, suggesting that the conserved MMP catalytic domain binds the membrane. This study demonstrates the importance of selecting the appropriate filter in MMP analysis to avoid incorrectly excluding MMP involvement in infection-related immunopathology.     

Matrix metalloproteinase 9 (gelatinase B) is expressed in multinucleated giant cells of human giant cell tumor of bone and is associated with vascular invasion.

Human giant cell tumor (GCT) consists of multinucleated giant cells and mononuclear stromal cells, and is characterized by frequent vascular invasion without distant metastases. To study the role of matrix metalloproteinases (MMPs) in the vascular invasion, we examined production of MMP-1 (tissue collagenase), -2 (gelatinase A), -3 (stromelysin-1), -9 (gelatinase B), and tissue inhibitors of metalloproteinases (TIMP-1 and -2) in GCT. MMP-9 was highly and predominantly expressed in giant cells by both immunohistochemistry and in situ hybridization. Expression of other MMPs was also observed in some cases but was inconstant. Sandwich enzyme immunoassays demonstrated that MMP-9 is the predominant MMP secreted by GCT. There was a definite imbalance between the amounts of MMP-9 and those of TIMPs in the culture media of GCT, leading to detectable gelatinolytic activity in an assay using 14C-gelatin. Gelatin zymography demonstrated the main activity at about 90 kd, which was identified as the zymogen of MMP-9 by immunoblotting. Immunohistochemistry for type IV collagen and laminin, major basement membrane components, showed that disappearance of the proteins is closely associated with MMP-9-positive giant cells. These results indicate the production of MMP-9 by multinucleated giant cells and suggest that the metalloproteinase may contribute to proteolysis associated with vascular invasion and local bone resorption in human GCT.     

Three antigenic variant groups in human respiratory syncytial virus subgroup B isolated in Japan

Summary Nineteen hybridomas producing monoclonal antibodies (MAbs) against the structural proteins of strain 58–17, a subgroup B field strain of respiratory syncytial virus (RSV) isolated in Japan, were obtained by fusion of X 63 myeloma cells with spleen cells from BALB/c mice immunized with the virus-infected HEp-2 cells. Seven clones were found to produce antibodies against the fusion protein (F), five against the large glycoprotein (G), five against the nucleoprotein (NP) and two against the 22k protein by radioimmunoprecipitation assay. By competitive binding assay with the MAbs, at least seven, two, three and one epitopes were defined on the F, G, NP and 22k protein components of subgroup B strain, respectively. Of these epitopes, three, two and one epitopes on the F, G and NP components were different from subgroup A strain, respectively. Fifty-three other field strains of subgroup B isolated in Sapporo, Japan, during nine epidemic years from 1980 to 1989, were examined for reactivity with the MAbs by ELISA. Different reactivity to one anti-NP antibody suggested that the 53 strains can be divided into three groups (B-a: 26 strains, B-b: 26 strains, and one other strain). The dominant strain prevailing during the 1984 to 1988 epidemic years had changed from B-a to B-b. All of the 53 subgroup B strains reacted similarly with the other 18 MAbs.