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           Search results for: Hepatitis A Virus antibody, Monoclonal Antibodies, Host Mouse, Isotype IgG1   

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#25628391   2015/02/25 Save this To Up

Discovery of anti-claudin-1 antibodies as candidate therapeutics against hepatitis C virus.

Claudin-1 (CLDN1), a known host factor for hepatitis C virus (HCV) entry and cell-to-cell transmission, is a target molecule for inhibiting HCV infection. We previously developed four clones of mouse anti-CLDN1 monoclonal antibody (mAb) that prevented HCV infection in vitro. Two of these mAbs showed the highest antiviral activity. Here, we optimized the anti-CLDN1 mAbs as candidates for therapeutics by protein engineering. Although Fab fragments of the mAbs prevented in vitro HCV infection, their inhibitory effects were much weaker than those of the whole mAbs. In contrast, human chimeric IgG1 mAbs generated by grafting the variable domains of the mouse mAb light and heavy chains inhibited in vitro HCV infection as efficiently as the parental mouse mAbs. However, the chimeric IgG1 mAbs activated Fcγ receptor, suggesting that cytotoxicity against mAb-bound CLDN1-expressing cells occurred through the induction of antibody-dependent cellular cytotoxicity (ADCC). To avoid ADCC-induced side effects, we prepared human chimeric IgG4 mAbs. The chimeric IgG4 mAbs did not activate Fcγ receptor or induce ADCC, but they prevented in vitro HCV infection as efficiently as did the parental mouse mAbs. These findings indicate that the IgG4 form of human chimeric anti-CLDN1 mAb may be a candidate molecule for clinically applicable HCV therapy.

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#19805910   2009/11/03 Save this To Up

Adoptive immunotherapy with liver allograft-derived lymphocytes induces anti-HCV activity after liver transplantation in humans and humanized mice.

After liver transplantation in HCV-infected patients, the virus load inevitably exceeds pre-transplantation levels. This phenomenon reflects suppression of the host-effector immune responses that control HCV replication by the immunosuppressive drugs used to prevent rejection of the transplanted liver. Here, we describe an adoptive immunotherapy approach, using lymphocytes extracted from liver allograft perfusate (termed herein liver allograft-derived lymphocytes), which includes an abundance of NK/NKT cells that mounted an anti-HCV response in HCV-infected liver transplantation recipients, despite the immunosuppressive environment. This therapy involved intravenously injecting patients 3 days after liver transplantation with liver allograft-derived lymphocytes treated with IL-2 and the CD3-specific mAb OKT3. During the first month after liver transplantation, the HCV RNA titers in the sera of recipients who received immunotherapy were markedly lower than those in the sera of recipients who did not receive immunotherapy. We further explored these observations in human hepatocyte-chimeric mice, in which mouse hepatocytes were replaced by human hepatocytes. These mice unfailingly developed HCV infections after inoculation with HCV-infected human serum. However, injection of human liver-derived lymphocytes treated with IL-2/OKT3 completely prevented HCV infection. Furthermore, an in vitro study using genomic HCV replicon-containing hepatic cells revealed that IFN-gamma-secreting cells played a pivotal role in such anti-HCV responses. Thus, our study presents what we believe to be a novel paradigm for the inhibition of HCV replication in HCV-infected liver transplantation recipients.

1156 related Products with: Adoptive immunotherapy with liver allograft-derived lymphocytes induces anti-HCV activity after liver transplantation in humans and humanized mice.

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#2158698   1990/05/25 Save this To Up

Immunoglobulin Fc binding activity is associated with the mouse hepatitis virus E2 peplomer protein.

Antigenic variation among murine coronaviruses is associated primarily with the surface peplomer protein E2 (180,000 Da). E2 is responsible for attachment of the virus to the host cell, MHV-induced cell fusion, and eliciting neutralizing antibody. We report here the molecular mimicry between E2 and Fc gamma receptor (Fc gamma R). Molecular mimicry between E2 and Fc gamma R may allow the escape of virus-infected cells from destruction by immunological mechanisms. Rabbit IgG, monoclonal rat IgG1 and IgG2b, monoclonal mouse IgG2a and IgG2b, and the rat anti-mouse Fc gamma R monoclonal antibody 2.4G2 immunoprecipitated from MHV-JHM-infected cells a polypeptide with a molecular mass identical to that immunoprecipitated by anti-E2 antibodies. F(ab')2 fragments of rabbit IgG did not immunoprecipitate any proteins from MHV-infected cells. All of these antibodies did not immunoprecipitate any proteins from uninfected cells. The anti-mouse Fc gamma R monoclonal antibody 2.4G2 immunoprecipitated from MHV-JHM-, MHV-3-, or MHV-A59-infected L-2 cells and 17CL-1 cells, or MHV-JHM-infected cultures of neonatal BALB/c brain cells, a protein with a molecular weight identical to that of MHV-JHM E2. The anti-Fc gamma R monoclonal antibody did not immunoprecipitate any proteins from uninfected cells. Furthermore, the 2.4G2 monoclonal antibody (mab), unrelated rat and mouse monoclonal antibodies, and a goat antiserum against E2, but not normal goat serum, immunoprecipitated a 75,000- to 77,000-Da molecule from uninfected WEHI-3 cells, a Fc gamma R bearing cell line. Several lines of evidence demonstrated that the protein immunoprecipitated by the anti-Fc gamma R mab from MHV-JHM-infected cells is the E2 glycoprotein: (1) Partial proteolytic maps obtained by Staphylococcus aureus V-8 protease treatment of the 180,000-Da proteins immunoprecipitated by the anti Fc gamma R mab and the anti-E2 mab were identical. (2) Sequential immunoprecipitation experiments from MHV-JHM-infected cells revealed that the same polypeptide chain was recognized by the anti-E2 mab and by the anti-Fc gamma R mab 2.4G2, (3) Actinomycin D did not influence the induction and expression of the 180,000-Da polypeptide chain that was immunoprecipitated by the anti-Fc gamma R mab, demonstrating that this protein is of viral origin.

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