A Novel Gene Delivery Vector of Agonistic Anti-Radioprotective 105 Expressed on Cell Membranes Shows Adjuvant Effect for DNA Immunization Against Influenza

Front Immunol. 2020 Dec 22:11:606518. doi: 10.3389/fimmu.2020.606518. eCollection 2020.

Abstract

Radioprotective 105 (RP105) (also termed CD180) is an orphan and unconventional Toll-like receptor (TLR) that lacks an intracellular signaling domain. The agonistic anti-RP105 monoclonal antibody (mAb) can cross-link RP105 on B cells, resulting in the proliferation and activation of B cells. Anti-RP105 mAb also has a potent adjuvant effect, providing higher levels of antigen-specific antibodies compared to alum. However, adjuvanticity is required for the covalent link between anti-RP105 mAb and the antigen. This is a possible obstacle to immunization due to the link between anti-RP105 mAb and some antigens, especially multi-transmembrane proteins. We have previously succeeded in inducing rapid and potent recombinant mAbs in mice using antibody gene-based delivery. To simplify the covalent link between anti-RP105 mAb and antigens, we generated genetic constructs of recombinant anti-RP105 mAb (αRP105) bound to the transmembrane domain of the IgG-B cell receptor (TM) (αRP105-TM), which could enable the anti-RP105 mAb to link the antigen via the cell membrane. We confirmed the expression of αRP105-TM and the antigen hemagglutinin, which is a membrane protein of the influenza virus, on the same cell. We also found that αRP105-TM could activate splenic B cells, including both mature and immature cells, depending on the cell surface RP105 in vitro. To evaluate the adjuvanticity of αRP105-TM, we conducted DNA immunization in mice with the plasmids encoding αRP105-TM and hemagglutinin, followed by challenge with an infection of a lethal dose of an influenza virus. We then obtained partially but significantly hemagglutinin-specific antibodies and observed protective effects against a lethal dose of influenza virus infection. The current αRP105-TM might provide adjuvanticity for a vaccine via a simple preparation of the expression plasmids encoding αRP105-TM and of that encoding the target antigen.

Keywords: DNA immunization; RP105; adjuvant; agonistic antibody; antibody gene-vector delivery; cell membrane; influenza; targeting antigen to B cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adjuvants, Immunologic / genetics
  • Adjuvants, Immunologic / pharmacology*
  • Animals
  • Antibodies, Monoclonal / genetics
  • Antibodies, Monoclonal / immunology
  • Antibodies, Monoclonal / pharmacology*
  • Antigens, CD / genetics
  • Antigens, CD / immunology
  • Antigens, CD / metabolism*
  • Antigens, Surface / genetics
  • Antigens, Surface / metabolism
  • B-Lymphocytes / drug effects*
  • B-Lymphocytes / immunology
  • B-Lymphocytes / metabolism
  • Cell Membrane / drug effects*
  • Cell Membrane / immunology
  • Cell Membrane / metabolism
  • Cell Proliferation / drug effects
  • Coculture Techniques
  • Gene Transfer Techniques*
  • Genetic Vectors*
  • HEK293 Cells
  • Hemagglutinin Glycoproteins, Influenza Virus / genetics
  • Hemagglutinin Glycoproteins, Influenza Virus / immunology
  • Hemagglutinin Glycoproteins, Influenza Virus / pharmacology*
  • Humans
  • Hybridomas
  • Immunization
  • Influenza Vaccines / genetics
  • Influenza Vaccines / immunology
  • Influenza Vaccines / pharmacology*
  • Lymphocyte Activation / drug effects
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism
  • Mice, Inbred BALB C
  • Mice, Knockout
  • Orthomyxoviridae Infections / immunology
  • Orthomyxoviridae Infections / metabolism
  • Orthomyxoviridae Infections / prevention & control*
  • Orthomyxoviridae Infections / virology
  • Rats
  • Receptors, IgG / genetics
  • Receptors, IgG / immunology
  • Spleen / drug effects*
  • Spleen / immunology
  • Spleen / metabolism
  • Vaccines, DNA / pharmacology

Substances

  • Adjuvants, Immunologic
  • Antibodies, Monoclonal
  • Antigens, CD
  • Antigens, Surface
  • H1N1 virus hemagglutinin
  • Hemagglutinin Glycoproteins, Influenza Virus
  • Influenza Vaccines
  • Ly78 protein, mouse
  • Ly86 protein, mouse
  • Membrane Glycoproteins
  • Receptors, IgG
  • Vaccines, DNA