Vaccination with a fusion protein that introduces HIV-1 gag antigen into a multitrimer CD40L construct results in enhanced CD8+ T cell responses and protection from viral challenge by vaccinia-gag

J Virol. 2014 Feb;88(3):1492-501. doi: 10.1128/JVI.02229-13. Epub 2013 Nov 13.


CD40 ligand (CD40L, CD154) is a membrane protein that is important for the activation of dendritic cells (DCs) and DC-induced CD8(+) T cell responses. To be active, CD40L must cluster CD40 receptors on responding cells. To produce a soluble form of CD40L that clusters CD40 receptors necessitates the use of a multitrimer construct. With this in mind, a tripartite fusion protein was made from surfactant protein D (SPD), HIV-1 Gag as a test antigen, and CD40L, where SPD serves as a scaffold for the multitrimer protein complex. This SPD-Gag-CD40L protein activated CD40-bearing cells and bone marrow-derived DCs in vitro. Compared to a plasmid for Gag antigen alone (pGag), DNA vaccination of mice with pSPD-Gag-CD40L induced an increased number of Gag-specific CD8(+) T cells with increased avidity for major histocompatibility complex class I-restricted Gag peptide and improved vaccine-induced protection from challenge by vaccinia-Gag virus. The importance of the multitrimeric nature of the complex was shown using a plasmid lacking the N terminus of SPD that produced a single trimer fusion protein. This plasmid, pTrimer-Gag-CD40L, was only weakly active on CD40-bearing cells and did not elicit strong CD8(+) T cell responses or improve protection from vaccinia-Gag challenge. An adenovirus 5 (Ad5) vaccine incorporating SPD-Gag-CD40L was much stronger than Ad5 expressing Gag alone (Ad5-Gag) and induced complete protection (i.e., sterilizing immunity) from vaccinia-Gag challenge. Overall, these results show the potential of a new vaccine design in which antigen is introduced into a construct that expresses a multitrimer soluble form of CD40L, leading to strongly protective CD8(+) T cell responses.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • AIDS Vaccines / administration & dosage
  • AIDS Vaccines / genetics
  • AIDS Vaccines / immunology*
  • Animals
  • Antigens, Viral / administration & dosage
  • Antigens, Viral / genetics
  • Antigens, Viral / immunology
  • CD40 Ligand / administration & dosage
  • CD40 Ligand / chemistry
  • CD40 Ligand / genetics
  • CD40 Ligand / immunology*
  • CD8-Positive T-Lymphocytes / immunology*
  • CD8-Positive T-Lymphocytes / virology
  • Female
  • Gene Products, gag / genetics
  • Gene Products, gag / immunology*
  • HIV Infections / immunology
  • HIV Infections / prevention & control*
  • HIV Infections / virology
  • HIV-1 / genetics
  • HIV-1 / immunology*
  • Humans
  • Mice
  • Mice, Inbred C57BL
  • Recombinant Fusion Proteins / administration & dosage
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / immunology
  • Vaccination
  • Vaccinia / genetics
  • Vaccinia / immunology
  • Vaccinia virus / genetics
  • Vaccinia virus / immunology
  • gag Gene Products, Human Immunodeficiency Virus / administration & dosage
  • gag Gene Products, Human Immunodeficiency Virus / genetics
  • gag Gene Products, Human Immunodeficiency Virus / immunology*


  • AIDS Vaccines
  • Antigens, Viral
  • Gene Products, gag
  • Recombinant Fusion Proteins
  • gag Gene Products, Human Immunodeficiency Virus
  • CD40 Ligand