title: A stabilized HIV-1 envelope glycoprotein trimer fused to CD40 ligand targets and activates dendritic cells.
abstract: BACKGROUND
  One reason why subunit protein and DNA vaccines are often less immunogenic than live-attenuated and whole-inactivated virus vaccines is that they lack the co-stimulatory signals provided by various components of the more complex vaccines. The HIV-1 envelope glycoprotein complex (Env) is no exception to this rule. Other factors that limit the induction of neutralizing antibodies against HIV-1 lie in the structure and instability of Env. We have previously stabilized soluble trimeric mimics of Env by introducing a disulfide bond between gp120 and gp41 and adding a trimer stabilizing mutation in gp41 (SOSIP.R6 gp140).
  
  
  RESULTS
  We further stabilized the SOSIP.R6 gp140 using a GCN4-based isoleucine zipper motif, creating SOSIP.R6-IZ gp140. In order to target SOSIP.R6-IZ to immune cells, including dendritic cells, while at the same time activating these cells, we fused SOSIP.R6-IZ to the active domain of CD40 ligand (CD40L), which may serve as a 'cis-adjuvant'. The Env component of the SOSIP.R6-IZ-CD40L fusion construct bound to CD4 and neutralizing antibodies, while the CD40L moiety interacted with CD40. Furthermore, the chimeric molecule was able to signal efficiently through CD40 and induce maturation of human dendritic cells. Dendritic cells secreted IL-6, IL-10 and IL-12 in response to stimulation by SOSIP.R6-IZ-CD40L and were able to activate naïve T cells.
  
  
  CONCLUSIONS
  Chimeric HIV-1 gp140 - CD40L trimers can target and activate dendritic cells. Targeting and activating immune cells using CD40L and other 'cis-adjuvants' may improve subunit protein vaccine immunogenicity for HIV-1 and other infectious diseases.
authors.affiliation: Laboratory of Experimental Virology, Department of Medical Microbiology Center for Infection and Immunity Amsterdam, Netherlands.
authors.forename: Mark
authors.initials: M
authors.lastname: Melchers
authors.forename: Katie
authors.initials: K
authors.lastname: Matthews
authors.forename: Robert P
authors.initials: RP
authors.lastname: de Vries
authors.forename: Dirk
authors.initials: D
authors.lastname: Eggink
authors.forename: Thijs
authors.initials: T
authors.lastname: van Montfort
authors.forename: Ilja
authors.initials: I
authors.lastname: Bontjer
authors.forename: Carolien
authors.initials: C
authors.lastname: van de Sandt
authors.forename: Kathryn
authors.initials: K
authors.lastname: David
authors.forename: Ben
authors.initials: B
authors.lastname: Berkhout
authors.forename: John P
authors.initials: JP
authors.lastname: Moore
authors.forename: Rogier W
authors.initials: RW
authors.lastname: Sanders
mesh_terms: D023201:CD40 Ligand / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology* / Q000378:metabolism*; D015497:HIV-1 / Q000235:genetics / Q000276:immunology*; D006801:Humans; D055550:Protein Stability; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D054299:env Gene Products, Human Immunodeficiency Virus / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*
chemical_list: D016207:Cytokines; D011993:Recombinant Fusion Proteins; D054299:env Gene Products, Human Immunodeficiency Virus; D023201:CD40 Ligand