title: Design and In Vivo Characterization of Immunoconjugates Targeting HIV gp160.
abstract: The envelope (Env) glycoprotein of HIV is expressed on the surface of productively infected cells and can be used as a target for cytotoxic immunoconjugates (ICs), in which cell-killing moieties, including toxins, drugs, or radionuclides, are chemically or genetically linked to monoclonal antibodies (MAbs) or other targeting ligands. Such ICs could be used to eliminate persistent reservoirs of HIV infection. We have found that MAbs which bind to the external loop of gp41, e.g., MAb 7B2, make highly effective ICs, particularly when used in combination with soluble CD4. We evaluated the toxicity, immunogenicity, and efficacy of the ICs targeted with 7B2 in mice and in simian-human immunodeficiency virus-infected macaques. In the macaques, we tested immunotoxins (ITs), consisting of protein toxins bound to the targeting agent. ITs were well tolerated and initially efficacious but were ultimately limited by their immunogenicity. In an effort to decrease immunogenicity, we tested different toxic moieties, including recombinant toxins, cytotoxic drugs, and tubulin inhibitors. ICs containing deglycosylated ricin A chain prepared from ricin toxin extracted from castor beans were the most effective in killing HIV-infected cells. Having identified immunogenicity as a major concern, we show that conjugation of IT to polyethylene glycol limits immunogenicity. These studies demonstrate that cytotoxic ICs can target virus-infected cells in vivo but also highlight potential problems to be addressed.
  
  
  OBJECTIVE
  It is not yet possible to cure HIV infection. Even after years of fully effective antiviral therapy, a persistent reservoir of virus-infected cells remains. Here we propose that a targeted conjugate consisting of an anti-HIV antibody bound to a toxic moiety could function to kill the HIV-infected cells that constitute this reservoir. We tested this approach in HIV-infected cells grown in the lab and in animal infections. Our studies demonstrated that these immunoconjugates are effective both in vitro and in test animals. In particular, ITs constructed with the deglycosylated A chain prepared from native ricin were the most effective in killing cells, but their utility was blunted because they provoked immune reactions that interfered with the therapeutic effects. We then demonstrated that coating of the ITs with polyethylene glycol minimized the immunogenicity, as has been demonstrated with other protein therapies.
authors: Research Institute for Children, Children's Hospital, New Orleans, Louisiana, USA spincu@lsuhsc.edu.|Department of Pediatrics and Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA.
authors: Seth H
authors: SH
authors: Pincus
authors: Research Institute for Children, Children's Hospital, New Orleans, Louisiana, USA.
authors: Kejing
authors: K
authors: Song
authors: Research Institute for Children, Children's Hospital, New Orleans, Louisiana, USA.
authors: Grace A
authors: GA
authors: Maresh
authors: Research Institute for Children, Children's Hospital, New Orleans, Louisiana, USA.
authors: Anderson
authors: A
authors: Frank
authors: Department of Pediatrics and Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA.
authors: David
authors: D
authors: Worthylake
authors: Advanced Biosciences Laboratories, Inc., Rockville, Maryland, USA.
authors: Hye-Kyung
authors: HK
authors: Chung
authors: Washington National Primate Research Center, University of Washington, Seattle, Washington, USA.
authors: Patricia
authors: P
authors: Polacino
authors: Laboratory of Biochemistry, Center for Cancer Research, NCI, Bethesda, Maryland, USA.
authors: Dean H
authors: DH
authors: Hamer
authors: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, USA.
authors: Cody P
authors: CP
authors: Coyne
authors: Department of Experimental Therapeutics, M. D. Anderson Cancer Center, Houston, Texas, USA.
authors: Michael G
authors: MG
authors: Rosenblum
authors: Department of Experimental Therapeutics, M. D. Anderson Cancer Center, Houston, Texas, USA.
authors: John W
authors: JW
authors: Marks
authors: Concortis Biosystems, San Diego, California, USA.
authors: Gang
authors: G
authors: Chen
authors: Advanced Biosciences Laboratories, Inc., Rockville, Maryland, USA.
authors: Deborah
authors: D
authors: Weiss
authors: Departments of Immunology and Microbiology, UT Southwestern Medical Center, Dallas, Texas, USA.
authors: Victor
authors: V
authors: Ghetie
authors: Departments of Immunology and Microbiology, UT Southwestern Medical Center, Dallas, Texas, USA.
authors: Ellen S
authors: ES
authors: Vitetta
authors: Department of Pediatrics, Tulane University School of Medicine, New Orleans, Louisiana, USA.
authors: James E
authors: JE
authors: Robinson
authors: Washington National Primate Research Center, University of Washington, Seattle, Washington, USA.
authors: Shiu-Lok
authors: SL
authors: Hu
mesh_terms: D000818:Animals; D019380:Anti-HIV Agents / Q000737:chemistry / Q000494:pharmacology*; D000911:Antibodies, Monoclonal / Q000276:immunology; D002478:Cells, Cultured; D004195:Disease Models, Animal; D015195:Drug Design; D019302:HIV Envelope Protein gp160 / Q000037:antagonists & inhibitors* / Q000276:immunology; D015658:HIV Infections / Q000188:drug therapy / Q000821:virology; D015497:HIV-1 / Q000187:drug effects; D006801:Humans; D018796:Immunoconjugates / Q000737:chemistry / Q000494:pharmacology*; D000922:Immunotoxins / Q000494:pharmacology; D008254:Macaca nemestrina; D051379:Mice; D011092:Polyethylene Glycols / Q000737:chemistry
chemical_list: D019380:Anti-HIV Agents; D000911:Antibodies, Monoclonal; D019302:HIV Envelope Protein gp160; D018796:Immunoconjugates; D000922:Immunotoxins; D011092:Polyethylene Glycols
keywords: antibody drug conjugate; human immunodeficiency virus; immunoglobulins; immunotoxins; monoclonal antibodies