title: Directed Molecular Evolution of an Engineered Gammaretroviral Envelope Protein with Dual Receptor Use Shows Stable Maintenance of Both Receptor Specificities.
abstract: We have previously reported the construction of a murine leukemia virus-based replication-competent gammaretrovirus (SL3-AP) capable of utilizing the human G protein-coupled receptor APJ (hAPJ) as its entry receptor and its natural receptor, the murine Xpr1 receptor, with equal affinities. The apelin receptor has previously been shown to function as a coreceptor for HIV-1, and thus, adaptation of the viral vector to this receptor is of significant interest. Here, we report the molecular evolution of the SL3-AP envelope protein when the virus is cultured in cells harboring either the Xpr1 or the hAPJ receptor. Interestingly, the dual receptor affinity is maintained even after 10 passages in these cells. At the same time, the chimeric viral envelope protein evolves in a distinct pattern in the apelin cassette when passaged on D17 cells expressing hAPJ in three separate molecular evolution studies. This pattern reflects selection for reduced ligand-receptor interaction and is compatible with a model in which SL3-AP has evolved not to activate hAPJ receptor internalization.
  
  
  OBJECTIVE
  Few successful examples of engineered retargeting of a retroviral vector exist. The engineered SL3-AP envelope is capable of utilizing either the murine Xpr1 or the human APJ receptor for entry. In addition, SL3-AP is the first example of an engineered retrovirus retaining its dual tropism after several rounds of passaging on cells expressing only one of its receptors. We demonstrate that the virus evolves toward reduced ligand-receptor affinity, which sheds new light on virus adaptation. We provide indirect evidence that such reduced affinity leads to reduced receptor internalization and propose a novel model in which too rapid receptor internalization may decrease virus entry.
authors.affiliation: Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark Laboratory of Central Neuropeptides in the Regulation of Body Fluid Homeostasis and Cardiovascular Functions, INSERM U1050, Paris, France.
authors.forename: Kristina Pagh
authors.initials: KP
authors.lastname: Friis
authors.affiliation: Laboratory of Central Neuropeptides in the Regulation of Body Fluid Homeostasis and Cardiovascular Functions, INSERM U1050, Paris, France Center for Interdisciplinary Research in Biology (CIRB), Collège de France, Paris, France CNRS, UMR 7241, Paris, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Iturrioz
authors.affiliation: Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.
authors.forename: Jonas
authors.initials: J
authors.lastname: Thomsen
authors.affiliation: Laboratory of Central Neuropeptides in the Regulation of Body Fluid Homeostasis and Cardiovascular Functions, INSERM U1050, Paris, France Center for Interdisciplinary Research in Biology (CIRB), Collège de France, Paris, France CNRS, UMR 7241, Paris, France.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Alvear-Perez
authors.affiliation: Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark SKAUvaccines, Aarhus, Denmark.
authors.forename: Shervin
authors.initials: S
authors.lastname: Bahrami
authors.affiliation: Laboratory of Central Neuropeptides in the Regulation of Body Fluid Homeostasis and Cardiovascular Functions, INSERM U1050, Paris, France Center for Interdisciplinary Research in Biology (CIRB), Collège de France, Paris, France CNRS, UMR 7241, Paris, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Llorens-Cortes
authors.affiliation: Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark fsp@mb.au.dk.
authors.forename: Finn Skou
authors.initials: FS
authors.lastname: Pedersen
mesh_terms: D000818:Animals; D000075244:Apelin Receptors; D002460:Cell Line; D019020:Directed Molecular Evolution; D017988:Gammaretrovirus / Q000235:genetics / Q000502:physiology*; D042822:Genomic Instability; D006801:Humans; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D011991:Receptors, Virus / Q000378:metabolism; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism*; D056189:Viral Tropism; D053586:Virus Internalization; D000089842:Xenotropic and Polytropic Retrovirus Receptor
chemical_list: C104575:APLNR protein, human; D000075244:Apelin Receptors; D043562:Receptors, G-Protein-Coupled; D011991:Receptors, Virus; D014759:Viral Envelope Proteins; C000715267:XPR1 protein, human; D000089842:Xenotropic and Polytropic Retrovirus Receptor