title: Probing sequence variation in the receptor-targeting domain of feline leukemia virus envelope proteins with peptide display libraries.
abstract: Determinants of cellular tropism and receptor targeting lie within a short peptide in the Vr1 region of the envelope (Env) proteins of feline leukemia virus (FeLV) subgroups A and C. Libraries of FeLV Env proteins with random amino acid substitutions in the peptide were screened for their ability to deliver a marker gene to D17 and AH927 cells. Screening on D17 canine cells yielded D17-specific Env proteins that used the FeLV-C receptor. Screening on AH927 cells yielded Env proteins with a broader host range, with maximal titers on AH927 cells and similar or lower titers on other cells. These Env proteins used an unidentified non-FeLV receptor for entry. The A5 isolate obtained from the AH927 screen was readily concentrated to yield titers of 10(5) on human PC-3 prostate tumor cells. The sequence divergence observed among targeting peptides of library-selected Env proteins was greater than that found in parental FeLV isolates. Substitution analyses of a conserved R in the middle of the targeting peptide held constant during screening indicated that maximal titers were obtained only when R was present in both a D17 selected isolate and an AH927 selected isolate. The ability to isolate Env proteins with unique tropisms dependent on the cells on which the library is screened has direct implications for targeting gene delivery vectors.
authors.affiliation: Department of Biochemistry, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, 675 Hoes Lane, Piscataway, NJ 08854, USA. buppka@umdnj.edu
authors.forename: Keith
authors.initials: K
authors.lastname: Bupp
authors.forename: Anindita
authors.initials: A
authors.lastname: Sarangi
authors.forename: Monica J
authors.initials: MJ
authors.lastname: Roth
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D002415:Cats; D002460:Cell Line; D004285:Dogs; D015686:Gene Products, env / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014644:Genetic Variation; D006801:Humans; D005256:Leukemia Virus, Feline / Q000472:pathogenicity*; D008969:Molecular Sequence Data; D019151:Peptide Library; D011991:Receptors, Virus / Q000378:metabolism*
chemical_list: D015686:Gene Products, env; D019151:Peptide Library; D011991:Receptors, Virus