title: Effects of cell-penetrating peptides on transduction efficiency of PEGylated adenovirus.
abstract: BACKGROUND
  Adenovirus (Ad) is one of the viral vectors most widely used for gene delivery. The virus, however, has serious shortcomings such as immunogenicity, promiscuous tropism, and the inability to efficiently infect certain types of cells. The goal of this study was to improve the ability of an Ad-based vector to efficiently transform cells that lack the native coxsackie-adenovirus receptor (CAR(-)) by modifying the virus with CPP-PEG conjugates.
  
  
  METHODS
  The vector was produced by PEGylating Ad, which packages a lacZ reporter gene, and then conjugating CPPs to form CPP-PEG-Ad particles. The study compared the effectiveness of four different CPPs: Pen, Tat, Pep1, and pArg. The effects of CPP amount per virus, degree of PEGylation, and PEG molecular weight on transduction efficiency were studied on CAR(-) NIH/3T3 cells.
  
  
  RESULTS
  CPP-PEG-Ad particles transduced CAR(-) cells significantly better than unmodified Ad. Pen, the most effective CPP, produced an 80-fold improvement in transduction compared to the unmodified virus. The Pen peptide utilized a combination of electrostatic and hydrophobic interactions with the cell membrane to maximize cellular association while the other CPPs used only electrostatic or hydrophobic interactions but not both. Lastly, higher degrees of PEGylation, which prompted PEG to adopt a "brush" conformation, resulted in more efficient CPP-PEG-Ad particles because of both better conjugation of CPPs to the PEGylated virus and better exposure of the conjugated CPPs on the surface of the particle.
  
  
  CONCLUSIONS
  CPP-PEG-Ad particles efficiently deliver genes to cells that Ad alone would not efficiently infect, thereby extending potential gene therapy treatments to a much broader range of cell types and diseases.
authors.affiliation: School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078, USA.
authors.forename: Adane S
authors.initials: AS
authors.lastname: Nigatu
authors.affiliation: School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078, USA.
authors.forename: Sravanthi
authors.initials: S
authors.lastname: Vupputuri
authors.affiliation: School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078, USA.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Flynn
authors.affiliation: School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078, USA. Electronic address: josh.ramsey@okstate.edu.
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Ramsey
mesh_terms: D000256:Adenoviridae / Q000187:drug effects / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D057846:Cell-Penetrating Peptides / Q000737:chemistry / Q000494:pharmacology*; D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D041681:NIH 3T3 Cells; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry*; D055672:Static Electricity; D013499:Surface Properties; D014161:Transduction, Genetic
chemical_list: D057846:Cell-Penetrating Peptides; D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein; D011092:Polyethylene Glycols
keywords: Adenovirus; Cell-penetrating peptides; Coxsackie virus and adenovirus receptor; Gene vector; PEGylation