title: Polymers for the stabilization and delivery of proteins topically and per os to the insect hemocoel through conjugation with aliphatic polyethylene glycol.
abstract: Co-feeding of aliphatic polyethylene glycol (PEG), phospholipase A2, anionic and ionic detergents, and amphipathic glycoside with bovine serum albumin (BSA) as a model protein to fourth stadium tobacco budworms, Heliothis virescens, did not affect the levels of BSA in the hemolymph. Covalent conjugation of small proteins like the decapeptide trypsin modulating oostatic factor (TMOF) to polyethylene glycol was previously shown to protect the peptide from protease attack and enhance its accumulation in the insect hemocoel. Whether this polymer chemistry could do the same for larger proteins was examined. The chemistry for the synthesis of polydispersed aliphatic PEG350-insulin and monodispersed aliphatic PEG333-insulin are described herein. Insulin was used for this synthesis and not BSA to better control conjugation among the available free amine groups. When PEGylated insulin or free insulin were fed in artificial diet to fifth stadium budworms, greater concentrations of insulin using the PEGylated variants were found in the hemolymph than when free insulin was used (a 6.7 and 7.3-fold increase for the PEG350 and PEG333 conjugates, respectively). When insulin is topically applied to the dorsum of H. virescens, no insulin is found in the hemolymph. However, after topical application of the PEGylated insulins, PEG350-insulin and PEG333-insulin were detected in the hemolymph. After injections of insulin into the hemocoel of fourth stadium H. virescens, insulin is completely cleared from the hemolymph in 120min. In comparison, PEG350-insulin and PEG333-insulin were present in the hemolymph for 300 and 240min after injection, respectively, translating to a 3.3 and 2.7-fold increase in the length of time insulin remains in the hemolymph after injection.
authors.affiliation: Department of Entomology, Campus Box 7647, North Carolina State University, Raleigh, NC 27695-7647, USA.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Jeffers
authors.affiliation: Department of Entomology, Campus Box 7647, North Carolina State University, Raleigh, NC 27695-7647, USA; Department of Chemistry, Campus Box 8204, North Carolina State University, Raleigh, NC 27695-8204, USA.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Shen
authors.affiliation: Department of Entomology, Campus Box 7647, North Carolina State University, Raleigh, NC 27695-7647, USA; TyraTech, Inc., 5151 McCrimmon Pkwy, Suite 275, Morrisville, NC 27560, USA.
authors.forename: Brooke W
authors.initials: BW
authors.lastname: Bissinger
authors.affiliation: Department of Entomology, Campus Box 7647, North Carolina State University, Raleigh, NC 27695-7647, USA; Agricultural Genetic Engineering Research Institute (AGERI), 9 Gamaa Street, Giza, Egypt.
authors.forename: Sayed
authors.initials: S
authors.lastname: Khalil
authors.affiliation: Department of Chemistry, Campus Box 8204, North Carolina State University, Raleigh, NC 27695-8204, USA; Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA.
authors.forename: T Brent
authors.initials: TB
authors.lastname: Gunnoe
authors.affiliation: Department of Entomology, Campus Box 7647, North Carolina State University, Raleigh, NC 27695-7647, USA. Electronic address: michael_roe@ncsu.edu.
authors.forename: R Michael
authors.initials: RM
authors.lastname: Roe
mesh_terms: D000818:Animals; D002417:Cattle; D016503:Drug Delivery Systems / Q000379:methods*; D006458:Hemolymph / Q000378:metabolism; D007328:Insulin / Q000737:chemistry / Q000378:metabolism*; D007814:Larva / Q000254:growth & development / Q000378:metabolism; D009036:Moths / Q000254:growth & development* / Q000378:metabolism*; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry / Q000378:metabolism*; D055550:Protein Stability; D012710:Serum Albumin, Bovine / Q000737:chemistry / Q000378:metabolism
chemical_list: D007328:Insulin; D011108:Polymers; D012710:Serum Albumin, Bovine; D011092:Polyethylene Glycols
keywords: Heliothis virescens; Insulin; PEGylation; Polyethylene glycol; Protein delivery; Tobacco budworm