title: Characterization of an oncolytic herpes simplex virus drug candidate.
abstract: The structural integrity and conformational stability of a genetically modified live, oncolytic herpes simplex virus (o-HSV) were investigated across a wide pH (5.5-8.0) and temperature (10°C-87.5°C) range. A combination of circular dichroism, intrinsic and extrinsic fluorescence, and static light scattering results was visualized using an empirical phase diagram approach to provide a global assessment of physical stability. Distinct phases were identified including the native state of the virus, an intermediate phase that could represent gradual swelling and/or shedding of the viral envelope, and a highly disrupted, aggregated phase. The nature of these altered forms of the virus was further evaluated by transmission electron microscopy and viral plaque assays. The effect of freeze-thaw (F/T) stress on o-HSV was also examined. After one F/T cycle, a loss of infectious virus titers was observed. In addition, the monomeric virus particle concentration decreased during F/T stress, whereas there was a concurrent increase in larger particles (2-10 μm). The comprehensive biophysical characterization of viral stability conducted in this study identified major degradation events leading to loss of infectivity of o-HSV and represents an important step toward stabilization of the virus against thermal and F/T stresses.
authors.affiliation: Department of Pharmaceutical Chemistry, Macromolecule and Vaccine Stabilization Center, University of Kansas, Lawrence, Kansas, 66047.
authors.forename: Ozan S
authors.initials: OS
authors.lastname: Kumru
authors.forename: Sangeeta B
authors.initials: SB
authors.lastname: Joshi
authors.forename: Prem
authors.initials: P
authors.lastname: Thapa
authors.forename: Nigel
authors.initials: N
authors.lastname: Pheasey
authors.forename: Paul S
authors.initials: PS
authors.lastname: Bullock
authors.forename: Houman
authors.initials: H
authors.lastname: Bashiri
authors.forename: Christine S
authors.initials: CS
authors.lastname: Siska
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Kerwin
authors.forename: Feng
authors.initials: F
authors.lastname: He
authors.forename: David B
authors.initials: DB
authors.lastname: Volkin
authors.forename: C Russell
authors.initials: CR
authors.lastname: Middaugh
mesh_terms: D002942:Circular Dichroism; D006863:Hydrogen-Ion Concentration; D009369:Neoplasms / Q000628:therapy*; D050130:Oncolytic Virotherapy; D012542:Scattering, Radiation; D018139:Simplexvirus / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure; D013696:Temperature
keywords: biotechnology; cancer; formulation; particle size; phase diagram; physical stability; preformulation; viral vectors