title: Characterization of virus-like particles in GARDASIL® by cryo transmission electron microscopy.
abstract: Cryo-transmission electron microscopy (cryoTEM) is a powerful characterization method for assessing the structural properties of biopharmaceutical nanoparticles, including Virus Like Particle-based vaccines. We demonstrate the method using the Human Papilloma Virus (HPV) VLPs in GARDASIL®. CryoTEM, coupled to automated data collection and analysis, was used to acquire images of the particles in their hydrated state, determine their morphological characteristics, and confirm the integrity of the particles when absorbed to aluminum adjuvant. In addition, we determined the three-dimensional structure of the VLPs, both alone and when interacting with neutralizing antibodies. Two modes of binding of two different neutralizing antibodies were apparent; for HPV type 11 saturated with H11.B2, 72 potential Fab binding sites were observed at the center of each capsomer, whereas for HPV 16 interacting with H16.V5, it appears that 60 pentamers (each neighboring 6 other pentamers) bind five Fabs per pentamer, for the total of 300 potential Fab binding sites per VLP.
authors.affiliation: State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics; School of Public Health; Xiamen University; Xiamen, Fujian, PR China; Bioprocess R&D; Merck Research Laboratories; West Point, PA USA.
authors.forename: Qinjian
authors.initials: Q
authors.lastname: Zhao
authors.affiliation: NanoImaging Services, Inc.; San Diego, CA USA; Department of Integrative Structural and Computational Biology; The Scripps Research Institute; La Jolla, CA USA.
authors.forename: Clinton S
authors.initials: CS
authors.lastname: Potter
authors.affiliation: NanoImaging Services, Inc.; San Diego, CA USA; Department of Integrative Structural and Computational Biology; The Scripps Research Institute; La Jolla, CA USA.
authors.forename: Bridget
authors.initials: B
authors.lastname: Carragher
authors.affiliation: Department of Integrative Structural and Computational Biology; The Scripps Research Institute; La Jolla, CA USA.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Lander
authors.affiliation: Bioprocess R&D; Merck Research Laboratories; West Point, PA USA.
authors.forename: Jaime
authors.initials: J
authors.lastname: Sworen
authors.affiliation: Vaccine Manufacturing Science and Commercialization; Merck Manufacturing Division; West Point, PA USA.
authors.forename: Victoria
authors.initials: V
authors.lastname: Towne
authors.affiliation: Vaccine Manufacturing Science and Commercialization; Merck Manufacturing Division; West Point, PA USA.
authors.forename: Dicky
authors.initials: D
authors.lastname: Abraham
authors.affiliation: Bioprocess R&D; Merck Research Laboratories; West Point, PA USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Duncan
authors.affiliation: Bioprocess R&D; Merck Research Laboratories; West Point, PA USA.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Washabaugh
authors.affiliation: Vaccine Manufacturing Science and Commercialization; Merck Manufacturing Division; West Point, PA USA.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Sitrin
mesh_terms: D057134:Antibodies, Neutralizing / Q000378:metabolism; D000914:Antibodies, Viral / Q000378:metabolism; D020285:Cryoelectron Microscopy; D000068857:Human Papillomavirus Recombinant Vaccine Quadrivalent, Types 6, 11, 16, 18; D006801:Humans; D053758:Nanoparticles / Q000648:ultrastructure*; D053918:Papillomavirus Vaccines; D011485:Protein Binding; D058425:Vaccines, Virus-Like Particle / Q000648:ultrastructure*; D015678:Viral Structural Proteins / Q000378:metabolism
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D000068857:Human Papillomavirus Recombinant Vaccine Quadrivalent, Types 6, 11, 16, 18; D053918:Papillomavirus Vaccines; D058425:Vaccines, Virus-Like Particle; D015678:Viral Structural Proteins
keywords: CryoTEM; Gardasil; VLP; adjuvant; aluminum; epitope; structure