title: Photothermal imaging and measurement of protein shell stoichiometry of single HIV-1 Gag virus-like nanoparticles.
abstract: Virus life stages often constitute a complex chain of events, difficult to track in vivo and in real-time. Challenges are associated with spatial and time limitations of current probes: most viruses are smaller than the diffraction limit of optical microscopes while the entire time scale of virus dynamics spans over 8 orders of magnitude. Thus, virus processes such as entry, disassembly, and egress have generally remained poorly understood. Here we discuss photothermal heterodyne imaging (PHI) as a possible alternative to fluorescence microscopy in the study of single virus-like nanoparticle (VNP) dynamics, with relevance in particular to virus uncoating. Being based on optical absorption rather than emission, PHI could potentially surpass some of the current limitations associated with fluorescent labels. As proof-of-principle, single VNPs self-assembled from 60 nm DNA-functionalized gold nanoparticles (DNA-Au NPs) encapsulated in a Gag protein shell of the human immunodeficiency virus (HIV-1) were imaged, and their photothermal response was compared with DNA-Au NPs. For the first time, the protein stoichiometry of a single virus-like particle was estimated by a method other than electron microscopy.
authors.affiliation: Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA.
authors.forename: Mario
authors.initials: M
authors.lastname: Vieweger
authors.forename: Nancy
authors.initials: N
authors.lastname: Goicochea
authors.forename: Eun Sohl
authors.initials: ES
authors.lastname: Koh
authors.forename: Bogdan
authors.initials: B
authors.lastname: Dragnea
mesh_terms: D015683:Gene Products, gag / Q000737:chemistry*; D015497:HIV-1 / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D053758:Nanoparticles
chemical_list: D015683:Gene Products, gag