Single-Molecule Analysis of Genome Uncoating from Individual Human Rhinovirus Particles, and Modulation by Antiviral Drugs

Infection of humans by many viruses is typically initiated by the internalization of a single virion in each of a few susceptible cells. Thus, the outcome of the infection process may depend on stochastic single-molecule events. A crucial process for viral infection, and thus a target for developing antiviral drugs, is the uncoating of the viral genome. Here a force spectroscopy procedure using an atomic force microscope is implemented to study uncoating for individual human rhinovirus particles. Application of an increasing mechanical force on a virion led to a high force-induced structural transition that facilitated extrusion of the viral RNA molecule without loss of capsid integrity. Application of force to virions that h ad previously extruded the RNA, or to RNA-free capsids, led to a lower force-induced event associated with capsid disruption. The kinetic parameters are determined for each reaction. The high-force event is a stochastic process governed by a moderate free energy barrier (approximate to 20 kcal mol-1), which results in a heterogeneous population of structurally weakened virions in which different fractions of the RNA molecule are externalized. The effects of antiviral compounds or capsid mutation on the kinetics of this reaction reveal a correlation between the reaction rate and virus infectivity. The exit of the genomic RNA molecule from the common cold virus is analyzed by the application of an increasing mechanical force on individual virus particles. The results reveal a stochastic process that resulted in a heterogeneous population of weakened virus particles in which the RNA molecule w as extruded to different extents. Compounds that inhibit this process impair viral infection.image

Automated summary

This study investigates the uncoating process of human rhinovirus particles using an atomic force microscope. The results show that the high-force event is a stochastic process that leads to structurally weakened virus particles, with different fractions of the RNA molecule being externalized. The kinetics of this reaction are influenced by antiviral compounds or capsid mutation.