Exploring nucleic acid condensation and release from individual parvovirus particles with different physicochemical cues

In the infection cycle, viruses release their genome in the host cell during uncoating. Here we use a variety of physicochemical procedures to induce and monitor the in vitro uncoating of ssDNA from individual Minute Virus of Mice (MVM) particles. Our experiments revealed two pathways of genome release: i) filamentous ssDNA appearing around intact virus particles when using gradual mechanical fatigue and heating at moderate tem-perature (50 degrees C). ii) thick structures of condensed ssDNA appearing when the virus particle is disrupted by mechanical nanoindentations, denaturing agent guanidinium chloride and high temperature (70 degrees C). We propose that in the case of filamentous ssDNA, when the capsid integrity is conserved, the genome is externalized through one channel of the capsid pores. However, the disruption of virus particles revealed a native structure of condensed genome. The mechanical analysis of intact particles after DNA strands ejection confirm the stabili-zation role of ssDNA in MVM.

Automated summary

In the infection cycle of viruses, the release of their genome in the host cell occurs during uncoating. Through various physicochemical procedures, we induce and monitor the in vitro uncoating of ssDNA from individual MVM particles. Our experiments reveal two pathways of genome release: i) filamentous ssDNA appears around intact virus particles with gradual mechanical fatigue and moderate heating (50 degrees C). ii) condensed ssDNA structures appear when the virus particles are disrupted by mechanical nanoindentations, guanidinium chloride denaturing agent, and high temperature (70 degrees C). It is proposed that filamentous ssDNA is externalized through one channel of the capsid pores when the capsid integrity is conserved. However, the disruption of virus particles reveals a native structure of condensed genome. Mechanical analysis confirms the stabilization role of ssDNA in MVM after DNA strands ejection.