Temperature-induced DNA density transition in phage λ capsid revealed with contrast-matching SANS.

Structural details of a genome packaged in a viral capsid are essential for understanding how the structural arrangement of a viral genome in a capsid controls its release dynamics during infection, which critically affects viral replication. We previously found a temperature-induced, solid-like to fluid-like mechanical transition of packaged λ-genome that leads to rapid DNA ejection. However, an understanding of the structural origin of this transition was lacking.

'SAXS-osmometer' method provides measurement of DNA pressure in viral capsids and delivers an empirical equation of state.

We present a novel method that provides a measurement of DNA pressure in viral capsids using small angle X-ray scattering (SAXS). This method, unlike our previous assay, does not require triggering genome release with a viral receptor. Thus, it can be used to determine the existence of a pressurized genome state in a wide range of virus systems, even if the receptor is not known, leading to a better understanding of the processes of viral genome uncoating and encapsidation in the course of infection.

Intranuclear HSV-1 DNA ejection induces major mechanical transformations suggesting mechanoprotection of nucleus integrity.

Maintaining nuclear integrity is essential to cell survival when exposed to mechanical stress. Herpesviruses, like most DNA and some RNA viruses, put strain on the nuclear envelope as hundreds of viral DNA genomes replicate and viral capsids assemble. It remained unknown, however, how nuclear mechanics is affected at the initial stage of herpesvirus infection-immediately after viral genomes are ejected into the nuclear space-and how nucleus integrity is maintained despite an increased strain on the nuclear envelope.

Role of HSV-1 Capsid Vertex-Specific Component (CVSC) and Viral Terminal DNA in Capsid Docking at the Nuclear Pore.

Penetration of the viral genome into a host cell nucleus is critical for initiation of viral replication for most DNA viruses and a few RNA viruses. For herpesviruses, viral DNA ejection into a nucleus occurs when the capsid docks at the nuclear pore complex (NPC) basket with the correct orientation of the unique capsid portal vertex. It has been shown that capsid vertex-specific component (CVSC) proteins, which are located at the twelve vertices of the human herpes simplex virus type 1 (HSV-1) capsid, interact with nucleoporins (Nups) of NPCs.

Reconstituted virus-nucleus system reveals mechanics of herpesvirus genome uncoating.

The viral replication cycle is controlled by information transduced through both molecular and mechanical interactions. Viral infection mechanics remains largely unexplored, however, due to the complexity of cellular mechanical responses over the course of infection as well as a limited ability to isolate and probe these responses. Here, we develop an experimental system consisting of herpes simplex virus type 1 (HSV-1) capsids bound to isolated and reconstituted cell nuclei, which allows direct probing of capsid-nucleus mechanics with atomic force microscopy (AFM).