Herpes virus infection softens cell nuclei through internal mechanical changes

A recent international research project has used advanced microscopy techniques and computational modeling to discover why virus infection changes the nuclear structures and biomechanical forces affecting the nucleus.

Researchers at the University of Jyväskylä (Finland), in cooperation with national and international research groups, have shown that DNA viruses infect cells and take over the host cell nucleus induce dramatic structural modifications. Herpes simplex virus 1 (HSV-1) infection and the emergence of nuclear enlarged, low-density viral replication compartments lead to changes in nuclear volume, chromatin organization, and the structure of nuclear lamina.

Understanding the softening of the nucleus enables early diagnosis

Researchers show that the infection remodels nuclear biomechanics, leading to dramatic softening of the nucleus. To understand the phenomenon, advanced microscopy, including cryo-soft X-ray tomography (SXT), atomic force microscopy (AFM), combined with computational modeling, was employed.

Our mechanical simulations and in vitro experiments showed that a reduction in outward forces, such as actin cytoskeleton pull or osmotic pressure, is the most likely factor in nuclear softening."

Maija Vihinen-Ranta, Research Director, University of Jyväskylä

The study was published in the top publication series in the field of virology, PLOS Pathogens and sheds new light on the virus-induced fundamental nuclear remodeling.

- Modern science is increasingly seeking to identify the forces acting on cells that shape their biomechanics. Usually, these forces come from outside the cell. However, the changes caused by the viral infection take place inside the nucleus of the cell, thus shedding light on the influence of intranuclear forces on the mechanical changes in the nucleus, explains Vihinen-Ranta.

This work was financed by the Jane and Aatos Erkko Foundation, the Academy of Finland, the European Union's Horizon 2020 research and innovation program, and the National Institute of Health (USA).