Two-Dimensional Phase Transition of Viral Capsid Gives Insights into Subunit Interactions

A virus is made up of a protein shell, the $c\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}p\phantom{\rule{0}{0ex}}s\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}d$, protecting its genetic material, and that's all. The subunits of the shell are arranged in a two-dimensional structure, held in place by a fine interplay between short-range and electrostatic interactions. The authors show that thermal dissociation of the capsid proceeds through a two-dimensional phase transition, providing direct quantitative insight into the strengths of the interactions and their variations in different ionic environments.