A good catch: packaging the virus genome

In tailed bacteriophages and herpesviruses, double-stranded DNA is packaged into a pre-existing protein shell, through a dedicated channel known as the portal. In a recent issue of Molecular Cell, Zheng et al. determined the structure of the bacteriophage P22 portal complex in pre- and postpackaging conformations, identifying structural changes that serve to retain the genome within the virus particle and prime it for injection into a new host.