In vitro assembly of polymorphic virus-like particles from the capsid protein of a nodavirus.

Viral capsid proteins are programmed to assemble into homogeneous structures in native environments; but the molecular details of these assembly pathways are seldom clearly understood. In order to define the chain of events in the construction of a minimal system, we attempted controlled assembly of the capsid protein of a small insect nodavirus, Flock House Virus (FHV). Bacterial expression of the FHV capsid protein, and subsequent in vitro assembly, generated a heterogeneous population of closed particles. We show that in spite of the altered structure, these particles are capable of membrane disruption, like native viruses, and of incorporating and delivering foreign cargo to specific locations. The unique structure and characteristics of these particles extends our understanding of nodavirus assembly. Additionally, the establishment of a bacterial production system, and methods for in vitro assembly and packaging are of considerable benefit for biotechnological applications of FHV.