Development of a Hepatitis B virus capsid as a nanocontainer and a carrier for protein delivery into cells

Abstract: Encapsulation systems have long been studied, and the designs have varied in both capsule material as well as the type of cargo. The intended use have ranged from nanoreactors to delivery systems. This work presents an encapsulation system consisting of protein capsule and a protein cargo. The capsule is a redesigned hepatitis B virus capsid protein, in which the luminal extension has been altered to bind the protein calmodulin instead of the viral genome. The cargo is consequently a calmodulin fused protein. It is shown that co-expression of the redesigned capsid protein together with a capsid protein lacking a luminal extension greatly aids the solubility and assembly of redesigned capsids. Furthermore it is shown that the approximate 1:1 ratio resulting from the co-expression is maintained throughout disassembly and reassembly of the capsids.