Abstract: The hepatitis B virus (HBV) capsid is made up of a single species of protein called the core antigen (HBcAg) which self-assembles into particles. The particles are highly immunogenic and are able to present heterologous epitopes to the immune system when the epitopes are inserted into a surface-exposed region of the particles called the “e1 loop”. The structural building blocks of the particles are tightly associated dimers of HBcAg in which the adjacent e1 loops are closely juxtaposed. It is proposed that sequences inserted into the e1 loop are conformationally restrained in the assembled particles when presented in monomeric core protein. The invention seeks to solve this problem by covalently linking core proteins as tandem copies (e.g., as dimers) so that insertions can be made independently in each copy.

Abstract: The hepatitis B virus (HBV) capsid is made up of a single species of protein called the core antigen (HBcAg) which self-assembles into particles. The particles are highly immunogenic and are able to present heterologous epitopes to the immune system when the epitopes are inserted into a surface-exposed region of the particles called the “el loop”. The structural building blocks of the particles are tightly associated dimers of HBcAg in which the adjacent el loops are closely juxtaposed. It is proposed that sequences inserted into the el loop are conformationally restrained in the assembled particles when presented in monomeric core protein. The invention seeks to solve this problem by covalently linking core proteins as tandem copies, e.g., as dimers, so that insertions can be made independently in each copy.