HBV virion and genomic organization. The HBV virion is composed of a viral envelop that contains the surface proteins, which are of different lengths (L, M, and S). The nucleocapsid or core wraps the viral DNA. The viral genome contains four open reading frames, the S that encodes for the surface protein (red), P that encodes for the viral polymerase (blue), preC and C that encode for the core (yellow) and X that encodes for the X protein (green).