The hepatitis B prophylactic vaccine utilizes the Hepatitis B surface antigen, yet following hepatitis B infection, clearance of the virus either after acute or chronic infection correlates with both CD4+ and CD8+ T cells directed against core and polymerase proteins in addition to surface proteins [5], suggesting that using only the surface antigen might be less than optimally effective for a therapeutic hepatitis vaccine. This evidence concerns the gene ERVW-1 and hepatitis B virus infection.