Commonly used hepatitis B vaccines belong to the second-generation vaccines and are composed of the yeast-derived recombinant non-glycosylated small (S) HBV envelope protein (HBsAg) (3), whereas third-generation hepatitis B vaccines like Sci-B-VacTM, consist of glycosylated and non-glycosylated pre-S1, pre-S2, and S proteins produced in mammalian cells (48). The gene discussed is ERVW-1; the disease is hepatitis B virus infection.