Figure 2.

Structure of hepatitis B virus (HBV) surface proteins. Large HBV surface proteins (LHBs), medium HBV surface proteins (MHBs), and small HBV surface proteins (SHBs) consist of 389–400, 281, and 226 aa (amino acids), respectively. SHBs have four transmembrane domains (I–IV). LHBs are myristoylated (myr) at its amino-terminal end, which is critically involved in HBV and HDV infection. The aa 2–48 portion of the preS1 region is essential for viral infection through receptor binding. The antigenic loop within SHBs also plays a significant role in viral infection.