Mouse anti-HBV PreS1 B subtype monoclonal antibody for ELISA, CLIA, LFIA. Hepatitis B virus (HBV) is a human pathogen, causing serious liver disease. The HBV surface protein antigens (HBsAg) are comprised of three carboxyl co terminal HBs proteins termed large (LHBs), middle (MHBs) and small (SHBs, also called major) protein. LHBs and MHBs also share the highly hydrophobic, repetitive, membrane spanning S domain. In addition, LHBs has a 119 amino acid region called preS1.