ABSTRACT
The surface antigen of human hepatitis B virus (HBV) was discovered even before the virus itself was identified. The history of its discovery reflects some of the biological features that are shared by the surface antigens of all known hepadnaviruses. The morphology of the HBs particles is very similar in hepadnavirus-infected woodchucks or ground squirrels. The envelope proteins of animal hepadnaviruses are currently also named surface (HBs) proteins. Cloning of the HBV genome rapidly allowed the identification of the gene for the major HBs protein. Large HBs (LHB) was clearly detected in silver-stained sodium dodecyl sulfate (SDS) gels of purified virions and filaments as proteins P39 and GP42. The proportion of LHBs to the other HBs proteins has a strong effect on the secretion of HBs particles. There are three coterminal HBs proteins, LHBs, medium HBs, and small HBs, which are encoded by three domains, preS1, preS2, and S.
