The pre-S1 and -S2 domains are thought to be important factors in the immunogenicity of hepatitis B virus vaccines. A recombinant hepatitis B virus vaccine (Bio-Hep-BTM,Sci-B-Vac®) which expresses all the antigenic epitopes and domains of the hepatitis B virus envelope, including the S1, pre-S1 and pre-S2 antigens, was produced from Chinese hamster ovary cells at the Weizmann Institute in Israel, in association with Yeda. (Yeda is the commercial arm of the Weizmann Institute.) However, all development and marketing rights to the vaccine have been transferred to Bio-Technology General in the US, and Scitech holds a licence for all Pacific Rim countries excluding China and Japan.Bio-Technology General's vaccine is in preregistration in Israel, phase III clinical trials in the US, and is undergoing or has undergone clinical trials in India, Singapore, Thailand and the Commonwealth of Independent States (former USSR). The vaccine is available for licensing in China, Europe, Japan, Mexico, Central and South America, and the US. It appears that Bio-Technology General has also entered into a development and licensing agreement with Swiss Serum and Vaccine Institute in Berne, Switzerland for Western Europe, most of Latin America and various other countries. Bio-Technology General will receive milestone payments from Swiss Serum and Vaccine Institute as well as royalties on sales of the vaccine.The company believes that Bio-Technology General's vaccine is a cost-effective alternative to other hepatitis B vaccines in the market. Bio-Technology General's vaccine elicits a quicker immune response and provides protection with lower doses than existing commercial vaccines.