Expression and purification of hepatitis B surface antigen S from Escherichia coli; a new simple method

BACKGROUND: Hepatitis B is a liver disease primarily caused by hepatitis B virus (HBV) infection. It is distributed worldwide and associated with high mortality and morbidity rates. HBV infections can be avoided by the administration of the currently available vaccine and can be easily diagnosed through commercially available kits. Both the vaccine and the diagnostic kits depend on using the hepatitis B surface antigen (HBsAg) as an antigen. Developing countries such as, Egypt, suffer from the widespread of HBV infections and the limited resources to provide adequate supplies of either the vaccine or the diagnostic kits. Therefore the need for an easy, rapid, low cost method to produce HBsAg is urgently needed within this setting. FINDINGS: To achieve this goal, the gene encoding the HBsAg(S) protein was cloned and expressed as a fusion protein with a GST tag in Escherichia coli. The recombinant protein was successfully expressed and purified in both good quality and quantity. CONCLUSIONS: The simplified and the relatively low cost of the used protocol make this an attractive alternative to protocols currently used for the purification of HBsAg(S). The exploiting of this achievement for new diagnostics can be directed for application in the developing countries where they are extremely needed.