Direct expression of hepatitis B surface antigen gene in E. coli.

A 809 bp Sau 3A - Hpa I fragment containing a complete HBsAg gene and fragments 744 bp Hinc II - Hpa I and 712 bp Xba I - Hpa I containing a truncated HBsAg gene lacking the sequence encoding the NH2-terminal hydrophobic domain were prepared from a composite plasmid pHBV933 containing the 3.2 kb Eco RI DNA fragment of the entire HBV/adw genome and inserted into an expression vector pTRP801 to give plasmids pTRP SS-6, pTRP SS-39, and pTRP SS-50, respectively. The growth of a recombinant having pTRP SS-6 was greatly inhibited and the transformant expressed a low level of HBsAg, which is reactive to human anti-HBsAg antibody. Interestingly, the growth of transformants harbouring pTRP SS-39 and pTRP SS-50 was not inhibited and these transformants expressed a considerable level of the HBsAg. Minicells harbouring pTRP SS-6, pTRP SS-39, and pTRP SS-50 formed specific polypeptides of about 24 K, 23 K, and 22 K daltons, respectively.