Expression of hepatitis B surface antigen with a recombinant adenovirus.

Early region 1 of the adenovirus type 5 genome was replaced with a DNA sequence containing the gene coding for the hepatitis B surface antigen (HBsAg) flanked by the major late promoter from adenovirus 2 and processing and polyadenylylation signals from simian virus 40. In one type of hybrid virus only the adenovirus 2 major late promoter, including just 33 base pairs of the adenovirus type 2 tripartite leader, preceded the coding region of the HBsAg gene. In another, this region was preceded by both the adenovirus major late promoter and almost the entire tripartite leader. The structure of the substituted sequence in each of the recombinant viral DNAs was identical to that in the plasmids used to construct the viruses. Approximately equivalent amounts of HBsAg-specific mRNA were produced late in infection with each recombinant virus. Although HBsAg production was detected late in infection of the hybrid virus not containing the full tripartite leader sequence, its level was 1/70th of that obtained with the hybrid virus containing this sequence. One likely interpretation is that the presence of the tripartite leader at the 5' end of this mRNA is critical for the synthesis of HBsAg polypeptide in the late stage of infection. HBsAg produced upon infection with the hybrid adenoviruses was glycosylated and secreted into the culture medium as particles that were essentially indistinguishable from the 22-nm particles found in human serum.