Construction and characterization of adenovirus co-expressing hepatitis B virus surface antigen and interleukin-6

Coexpression of biologically active interleukin 6 (IL-6), an immunoregulator, and hepatitis B virus surface antigen (HBsAg), an immunogen, was obtained using an adenovirus type 7 (Ad7) vector. Two recombinant adenoviruses (re-Ad) containing both the HBsAg and IL6 genes were constructed: one virus was capable of expressing IL6 with its signal peptide (spIL6) (Ad7::spIL6::HBsAg), and the second virus lacked this sequence (Ad7::IL6::HBsAg). A third recombinant contained only HBsAg (Ad7::HBsAg). All three Ad constructs were plaque purified and characterized in the A549 human lung cell line. The growth kinetics of the recombinants were similar to wild-type (wt) Ad7. The production and secretion of HBsAg (p24 and gp27) from cells infected with each re-Ad were at a level greater than 9 micrograms/10(6) cells by 118 h postinfection. Two IL-6 of approx. 24 and 27 kDa were produced and secreted into the culture medium from cells infected with Ad7::spIL6::HBsAg, and maximal accumulation occurred by 92 h p.i. at a level > 260 ng/10(6) cells. One cell-associated IL-6 of approx. 23 kDa was produced from cells infected with Ad7::IL6::HBsAg at a level > 12 ng/10(6) cells. Importantly, the Ad-produced IL-6 were determined to be biologically active by enhancing immunoglobulin production in lymphoblastoid cells. The co-production of IL-6 with HBsAg did not affect growth of these recombinant Ad, immunoreactivity of HBsAg, or the biological activity of IL-6 in tissue culture cells.