To determine whether hepatitis B virus (HBV) regulates the expression of the human beta-interferon gene, a series of recombinant bovine papilloma virus plasmids containing the human interferon gene and various fragments of the HBV genome were constructed and used to transform C127 cells, a murine fibroblast line. Analysis of the DNA from transformed C127 cells indicated that the interferon gene was intact and that the plasmids replicated as stable multicopy elements. The 1828-base-pair BamHI HBV DNA fragment containing the core antigen gene, but not the 2755-base-pair Bgl II HBV DNA fragment encoding both the surface antigen and the X antigen, suppressed the production of human beta-interferon. No effect by any of the recombinant plasmids on the synthesis of murine interferon was detected. The suppression of human beta-interferon by HBV occurs via a trans-acting factor. A frameshift mutation within the HBV core gene alleviates the inhibitory activity; thus we infer that the core protein is this factor or is crucially associated with this activity.
Animals Bovine papillomavirus 1