This case has its origin in the fundamental research of Hepatitis B virus (HBV). Researchers came up with the idea of creating a hybrid virus to enable the study of HBV replication in mice. This hybrid virus consisted of the HBV genome integrated into the adenovirus (AdV1) genome. The adenovirus efficiently infects the mice cells and delivers the HBV genome into them. What serious safety questions are raised by broadening the host spectrum of a virus in such a way?