11. The cloning vectors used for human gene therapy are mainly based on _________. A. bacterial viruses (i.e. phages) b.animal viruses c.plasmids d. BACs e.YACs Solution Answers : The correct answer is B (Animal viruses) Supplementary information :The introduction of DNA into the cells of live animals in order to treat disease. Viral gene-delivery vectors are favoured for therapeutic applications because of their efficiency. Commonly used viral vectors used for gene therapy includes, adenovirus, herpes simplex and adeno-associated virus..