“…The above observation has laid a foundation for the following in vitro tumor cell cultures and in vivo transfection in mice. It has been shown that infection of Rous virus leads to the occurrence of tumor cell traits in the cultured cells in vitro, which include a loss of contact inhibition, continued proliferation and anchoring independence (17). To date, several tumor viruses have been identified, including human herpes virus 8 (HHV-8) (18)(19)(20), human papilloma virus (HPV) (19,(21)(22)(23)(24)(25)(26)(27), hepatitis B virus (HBV) (19,(28)(29)(30), Epstein-Barr virus (EBV) (19,26,(31)(32)(33)(34)(35), Cytomegalovirus (CMV) (19,27,(36)(37)(38), human immunodeficiency virus (HIV) (19,(39)(40)(41)(42), human T cell lymphotropic virus (HTLV) (43,44) and hepatitis C virus (HCV) (45)(46)(47)(48) (Fig.…”